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3031 lines
101 KiB
3031 lines
101 KiB
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
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"http://www.w3.org/TR/REC-html40/loose.dtd">
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<HTML>
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<HEAD>
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<!-- Created with AOLpress/2.0 -->
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<TITLE>Synchronized Multimedia Integration Language</TITLE>
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</HEAD>
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<BODY BGCOLOR="#FFFFFF" TEXT="#000000">
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<H4 align=right>
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<A HREF="http://www.w3.org/"><IMG align=left alt="W3C" BORDER=0 SRC="http://www.w3.org/pub/WWW/Icons/WWW/w3c_home.gif"
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WIDTH="72" HEIGHT=48></A> REC-smil-19980615
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</H4>
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<P>
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<BR clear=left>
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<H1 class=maintitle align=center STYLE="text-align: center">
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Synchronized Multimedia Integration Language (SMIL) 1.0 Specification
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</H1>
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<P ALIGN=Center>
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<STRONG>W3C Recommendation 15-June-1998</STRONG>
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<P ALIGN=Center>
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<DL>
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<DT>
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This version:
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<DD>
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<A HREF="http://www.w3.org/TR/1998/REC-smil-19980615">http://www.w3.org/TR/1998/REC-smil-19980615</A>
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<DT>
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Latest version:
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<DD>
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<A HREF="http://www.w3.org/TR/REC-smil">http://www.w3.org/TR/REC-smil</A>
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<DT>
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Previous version:
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<DD>
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<A HREF="http://www.w3.org/TR/1998/PR-smil-19980409">http://www.w3.org/TR/1998/PR-smil-19980409</A>
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<DT>
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</DL>
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<P>
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<SMALL><A href="/Consortium/Legal/ipr-notice#Copyright">Copyright</A>
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© 1998 <A href="http://www.w3.org/">W3C</A>
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(<A href="http://www.lcs.mit.edu/">MIT</A>,
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<A href="http://www.inria.fr/">INRIA</A>,
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<A href="http://www.keio.ac.jp/">Keio</A>), All Rights Reserved. W3C
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<A href="/Consortium/Legal/ipr-notice#Legal Disclaimer">liability,</A>
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<A href="/Consortium/Legal/ipr-notice#W3C Trademarks">trademark</A>,
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<A href="/Consortium/Legal/copyright-documents">document use </A>and
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<A href="/Consortium/Legal/copyright-software">software licensing
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</A>rules apply. Your interactions with this site are in accordance with
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our <A href="/Consortium/Legal/privacy-statement#Public">public</A>
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and <A href="/Consortium/Legal/privacy-statement#Members">Member</A>
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privacy statements.</SMALL>
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<H2>
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About this Document
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</H2>
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<P>
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This document has been prepared by the Synchronized Multimedia Working Group
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(WG) of the World Wide Web Consortium. The WG included the following individuals:
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<UL>
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<LI>
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Stephan Bugaj, Lucent/Bell Labs
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<LI>
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Dick Bulterman, CWI
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<LI>
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Bruce Butterfield, RealNetworks
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<LI>
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Wo Chang, NIST
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<LI>
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Guy Fouquet, Alcatel
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<LI>
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Christian Gran, GMD
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<LI>
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Mark Hakkinen, The Productivity Works
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<LI>
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Lynda Hardman, CWI
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<LI>
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Peter Hoddie, Apple
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<LI>
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Klaus Hofrichter, GMD
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<LI>
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Philipp Hoschka, W3C
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<LI>
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Jack Jansen, CWI
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<LI>
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George Kerscher, DAISY Consortium
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<LI>
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Rob Lanphier, RealNetworks
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<LI>
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Nabil Layaïda, INRIA
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<LI>
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Stephanie Leif, RealNetworks
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<LI>
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Sjoerd Mullender, CWI
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<LI>
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Didier Pillet, CNET/DSM
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<LI>
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Anup Rao, Netscape
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<LI>
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Lloyd Rutledge, CWI
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<LI>
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Patrick Soquet, Havas
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<LI>
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Warner ten Kate, Philips
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<LI>
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Jacco van Ossenbruggen, CWI
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<LI>
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Michael Vernick, Lucent/Bell Labs
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<LI>
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Jin Yu, DEC
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</UL>
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<P>
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<EM><B>Acknowledgments:</B></EM> In addition to the working group members,
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the following people contributed to the SMIL effort: Bert Bos (W3C), Dan
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Connolly (W3C), Patrick Deunhouwer (Philips), Martin Dürst (W3C), Al
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Gilman, Håkon Lie (W3C), Chris Lilley (W3C), Curtis Reynolds
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(RealNetworks), Michael Riesman, Curtis Reynolds (RealNetworks), Henning
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Schulzrinne (Columbia University) and Koga Youichirou (W3C).
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<P>
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<B><I>Editor: </I></B>Philipp Hoschka, W3C
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(<A HREF="mailto:hoschka@w3.org">hoschka@w3.org</A>)
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<H2>
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Abstract
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</H2>
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<P>
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This document specifies version 1 of the Synchronized Multimedia Integration
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Language (SMIL 1.0, pronounced "smile"). SMIL allows integrating a set of
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independent multimedia objects into a synchronized multimedia presentation.
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Using SMIL, an author can
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<OL>
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<LI>
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describe the temporal behavior of the presentation
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<LI>
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describe the layout of the presentation on a screen
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<LI>
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associate hyperlinks with media objects
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</OL>
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<P>
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This specification is structured as follows: Section 1 presents the specification
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approach. Section 2 defines the "smil" element. Section 3 defines the elements
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that can be contained in the head part of a SMIL document. Section
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4 defines the elements that can be contained in the body part of a SMIL document.
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In particular, this Section defines the time model used in SMIL. Section
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5 describes the SMIL DTD.
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<H2>
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Status of this Document
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</H2>
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<P>
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This document has been reviewed by W3C Members and other interested parties
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and has been endorsed by the Director as a W3C Recommendation. It is a stable
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document and may be used as reference material or cited as a normative reference
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from another document. W3C's role in making the Recommendation is to draw
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attention to the specification and to promote its widespread deployment.
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This enhances the functionality and interoperability of the Web.
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<P>
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Comments on this Recommendation may be sent to the <A HREF="http://lists.w3.org/Archives/Public/www-smil/">public mailing list</A>
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<A HREF="mailto:www-smil@w3.org">www-smil@w3.org</A>.
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<H2>
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Available languages
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</H2>
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<P>
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The English version of this specification is the only normative version.
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However, for translations in other languages see
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<A HREF="/AudioVideo/SMIL/translations">http://www.w3.org/AudioVideo/SMIL/translations</A>.
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<H2>
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Errata
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</H2>
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<P>
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The list of known errors in this specification is available at
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<A HREF="/AudioVideo/SMIL/errata">http://www.w3.org/AudioVideo/SMIL/errata</A>.
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<H2>
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Table of Contents
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</H2>
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<UL>
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<LI>
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<A HREF="#specification">1 Specification Approach</A>
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<LI>
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<A HREF="#smil">2 The smil Element</A>
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<LI>
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<A HREF="#document-head">3 The Document Head</A>
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<UL>
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<LI>
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<A href="#head">3.1 The head Element</A>
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<LI>
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<A HREF="#layout">3.2 The layout Element</A>
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<LI>
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<A HREF="#layout-elements">3.3 SMIL Basic Layout Language</A>
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<UL>
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<LI>
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<A href="#region">3.3.1 The region Element</A>
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<LI>
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<A href="#root-layout">3.3.2 The root-layout Element</A>
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</UL>
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<LI>
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<A href="#meta">3.4 The meta Element</A>
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</UL>
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<LI>
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<A HREF="#document-body">4 The Document Body</A>
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<UL>
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<LI>
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<A HREF="#body">4.1 The body Element</A>
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<LI>
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<A href="#synchronization-elements">4.2 Synchronization Elements</A>
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<UL>
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<LI>
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<A HREF="#par">4.2.1 The par Element</A>
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<LI>
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<A HREF="#seq">4.2.2 The seq Element</A>
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<LI>
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<A HREF="#media-object">4.2.3 Media Object Element</A>: The ref, animation,
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audio, img, video, text and textstream elements
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<LI>
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<A HREF="#SMIL_Time_Model">4.2.4 SMIL Time Model</A>
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<UL>
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<LI>
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<A HREF="#Time_Model_Variables">4.2.4.1 Time Model Values</A>
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<LI>
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<A HREF="#Determining_Values">4.2.4.2 Determining Values of Model Values
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for SMIL 1.0 Elements</A>
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</UL>
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</UL>
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<LI>
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<A HREF="#switch">4.3 The switch Element</A>
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<LI>
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<A HREF="#test">4.4 Test Attributes</A>
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<LI>
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<A HREF="#hyperlinking">4.5 Hyperlinking</A> Elements
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<UL>
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<LI>
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<A HREF="#a">4.5.1 The a Element</A>
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<LI>
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<A HREF="#anchor">4.5.2 The anchor Element</A>
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</UL>
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</UL>
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<LI>
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<A HREF="#smil-dtd">5 SMIL DTD</A>
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<UL>
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<LI>
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<A HREF="#relation">5.1 Relation to XML</A>
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<LI>
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<A HREF="#dtd">5.2 DTD</A>
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</UL>
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<LI>
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<A HREF="#Appendix">Appendix</A>
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<UL>
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<LI>
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<A HREF="#handling-extensions">Extending SMIL 1.0</A>
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<LI>
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<A HREF="#Using">Using SMIL 1.0 as an Extension</A>
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</UL>
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</UL>
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<H2>
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<A name="specification">1 Specification Approach</A>
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</H2>
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<P>
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SMIL documents are XML 1.0 documents <A HREF="#ref-XML10">[XML10]</A>. The
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reader is expected to be familiar with the concepts and terms defined in
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XML 1.0.
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<P>
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This specification does not rely on particular features defined in URLs that
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cannot potentially be expressed using URNs. Therefore, the more generic term
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URI <A HREF="#ref-URI">[URI] </A>is used throughout the specification.
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<P>
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The syntax of SMIL documents is defined by the DTD in <A HREF="#dtd">Section
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5.2</A>. The syntax of an attribute value that cannot be defined using the
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DTD notation is defined together with the first element using an attribute
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that can contain the attribute value. The syntax of such attribute values
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is defined using the Extended Backus-Naur Form (EBNF) defined in the XML
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1.0 specification.
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<P>
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An element definition is structured as follows: First, all attributes of
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the element are defined in alphabetical order. An attribute is defined in
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the following way: If the attribute is used by an element for the first time
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in the specification, the semantics of the attribute are defined. If the
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attribute has already been used by another element, the specification refers
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to the definition of the attribute in the first element that used it. The
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definition of element attributes is followed by the definition of any attribute
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values whose syntax cannot be defined using the DTD notation. The final
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section in an element definition specifies the element content.
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<H2>
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<A name="smil">2 The <TT>smil</TT> Element</A>
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</H2>
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<P>
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<STRONG>Element Attributes</STRONG>
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<P>
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The "smil" element can have the following attribute:
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<DL>
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<DT>
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<A NAME="id">id</A>
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<DD>
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This attribute uniquely identifies an element within a document. Its value
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is an XML identifier.
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</DL>
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<P>
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<STRONG>Element Content</STRONG>
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<P>
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The "smil" element can contain the following children:
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<DL>
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<DT>
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body
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<DD>
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Defined in <A HREF="#body">Section 4.1</A>
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<DT>
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|
head
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<DD>
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Defined in <A HREF="#head">Section 3.1</A>
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</DL>
|
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<H2>
|
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<A NAME="document-head">3 The Document Head</A>
|
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</H2>
|
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<H3>
|
|
<A NAME="head">3.1 </A>The <CODE>head</CODE> Element
|
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</H3>
|
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<P>
|
|
The "head" element contains information that is not related to the temporal
|
|
behavior of the presentation.
|
|
<P>
|
|
<STRONG>Element Attributes</STRONG>
|
|
<P>
|
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The "head" element can have the following attribute:
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<DL>
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<DT>
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id
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<DD>
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Defined in <A HREF="#smil">Section 2</A>
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</DL>
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<P>
|
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<STRONG>Element Content</STRONG>
|
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<P>
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|
The "head" element can contain the following children:
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<DL>
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<DT>
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layout
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<DD>
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Defined in <A HREF="#layout">Section 3.2</A>
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<DT>
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meta
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<DD>
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Defined in <A HREF="#meta">Section 3.4</A>
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<DT>
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switch
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<DD>
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Defined in <A HREF="#switch">Section 4.3</A>
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</DL>
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<P>
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The "head" element may contain any number of "meta" elements and either a
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"layout" element or a "switch" element.
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<H3>
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<A name="layout">3.2</A> The <TT>layout</TT> Element
|
|
</H3>
|
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<P>
|
|
The "layout" element determines how the elements in the document's body are
|
|
positioned on an abstract rendering surface (either visual or acoustic).
|
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<P>
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|
If a document contains no layout element, the positioning of the body elements
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is implementation-dependent.
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<P>
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A SMIL document can contain multiple alternative layouts by enclosing several
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layout elements within a "switch" element (defined in <A HREF="#switch">Section
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4.3</A>). This can be used for example to describe the document's layout
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using different layout languages.
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<P>
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The following example shows how CSS2 can be used as alternative to the SMIL
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|
basic layout language (defined in <A HREF="#layout-elements">Section 3.3</A>):
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<PRE><smil>
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<head>
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<switch>
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<layout type="text/css">
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[region="r"] { top: 20px; left: 20px }
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</layout>
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<layout>
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<region id="r" top="20" left="20" />
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</layout>
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</switch>
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</head>
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<body>
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<seq>
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<img region="r" src="http://www.w3.org/test" dur="10s" />
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</seq>
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</body>
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</smil>
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</PRE>
|
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<P>
|
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(note that in this example, both layout alternatives result in the same layout)
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<P>
|
|
<STRONG>Element Attributes </STRONG>
|
|
<DL>
|
|
<DT>
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id
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<DD>
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|
Defined in <A HREF="#smil">Section 2</A>
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|
<DT>
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|
<A NAME="layout-type">type</A>
|
|
<DD>
|
|
This attribute specifies which layout language is used in the layout element.
|
|
If the player does not understand this language, it must skip all content
|
|
up until the next "</layout>" tag. The default value of the type attribute
|
|
is "text/smil-basic-layout".
