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<div class="head">
<p><a href="http://www.w3.org/"><img width="72" height="48" alt="W3C"
src="http://www.w3.org/Icons/w3c_home" /></a></p>

<h1><a id="title" name="title"></a>Use cases and requirements for Media
Fragments</h1>

<h2><a id="w3c-doctype" name="w3c-doctype"></a>W3C Working Draft 17 December
2009</h2>
<dl>
  <dt>This version:</dt>
    <dd><a
      href="http://www.w3.org/TR/2009/WD-media-frags-reqs-20091217">http://www.w3.org/TR/2009/WD-media-frags-reqs-20091217</a>
    </dd>
  <dt>Latest version:</dt>
    <dd><a
      href="http://www.w3.org/TR/media-frags-reqs">http://www.w3.org/TR/media-frags-reqs</a>
    </dd>
  <dt>Previous version:</dt>
    <dd><a
      href="http://www.w3.org/TR/2009/WD-media-frags-reqs-20090430">http://www.w3.org/TR/2009/WD-media-frags-reqs-20090430</a>
    </dd>
  <dt>Editors:</dt>
    <dd><a href="http://www.eurecom.fr/~troncy/">Raphaël Troncy </a>, Center
      for Mathematics and Computer Science (CWI Amsterdam)</dd>
    <dd><a href="mailto:erik.mannens@ugent.be">Erik Mannens </a>, IBBT
      Multimedia Lab, University of Ghent</dd>
  <dt>Contributors:</dt>
    <dd><a href="http://www.cwi.nl/~jack/">Jack Jansen </a>, Center for
      Mathematics and Computer Science (CWI Amsterdam)</dd>
    <dd><a href="http://www.w3.org/People/Lafon/">Yves Lafon </a>, W3C</dd>
    <dd><a href="http://blog.gingertech.net/">Silvia Pfeiffer </a>, W3C Invited
      Expert</dd>
    <dd><a href="mailto:davy.vandeursen@ugent.be">Davy van Deursen </a>, IBBT
      Multimedia Lab, University of Ghent</dd>
</dl>

<p class="copyright"><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2009 <a
href="http://www.w3.org/"><acronym
title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><acronym
title="Massachusetts Institute of Technology">MIT</acronym></a>, <a
href="http://www.ercim.org/"><acronym
title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>,
<a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
</div>
<hr />

<div>
<h2><a id="abstract" name="abstract"></a>Abstract</h2>

<p>This document describes use cases and requirements for the development of
the Media Fragments 1.0 specification. It includes a technology survey for
addressing fragments of multimedia document. </p>
</div>

<div>
<h2><a id="status" name="status"></a>Status of this Document</h2>

<p><em>This section describes the status of this document at the time of its
publication. Other documents may supersede this document. A list of current W3C
publications and the latest revision of this technical report can be found in
the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at
http://www.w3.org/TR/.</em></p>

<p>This is the <a
href="http://www.w3.org/2005/10/Process-20051014/tr.html#first-wd">First Public
Working Draft</a> of the Use cases and requirements for Media Fragments
specification. It has been produced by the <a
href="http://www.w3.org/2008/WebVideo/Fragments/">Media Fragments Working
Group</a>, which is part of the <a href="http://www.w3.org/2008/WebVideo/">W3C
Video on the Web Activity</a>.</p>

<p>A list of changes is available in <a href="#change-log"><b>E Change
Log</b></a>. </p>

<p>Please send comments about this document to <a
href="mailto:public-media-fragment@w3.org">public-media-fragment@w3.org</a>
mailing list (<a
href="http://lists.w3.org/Archives/Public/public-media-fragment/">public
archive</a>).</p>

<p>Publication as a Working Draft does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or obsoleted
by other documents at any time. It is inappropriate to cite this document as
other than work in progress. </p>