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
If the type attribute of the layout element has the value
|
|
"text/smil-basic-layout", it can contain the following elements:
|
|
<DL>
|
|
<DT>
|
|
region
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|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A>
|
|
<DT>
|
|
root-layout
|
|
<DD>
|
|
Defined in <A HREF="#root-layout">Section 3.3.2</A>
|
|
</DL>
|
|
<P>
|
|
If the type attribute of the "layout" element has another value, the element
|
|
contains character data.
|
|
<H3>
|
|
<A name="layout-elements">3.3 SMIL Basic Layout Language</A>
|
|
</H3>
|
|
<P>
|
|
This section defines a basic layout language for SMIL. SMIL basic layout
|
|
is consistent with the visual rendering model defined in CSS2, it reuses
|
|
the formatting properties defined by the CSS2 specification, and newly introduces
|
|
the "fit" attribute <A HREF="#ref-CSS2">[CSS2]</A>. The reader is expected
|
|
to be familiar with the concepts and terms defined in CSS2.
|
|
<P>
|
|
SMIL basic layout only controls the layout of media object elements (defined
|
|
in <A HREF="#media-object">Section 4.2.3</A>). It is illegal to use SMIL
|
|
basic layout for other SMIL elements.
|
|
<P>
|
|
The type identifier for SMIL basic layout is "text/smil-basic-layout".
|
|
<P>
|
|
<STRONG>Fixed Property Values</STRONG>
|
|
<P>
|
|
The following stylesheet defines the values of the CSS2 properties "display"
|
|
and "position" that are valid in SMIL basic layout. These property values
|
|
are fixed:
|
|
<PRE>a {display:block}
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|
anchor {display:block}
|
|
animation {display: block;
|
|
position: absolute}
|
|
body {display: block}
|
|
head {display: none}
|
|
img {display: block;
|
|
position: absolute}
|
|
layout {display: none}
|
|
meta {display: none}
|
|
par {display: block}
|
|
region {display: none}
|
|
ref {display: block;
|
|
position: absolute}
|
|
root-layout {display: none}
|
|
seq {display: block}
|
|
smil {display: block}
|
|
switch {display:block}
|
|
text {display: block;
|
|
position: absolute}
|
|
textstream {display: block;
|
|
position: absolute}
|
|
video {display: block;
|
|
position: absolute}
|
|
</PRE>
|
|
<P>
|
|
Note that as a result of these definitions, all absolutely positioned elements
|
|
(animation, img, ref, text, textstream and video) are contained within a
|
|
single containing block defined by the content content edge of the root element
|
|
(smil).
|
|
<P>
|
|
<STRONG>Default Values</STRONG>
|
|
<P>
|
|
SMIL basic layout defines default values for all layout-related attributes.
|
|
These are consistent with the initial values of the corresponding properties
|
|
in CSS2.
|
|
<P>
|
|
If the author wants to select the default layout values for <EM>all</EM>
|
|
media object elements in a document, the document must contain an empty layout
|
|
element of type "text/smil-basic-layout" such as:
|
|
<PRE><layout type="text/smil-basic-layout"></layout>
|
|
</PRE>
|
|
<H4>
|
|
<A name="region">3.3.1 <STRONG>The <TT>region </TT>Element</STRONG></A>
|
|
</H4>
|
|
<P>
|
|
The region element controls the position, size and scaling of media object
|
|
elements.
|
|
<P>
|
|
In the following example fragment, the position of a text element is set
|
|
to a 5 pixel distance from the top border of the rendering window:
|
|
<PRE><smil>
|
|
<head>
|
|
<layout>
|
|
<region id="a" top="5" />
|
|
</layout>
|
|
</head>
|
|
<body>
|
|
<text region="a" src="text.html" dur="10s" />
|
|
</body>
|
|
</smil>
|
|
</PRE>
|
|
<P>
|
|
<STRONG>Element Attributes </STRONG>
|
|
<P>
|
|
The "region" element can have the following attributes:
|
|
<DL>
|
|
<DT>
|
|
background-color
|
|
<DD>
|
|
The use and definition of this attribute are identical to the "background-color"
|
|
property in the CSS2 specification, except that SMIL basic layout does not
|
|
require support for "system colors". <BR>
|
|
If the background-color attribute is absent, the background is transparent.
|
|
<DT>
|
|
<A NAME="scale">fit</A>
|
|
<DD>
|
|
This attribute specifies the behavior if the intrinsic height and width of
|
|
a visual media object differ from the values specified by the height and
|
|
width attributes in the "region" element. This attribute does not have a
|
|
1-1 mapping onto a CSS2 property, but can be simulated in CSS2.<BR>
|
|
This attribute can have the following values:
|
|
<DL>
|
|
<DT>
|
|
fill
|
|
<DD>
|
|
Scale the object's height and width independently so that the content just
|
|
touches all edges of the box.
|
|
<DT>
|
|
hidden
|
|
<DD>
|
|
<UL>
|
|
<LI>
|
|
If the intrinsic height (width) of the media object element is smaller than
|
|
the height (width) defined in the "region" element, render the object starting
|
|
from the top (left) edge and fill up the remaining height (width) with the
|
|
background color.
|
|
<LI>
|
|
If the intrinsic height (width) of the media object element is greater than
|
|
the height (width) defined in the "region" element, render the object starting
|
|
from the top (left) edge until the height (width) defined in the "region"
|
|
element is reached, and clip the parts of the object below (right of) the
|
|
height (width).
|
|
</UL>
|
|
<DT>
|
|
meet
|
|
<DD>
|
|
Scale the visual media object while preserving its aspect ratio until its
|
|
height or width is equal to the value specified by the height or width
|
|
attributes, while none of the content is clipped. The object's left top corner
|
|
is positioned at the top-left coordinates of the box, and empty space at
|
|
the left or bottom is filled up with the background color.
|
|
<DT>
|
|
scroll
|
|
<DD>
|
|
A scrolling mechanism should be invoked when the element's rendered contents
|
|
exceed its bounds.
|
|
<DT>
|
|
slice
|
|
<DD>
|
|
Scale the visual media object while preserving its aspect ratio so that its
|
|
height or width are equal to the value specified by the height and width
|
|
attributes while some of the content may get clipped. Depending on the exact
|
|
situation, either a horizontal or a vertical slice of the visual media object
|
|
is displayed. Overflow width is clipped from the right of the media object.
|
|
Overflow height is clipped from the bottom of the media object.
|
|
</DL>
|
|
<P>
|
|
The default value of "fill" is "hidden".
|
|
<DT>
|
|
<A NAME="height">height</A>
|
|
<DD>
|
|
The use and definition of this attribute are identical to the "height"
|
|
property in the CSS2 specification. Attribute values can be "percentage"
|
|
values, and a variation of the "length" values defined in CSS2. For "length"
|
|
values, SMIL basic layout only supports pixel units as defined in CSS2. It
|
|
allows to leave out the "px" unit qualifier in pixel values (the "px" qualifier
|
|
is required in CSS2).
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A><BR>
|
|
A region element is applied to a positionable element by setting the
|
|
<A HREF="#loc">region</A> attribute of the positionable element to the id
|
|
value of the region.<BR>
|
|
The "id" attribute is required for "region" elements.
|
|
<DT>
|
|
<A NAME="left">left</A>
|
|
<DD>
|
|
The use and definition of this attribute are identical to the "left"
|
|
property in the CSS2 specification. Attribute values have the same restrictions
|
|
as the attribute values of the "height" attribute.<BR>
|
|
The default value is zero.
|
|
<DT>
|
|
skip-content
|
|
<DD>
|
|
This attribute is introduced for future extensibility of SMIL (see
|
|
<A HREF="#Appendix">Appendix</A>). It is interpreted in the following two
|
|
cases:
|
|
<UL>
|
|
<LI>
|
|
If a new element is introduced in a future version of SMIL, and this
|
|
element allows SMIL 1.0 elements as element content, the "skip-content" attribute
|
|
controls whether this content is processed by a SMIL 1.0 player.
|
|
<LI>
|
|
If an empty element in SMIL version 1.0 becomes non-empty in a future SMIL
|
|
version, the "skip-content" attribute controls whether this content is ignored
|
|
by a SMIL 1.0 player, or results in a syntax error.
|
|
</UL>
|
|
<P>
|
|
If the value of the "skip-content" attribute is "true", and one of the cases
|
|
above apply, the content of the element is ignored. If the value is "false",
|
|
the content of the element is processed. <BR>
|
|
The default value for "skip-content" is "true".
|
|
<DT>
|
|
title
|
|
<DD>
|
|
This attribute offers advisory information about the element for which it
|
|
is set. Values of the title attribute may be rendered by user agents in a
|
|
variety of ways. For instance, visual browsers frequently display the title
|
|
as a "tool tip" (a short message that appears when the pointing device pauses
|
|
over an object). <FONT COLOR="Red"><B><BR>
|
|
</B></FONT>It is strongly recommended that all "region" elements have
|
|
a "title" attribute with a meaningful description. Authoring tools should
|
|
ensure that no element can be introduced into a SMIL document without this
|
|
attribute.
|
|
<DT>
|
|
<A NAME="top">top</A>
|
|
<DD>
|
|
The use and definition of this attribute are identical to the "top"
|
|
property in the CSS2 specification. Attribute values have the same restrictions
|
|
as the attribute values of the "height" attribute.<BR>
|
|
The default value is zero.
|
|
<DT>
|
|
<A NAME="width">width</A>
|
|
<DD>
|
|
The use and definition of this attribute are identical to the "width"
|
|
property in the CSS2 specification. Attribute values have the same restrictions
|
|
as the attribute values of the "height" attribute.
|
|
<DT>
|
|
z-index
|
|
<DD>
|
|
The use and definition of this attribute are identical to the "z-index"
|
|
property in the CSS2 specification, with the following exception:
|
|
</DL>
|
|
<DL>
|
|
<DD>
|
|
<UL>
|
|
<LI>
|
|
If two boxes<FONT COLOR="Red"> </FONT>generated by elements A and B have
|
|
the same stack level, then
|
|
<OL>
|
|
<LI>
|
|
If the display of an element A starts later than the display of an element
|
|
B, the box of A is stacked on top of the box of B (temporal order).
|
|
<LI>
|
|
If the display of the elements starts at the same time, and an element A
|
|
occurs later in the SMIL document text than an element B, the box of A is
|
|
stacked on top of the box of B (document tree order as defined in CSS2).
|
|
</OL>
|
|
</UL>
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
"region" is an empty element.
|
|
<H4>
|
|
<A name="root-layout">3.3.2 The <CODE>root-layout</CODE> element</A>
|
|
</H4>
|
|
<P>
|
|
The "root-layout" element determines the value of the layout properties of
|
|
the root element, which in turn determines the size of the viewport, e.g.
|
|
the window in which the SMIL presentation is rendered.
|
|
<P>
|
|
If a document contains more than one "root-layout" element, this is an error,
|
|
and the document should not be displayed.
|
|
<P>
|
|
<STRONG>Element Attributes </STRONG>
|
|
<P>
|
|
The "root-layout" element can have the following attributes:
|
|
<DL>
|
|
<DT>
|
|
background-color
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A>
|
|
<DT>
|
|
height
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A><BR>
|
|
Sets the height of the root element. Only length values are allowed.
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A>
|
|
<DT>
|
|
skip-content
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A>
|
|
<DT>
|
|
title
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A>
|
|
<DT>
|
|
width
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A><BR>
|
|
Sets the width of the root element. Only length values are allowed.
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
"root-layout" is an empty element.
|
|
<H3>
|
|
<A NAME="meta">3.4 The <TT>meta</TT> Element</A>
|
|
</H3>
|
|
<P>
|
|
The "meta" element can be used to define properties of a document (e.g.,
|
|
author, expiration date, a list of key words, etc.) and assign values to
|
|
those properties. Each "meta" element specifies a single property/value pair.
|
|
<P>
|
|
<STRONG>Element Attributes</STRONG>
|
|
<P>
|
|
The "meta" element can have the following attributes:
|
|
<DL>
|
|
<DT>
|
|
content
|
|
<DD>
|
|
This attribute specifies the value of the property defined in the meta
|
|
element.<FONT COLOR="Red"><BR>
|
|
</FONT>The "content" attribute is required for "meta" elements.
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A>
|
|
<DT>
|
|
name
|
|
<DD>
|
|
This attribute identifies the property defined in the meta
|
|
element.<FONT COLOR="Red"><BR>
|
|
</FONT>The "name" attribute is required for "meta" elements.
|
|
<DT>
|
|
skip-content
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A>
|
|
</DL>
|
|
<P>
|
|
The list of properties is open-ended. This specification defines the following
|
|
properties:
|
|
<DL>
|
|
<DT>
|
|
base
|
|
<DD>
|
|
The value of this property determines the base URI for all relative URIs
|
|
used in the document.
|
|
<DT>
|
|
pics-label or PICS-Label
|
|
<DD>
|
|
The value of this property specifies a valid rating label for the document
|
|
as defined by PICS <A HREF="#ref-PICS">[PICS]</A>.
|
|
<DT>
|
|
title
|
|
<DD>
|
|
The value of this property contains the title of the presentation.
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
"meta" is an empty element.
|
|
<H2>
|
|
<A name="document-body">4 The Document Body</A>
|
|
</H2>
|
|
<H3>
|
|
<A NAME="body">4.1</A> The <CODE>body</CODE> Element
|
|
</H3>
|
|
<P>
|
|
The "body" element contains information that is related to the temporal and
|
|
linking behavior of the document. It implicitly defines a "seq" element (defined
|
|
in Section 4.2.2, see Section 4.2.4 for a definition of the temporal semantics
|
|
of the "body" element).
|
|
<P>
|
|
<STRONG>Element Attributes </STRONG>
|
|
<P>
|
|
The "body" element can have the following attribute:
|
|
<DL>
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A>
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
The "body" element can contain the following children:
|
|
<DL>
|
|
<DT>
|
|
a
|
|
<DD>
|
|
Defined in <A HREF="#a">Section 4.5.1</A>
|
|
<DT>
|
|
animation
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
audio
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
img
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
par
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
ref
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
seq
|
|
<DD>
|
|
Defined in <A HREF="#seq">Section 4.2.2</A>
|
|
<DT>
|
|
switch
|
|
<DD>
|
|
Defined in <A HREF="#switch">Section 4.3</A>
|
|
<DT>
|
|
text
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
textstream
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
video
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
</DL>
|
|
<H3>
|
|
<A name="synchronization-elements">4.2</A> Synchronization Elements
|
|
</H3>
|
|
<H4>
|
|
<A name="par">4.2.1</A> The <TT>par</TT> Element
|
|
</H4>
|
|
<P>
|
|
The children of a par element can overlap in time. The textual order of
|
|
appearance of children in a par has no significance for the timing of their
|
|
presentation.
|
|
<P>
|
|
<STRONG>Element Attributes</STRONG>
|
|
<P>
|
|
The "par" element can have the following attributes:
|
|
<DL>
|
|
<DT>
|
|
abstract
|
|
<DD>
|
|
A brief description of the content contained in the element.
|
|
<DT>
|
|
author
|
|
<DD>
|
|
The name of the author of the content contained in the element.
|
|
<DT>
|
|
begin
|
|
<DD>
|
|
This attribute specifies the time for the explicit begin of an element. See
|
|
<A HREF="#SMIL_Time_Model">Section 4.2.4</A> for a definition of its semantics.
|
|
<BR>
|
|
The attribute can contain the following two types of values:
|
|
<DL>
|
|
<DT>
|
|
delay-value
|
|
<DD>
|
|
A delay value is a clock-value measuring presentation time. Presentation
|
|
time advances at the speed of the presentation. It behaves like the timecode
|
|
shown on a counter of a tape-deck. It can be stopped, decreased or increased
|
|
either by user actions, or by the player itself.<BR>
|
|
The semantics of a delay value depend on the element's first ancestor that
|
|
is a synchronization element (i.e. ancestors that are "a" or "switch" elements
|
|
are ignored):
|
|
<UL>
|
|
<LI>
|
|
If this ancestor is a "par" element, the value defines a delay from the effective
|
|
begin of that element (see Figure 4.1).
|
|
<LI>
|
|
If this ancestor is a "seq" element (defined in <A HREF="#seq">Section
|
|
4.2.2</A>), the value defines a delay from the effective end of the first
|
|
lexical predecessor that is a synchronization element (see Figure 4.2).
|
|
</UL>
|
|
<DT>
|
|
event-value
|
|
<DD>
|
|
The element begins when a certain event occurs (see Figure 4.3). Its value
|
|
is an element-event (see Definition below). <BR>
|
|
The element generating the event must be "in scope". The set of "in scope"
|
|
elements S is determined as follows:
|
|
<OL>
|
|
<LI>
|
|
Take all children from the element's first ancestor that is a synchronization
|
|
element and add them to S.
|
|
<LI>
|
|
Remove all "a" and "switch" elements from S. Add the children of all "a"
|
|
elements to S, unless they are "switch" elements.
|
|
</OL>
|
|
<P>
|
|
The resulting set S is the set of "in scope" elements.
|
|
</DL>
|
|
</DL>
|
|
<P>
|
|
<HR>
|
|
<PRE><par>
|
|
<audio id="a" begin="6s" src="audio" />
|
|
</par>
|
|
</PRE>
|
|
<P>
|
|
<IMG WIDTH="143" HEIGHT="61" alt="delay in 'par' element" SRC="par-offset.gif">
|
|
<A HREF="ld#longdesc-par-delay">D</A>
|
|
<P>
|
|
<HR>
|
|
<I>Figure 4.1: Using a delay value within a "par" element</I>
|
|
<HR>
|
|
<PRE><seq>
|
|
<audio src="audio1" />
|
|
<audio begin="5s" src="audio2" />
|
|
</seq>
|
|
</PRE>
|
|
<P>
|
|
<IMG WIDTH="187" HEIGHT="40" alt="delay in 'seq' element" SRC="seq-offset.gif">
|
|
<A HREF="ld#longdesc-seq-delay">D</A>
|
|
<HR>
|
|
<I>Figure 4.2: Using a delay value within a "seq" element</I>
|
|
<HR>
|
|
<PRE><par>
|
|
<audio id="a" begin="6s" ... />
|
|
<img begin="id(a)(4s)" ... />
|
|
</par>
|
|
</PRE>
|
|
<P>
|
|
<IMG WIDTH="127" HEIGHT="98" alt="element with event value" SRC="element-event.gif">
|
|
<A HREF="ld#longdesc-event-value">D</A>
|
|
<P>
|
|
<HR>
|
|
<I>Figure 4.3: Synchronization attribute with element event value</I>
|
|
<DL>
|
|
<DT>
|
|
copyright
|
|
<DD>
|
|
The copyright notice of the content contained in the element.
|
|
<DT>
|
|
dur
|
|
<DD>
|
|
This attribute specifies the explicit duration of an element. See
|
|
<A HREF="#SMIL_Time_Model">Section 4.2.4</A> for a definition of its semantics.
|
|
The attribute value can be a clock value, or the string "indefinite".
|
|
<DT>
|
|
end
|
|
<DD>
|
|
This attribute specifies the explicit end of an element. See
|
|
<A HREF="#SMIL_Time_Model">Section 4.2.4</A> for a definition of its semantics.
|
|
The attribute can contain the same types of attribute values as the "begin"
|
|
attribute.
|
|
<DT>
|
|
<A NAME="endsync">endsync</A>
|
|
<DD>
|
|
For a definition of the semantics of this attribute, see
|
|
<A HREF="#SMIL_Time_Model">Section 4.2.4</A>. The attribute can have the
|
|
following values:
|
|
<UL>
|
|
<LI>
|
|
first<FONT COLOR="Red"><BR>
|
|
</FONT>For a definition of the semantics of this value, see
|
|
<A HREF="#SMIL_Time_Model">Section 4.2.4</A>.
|
|
<LI>
|
|
id-ref<BR>
|
|
This attribute value has the following syntax:<BR>
|
|
<BR>
|
|
<CODE>id-ref ::= "id(" id-value ")"</CODE><BR>
|
|
where "id-value" must be a legal XML identifier.<FONT COLOR="Red"><BR>
|
|
</FONT>For a definition of the semantics of this value, see
|
|
<A HREF="#SMIL_Time_Model">Section 4.2.4</A>.
|
|
<LI>
|
|
last<FONT COLOR="Red"><BR>
|
|
</FONT>For a definition of the semantics of this value, see
|
|
<A HREF="#SMIL_Time_Model">Section 4.2.4</A>.
|
|
</UL>
|
|
<P>
|
|
The default value of "endsync" is "last".
|
|
</DL>
|
|
<DL>
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A>
|
|
<DT>
|
|
region
|
|
<DD>
|
|
This attribute specifies an abstract rendering surface (either visual or
|
|
acoustic) defined within the layout section of the document. Its value must
|
|
be an XML identifier. If no rendering surface with this id is defined in
|
|
the layout section, the values of the formatting properties of this element
|
|
are determined by the default layout.<BR>
|
|
The "region" attribute on "par" elements cannot be used by the basic layout
|
|
language for SMIL defined in this specification. It is added for completeness,
|
|
since it may be required by other layout languages.
|
|
<DT>
|
|
<A NAME="repeat">repeat</A>
|
|
<DD>
|
|
For a definition of the semantics of this attribute, see
|
|
<A HREF="#SMIL_Time_Model">Section 4.2.4</A>. The attribute value can be
|
|
an integer, or the string "indefinite". The default value is 1.
|
|
<DT>
|
|
<A NAME="bitrate">system-bitrate</A>
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-captions
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-<A NAME="language">language</A>
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-overdub-or-caption
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-required
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-<A NAME="screen">screen</A>-size
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
<A NAME="screen-depth">system-screen-depth</A>
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
<A NAME="title">title</A>
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A><BR>
|
|
It is strongly recommended that all "par" elements have a "title" attribute
|
|
with a meaningful description. Authoring tools should ensure that no element
|
|
can be introduced into a SMIL document without this attribute.
|
|
</DL>
|
|
<P>
|
|
<STRONG>Note on Synchronization between Children</STRONG>
|
|
<P>
|
|
The accuracy of synchronization between the children in a parallel group
|
|
is implementation-dependent. Take the example of synchronization in case
|
|
of playback delays, i.e. the behavior when<FONT COLOR="Green"> </FONT>the
|
|
"par" element contains two or more continuous media types such as audio or
|
|
video, and one of them experiences a delay. <BR>
|
|
A player can show the following synchronization behaviors:
|
|
<DL>
|
|
<DT>
|
|
hard synchronization
|
|
<DD>
|
|
The player synchronizes the children in the "par" element to a common clock
|
|
(see Figure 4.4 a)).
|
|
<DT>
|
|
soft synchronization
|
|
<DD>
|
|
Each child of the "par" element has its own clock, which runs independently
|
|
of the clocks of other children in the "par" element (see Figure 4.4 b)).
|
|
</DL>
|
|
<P>
|
|
<HR>
|
|
<P>
|
|
<IMG WIDTH="126" HEIGHT="115" alt="hard synchronization" SRC="sync-hard.gif">
|
|
<A HREF="ld#longdesc-sync-hard">D</A>
|
|
<P>
|
|
<I>a) hard synchronization: Delay in video: Either the audio is stopped,
|
|
or some video frames are dropped. The exact behavior is
|
|
implementation-dependent</I>
|
|
<P>
|
|
<IMG WIDTH="114" HEIGHT="50" alt="soft synchronization" SRC="sync-soft.gif">
|
|
<A HREF="ld#longdesc-sync-soft">D</A>
|
|
<P>
|
|
<I>b) soft synchronization</I>
|
|
<P>
|
|
<HR>
|
|
<P>
|
|
<I>Figure 4.4: Effect of a delay on playout schedule for players using different
|
|
synchronization policies</I>
|
|
<P>
|
|
<STRONG>Attribute Values</STRONG>
|
|
<DL>
|
|
<DT>
|
|
clock value
|
|
<DD>
|
|
Clock values have the following syntax:
|
|
<DD>
|
|
<PRE>Clock-val ::= Full-clock-val | Partial-clock-val | Timecount-val
|
|
Full-clock-val ::= Hours ":" Minutes ":" Seconds ("." Fraction)?
|
|
Partial-clock-val ::= Minutes ":" Seconds ("." Fraction)?
|
|
Timecount-val ::= Timecount ("." Fraction)?
|
|
("h" | "min" | "s" | "ms")? ; default is "s"
|
|
Hours ::= 2DIGIT; any positive number
|
|
Minutes ::= 2DIGIT; range from 00 to 59
|
|
Seconds ::= 2DIGIT; range from 00 to 59
|
|
Fraction ::= DIGIT+
|
|
Timecount ::= DIGIT+
|
|
2DIGIT ::= DIGIT DIGIT
|
|
DIGIT ::= [0-9]
|
|
|
|
</PRE>
|
|
<P>
|
|
The following are examples of legal clock values:
|
|
<UL>
|
|
<LI>
|
|
Full clock value: 02:30:03 = 2 hours, 30 minutes and 3 seconds
|
|
<LI>
|
|
Partial clock value: 02:33 = 2 minutes and 33 seconds
|
|
<LI>
|
|
Timecount values:<BR>
|
|
3h = 3 hours<BR>
|
|
45min = 45 minutes<BR>
|
|
30s = 30 seconds<BR>
|
|
5ms = 5 milliseconds
|
|
</UL>
|
|
<P>
|
|
<BR>
|
|
A fraction x with n digits represents the following value: <BR>
|
|
<BR>
|
|
x * 1/10**n<BR>
|
|
<BR>
|
|
Examples:<BR>
|
|
<BR>
|
|
00.5s = 5 * 1/10 seconds = 500 milliseconds<BR>
|
|
00:00.005 = 5 * 1/1000 seconds = 5 milliseconds
|
|
</DL>
|
|
<DL>
|
|
<DT>
|
|
element-event value
|
|
<DD>
|
|
An <I>element event</I> value specifies a particular event in a synchronization
|
|
element.<BR>
|
|
An element event has the following syntax:<BR>
|
|
<DD>
|
|
<PRE>Element-event ::= "id(" Event-source ")(" Event ")"
|
|
Event-source ::= Id-value
|
|
Event ::= "begin" | Clock-val | "end"<BR>
|
|
</PRE>
|
|
<DD>
|
|
The following events are defined:
|
|
<DL>
|
|
<DT>
|
|
begin
|
|
<DD>
|
|
This event is generated at an element's effective begin. <BR>
|
|
Example use: <CODE>begin="id(x)(begin)"</CODE>
|
|
<DT>
|
|
clock-val
|
|
<DD>
|
|
This event is generated when a clock associated with an element reaches a
|
|
particular value. This clock starts at 0 at the element's effective begin.
|
|
For "par" and "seq" elements, the clock gives the presentation time elapsed
|
|
since the effective begin of the element. For media object elements, the
|
|
semantics are implementation-dependent. The clock may either give presentation
|
|
time elapsed since the effective begin, or it may give the media time of
|
|
the object. The latter may differ from the presentation time that elapsed
|
|
since the object's display was started e.g. due to rendering or network delays,
|
|
and is the recommended approach.<BR>
|
|
It is an error to use a clock value that exceeds the value of the effective
|
|
duration of the element generating the event.
|
|
<P>
|
|
Example use: <CODE>begin="id(x)(45s)"</CODE>
|
|
<DT>
|
|
end
|
|
<DD>
|
|
This event is generated at the element's effective end. <BR>
|
|
Example use: <CODE>begin="id(x)(end)"</CODE>
|
|
</DL>
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
The par element can contain the following children:
|
|
<DL>
|
|
<DT>
|
|
a
|
|
<DD>
|
|
Defined in <A HREF="#a">Section 4.5.1</A>
|
|
<DT>
|
|
animation
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
audio
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
img
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
par
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
ref
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
seq
|
|
<DD>
|
|
Defined in <A HREF="#seq">Section 4.2.2</A>
|
|
<DT>
|
|
switch
|
|
<DD>
|
|
Defined in <A HREF="#switch">Section 4.3</A>
|
|
<DT>
|
|
text
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
textstream
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
video
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
</DL>
|
|
<P>
|
|
All of these elements may appear multiple times as direct children of a par
|
|
element.
|
|
<H4>
|
|
<A name="seq">4.2.2</A> The <TT>seq</TT> Element
|
|
</H4>
|
|
<P>
|
|
The children of a "seq" element form a temporal sequence.
|
|
<P>
|
|
<STRONG>Attributes</STRONG>
|
|
<P>
|
|
The seq element can have the following attributes:
|
|
<DL>
|
|
<DT>
|
|
abstract
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
author
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
begin
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
copyright
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
dur
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
end
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A>
|
|
<DT>
|
|
region
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A><BR>
|
|
The region attribute on "seq" elements cannot be used by the basic layout
|
|
language for SMIL defined in this specification. It is added for completeness,
|
|
since it may be required by other layout languages.
|
|
<DT>
|
|
repeat
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
<A NAME="bitrate">system-bitrate</A>
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-captions
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-<A NAME="language">language</A>
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-overdub-or-caption
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-required
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-<A NAME="screen">screen</A>-size
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
<A NAME="screen-depth">system-screen-depth</A>
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
title
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A><BR>
|
|
It is strongly recommended that all "seq" elements have a "title" attribute
|
|
with a meaningful description. Authoring tools should ensure that no element
|
|
can be introduced into a SMIL document without this attribute.