<p></p>

<p>This document was produced by a group operating under the <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 W3C
Patent Policy</a>. W3C maintains a <a rel="disclosure"
href="http://www.w3.org/2004/01/pp-impl/42785/status">public list of any patent
disclosures</a> made in connection with the deliverables of the group; that
page also includes instructions for disclosing a patent. An individual who has
actual knowledge of a patent which the individual believes contains <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
6 of the W3C Patent Policy</a>. </p>
</div>

<div class="toc">
<h2><a id="contents" name="contents"></a>Table of Contents</h2>

<p class="toc">1 <a href="#introduction">Introduction</a><br />
2 <a href="#terminology">Terminology</a><br />
3 <a href="#side-conditions">Side Conditions</a><br />
    3.1 <a href="#side1">Single Media Resource Definition</a><br />
    3.2 <a href="#side2">Existing Standards</a><br />
    3.3 <a href="#side3">Unique Resource</a><br />
    3.4 <a href="#side4">Valid Resource</a><br />
    3.5 <a href="#side5">Parent Resource</a><br />
    3.6 <a href="#side6">Single Fragment</a><br />
    3.7 <a href="#side7">Relevant Protocols</a><br />
    3.8 <a href="#side8">No Recompression</a><br />
    3.9 <a href="#side9">Minimize Impact on Existing Infrastructure</a><br
/>
    3.10 <a href="#side10">Focus for Changes</a><br />
    3.11 <a href="#side11">Browser Impact</a><br />
    3.12 <a href="#side12">Fallback Action</a><br />
4 <a href="#use-cases">Use Cases</a><br />
    4.1 <a href="#uc1">Linking to and Display of Media Fragments</a><br />
        4.1.1 <a href="#scenario1.1">Scenario 1: Retrieve only segment
of a video</a><br />
        4.1.2 <a href="#scenario1.2">Scenario 2: Region of an
Image</a><br />
        4.1.3 <a href="#scenario1.3">Scenario 3: Portion of
Music</a><br />
        4.1.4 <a href="#scenario1.4">Scenario 4: Image Region of video
over time</a><br />
    4.2 <a href="#uc2">Browsing and Bookmarking Media Fragments</a><br />
        4.2.1 <a href="#scenario2.1">Scenario 1: Temporal Video
Pagination</a><br />
        4.2.2 <a href="#scenario2.2">Scenario 2: Audio Passage
Bookmark</a><br />
        4.2.3 <a href="#scenario2.3">Scenario 3: Audio
Navigation</a><br />
        4.2.4 <a href="#scenario2.4">Scenario 4: Caption and chapter
tracks for browsing Video</a><br />
        4.2.5 <a href="#scenario2.5">Scenario 5: Jumping back in time
during live streaming</a><br />
        4.2.6 <a href="#scenario2.6">Scenario 6: Jumping to a
particular event in a live stream</a><br />
    4.3 <a href="#uc3">Recompositing Media Fragments </a><br />
        4.3.1 <a href="#scenario3.1">Scenario 1: Reframing a photo in a
slideshow</a><br />
        4.3.2 <a href="#scenario3.2">Scenario 2: Mosaic</a><br />
        4.3.3 <a href="#scenario3.3">Scenario 3: Video Mashup</a><br />
        4.3.4 <a href="#scenario3.4">Scenario 4: Spatial Video
Navigation</a><br />
        4.3.5 <a href="#scenario3.5">Scenario 5: Selective
previews</a><br />
        4.3.6 <a href="#scenario3.6">Scenario 6: Music Samples</a><br />
        4.3.7 <a href="#scenario3.7">Scenario 7: Highlighting regions
(out-of-scope)</a><br />
    4.4 <a href="#uc4">Annotating Media Fragments</a><br />
        4.4.1 <a href="#scenario4.1">Scenario 1: Spatial Tagging of
Images</a><br />
        4.4.2 <a href="#scenario4.2">Scenario 2: Temporal Tagging of
Audio and Video</a><br />
        4.4.3 <a href="#scenario4.3">Scenario 3: Named Anchors</a><br />
        4.4.4 <a href="#scenario4.4">Scenario 4: Spatial and Temporal
Tagging</a><br />
        4.4.5 <a href="#scenario4.5">Scenario 5: Search Engine</a><br />
    4.5 <a href="#uc5">Adapting Media Resources</a><br />
        4.5.1 <a href="#scenario5.1">Scenario 1: Changing Video quality
(out-of-scope)</a><br />
        4.5.2 <a href="#scenario5.2">Scenario 2: Selecting Regions in
Images </a><br />
        4.5.3 <a href="#scenario5.3">Scenario 3: Selecting an Image
from a multi-part document (out-of-scope)</a><br />
        4.5.4 <a href="#scenario5.4">Scenario 4: Retrieving an Image
embedded thumbnail (out-of-scope)</a><br />
        4.5.5 <a href="#scenario5.5">Scenario 5: Switching of Video
Transmission</a><br />
        4.5.6 <a href="#scenario5.6">Scenario 6: Toggle All Audio
OFF</a><br />
        4.5.7 <a href="#scenario5.7">Scenario 7: Toggle specific Audio
tracks</a><br />
        4.5.8 <a href="#scenario5.8">Scenario 8: Video aspect ratio
(out-of-scope)</a><br />
5 <a href="#media-fragment-requirements">Requirements for Media Fragment
URIs</a><br />
    5.1 <a href="#req_temporal">Requirement r01: Temporal fragments</a><br
/>
    5.2 <a href="#req_spatial">Requirement r02: Spatial fragments</a><br />
    5.3 <a href="#req_tracks">Requirement r03: Track fragments</a><br />
    5.4 <a href="#req_named">Requirement r04: Named fragments</a><br />
    5.5 <a href="#fitness_req">Fitness Conditions on Media
Containers/Resources</a><br />
</p>

<h3><a id="appendices" name="appendices"></a>Appendices</h3>

<p class="toc">A <a href="#references-normative">References</a><br />
B <a href="#fitness-table">Evaluation of fitness per media formats</a><br />
C <a href="#technologies-survey">Technologies Survey</a><br />
    C.1 <a href="#ExistingSchemes">Existing URI fragment schemes</a><br />
        C.1.1 <a href="#GeneralURISchemes">General specification of URI
fragments</a><br />
        C.1.2 <a href="#NonAudioVideoURISchemes">Fragment
specifications not for audio/video</a><br />
        C.1.3 <a href="#AudioVideoURISchemes">Fragment specifications
for audio/video</a><br />
    C.2 <a href="#ExistingApplications">Existing applications using
proprietary temporal media fragment URI schemes</a><br />
    C.3 <a href="#MediaFragmentApproaches">Media fragment specification
approaches</a><br />
        C.3.1 <a href="#URI-based">URI based</a><br />
            C.3.1.1 <a href="#SVG_URI">SVG</a><br />
                C.3.1.1.1 <a
href="#Spatial_SVG_URI">Spatial</a><br />
            C.3.1.2 <a href="#TemporalURI">Temporal URI/Ogg
technologies</a><br />
                C.3.1.2.1 <a
href="#Temporal_TemporalURI">Temporal</a><br />
                C.3.1.2.2 <a
href="#Track_TemporalURI">Track</a><br />
                C.3.1.2.3 <a
href="#Named_TemporalURI">Named</a><br />
            C.3.1.3 <a href="#MPEG-21">MPEG-21</a><br />
                C.3.1.3.1 <a
href="#Temporal_MPEG-21">Temporal</a><br />
                C.3.1.3.2 <a
href="#Spatial_MPEG-21">Spatial</a><br />
                C.3.1.3.3 <a href="#Track_MPEG-21">Track</a><br
/>
                C.3.1.3.4 <a href="#Named_MPEG-21">Named</a><br
/>
        C.3.2 <a href="#Non-URI-based">Non-URI-based</a><br />
            C.3.2.1 <a href="#SMIL">SMIL</a><br />
                C.3.2.1.1 <a
href="#Temporal_SMIL">Temporal</a><br />
                C.3.2.1.2 <a
href="#Spatial_SMIL">Spatial</a><br />
                C.3.2.1.3 <a href="#Track_SMIL">Track</a><br />
                C.3.2.1.4 <a href="#Named_SMIL">Named</a><br />
            C.3.2.2 <a href="#MPEG-7">MPEG-7</a><br />
                C.3.2.2.1 <a
href="#Temporal_MPEG-7">Temporal</a><br />
                C.3.2.2.2 <a
href="#Spatial_MPEG-7">Spatial</a><br />
                C.3.2.2.3 <a href="#Track_MPEG-7">Track</a><br
/>
                C.3.2.2.4 <a href="#Named_MPEG-7">Named</a><br
/>
            C.3.2.3 <a href="#SVG">SVG</a><br />
                C.3.2.3.1 <a
href="#Temporal_SVG">Temporal</a><br />
                C.3.2.3.2 <a href="#Spatial_SVG">Spatial</a><br
/>
            C.3.2.4 <a href="#TV-Anytime">TV-Anytime</a><br />
                C.3.2.4.1 <a
href="#Temporal_TV-Anytime">Temporal</a><br />
                C.3.2.4.2 <a
href="#Named_TV-Anytime">Named</a><br />
            C.3.2.5 <a href="#ImageMaps">ImageMaps</a><br />
                C.3.2.5.1 <a
href="#Spatial_ImageMaps">Spatial</a><br />
            C.3.2.6 <a href="#HTML5">HTML 5</a><br />
D <a href="#acknowledgments">Acknowledgements</a> (Non-Normative)<br />
E <a href="#change-log">Change Log</a> (Non-Normative)<br />
</p>
</div>
<hr />