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
The seq element can contain the following children:
|
|
<DL>
|
|
<DT>
|
|
a
|
|
<DD>
|
|
Defined in <A HREF="#a">Section 4.5.1</A>
|
|
<DT>
|
|
animation
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
audio
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
img
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
par
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
ref
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
seq
|
|
<DD>
|
|
Defined in <A HREF="#seq">Section 4.2.2</A>
|
|
<DT>
|
|
switch
|
|
<DD>
|
|
Defined in <A HREF="#switch">Section 4.3</A>
|
|
<DT>
|
|
text
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
textstream
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
video
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
</DL>
|
|
<H4>
|
|
<A name="media-object">4.2.3</A> Media Object Elements: The <TT>ref</TT>,
|
|
<CODE>animation</CODE>, <TT>audio,img</TT>, <TT>video,text</TT> and
|
|
<CODE>textstream</CODE> elements
|
|
</H4>
|
|
<P>
|
|
The media object elements allow the inclusion of media objects into a SMIL
|
|
presentation. Media objects are included by reference (using a URI).
|
|
<P>
|
|
There are two types of media objects: media objects with an intrinsic duration
|
|
(e.g. video, audio) (also called "continuous media"), and media objects without
|
|
intrinsic duration (e.g. text, image) (also called "discrete media").
|
|
<P>
|
|
Anchors and links can be attached to visual media objects, i.e. media objects
|
|
rendered on a visual abstract rendering surface.
|
|
<P>
|
|
When playing back a media object, the player must not derive the exact type
|
|
of the media object from the name of the media object element. Instead, it
|
|
must rely solely on other sources about the type, such as type information
|
|
contained in the "type" attribute, or the type information communicated by
|
|
a server or the operating system.
|
|
<P>
|
|
Authors, however, should make sure that the group into which of the media
|
|
object falls (animation, audio, img, video, text or textstream) is reflected
|
|
in the element name. This is in order to increase the readability of the
|
|
SMIL document. When in doubt about the group of a media object, authors should
|
|
use the generic "ref" element.
|
|
<P>
|
|
<STRONG>Element Attributes</STRONG>
|
|
<P>
|
|
Media object elements can have the following attributes:
|
|
<DL>
|
|
<DT>
|
|
abstract
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
alt
|
|
<DD>
|
|
For user agents that cannot display a particular media-object, this attribute
|
|
specifies alternate text.<B> </B>It is strongly recommended that all
|
|
media object elements have an "alt" attribute with a meaningful description.
|
|
Authoring tools should ensure that no element can be introduced into a SMIL
|
|
document without this attribute.
|
|
<DT>
|
|
author
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
begin
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
clip-begin
|
|
<DD>
|
|
The clip-begin attribute specifies the beginning of a sub-clip of a continuous
|
|
media object as offset from the start of the media object. <BR>
|
|
Values in the clip-begin attribute have the following syntax:
|
|
<PRE>Clip-time-value ::= Metric "=" ( Clock-val | Smpte-val )
|
|
Metric ::= Smpte-type | "npt"
|
|
Smpte-type ::= "smpte" | "smpte-30-drop" | "smpte-25"
|
|
Smpte-val ::= Hours ":" Minutes ":" Seconds
|
|
[ ":" Frames [ "." Subframes ]]
|
|
Hours ::= 2DIGIT
|
|
Minutes ::= 2DIGIT
|
|
Seconds ::= 2DIGIT
|
|
Frames ::= 2DIGIT
|
|
Subframes ::= 2DIGIT
|
|
</PRE>
|
|
<P>
|
|
The value of this attribute consists of a metric specifier, followed by a
|
|
time value whose syntax and semantics depend on the metric specifier. The
|
|
following formats are allowed:
|
|
<DL>
|
|
<DT>
|
|
SMPTE Timestamp
|
|
<DD>
|
|
SMPTE time codes <A HREF="#ref-smpte">[SMPTE]</A> can be used for frame-level
|
|
access accuracy. The metric specifier can have the following values:
|
|
<DL>
|
|
<DT>
|
|
smpte
|
|
<DT>
|
|
smpte-30-drop
|
|
<DD>
|
|
These values indicate the use of the "SMPTE 30 drop" format with 29.97 frames
|
|
per second. The "frames" field in the time value can assume the values 0
|
|
through 29. The difference between 30 and 29.97 frames per second is handled
|
|
by dropping the first two frame indices (values 00 and 01) of every minute,
|
|
except every tenth minute.
|
|
<DT>
|
|
smpte-25
|
|
<DD>
|
|
The "frames" field in the time specification can assume the values 0 through
|
|
24.
|
|
</DL>
|
|
<P>
|
|
The time value has the format hours:minutes:seconds:frames.subframes. If
|
|
the frame value is zero, it may be omitted. Subframes are measured in
|
|
one-hundredth of a frame.<BR>
|
|
Examples:<BR>
|
|
<CODE>clip-begin="smpte=10:12:33:20"</CODE>
|
|
<DT>
|
|
Normal Play Time
|
|
<DD>
|
|
Normal Play Time expresses time in terms of SMIL clock values. The metric
|
|
specifier is "npt", and the syntax of the time value is identical to the
|
|
syntax of SMIL clock values.<BR>
|
|
Examples:<BR>
|
|
<CODE>clip-begin="npt=123.45s"<BR>
|
|
clip-begin="npt=12:05:35.3</CODE>"
|
|
</DL>
|
|
<DT>
|
|
clip-end
|
|
<DD>
|
|
The clip-end attribute specifies the end of a sub-clip of a continuous media
|
|
object (such as audio, video or another presentation) that should be played.
|
|
It uses the same attribute value syntax as the clip-begin
|
|
attribute.<FONT COLOR="Red"><BR>
|
|
</FONT>If the value of the "clip-end" attribute exceeds the duration of the
|
|
media object, the value is ignored, and the clip end is set equal to the
|
|
effective end of the media object.
|
|
<DT>
|
|
copyright
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
<A NAME="dur">dur</A>
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
end
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
fill
|
|
<DD>
|
|
For a definition of the semantics of this attribute, see Section 4.2.4. The
|
|
attribute can have the values "remove" and "freeze".
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A>
|
|
<DT>
|
|
longdesc
|
|
<DD>
|
|
This attribute specifies a link (URI) to a long description of a media object.
|
|
This description should supplement the short description provided using the
|
|
alt attribute. When the media-object has associated anchors, this attribute
|
|
should provide information about the anchor's contents.
|
|
<DT>
|
|
<A NAME="loc">region</A>
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
<A NAME="href">src </A>
|
|
<DD>
|
|
The value of the src attribute is the URI of the media object.
|
|
<DT>
|
|
<A NAME="bitrate">system-bitrate</A>
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-captions
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-<A NAME="language">language</A>
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-overdub-or-caption
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-required
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
system-<A NAME="screen">screen</A>-size
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
<A NAME="screen-depth">system-screen-depth</A>
|
|
<DD>
|
|
Defined in <A HREF="#test">Section 4.4</A>
|
|
<DT>
|
|
title
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A><BR>
|
|
It is strongly recommended that all media object elements have a "title"
|
|
attribute with a meaningful description. Authoring tools should ensure that
|
|
no element can be introduced into a SMIL document without this attribute.
|
|
<DT>
|
|
<A NAME="type">type</A>
|
|
<DD>
|
|
MIME type of the media object referenced by the "src" attribute.
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
Media Object Elements can contain the following element:
|
|
<DL>
|
|
<DT>
|
|
anchor
|
|
<DD>
|
|
Defined in <A HREF="#anchor">Section 4.5.2</A>
|
|
</DL>
|
|
<H4>
|
|
<A NAME="SMIL_Time_Model">4.2.4 SMIL Time Model</A>
|
|
</H4>
|
|
<H5>
|
|
<A NAME="Time_Model_Variables">4.2.4.1 Time Model Values</A>
|
|
</H5>
|
|
<P>
|
|
In the following discussion, the term "element" refers to synchronization
|
|
elements only.
|
|
<P>
|
|
For each element we define the implicit, explicit, desired, and effective
|
|
begin, duration, and end.
|
|
<P>
|
|
The effective begin/duration/end specify what the reader of the document
|
|
will perceive.
|
|
<P>
|
|
The implicit, explicit, and desired values are auxiliary values used to define
|
|
the effective values.
|
|
<P>
|
|
The rules for calculating each of these values for the elements defined in
|
|
SMIL 1.0 are described in the next section.
|
|
<OL>
|
|
<LI>
|
|
Each element in SMIL has an <EM>implicit begin</EM>.
|
|
<LI>
|
|
Each element can be assigned an <EM>explicit begin</EM> by adding a "begin"
|
|
attribute to the element:
|
|
<BLOCKQUOTE>
|
|
<CODE>begin = "<I>value of explicit-begin</I></CODE>"
|
|
</BLOCKQUOTE>
|
|
<P>
|
|
It is an error if the explicit begin is earlier than the implicit begin of
|
|
the element.
|
|
<LI>
|
|
Each element in SMIL has an <EM>implicit end</EM>.
|
|
<LI>
|
|
Each element can be assigned an <EM>explicit end</EM> by adding an "end"
|
|
attribute to the element:
|
|
<BLOCKQUOTE>
|
|
<CODE>end = "<I>value of explicit-end</I>"</CODE>
|
|
</BLOCKQUOTE>
|
|
<LI>
|
|
The <EM>implicit duration</EM> of an element is the difference between the
|
|
implicit end and the implicit begin.
|
|
<LI>
|
|
Each element in SMIL can be assigned an <EM>explicit duration</EM> by adding
|
|
a "dur" attribute to the element:
|
|
<BLOCKQUOTE>
|
|
<CODE>dur = "<I>value of explicit-duration</I>"</CODE>
|
|
</BLOCKQUOTE>
|
|
<LI>
|
|
The <EM>desired begin</EM> of an element is equal to the explicit begin if
|
|
one is given, otherwise the desired begin is equal to the implicit begin.
|
|
<LI>
|
|
Each element has a <EM>desired end</EM>.
|
|
<LI>
|
|
The <EM>desired duration</EM> of an element is the difference between the
|
|
desired end and the desired begin.
|
|
<LI>
|
|
Each element has an <EM>effective begin</EM>.
|
|
<LI>
|
|
Each element has an <EM>effective end</EM>. (Note: the effective end of a
|
|
child element can never be later than the effective end of its parent.)
|
|
<LI>
|
|
The <EM>effective duration</EM> of an element is the difference between the
|
|
effective end and the effective begin.
|
|
</OL>
|
|
<H5>
|
|
<A NAME="Determining_Values">4.2.4.2 Determining Time Model Values for SMIL
|
|
1.0 Elements</A>
|
|
</H5>
|
|
<P>
|
|
This section defines how time model values are calculated for the synchronization
|
|
elements of SMIL 1.0 in cases that are not covered by the rules in
|
|
<A HREF="#Time_Model_Variables">Section 4.2.4.1</A>.
|
|
<H4>
|
|
Determining the <EM>implicit begin</EM> of an element
|
|
</H4>
|
|
<UL>
|
|
<LI>
|
|
The implicit begin of the first child of the "body" element is when the document
|
|
starts playing. When this is falls outside the scope of this document.
|
|
<LI>
|
|
The implicit begin of a child of a "par" element is equal to the effective
|
|
begin of the "par" element.
|
|
<LI>
|
|
The implicit begin of the first child of a "seq" element is equal to the
|
|
effective begin of the "seq" element.
|
|
<LI>
|
|
The implicit begin of any other child of a "seq" element is equal to the
|
|
desired end time of the previous child of the "seq" element.
|
|
</UL>
|
|
<H4>
|
|
Determining the <EM>implicit end</EM> of an element
|
|
</H4>
|
|
<P>
|
|
The first description that matches the element is the one that is to be used:
|
|
<UL>
|
|
<LI>
|
|
An element with a "repeat" attribute with value "indefinite" has an implicit
|
|
end immediately after its effective begin.
|
|
<LI>
|
|
An element with a "repeat" attribute with a value other than "indefinite"
|
|
has an implicit end equal to the implicit end of a seq element with the stated
|
|
number of copies of the element without "repeat" attribute as children.
|
|
<LI>
|
|
A media object element referring to a continuous media object has an implicit
|
|
end equal to the sum of the effective begin of the element and the intrinsic
|
|
duration of the media object.
|
|
<LI>
|
|
A media object element referring to a discrete media object such as text
|
|
or image has an implicit end immediately after its effective begin.
|
|
<LI>
|
|
A "seq" element has an implicit end equal to the desired end of its last
|
|
child.
|
|
<LI>
|
|
A "par" element has an implicit end that depends on the value of the "endsync"
|
|
attribute. The implicit end is equal to the sum of the effective begin of
|
|
the "par" element and the implicit duration which is derived as follows:
|
|
<UL>
|
|
<LI>
|
|
If the value of the "endsync" attribute is "last", or if the "endsync" attribute
|
|
is missing, the implicit duration of the "par" element is the maximum of
|
|
the desired durations of its children.
|
|
<LI>
|
|
If the value of the "endsync" attribute is "first", the implicit duration
|
|
of the "par" element is the minimum of the desired durations of its children.
|
|
<LI>
|
|
If the value of the "endsync" attribute is an id-ref, the implicit duration
|
|
of the "par" element is equal to the desired duration of the child referenced
|
|
by the "id-ref".
|
|
</UL>
|
|
</UL>
|
|
<H4>
|
|
Determining the <EM>desired end</EM> of an element
|
|
</H4>
|
|
<UL>
|
|
<LI>
|
|
If the element has both an explicit duration and an explicit end, the desired
|
|
end is the minimum of:
|
|
<UL>
|
|
<LI>
|
|
the sum of the desired begin and the explicit duration; and
|
|
<LI>
|
|
the explicit end.
|
|
</UL>
|
|
<LI>
|
|
If the element has an explicit duration but no explicit end, the desired
|
|
end is the sum of the desired begin and the explicit duration.
|
|
<LI>
|
|
If the element has an explicit end but no explicit duration, the desired
|
|
end is equal to the explicit end
|
|
<LI>
|
|
Otherwise, the desired end is equal to the implicit end.
|
|
</UL>
|
|
<P>
|
|
<STRONG>Determining the <EM>desired begin</EM> of an element</STRONG>
|
|
<P>
|
|
The desired begin of an element is determined by using rule 7 in
|
|
<A HREF="#Time_Model_Variables">Section 4.2.4.1</A>.
|
|
<H4>
|
|
Determining the <EM>effective begin</EM> of an element
|
|
</H4>
|
|
<P>
|
|
The <EM>effective begin</EM> of an element is equal to the desired begin
|
|
of the element, unless the effective end of the parent element is earlier
|
|
than this time, in which case the element is not shown at all.
|
|
<H4>
|
|
Determining the <EM>effective end</EM> of an element
|
|
</H4>
|
|
<UL>
|
|
<LI>
|
|
The effective end of the last child of the body element is player-dependent.
|
|
The effective end is at least as late as the desired end, but whether it
|
|
is any later is implementation-dependent.
|
|
<LI>
|
|
The effective end of the child of a "par" element can be derived as follows:
|
|
<UL>
|
|
<LI>
|
|
If the child has a "fill" attribute, and the value of the "fill" attribute
|
|
is "freeze", the effective end of the child element is equal to the effective
|
|
end of the parent.<FONT COLOR="Red"><BR>
|
|
</FONT>The last state of the element is retained on the screen until the
|
|
effective end of the element.
|
|
<LI>
|
|
If the child has a "fill" attribute, and the value of the "fill" attribute
|
|
is "remove", the effective end of the child element is the minimum of the
|
|
effective end of the parent and the desired end of the child element.
|
|
<LI>
|
|
If the child element has no "fill" attribute, the effective end of the child
|
|
depends on whether or not the child has an explicit duration or end.
|
|
<UL>
|
|
<LI>
|
|
If the child has an explicit duration or end, the effective end is determined
|
|
as if the element had a "fill" attribute with value "remove".
|
|
<LI>
|
|
If the child has neither an explicit duration nor an explicit end, the effective
|
|
end is determined as if the element had a "fill" attribute with value "freeze".
|
|
</UL>
|
|
</UL>
|
|
<LI>
|
|
The effective end of the last child of a "seq" element is derived in the
|
|
same way as the effective end of a child of a "par" element.
|
|
<LI>
|
|
The effective end of any other child of a "seq" element can be derived as
|
|
follows:
|
|
<UL>
|
|
<LI>
|
|
If the child has a "fill" attribute, and the value of the "fill" attribute
|
|
is "freeze", the effective end of the child element is equal to the effective
|
|
begin of the next element
|
|
<LI>
|
|
If the child has a "fill" attribute, and the value of the "fill" attribute
|
|
is "remove", the effective end of the child element is the minimum of the
|
|
effective begin of the next element and the desired end of the next child
|
|
element.
|
|
<LI>
|
|
If the child element has no "fill" attribute, the effective end of the child
|
|
depends on whether or not the child has an explicit duration or end.
|
|
<UL>
|
|
<LI>
|
|
If the child has an explicit duration or end, the effective end is determined
|
|
as if the element had a fill attribute with value "remove".
|
|
<LI>
|
|
If the child has neither an explicit duration nor an explicit end, the effective
|
|
end is determined as if the element had a fill attribute with value "freeze".
|
|
</UL>
|
|
</UL>
|
|
</UL>
|
|
<H3>
|
|
<A NAME="switch">4.3</A> The <TT>switch</TT> Element
|
|
</H3>
|
|
<P>
|
|
The switch element allows an author to specify a set of alternative elements
|
|
from which only one acceptable element should be chosen. An element is acceptable
|
|
if the element is a SMIL 1.0 element, the media-type can be decoded, and
|
|
all of the test-attributes (see <A HREF="#test">Section 4.4</A>) of the element
|
|
evaluate to "true".
|
|
<P>
|
|
An element is selected as follows: the player evaluates the elements in the
|
|
order in which they occur in the switch element. The first acceptable element
|
|
is selected at the exclusion of all other elements within the switch.
|
|
<P>
|
|
Thus, authors should order the alternatives from the most desirable to the
|
|
least desirable. Furthermore, authors should place a relatively fail-safe
|
|
alternative as the last item in the <switch> so that at least one item
|
|
within the switch is chosen (unless this is explicitly not desired).
|
|
Implementations should NOT arbitrarily pick an object within a
|
|
<switch> when test-attributes for all fail.
|
|
<P>
|
|
Note that http URIs provide for content-negotiation, which may be an alternative
|
|
to using the "switch" element in some cases.
|
|
<P>
|
|
<STRONG>Attributes</STRONG>
|
|
<P>
|
|
The switch element can have the following attributes:
|
|
<DL>
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A>
|
|
<DT>
|
|
title
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A><BR>
|
|
It is strongly recommended that all switch elements have a "title"
|
|
attribute with a meaningful description Authoring tools should ensure that
|
|
no element can be introduced into a SMIL document without this attribute.
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
If the "switch" element is used as a direct or indirect child of a "body"
|
|
element, it can contain the following children:
|
|
<DL>
|
|
<DT>
|
|
a
|
|
<DD>
|
|
Defined in <A HREF="#a">Section 4.5.1</A>
|
|
<DT>
|
|
animation
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
audio
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
img
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
par
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
ref
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
seq
|
|
<DD>
|
|
Defined in <A HREF="#seq">Section 4.2.2</A>
|
|
<DT>
|
|
switch
|
|
<DD>
|
|
Defined in <A HREF="#switch">Section 4.3</A>
|
|
<DT>
|
|
text
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
textstream
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
video
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
</DL>
|
|
<P>
|
|
All of these elements may appear multiple times as children of a "switch"
|
|
element.
|
|
<P>
|
|
If the "switch" element is used within a "head" element, it can contain the
|
|
following child:
|
|
<DL>
|
|
<DT>
|
|
layout
|
|
<DD>
|
|
Defined in <A HREF="#layout">Section 3.2</A><BR>
|
|
Multiple layout elements may occur within the switch element.
|
|
</DL>
|
|
<H3>
|
|
<A NAME="test">4.4 </A>Test <STRONG>Attributes</STRONG>
|
|
</H3>
|
|
<P>
|
|
This specification defines a list of test attributes that can be added to
|
|
any synchronization element, and that test system capabilities and settings.
|
|
Conceptually, these attributes represent boolean tests. When one of the
|
|
test attributes specified for an element evaluates to "false", the element
|
|
carrying this attribute is ignored.
|
|
<P>
|
|
Within the list below, the concept of "user preference" may show up. User
|
|
preferences are usually set by the playback engine using a preferences dialog
|
|
box, but this specification does not place any restrictions on how such
|
|
preferences are communicated from the user to the SMIL player.
|
|
<P>
|
|
The following test attributes are defined in SMIL 1.0:
|
|
<DL>
|
|
<DT>
|
|
<A NAME="bitrate">system-bitrate</A>
|
|
<DD>
|
|
This attribute specifies the approximate bandwidth, in bits per second available
|
|
to the system. The measurement of bandwidth is application specific, meaning
|
|
that applications may use sophisticated measurement of end-to-end connectivity,
|
|
or a simple static setting controlled by the user. In the latter case, this
|
|
could for instance be used to make a choice based on the users connection
|
|
to the network. Typical values for modem users would be 14400, 28800, 56000
|
|
bit/s etc. Evaluates to "true" if the available system bitrate is equal to
|
|
or greater than the given value. Evaluates to "false" if the available system
|
|
bitrate is less than the given value. <BR>
|
|
The attribute can assume any integer value greater than 0. If the value exceeds
|
|
an implementation-defined maximum bandwidth value, the attribute always evaluates
|
|
to "false".
|
|
<DT>
|
|
system-captions
|
|
<DD>
|
|
This attribute allows authors to distinguish between a redundant text equivalent
|
|
of the audio portion of the presentation (intended for a audiences such as
|
|
those with hearing disabilities or those learning to read who want or need
|
|
this information) and text intended for a wide audience. The attribute can
|
|
has the value "on" if the user has indicated a desire to see closed-captioning
|
|
information, and it has the value "off" if the user has indicated that they
|
|
don't wish to see such information. Evaluates to "true" if the value is "on",
|
|
and evaluates to "false" if the value is "off".
|
|
<DT>
|
|
system-<A NAME="language">language</A>
|
|
<DD>
|
|
The attribute value is a comma-separated list of language names as defined
|
|
in [RFC1766].
|
|
<P>
|
|
Evaluates to "true" if one of the languages indicated by user preferences
|
|
exactly equals one of the languages given in the value of this parameter,
|
|
or if one of the languages indicated by
|
|
<P>
|
|
user preferences exactly equals a prefix of one of the languages given in
|
|
the value of this parameter such that the first tag character following the
|
|
prefix is "-".
|
|
<P>
|
|
Evaluates to "false" otherwise.
|
|
<P>
|
|
Note: This use of a prefix matching rule does not imply that language tags
|
|
are assigned to languages in such a way that it is always true that if a
|
|
user understands a language with a certain tag, then this user will also
|
|
understand all languages with tags for which this tag is a prefix.
|
|
<P>
|
|
The prefix rule simply allows the use of prefix tags if this is the case.
|
|
<P>
|
|
Implementation note: When making the choice of linguistic preference available
|
|
to the user, implementors should take into account the fact that users are
|
|
not familiar with the details of language matching as described above, and
|
|
should provide appropriate guidance. As an example, users may assume that
|
|
on selecting "en-gb", they will be served any kind of English document if
|
|
British English is not available. The user interface for setting user preferences
|
|
should guide the user to add "en" to get the best matching behavior.
|
|
<P>
|
|
Multiple languages MAY be listed for content that is intended for multiple
|
|
audiences. For example, a rendition of the "Treaty of Waitangi", presented
|
|
simultaneously in the original Maori and English versions, would call for:
|
|
<P>
|
|
<PRE> <audio src="foo.rm" system-language="mi, en"/>
|
|
</PRE>
|
|
<P>
|
|
However, just because multiple languages are present within the object on
|
|
which the system-language test attribute is placed, this does not mean that
|
|
it is intended for multiple linguistic audiences. An example would be a
|
|
beginner's language primer, such as "A First Lesson in Latin," which is clearly
|
|
intended to be used by an English-literate audience. In this case, the
|
|
system-language test attribute should only include "en".
|
|
<P>
|
|
Authoring note: Authors should realize that if several alternative language
|
|
objects are enclosed in a "switch", and none of them matches, this may lead
|
|
to situations such as a video being shown without any audio track. It is
|
|
thus recommended to include a "catch-all" choice at the end of such a switch
|
|
which is acceptable in all cases.
|
|
<DT>
|
|
system-overdub-or-caption
|
|
<DD>
|
|
This attribute is a setting which determines if users prefer overdubbing
|
|
or captioning when the option is available. The attribute can have the values
|
|
"caption" and "overdub". Evaluates to "true" if the user preference matches
|
|
this attribute value. Evaluates to "false" if they do not match.
|
|
<DT>
|
|
system-required
|
|
<DD>
|
|
This attribute specifies the name of an extension. Evaluates to "true" if
|
|
the extension is supported by the implementation, otherwise, this evaluates
|
|
to "false". In a future version of SMIL, this attribute value will be an
|
|
XML namespace <A NAME="ref-NAMESPACES">[NAMESPACES]</A>.
|
|
<DT>
|
|
system-<A NAME="screen">screen</A>-size
|
|
<DD>
|
|
Attribute values have the following syntax:<BR>
|
|
<CODE>screen-size-val ::= screen-height"X"screen-width</CODE><BR>
|
|
Each of these is a pixel value, and must be an integer value greater than
|
|
0. Evaluates to "true" if the SMIL playback engine is capable of displaying
|
|
a presentation of the given size. Evaluates to "false" if the SMIL playback
|
|
engine is only capable of displaying a smaller presentation.
|
|
<DT>
|
|
<A NAME="screen-depth">system-screen-depth</A>
|
|
<DD>
|
|
This attribute specifies the depth of the screen color palette in bits required
|
|
for displaying the element. The value must be greater than 0. Typical values
|
|
are <FONT COLOR="Green">1</FONT>, 8, 24 .... Evaluates to "true" if the SMIL
|
|
playback engine is capable of displaying images or video with the given color
|
|
depth. Evaluates to "false" if the SMIL playback engine is only capable of
|
|
displaying images or video with a smaller color depth.