<div class="body">

<div class="div1">
<h2><a id="introduction" name="introduction"></a>1 Introduction</h2>

<p>Audio and video resources on the World Wide Web are currently treated as
"foreign" objects, which can only be embedded using a plugin that is capable of
decoding and interacting with the media resource. Specific media servers are
generally required to provide for server-side features such as direct access to
time offsets into a video without the need to retrieve the entire resource.
Support for such media fragment access varies between different media formats
and inhibits standard means of dealing with such content on the Web. </p>

<p>This document collects background information to the Media Fragment URI
specification <cite><a href="#mf-spec">Media Fragments URI 1.0</a></cite>. It
contains a collection of side conditions under which the specification was
developed. It further contains a large collection of use cases that are either
regarded as relevant to this specification or as out-of-scope. From these use
cases, it deducts the different required dimensions for the Media Fragment URI
specification. Finally, this document finishes with a survey of existing media
fragment addressing approaches. </p>
</div>

<div class="div1">
<h2><a id="terminology" name="terminology"></a>2 Terminology</h2>

<p>The keywords <strong>MUST</strong>, <strong>MUST NOT</strong>,
<strong>SHOULD</strong> and <strong>SHOULD NOT</strong> are to be interpreted
as defined in <cite><a href="#rfc2119">RFC 2119</a></cite>. </p>

<p>According to <cite><a href="#rfc3986">RFC 3986</a></cite>, URIs that contain
a fragment are actually not URIs, but URI references relative to the namespace
of another URI. In this document, when the term 'media fragment URIs' is used,
it actually means 'media fragment URI references'. </p>
</div>

<div class="div1">
<h2><a id="side-conditions" name="side-conditions"></a>3 Side Conditions</h2>

<p>This section lists a number of conditions which have directed the
development of this specification. These conditions help clarify some of the
decisions made, e.g. about what types of use cases are within the realm of this
specification and which are outside. Spelling out these side conditions should
help increase transparency of the specifications. </p>

<div class="div2">
<h3><a id="side1" name="side1"></a>3.1 Single Media Resource Definition</h3>

<p>The following picture explains the generic composition of a media resource:
<img
src="http://www.w3.org/2008/WebVideo/Fragments/WD-media-fragments-reqs/800px-Model_of_a_Video_Resource.png"
alt="Model of a media resource" /> </p>