|
|
</DL>
|
|
<P>
|
|
<STRONG> Examples</STRONG>
|
|
<P>
|
|
<I>1) Choosing between content with different bitrate</I>
|
|
<P>
|
|
In a common scenario, implementations may wish to allow for selection via
|
|
a "system-bitrate" parameter on elements. The media player evaluates each
|
|
of the "choices" (elements within the switch) one at a time, looking for
|
|
an acceptable bitrate given the known characteristics of the link between
|
|
the media player and media server.
|
|
<PRE>...
|
|
<par>
|
|
<text .../>
|
|
<switch>
|
|
<par system-bitrate="40000">
|
|
...
|
|
</par>
|
|
<par system-bitrate="24000">
|
|
...
|
|
</par>
|
|
<par system-bitrate="10000">
|
|
........
|
|
</par>
|
|
</switch>
|
|
</par>
|
|
...
|
|
</PRE>
|
|
<P>
|
|
<I>2) Choosing between audio resources with different bitrate</I>
|
|
<P>
|
|
The elements within the switch may be any combination of elements. For instance,
|
|
one could merely be specifying an alternate audio track:
|
|
<PRE>...
|
|
<switch>
|
|
<audio src="joe-audio-better-quality" system-bitrate="16000" />
|
|
<audio src="joe-audio" system-bitrate="8000" />
|
|
</switch>
|
|
...
|
|
</PRE>
|
|
<P>
|
|
<I>3) Choosing between audio resources in different languages</I>
|
|
<P>
|
|
In the following example, an audio resource is available both in French and
|
|
in English. Based on the user's preferred language, the player can choose
|
|
one of these audio resources.
|
|
<PRE>...
|
|
<switch>
|
|
<audio src="joe-audio-french" system-language="fr"/>
|
|
<audio src="joe-audio-english" system-language="en"/>
|
|
</switch>
|
|
...
|
|
</PRE>
|
|
<P>
|
|
<I>4) Choosing between content written for different screens</I>
|
|
<P>
|
|
In the following example, the presentation contains alternative parts designed
|
|
for screens with different resolutions and bit-depths. Depending on the
|
|
particular characteristics of the screen, the player can choose one of the
|
|
alternatives.
|
|
<PRE>...
|
|
<par>
|
|
<text .../>
|
|
<switch>
|
|
<par system-screen-size="1280X1024" system-screen-depth="16">
|
|
........
|
|
</par>
|
|
<par system-screen-size="640X480" system-screen-depth="32">
|
|
...
|
|
</par>
|
|
<par system-screen-size="640X480" system-screen-depth="16">
|
|
...
|
|
</par>
|
|
</switch>
|
|
</par>
|
|
...
|
|
</PRE>
|
|
<P>
|
|
<EM>5) Distinguishing caption tracks from stock tickers</EM>
|
|
<P>
|
|
In the following example, captions are shown only if the user wants captions
|
|
on.
|
|
<PRE>...
|
|
<seq>
|
|
<par>
|
|
<audio src="audio.rm"/>
|
|
<video src="video.rm"/>
|
|
<textstream src="stockticker.rtx"/>
|
|
<textstream src="closed-caps.rtx" system-captions="on"/>
|
|
</par>
|
|
</seq>
|
|
...
|
|
</PRE>
|
|
<P>
|
|
<EM>6) Choosing the language of overdub and caption tracks</EM>
|
|
<P>
|
|
In the following example, a French-language movie is available with English,
|
|
German, and Dutch overdub and caption tracks. The following SMIL segment
|
|
expresses this, and switches on the alternatives that the user prefers.
|
|
<PRE>...
|
|
<par>
|
|
<switch>
|
|
<audio src="movie-aud-en.rm" system-language="en"
|
|
system-overdub-or-caption="overdub"/>
|
|
<audio src="movie-aud-de.rm" system-language="de"
|
|
system-overdub-or-caption="overdub"/>
|
|
<audio src="movie-aud-nl.rm" system-language="nl"
|
|
system-overdub-or-caption="overdub"/>
|
|
<!-- French for everyone else -->
|
|
<audio src="movie-aud-fr.rm"/>
|
|
</switch>
|
|
<video src="movie-vid.rm"/>
|
|
<switch>
|
|
<textstream src="movie-caps-en.rtx" system-language="en"
|
|
system-overdub-or-caption="caption"/>
|
|
<textstream src="movie-caps-de.rtx" system-language="de"
|
|
system-overdub-or-caption="caption"/>
|
|
<textstream src="movie-caps-nl.rtx" system-language="nl"
|
|
system-overdub-or-caption="caption"/>
|
|
<!-- French captions for those that really want them -->
|
|
<textstream src="movie-caps-fr.rtx" system-captions="on"/>
|
|
</switch>
|
|
</par>
|
|
...
|
|
</PRE>
|
|
<H3>
|
|
<A NAME="hyperlinking">4.5</A> Hyperlinking Elements
|
|
</H3>
|
|
<P>
|
|
The link elements allows the description of navigational links between objects.
|
|
<P>
|
|
SMIL provides only for in-line link elements. Links are limited to
|
|
uni-directional single-headed links (i.e. all links have exactly one source
|
|
and one destination resource). All links in SMIL are actuated by the user.
|
|
<P>
|
|
<STRONG>Handling of Links in Embedded Documents</STRONG>
|
|
<P>
|
|
Due to its integrating nature, the presentation of a SMIL document may involve
|
|
other (non-SMIL) applications or plug-ins. For example, a SMIL browser may
|
|
use an HTML plug-in to display an embedded HTML page. Vice versa, an HTML
|
|
browser may use a SMIL plug-in to display a SMIL document embedded in an
|
|
HTML page.
|
|
<P>
|
|
In such presentations, links may be defined by documents at different levels
|
|
and conflicts may arise. In this case, the link defined by the containing
|
|
document should take precedence over the link defined by the embedded object.
|
|
Note that since this might require communication between the browser and
|
|
the plug-in, SMIL implementations may choose not to comply with this
|
|
recommendation.
|
|
<P>
|
|
If a link is defined in an embedded SMIL document, traversal of the link
|
|
affects only the embedded SMIL document.
|
|
<P>
|
|
If a link is defined in a non-SMIL document which is embedded in a SMIL document,
|
|
link traversal can only affect the presentation of the embedded document
|
|
and not the presentation of the containing SMIL document. This restriction
|
|
may be released in future versions of SMIL.
|
|
<P>
|
|
<STRONG>Addressing</STRONG>
|
|
<P>
|
|
SMIL supports name fragment identifiers and the '#' connector. This means
|
|
that SMIL supports locators as currently used in HTML (e.g. it uses locators
|
|
of the form "http://foo.com/some/path#anchor1").
|
|
<P>
|
|
<STRONG>Linking to SMIL Fragments</STRONG>
|
|
<P>
|
|
A locator that points to a SMIL document may contain a fragment part (e.g.
|
|
http://www.w3.org/test.smi#par1). The fragment part is an id value that
|
|
identifies one of the elements within the referenced SMIL document. If a
|
|
link containing a fragment part is followed, the presentation should start
|
|
as if the user had fast-forwarded the presentation represented by the destination
|
|
document to the effective begin of the element designated by the fragment.
|
|
<P>
|
|
The following special cases can occur:
|
|
<OL>
|
|
<LI>
|
|
The element addressed by the link has a "repeat" attribute.
|
|
<OL>
|
|
<LI>
|
|
If the value of the "repeat" attribute is N, all N repetitions of the element
|
|
are played.
|
|
<LI>
|
|
If the value of the "repeat" attribute is "indefinite", playback ends according
|
|
to the rules defined for repeat value "indefinite".
|
|
</OL>
|
|
<LI>
|
|
The element addressed by the link is contained within another element that
|
|
contains a "repeat" attribute.
|
|
<OL>
|
|
<LI>
|
|
If the value of the "repeat" attribute is N, playback starts at the beginning
|
|
of the element addressed by the link, followed by N-1 repetitions of the
|
|
element containing the "repeat" attribute.
|
|
<LI>
|
|
If the value of the "repeat" attribute is "indefinite", playback starts at
|
|
the beginning of the element addressed by the link. Playback ends according
|
|
to the rules defined for repeat value "indefinite".
|
|
</OL>
|
|
<LI>
|
|
The element addressed by the link is content of a "switch" element: It is
|
|
forbidden to link to elements that are the content of "switch" elements.
|
|
</OL>
|
|
<H4>
|
|
<A NAME="a">4.5.1</A> The <TT>a</TT> Element
|
|
</H4>
|
|
<P>
|
|
The functionality of the "a" element is very similar to the functionality
|
|
of the "a" element in HTML 4.0 <A HREF="#ref-HTML40">[HTML40]</A> . SMIL
|
|
adds an attribute "show" that controls the temporal behavior
|
|
of the source when the link is followed. For synchronization purposes, the
|
|
"a" element is transparent, i.e. it does not influence the synchronization
|
|
of its child elements. "a" elements may not be nested. An "a" element must
|
|
have an <A HREF="#href">href</A> attribute.
|
|
<P>
|
|
<STRONG>Attributes</STRONG>
|
|
<P>
|
|
The "a" element can have the following attributes:
|
|
<DL>
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A>
|
|
<DT>
|
|
href
|
|
<DD>
|
|
This attribute contains the URI of the link's
|
|
destination.<FONT COLOR="Red"><BR>
|
|
</FONT>The "href" attribute is required for "a" elements.
|
|
<DT>
|
|
<A HREF="#show">show</A>
|
|
<DD>
|
|
This attribute controls the behavior of the source document containing the
|
|
link when the link is followed. It can have one of the following values:
|
|
<UL>
|
|
<LI>
|
|
"replace": The current presentation is paused at its current state and is
|
|
replaced by the destination resource. If the player offers a history mechanism,
|
|
the source presentation resumes from the state in which it was paused when
|
|
the user returns to it.
|
|
<LI>
|
|
"new": The presentation of the destination resource starts in a new context,
|
|
not affecting the source resource.
|
|
<LI>
|
|
"pause": The source presentation is paused at its current state, and the
|
|
destination resource starts in a new context. When the display of the destination
|
|
resource ends, the source presentation resumes from the state in which it
|
|
was paused.
|
|
</UL>
|
|
<P>
|
|
The default value of "show" is "replace".
|
|
<DT>
|
|
title
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A><BR>
|
|
It is strongly recommended that all "a" elements have a "title" attribute
|
|
with a meaningful description. Authoring tools should ensure that no element
|
|
can be introduced into a SMIL document without this attribute.
|
|
</DL>
|
|
<P>
|
|
<STRONG>Element Content</STRONG>
|
|
<P>
|
|
The "a" element can contain the following children:
|
|
<DL>
|
|
<DT>
|
|
animation
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
audio
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
img
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
par
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
ref
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
seq
|
|
<DD>
|
|
Defined in <A HREF="#seq">Section 4.2.2</A>
|
|
<DT>
|
|
switch
|
|
<DD>
|
|
Defined in <A HREF="#switch">Section 4.3</A>
|
|
<DT>
|
|
text
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
textstream
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
<DT>
|
|
video
|
|
<DD>
|
|
Defined in <A HREF="#media-object">Section 4.2.3</A>
|
|
</DL>
|
|
<P>
|
|
<STRONG> Examples</STRONG>
|
|
<P>
|
|
<I>Example 1</I>
|
|
<P>
|
|
The link starts up the new presentation replacing the presentation that was
|
|
playing.
|
|
<PRE>
|
|
<a href="http://www.cwi.nl/somewhereelse.smi">
|
|
<video src="rtsp://foo.com/graph.imf" region="l_window"/>
|
|
</a>
|
|
</PRE>
|
|
<P>
|
|
In the example, the second line can be replaced by a reference to any valid
|
|
subtree of an SMIL presentation.
|
|
<P>
|
|
<I>Example 2</I>
|
|
<P>
|
|
The link starts up the new presentation in addition to the presentation that
|
|
was playing.
|
|
<PRE>
|
|
<a href="http://www.cwi.nl/somewhereelse.smi" show="new">
|
|
<video src="rtsp://foo.com/graph.imf" region="l_window"/>
|
|
</a>
|
|
</PRE>
|
|
<P>
|
|
For example, this allows a SMIL player to spawn off an HTML browser.
|
|
<P>
|
|
<I>Example 3</I>
|
|
<P>
|
|
The link starts up the new presentation and pauses the presentation that
|
|
was playing.
|
|
<PRE>
|
|
<a href="http://www.cwi.nl/somewhereelse.smi" show="pause">
|
|
<video src="rtsp://foo.com/graph.imf" region="l_window"/>
|
|
</a>
|
|
</PRE>
|
|
<P>
|
|
<I>Example 4 </I>
|
|
<P>
|
|
The following example contains a link from an element in one presentation
|
|
A to the middle of another presentation B. This would play presentation B
|
|
starting from the effective begin of the element with id "next".
|
|
<PRE>
|
|
Presentation A:
|
|
|
|
<a href="http://www.cwi.nl/presentationB#next">
|
|
<video src="rtsp://foo.com/graph.imf"/>
|
|
</a>
|
|
|
|
|
|
Presentation B (http://www.cwi.nl/presentation):
|
|
|
|
...
|
|
<seq>
|
|
<video src="rtsp://foo.com/graph.imf"/>
|
|
<par>
|
|
<video src="rtsp://foo.com/timbl.rm" region="l_window"/>
|
|
<video id="next" src="rtsp://foo.com/v1.rm" region="r_window"/>
|
|
^^^^^^^^^
|
|
<text src="rtsp://foo.com/caption1.html" region="l_2_title"/>
|
|
<text src="rtsp://foo.com/caption2.rtx" region="r_2_title"/>
|
|
</par>
|
|
</seq>
|
|
...
|
|
</PRE>
|
|
<H4>
|
|
<A name="anchor">4.5.2 The <CODE>anchor</CODE> Element</A>
|
|
</H4>
|
|
<P>
|
|
The functionality of the "a" element is restricted in that it only allows
|
|
associating a link with a complete media object. HTML image maps have
|
|
demonstrated that it is useful to associate links with spatial subparts of
|
|
an object. The anchor element realizes similar functionality for SMIL:
|
|
<OL>
|
|
<LI>
|
|
The anchor element allows associating a link destination to spatial and temporal
|
|
subparts of a media object, using the "href" attribute (in contrast, the
|
|
"a" element only allows associating a link with a complete media object).
|
|
<LI>
|
|
The anchor element allows making a subpart of the media object the destination
|
|
of a link, using the "id" attribute.
|
|
<LI>
|
|
The anchor element allows breaking up an object into spatial subparts, using
|
|
the "coords" attribute.
|
|
<LI>
|
|
The anchor element allows breaking up an object into temporal subparts, using
|
|
the "begin" and "end" attributes. The values of the begin and end attributes
|
|
are relative to the beginning of the media object.
|
|
</OL>
|
|
<P>
|
|
<STRONG>Attributes</STRONG>
|
|
<P>
|
|
The anchor element can have the following attributes:
|
|
<DL>
|
|
<DT>
|
|
begin
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
<A NAME="coords">coords</A>
|
|
<DD>
|
|
The value of this attribute specifies a rectangle within the display area
|
|
of a visual media object. Syntax and semantics of this attribute are similar
|
|
to the coords attribute in HTML image maps, when the link is associated with
|
|
a rectangular shape. The rectangle is specified by four length values: The
|
|
first two values specify the coordinates of the upper left corner of the
|
|
rectangle.The second two values specify the coordinates of the lower right
|
|
corner of the rectangle. Coordinates are relative to the top left corner
|
|
of the visual media object (see Figure 4.5). If a coordinate is specified
|
|
as a percentage value, it is relative to the total width or height of the
|
|
media object display area. <BR>
|
|
An attribute with an erroneous coords value is ignored (right-x smaller or
|
|
equal to left-x, bottom-y smaller or equal to top-y). If the rectangle defined
|
|
by the coords attribute exceeds the area covered by the media object, exceeding
|
|
height and width are clipped at the borders of the media object.<BR>
|
|
Values of the coords attribute have the following syntax:<BR>
|
|
<PRE>coords-value ::= left-x "," top-y "," right-x "," bottom-y
|
|
|
|
</PRE>
|
|
</DL>
|
|
<P>
|
|
<HR>
|
|
<IMG WIDTH="266" HEIGHT="228" alt="semantics of coords attribute" SRC="coords.gif">
|
|
<A HREF="ld#longdesc-coords">D</A>
|
|
<P>
|
|
<HR>
|
|
<P>
|
|
<I>Figure 4.5: Semantics of "coords" attribute</I>
|
|
<DL>
|
|
<DT>
|
|
end
|
|
<DD>
|
|
Defined in <A HREF="#par">Section 4.2.1</A>
|
|
<DT>
|
|
id
|
|
<DD>
|
|
Defined in <A HREF="#smil">Section 2</A>
|
|
<DT>
|
|
show
|
|
<DD>
|
|
Defined in <A HREF="#a">Section 4.5.1</A>
|
|
<DT>
|
|
skip-content
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A>
|
|
<DT>
|
|
title
|
|
<DD>
|
|
Defined in <A HREF="#region">Section 3.3.1</A><BR>
|
|
It is strongly recommended that all anchor elements have a "title"
|
|
attribute with a meaningful description. Authoring tools should ensure that
|
|
no element can be introduced into a SMIL document without this attribute.
|
|
</DL>
|
|
<P>
|
|
<STRONG>Examples</STRONG>
|
|
<P>
|
|
<I>1) Associating links with spatial subparts</I>
|
|
<P>
|
|
In the following example, the screenspace taken up by a video clip is split
|
|
into two sections. A different link is associated with each of these sections.
|
|
<PRE><video src="http://www.w3.org/CoolStuff">
|
|
<anchor href="http://www.w3.org/AudioVideo" coords="0%,0%,50%,50%"/>
|
|
<anchor href="http://www.w3.org/Style" coords="50%,50%,100%,100%"/>
|
|
</video>
|
|
</PRE>
|
|
<P>
|
|
<I>2) Associating links with temporal subparts</I>
|
|
<P>
|
|
In the following example, the duration of a video clip is split into two
|
|
subintervals. A different link is associated with each of these subintervals.
|
|
<PRE><video src="http://www.w3.org/CoolStuff">
|
|
<anchor href="http://www.w3.org/AudioVideo" begin="0s" end="5s"/>
|
|
<anchor href="http://www.w3.org/Style" begin="5s" end="10s"/>
|
|
</video>
|
|
</PRE>
|
|
<P>
|
|
<I>3) Jumping to a subpart of an object</I>
|
|
<P>
|
|
The following example contains a link from an element in one presentation
|
|
A to the middle of a video object contained in another presentation B. This
|
|
would play presentation B starting from second 5 in the video (i.e. the
|
|
presentation would start as if the user had fast-forwarded the whole presentation
|
|
to the point at which the designated fragment in the "CoolStuff" video begins).
|
|
<PRE>Presentation A:
|
|
|
|
<a href="http://www.cwi.nl/mm/presentationB#tim">
|
|
<video id="graph" src="rtsp://foo.com/graph.imf" region="l_window"/>
|
|
</a>
|
|
|
|
|
|
Presentation B:
|
|
|
|
<video src="http://www.w3.org/CoolStuff">
|
|
<anchor id="joe" begin="0s" end="5s"/>
|
|
<anchor id="tim" begin="5s" end="10s"/>
|
|
</video>
|
|
</PRE>
|
|
<P>
|
|
<I>4) Combining different uses of links</I>
|
|
<P>
|
|
The following example shows how the different uses of associated links can
|
|
be used in combination.
|
|
<PRE>Presentation A:
|
|
|
|
<a href="http://www.cwi.nl/mm/presentationB#tim">
|
|
<video id="graph" src="rtsp://foo.com/graph.imf" region="l_window"/>
|
|
</a>
|
|
|
|
|
|
Presentation B:
|
|
|
|
<video src="http://www.w3.org/CoolStuff">
|
|
<anchor id="joe" begin="0s" end="5s" coords="0%,0%,50%,50%"
|
|
href="http://www.w3.org/"/>
|
|
<anchor id="tim" begin="5s" end="10s" coords="0%,0%,50%,50%"
|
|
href="http://www.w3.org/Tim"/>
|
|
</video>
|
|
</PRE>
|
|
<H2>
|
|
<A name="smil-dtd">5 SMIL DTD</A>
|
|
</H2>
|
|
<H3>
|
|
<A name="relation">5.1 <STRONG>Relation to XML</STRONG></A>
|
|
</H3>
|
|
<P>
|
|
A SMIL 1.0 document may optionally contain a document type declaration,
|
|
which names the document type definition (DTD) in use for the document.
|
|
For SMIL, the document type declaration should look as follows (the double
|
|
quotes can be replaced by single quotes):
|
|
<P>
|
|
<CODE><!DOCTYPE smil PUBLIC "-//W3C//DTD SMIL 1.0//EN"<BR>
|
|
|
|
"http://www.w3.org/TR/REC-smil/SMIL10.dtd"></CODE>
|
|
<P>
|
|
The XML 1.0 specification provides a way to extend the DTD using the
|
|
<!DOCTYPE> element, for instance to add a new set of entity definitions.
|
|
Authors must not use this feature with SMIL since many SMIL players will
|
|
not support it.
|
|
<P>
|
|
The following is illegal in SMIL:
|
|
<P>
|
|
<CODE><!DOCTYPE smil PUBLIC "-//W3C//DTD SMIL 1.0//EN"<BR>
|
|
|
|
"http://www.w3.org/TR/REC-smil/SMIL10.dtd" [<BR>
|
|
<!ENTITY % AcmeCorpSymbols PUBLIC<BR>
|
|
"-//Acme Corp//ENTITIES Corporate Symbols//EN"<BR>
|
|
"http://www.acme.com/corp_symbols.xml"<BR>
|
|
><BR>
|
|
%AcmeCorpSymbols;<BR>
|
|
]></CODE>
|
|
<H3>
|
|
<A NAME="dtd">5.2 DTD</A>
|
|
</H3>
|
|
<PRE><!--
|
|
|
|
This is the XML document type definition (DTD) for SMIL 1.0.
|
|
|
|
Date: 1998/06/15 08:56:30
|
|
|
|
Authors:
|
|
Jacco van Ossenbruggen <jrvosse@cwi.nl>
|
|
Sjoerd Mullender <sjoerd@cwi.nl>
|
|
|
|
Further information about SMIL is available at:
|
|
|
|
http://www.w3.org/AudioVideo/
|
|
|
|
-->
|
|
|
|
<!-- Generally useful entities -->
|
|
<!ENTITY % id-attr "id ID #IMPLIED">
|
|
<!ENTITY % title-attr "title CDATA #IMPLIED">
|
|
<!ENTITY % skip-attr "skip-content (true|false) 'true'">
|
|
<!ENTITY % desc-attr "
|
|
%title-attr;
|
|
abstract CDATA #IMPLIED
|
|
author CDATA #IMPLIED
|
|
copyright CDATA #IMPLIED
|
|
">
|
|
|
|
<!--=================== SMIL Document =====================================-->
|
|
<!--
|
|
The root element SMIL contains all other elements.
|
|
-->
|
|
<!ELEMENT smil (head?,body?)>
|
|
<!ATTLIST smil
|
|
%id-attr;
|
|
>
|
|
|
|
<!--=================== The Document Head =================================-->
|
|
<!ENTITY % layout-section "layout|switch">
|
|
|
|
<!ENTITY % head-element "(meta*,((%layout-section;), meta*))?">
|
|
|
|
<!ELEMENT head %head-element;>
|
|
<!ATTLIST head %id-attr;>
|
|
|
|
|
|
<!--=================== Layout Element ====================================-->
|
|
<!--
|
|
Layout contains the region and root-layout elements defined by
|
|
smil-basic-layout or other elements defined an external layout
|
|
mechanism.
|
|
-->
|
|
<!ELEMENT layout ANY>
|
|
<!ATTLIST layout
|
|
%id-attr;
|
|
type CDATA "text/smil-basic-layout"
|
|
>
|
|
|
|
|
|
<!--=================== Region Element ===================================-->
|
|
<!ENTITY % viewport-attrs "
|
|
height CDATA #IMPLIED
|
|
width CDATA #IMPLIED
|
|
background-color CDATA #IMPLIED
|
|
">
|
|
|
|
<!ELEMENT region EMPTY>
|
|
<!ATTLIST region
|
|
%id-attr;
|
|
%title-attr;
|
|
%viewport-attrs;
|
|
left CDATA "0"
|
|
top CDATA "0"
|
|
z-index CDATA "0"
|
|
fit (hidden|fill|meet|scroll|slice) "hidden"
|
|
%skip-attr;
|
|
>
|
|
|
|
<!--=================== Root-layout Element ================================-->
|
|
<!ELEMENT root-layout EMPTY>
|
|
<!ATTLIST root-layout
|
|
%id-attr;
|
|
%title-attr;
|
|
%viewport-attrs;
|
|
%skip-attr;
|
|
>
|
|
|
|
|
|
<!--=================== Meta Element=======================================-->
|
|
<!ELEMENT meta EMPTY>
|
|
<!ATTLIST meta
|
|
name NMTOKEN #REQUIRED
|
|
content CDATA #REQUIRED
|
|
%skip-attr;
|
|
>
|
|
|
|
<!--=================== The Document Body =================================-->
|
|
<!ENTITY % media-object "audio|video|text|img|animation|textstream|ref">
|
|
<!ENTITY % schedule "par|seq|(%media-object;)">
|
|
<!ENTITY % inline-link "a">
|
|
<!ENTITY % assoc-link "anchor">
|
|
<!ENTITY % link "%inline-link;">
|
|
<!ENTITY % container-content "(%schedule;)|switch|(%link;)">
|
|
<!ENTITY % body-content "(%container-content;)">
|
|
|
|
<!ELEMENT body (%body-content;)*>
|
|
<!ATTLIST body %id-attr;>
|
|
|
|
<!--=================== Synchronization Attributes ========================-->
|
|
<!ENTITY % sync-attributes "
|
|
begin CDATA #IMPLIED
|
|
end CDATA #IMPLIED
|
|
">
|
|
|
|
<!--=================== Switch Parameter Attributes =======================-->
|
|
<!ENTITY % system-attribute "
|
|
system-bitrate CDATA #IMPLIED
|
|
system-language CDATA #IMPLIED
|
|
system-required NMTOKEN #IMPLIED
|
|
system-screen-size CDATA #IMPLIED
|
|
system-screen-depth CDATA #IMPLIED
|
|
system-captions (on|off) #IMPLIED
|
|
system-overdub-or-caption (caption|overdub) #IMPLIED
|
|
">
|
|
|
|
<!--=================== Fill Attribute ====================================-->
|
|
<!ENTITY % fill-attribute "
|
|
fill (remove|freeze) 'remove'
|
|
">
|
|
|
|
|
|
<!--=================== The Parallel Element ==============================-->
|
|
<!ENTITY % par-content "%container-content;">
|
|
<!ELEMENT par (%par-content;)*>
|
|
<!ATTLIST par
|
|
%id-attr;
|
|
%desc-attr;
|
|
endsync CDATA "last"
|
|
dur CDATA #IMPLIED
|
|
repeat CDATA "1"
|
|
region IDREF #IMPLIED
|
|
%sync-attributes;
|
|
%system-attribute;
|
|
>
|
|
|
|
<!--=================== The Sequential Element ============================-->
|
|
<!ENTITY % seq-content "%container-content;">
|
|
<!ELEMENT seq (%seq-content;)*>
|
|
<!ATTLIST seq
|
|
%id-attr;
|
|
%desc-attr;
|
|
dur CDATA #IMPLIED
|
|
repeat CDATA "1"
|
|
region IDREF #IMPLIED
|
|
%sync-attributes;
|
|
%system-attribute;
|
|
>
|
|
|
|
<!--=================== The Switch Element ================================-->
|
|
<!-- In the head, a switch may contain only layout elements,
|
|
in the body, only container elements. However, this
|
|
constraint cannot be expressed in the DTD (?), so
|
|
we allow both:
|
|
-->
|
|
<!ENTITY % switch-content "layout|(%container-content;)">
|
|
<!ELEMENT switch (%switch-content;)*>
|
|
<!ATTLIST switch
|
|
%id-attr;
|
|
%title-attr;
|
|
>
|
|
|
|
<!--=================== Media Object Elements =============================-->
|
|
<!-- SMIL only defines the structure. The real media data is
|
|
referenced by the src attribute of the media objects.