<p>A media resource for the purposes of this Working Group is defined along a
single timeline. It can consist of multiple tracks of data that are parallel
along this timeline. These tracks can be audio, video, images, text or any
other time-aligned data. The main interest of this group is in audio and video.
A media resource also typically has some control information in data headers.
These may be located at a particular position in the resource, e.g. the
beginning or the end, or spread throughout the data tracks as headers for data
packets. There is possibly also a general header for the complete media
resource. The data tracks are typically encoded in an interleaved fashion,
which allows for progressive decoding. All of this is provided in a single
file. </p>
</div>

<div class="div2">
<h3><a id="side2" name="side2"></a>3.2 Existing Standards</h3>

<p>Media fragment URIs will work within the boundaries of existing standards as
much as possible, in particular within the URI specification <cite><a
href="#rfc3986">RFC 3986</a></cite>. </p>
</div>

<div class="div2">
<h3><a id="side3" name="side3"></a>3.3 Unique Resource</h3>

<p>Media fragments are a representation of the parent resource and should not
create a new resource, in particular not a new resource of a different Internet
media type (or MIME type). Note that there are use cases for creating a new
resource, such as the extraction of a thumbnail from a video. These are
currently outside the scope of this document. </p>
</div>

<div class="div2">
<h3><a id="side4" name="side4"></a>3.4 Valid Resource</h3>

<p>Resources delivered as a response to a media fragment URI request should be
valid media resources by themselves and thus be playable by existing media
players / image viewers. </p>
</div>

<div class="div2">
<h3><a id="side5" name="side5"></a>3.5 Parent Resource</h3>

<p>The entire resource should be accessible as the "context" of a fragment via
a simple change of the URI. The media fragment URI - as a selective view of the
resource - provides a mechanism to focus on a fragment whilst hinting at the
wider media context in which the fragment is included. </p>
</div>

<div class="div2">
<h3><a id="side6" name="side6"></a>3.6 Single Fragment</h3>

<table border="1" summary="Editorial note: Werner Bailer ">
  <tbody>
    <tr>
      <td width="50%" valign="top" align="left"><b>Editorial note: Werner
        Bailer </b></td>
      <td width="50%" valign="top" align="right"> </td>
    </tr>
    <tr>
      <td valign="top" align="left" colspan="2">Not sure that the term 'mask'
        is the best choice here, e.g. in MPEG-7 mask is used for the opposite,
        i.e. not a single segment but a segment composed of several unconnected
        parts. </td>
    </tr>
  </tbody>
</table>

<p>A media fragment URI should create only a single "mask" onto a media
resource and not a collection of potentially overlapping fragments. </p>
</div>

<div class="div2">
<h3><a id="side7" name="side7"></a>3.7 Relevant Protocols</h3>

<p>The main protocols we are concerned with are HTTP and RTSP, since they are
open protocols for media delivery. </p>
</div>

<div class="div2">
<h3><a id="side8" name="side8"></a>3.8 No Recompression</h3>

<p>Media fragments should preferably be delivered as byte-range subparts of the
media resource such as to make the fragments an actual subresource of the media
resource. The advantage of this is that such fragments are cachable as byte
ranges in existing caching Web proxies. This implies that we should avoid to
decode and recompress a media resource to create a fragment. </p>
</div>

<div class="div2">
<h3><a id="side9" name="side9"></a>3.9 Minimize Impact on Existing
Infrastructure</h3>

<p>The necessary changes to all software in the media delivery chain should be
kept to a minimum: User Agents, Proxies, Media Servers. </p>
</div>

<div class="div2">
<h3><a id="side10" name="side10"></a>3.10 Focus for Changes</h3>

<p>Focus for necessary changes should be as much as possible on the media
servers because in any case they have to implement fragmentation support for
the media formats as the most fundamental requirement for providing media
fragment addressing. </p>
</div>

<div class="div2">
<h3><a id="side11" name="side11"></a>3.11 Browser Impact</h3>

<p>Changes to the user agent need to be a one-off and not require adaptation
per media encapsulation/encoding format. </p>
</div>

<div class="div2">
<h3><a id="side12" name="side12"></a>3.12 Fallback Action</h3>