|
|
-->
|
|
|
|
<!-- Furthermore, they have the following attributes as defined
|
|
in the SMIL specification:
|
|
-->
|
|
<!ENTITY % mo-attributes "
|
|
%id-attr;
|
|
%desc-attr;
|
|
region IDREF #IMPLIED
|
|
alt CDATA #IMPLIED
|
|
longdesc CDATA #IMPLIED
|
|
src CDATA #IMPLIED
|
|
type CDATA #IMPLIED
|
|
dur CDATA #IMPLIED
|
|
repeat CDATA '1'
|
|
%fill-attribute;
|
|
%sync-attributes;
|
|
%system-attribute;
|
|
">
|
|
|
|
<!--
|
|
Most info is in the attributes, media objects are empty or
|
|
contain associated link elements:
|
|
-->
|
|
<!ENTITY % mo-content "(%assoc-link;)*">
|
|
<!ENTITY % clip-attrs "
|
|
clip-begin CDATA #IMPLIED
|
|
clip-end CDATA #IMPLIED
|
|
">
|
|
|
|
<!ELEMENT ref %mo-content;>
|
|
<!ELEMENT audio %mo-content;>
|
|
<!ELEMENT img %mo-content;>
|
|
<!ELEMENT video %mo-content;>
|
|
<!ELEMENT text %mo-content;>
|
|
<!ELEMENT textstream %mo-content;>
|
|
<!ELEMENT animation %mo-content;>
|
|
|
|
<!ATTLIST ref %mo-attributes; %clip-attrs;>
|
|
<!ATTLIST audio %mo-attributes; %clip-attrs;>
|
|
<!ATTLIST video %mo-attributes; %clip-attrs;>
|
|
<!ATTLIST animation %mo-attributes; %clip-attrs;>
|
|
<!ATTLIST textstream %mo-attributes; %clip-attrs;>
|
|
<!ATTLIST text %mo-attributes;>
|
|
<!ATTLIST img %mo-attributes;>
|
|
|
|
<!--=================== Link Elements =====================================-->
|
|
|
|
<!ENTITY % smil-link-attributes "
|
|
%id-attr;
|
|
%title-attr;
|
|
href CDATA #REQUIRED
|
|
show (replace|new|pause) 'replace'
|
|
">
|
|
|
|
|
|
<!--=================== Inline Link Element ===============================-->
|
|
<!ELEMENT a (%schedule;|switch)*>
|
|
<!ATTLIST a
|
|
%smil-link-attributes;
|
|
>
|
|
|
|
|
|
<!--=================== Associated Link Element ===========================-->
|
|
<!ELEMENT anchor EMPTY>
|
|
<!ATTLIST anchor
|
|
%skip-attr;
|
|
%smil-link-attributes;
|
|
%sync-attributes;
|
|
coords CDATA #IMPLIED
|
|
>
|
|
</PRE>
|
|
<H2>
|
|
References
|
|
</H2>
|
|
<DL>
|
|
<DT>
|
|
<B><A NAME="ref-CSS2">[CSS2]</A></B>
|
|
<DD>
|
|
"Cascading Style Sheets, level 2", B. Bos, H. Lie, C. Lilley, I. Jacobs,
|
|
12 May 1998.
|
|
<DD>
|
|
Available at
|
|
<A HREF="http://www.w3.org/TR/REC-CSS2/">http://www.w3.org/TR/REC-CSS2/</A>.
|
|
<DT>
|
|
<STRONG><A name="ref-HTML40" class="normref">[HTML40]</A></STRONG>
|
|
<DD>
|
|
"HTML 4.0 Specification", D. Raggett, A. Le Hors, I. Jacobs, 24 April 1998.<BR>
|
|
Available at <A href="http://www.w3.org/TR/REC-html40">
|
|
http://www.w3.org/TR/REC-html40/</A>.
|
|
<DT>
|
|
<STRONG><A NAME="ref-ISO/IEC 10646">[ISO/IEC 10646]</A></STRONG>
|
|
<DD>
|
|
ISO (International Organization for Standardization). ISO/IEC 10646-1993
|
|
(E). Information technology -- Universal Multiple-Octet Coded Character Set
|
|
(UCS) -- Part 1: Architecture and Basic Multilingual Plane. [Geneva]:
|
|
International Organization for Standardization, 1993 (plus amendments AM
|
|
1 through AM 7).
|
|
<DT>
|
|
<B><A NAME="ref-NAMESPACES">[NAMESPACES]</A></B>
|
|
<DD>
|
|
"Namespaces in XML", T. Bray, D. Hollander, A. Layman, 27 March 1998<BR>
|
|
W3C working draft. Available at
|
|
<A HREF="http://www.w3.org/TR/WD-xml-names">http://www.w3.org/TR/WD-xml-names</A>.
|
|
<DT>
|
|
<A NAME="rec-PICS"><B>[PICS]</B></A>
|
|
<DD>
|
|
"PICS 1.1 Label Distribution -- Label Syntax and Communication Protocols",
|
|
31 October 1996, T. Krauskopf, J. Miller, P. Resnick, W. Trees<BR>
|
|
Available at
|
|
<A HREF="http://www.w3.org/TR/REC-PICS-labels-961031">http://www.w3.org/TR/REC-PICS-labels-961031</A>
|
|
<DT>
|
|
<STRONG><A name="ref-RFC1738" class="normref">[RFC1738]</A></STRONG>
|
|
<DD>
|
|
"Uniform Resource Locators", T. Berners-Lee, L. Masinter, and M. McCahill,
|
|
December 1994.<BR>
|
|
Available at
|
|
<A HREF="ftp://ftp.isi.edu/in-notes/rfc1738.txt">ftp://ftp.isi.edu/in-notes/rfc1738.txt</A>.
|
|
<DT>
|
|
<B><A NAME="ref-RFC1766">[RFC1766]</A></B>
|
|
<DD>
|
|
"Tags for the Identification of Languages", H. Alvestrand, March 1995.<BR>
|
|
Available at <A HREF="ftp://ftp.isi.edu/in-notes/rfc1766.txt">
|
|
ftp://ftp.isi.edu/in-notes/rfc1766.txt</A>.
|
|
<DT>
|
|
<STRONG><A name="ref-RFC1808" class="normref">[RFC1808]</A></STRONG>
|
|
<DD>
|
|
"Relative Uniform Resource Locators", R. Fielding, June 1995.<BR>
|
|
Available at
|
|
<A HREF="ftp://ftp.isi.edu/in-notes/rfc1808.txt">ftp://ftp.isi.edu/in-notes/rfc1808.txt</A>.
|
|
<DT>
|
|
<STRONG><A name="ref-RFC2045" class="normref">[RFC2045]</A></STRONG>
|
|
<DD>
|
|
"Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet
|
|
Message Bodies", N. Freed and N. Borenstein, November 1996.<BR>
|
|
Available at <A HREF="ftp://ftp.isi.edu/in-notes/rfc2045.txt">
|
|
ftp://ftp.isi.edu/in-notes/rfc2045.txt</A>. Note that this RFC obsoletes
|
|
RFC1521, RFC1522, and RFC1590.
|
|
<DT>
|
|
<A NAME="ref-SMPTE"><STRONG>[SMPTE]</STRONG></A>
|
|
<DD>
|
|
"Time and Control Codes for 24, 25 or 30 Frame-Per-Second Motion-Picture
|
|
Systems - RP 136-1995". Society of Motion Picture & Television
|
|
Engineers.
|
|
<DT>
|
|
<STRONG><A name="ref-URI" class="normref">[URI]</A></STRONG>
|
|
<DD>
|
|
"Uniform Resource Identifiers (URI): Generic Syntax and Semantics", T.
|
|
Berners-Lee, R. Fielding, L. Masinter, 4 March 1998.<BR>
|
|
Available at
|
|
<A HREF="http://www.ics.uci.edu/pub/ietf/uri/draft-fielding-uri-syntax-02.txt">
|
|
http://www.ics.uci.edu/pub/ietf/uri/draft-fielding-uri-syntax-02.txt</A>.
|
|
This is a work in progress that is expected to update
|
|
<A href="#ref-RFC1738">[RFC1738]</A> and
|
|
<A href="#ref-RFC1808">[RFC1808]</A>.
|
|
<DT>
|
|
<STRONG><A name="ref-XML10" class="normref">[XML10]</A></STRONG>
|
|
<DD>
|
|
"Extensible Markup Language (XML) 1.0", T. Bray, J. Paoli, C.M. Sperberg-McQueen,
|
|
editors, 10 February 1998.<BR>
|
|
Available at <A href="http://www.w3.org/TR/REC-xml">
|
|
http://www.w3.org/TR/REC-xml/</A>
|
|
</DL>
|
|
<H2>
|
|
<A NAME="Appendix">Appendix</A>
|
|
</H2>
|
|
<H3>
|
|
<A name="handling-extensions">Extending SMIL 1.0</A>
|
|
</H3>
|
|
<P>
|
|
<EM>(non-normative)</EM>
|
|
<P>
|
|
In the future, SMIL 1.0 may be extended by another W3C recommendation, or
|
|
by private extensions.
|
|
<P>
|
|
For these extensions, it is recommended that the following rules are obeyed:
|
|
<UL>
|
|
<LI>
|
|
All elements introduced in extensions must have a "skip-content" attribute
|
|
(defined in Section 3.3.1) if it should be possible that their content is
|
|
processed by SMIL 1.0 players.
|
|
<LI>
|
|
Private extensions must be introduced using the syntax of the XML namespace
|
|
specification.
|
|
</UL>
|
|
<P>
|
|
It is recommended that SMIL 1.0 players are prepared to handle documents
|
|
that contain extension that obey these two rules.
|
|
<P>
|
|
Extensions should be handled using an XML namespace mechanism, once such
|
|
a mechanism becomes a W3C recommendation. In the rest of the section, the
|
|
syntax and semantics for XML namespaces defined in the W3C note [NAMESPACE]
|
|
will be used for demonstration purposes only.
|
|
<P>
|
|
The following cases can occur:
|
|
<OL>
|
|
<LI>
|
|
The document contains a namespace declaration for the SMIL 1.0 specification
|
|
that defines an empty prefix. In this case, non-SMIL 1.0 elements and attributes
|
|
are only allowed in a document if they are declared using an XML namespace.
|
|
The document may not contain a document type declaration for SMIL 1.0. If
|
|
it does, it is invalid.<BR>
|
|
In the following example, the element "new:a" is a legal extension. The elements
|
|
"mytags:a" and "b" are syntax errors, since they are not declared using an
|
|
XML namespace.
|
|
<PRE><?xml:namespace ns="http://www.acme.com/new-smil" prefix="new" ?>
|
|
<?xml:namespace ns="http://www.w3.org/TR/PR-smil" ?>
|
|
<smil>
|
|
<body>
|
|
<par>
|
|
<new:a>
|
|
...
|
|
</new:a>
|
|
<mytags:a ... />
|
|
...
|
|
</mytags:a><BR> <b>
|
|
...
|
|
</b>
|
|
</par>
|
|
</body>
|
|
</smil>
|
|
</PRE>
|
|
<LI>
|
|
The document contains no document type declaration, it contains a document
|
|
type declaration for a SMIL version higher than 1.0, or it contains a namespace
|
|
declaration for a SMIL specification with a version higher than 1.0. For
|
|
a SMIL 1.0 player to be able to recognize such a namespace declaration, it
|
|
is recommended that the URI of future SMIL versions starts with
|
|
http://www.w3.org/TR/REC-smil, and is followed by more characters which may
|
|
for example be a version number.<BR>
|
|
In this case, a SMIL 1.0 player should assume that it is processing a SMIL
|
|
document with a version number higher than 1.0.<BR>
|
|
The following cases can occur:
|
|
<DL>
|
|
<DT>
|
|
Unknown element
|
|
<DD>
|
|
Unknown elements are ignored<BR>
|
|
An unknown element may contain content that consists of SMIL 1.0 elements.
|
|
Whether such content is ignored or processed depends on the value of the
|
|
"skip-content" attribute. If the attribute is set to "true", or the attribute
|
|
is absent, the content is not processed. If it is set to "false", the content
|
|
is processed.
|
|
<DT>
|
|
Content in Element that was declared "Empty"
|
|
<DD>
|
|
A future version of SMIL may allow content in elements that are declared
|
|
as "empty" in SMIL 1.0.
|
|
<DD>
|
|
Whether this content is ignored or not depends on the value of the "skip-content"
|
|
attribute of the formerly empty element. If the attribute is set to "true",
|
|
the content is not processed. If it is set to "false", the content is processed.
|
|
<DT>
|
|
Unknown Attribute
|
|
<DD>
|
|
Unknown attributes are ignored.
|
|
<DT>
|
|
Unknown Attribute Value
|
|
<DD>
|
|
Attributes with unknown attribute values are ignored.
|
|
</DL>
|
|
<LI>
|
|
The document contains a document type declaration for SMIL 1.0. In this case,
|
|
it may not contain any non-SMIL 1.0 elements, even if they are declared using
|
|
XML namespaces. This is because such extensions would render the document
|
|
invalid.
|
|
</OL>
|
|
<H3>
|
|
<A NAME="Using">Using SMIL 1.0 as an Extension</A>
|
|
</H3>
|
|
<P>
|
|
When the XML namespace mechanism is used to include SMIL elements and attributes
|
|
in other XML-based documents, it is recommended to use the following namespace
|
|
identifier: <CODE>http://www.w3.org/TR/REC-smil</CODE>
|
|
</BODY></HTML>
|