<p>If a User Agent connects with a media fragment URI to a media server that
does not support media fragments, the media server should reply with the full
resource. The User Agent will then have to take action to either cancel this
connection (if e.g. the media resource is too long) or do a fragment offset
locally. </p>

<p>A User Agent that does not understand media fragment URIs will simply hand
on the URI (potentially with a stripped off fragment part) to the server and
receive the full resource in lieu of the fragment. This may lead to unexpected
behaviour with media fragment URIs in non-conformant User Agents, e.g. where a
mash-up of media fragments is requested, but a sequence of the full files is
played. This is acceptable during a transition phase. </p>

<table border="1" summary="Editorial note: David Singer">
  <tbody>
    <tr>
      <td width="50%" valign="top" align="left"><b>Editorial note: David
        Singer</b></td>
      <td width="50%" valign="top" align="right"> </td>
    </tr>
    <tr>
      <td valign="top" align="left" colspan="2">The fallback plan needs to be
        clarified. We must be able to handle the way the # is already used,
        e.g. in YouTube, without breaking what is already working. </td>
    </tr>
  </tbody>
</table>
</div>
</div>

<div class="div1">
<h2><a id="use-cases" name="use-cases"></a>4 Use Cases</h2>

<p>In which situations do users need media fragment URIs? This section explains
the types of user interactions with media resources that media fragment URIs
will enable. For each type it shows how media fragment URIs can improve the
usefulness, usability, and functionality of online audio and video. </p>

<div class="div2">
<h3><a id="uc1" name="uc1"></a>4.1 Linking to and Display of Media
Fragments</h3>

<p>In this use case, a user is only interested in consuming a fragment of a
media resource rather than the complete resource. A media fragment URI allows
addressing this part of the resource directly and thus enables the User Agent
to receive just the relevant fragment. </p>

<div class="div3">
<h4><a id="scenario1.1" name="scenario1.1"></a>4.1.1 Scenario 1: Retrieve only
segment of a video</h4>

<div class="exampleOuter">
<p>Tim does a keyword search on a video search service. That keyword is found
in several videos in the search service's collection and it relates to clips
inside the videos that appear at a time offset. Tim would like the search
result to point him to just these media fragments so he can watch the relevant
clips rather than having to watch the full videos and manually scroll for the
relevant clips. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario1.2" name="scenario1.2"></a>4.1.2 Scenario 2: Region of an
Image</h4>

<div class="exampleOuter">
<p>Tim has discovered on an image hosting service a photo of his third school
year class. He is keen to put a link to his own face inside this photo onto his
private Web site where he is collecting old photos of himself. He does not want
the full photo to be displayed and he does not want to have to download and
crop the original image since he wants to reference the original resource. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario1.3" name="scenario1.3"></a>4.1.3 Scenario 3: Portion of
Music</h4>

<div class="exampleOuter">
<p>Tim is a Last.fm user. He wants his friend Sue to listen to a cool song,
Gypsy Davy. However, not really the entire song is worth it, Tim thinks. He
wants Sue to listen to the last 10 seconds only and sends her an email with a
link to just that subpart of the media resource. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario1.4" name="scenario1.4"></a>4.1.4 Scenario 4: Image Region
of video over time</h4>

<div class="exampleOuter">
<p>Tim is now creating an analysis of the movements of muscles of horses during
trotting and finds a few relevant videos online. His analysis is collected on a
Web page and he'd like to reference the relevant video sections, cropped both
in time and space to focus his viewers' attention on specific areas of interest
that he'd like to point out. </p>
</div>
</div>
</div>

<div class="div2">
<h3><a id="uc2" name="uc2"></a>4.2 Browsing and Bookmarking Media Fragments</h3>

<p>Media resources - audio, video and even images - are often very large
resources that users want to explore progressively. Progressive exploration of
text is well-known in the Web space under the term "pagination". Pagination in
the text space is realized by creating a series of Web pages and enabling
paging through them by scripts on a server, each page having their own URI. For
large media resources, such pagination can be provided by media fragment URIs,
which enable direct access to media fragments. </p>

<div class="div3">
<h4><a id="scenario2.1" name="scenario2.1"></a>4.2.1 Scenario 1: Temporal Video
Pagination</h4>

<div class="exampleOuter">
<p>Michael has a Website that collects recordings of the sittings of his
government's parliament. These recordings tend to be very long - generally on
the order of 7 hours in duration. Instead of splitting up the recordings into
short files by manual inspection of the change of topics or some other
segmentation approach, he prefers to provide many handles to a unique video
resource. As he publishes the files, however, he provides pagination on the
videos such that people can watch them 20 min at a time. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario2.2" name="scenario2.2"></a>4.2.2 Scenario 2: Audio Passage
Bookmark</h4>

<p>Users not only want to receive links to highlights in media resources, but
also like to bookmark them in their browsers to be able to get back to them.
</p>

<div class="exampleOuter">
<p>Sue likes the song segment that Tim has sent her and decides to add this
specific segment to her bookmarks. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario2.3" name="scenario2.3"></a>4.2.3 Scenario 3: Audio
Navigation</h4>

<p>When regarding media resources (in particular audio and video) as monolithic
blocks, they are very inaccessible. For example, it is difficult to find out
what they are about, where the highlights are, or what the logical structure of
the resources are. Lack of these features, in particular lack of captions and
audio annotations, further make the resources inaccessible to disabled people.
Introducing an ability to directly access highlights, fragments, or the logical
structure of a media resource will provide a big contribution towards making a
media resource more accessible. </p>

<div class="exampleOuter">
<p>Lena would like to browse the descriptive audio tracks of a video as she
does with Daisy audio books, by following the logical structure of the media.
Audio descriptions and captions generally come in blocks either timed or
separated by silences. Chapter by chapter and then section by section she
eventually jumps to a specific paragraph and down to the sentence level by
using the "tab" control as she would normally do in audio books. The
descriptive audio track is an extra spoken track that provides a description of
scenes happening in a video. When the descriptive audio track is not present,
Lena can similarly browse through captions and descriptive text tracks which
are either rendered through her braille reading device or through her
text-to-speech engine. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario2.4" name="scenario2.4"></a>4.2.4 Scenario 4: Caption and
chapter tracks for browsing Video</h4>

<div class="exampleOuter">
<p>Silvia has a deaf friend, Elaine, who would like to watch the holiday videos
that Silvia is publishing on her website. Silvia has created subtitle tracks
for her videos and also a segmentation (e.g. using CMML <cite><a
href="#cmml">CMML</a></cite>) with unique identifiers on the clips that she
describes. The clips were formed based on locations that Silvia has visited. In
this way, Elaine is able to watch the videos by going through the clips and
reading the subtitles for those clips that she is interested in. She watches
the sections on Korea, Australia, and France, but jumps over the ones of Great
Britain and Holland. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario2.5" name="scenario2.5"></a>4.2.5 Scenario 5: Jumping back
in time during live streaming</h4>

<p>A URL to a live video stream may look no different than a URL to a canned
video file, e.g. http://www.example.com/video.ogv . However, in contrast to
canned video file URLs, this URL always points to the live video data, i.e.
what is transmitted "now". This leads to different requirements on fragment
addressing than with canned video files. </p>

<div class="exampleOuter">
<p>Thomas is watching a live video stream, but has to take a business call
right in the middle. He stops his video player to take the call. As he
reconnects, he gets connected back with the live stream, but has missed the
last 5 min. He would like to rewind to 5 min ago. A URL scheme that can capture
the time at which a live video stream was transmitted and allow for direct
access to any time within that real-world clock time will allow such direct
access. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario2.6" name="scenario2.6"></a>4.2.6 Scenario 6: Jumping to a
particular event in a live stream</h4>

<div class="exampleOuter">
<p>Thomas is watching a Formula 1 race on a Website that is streaming live
video with a real-time commentary and interactive textual descriptions of
particular events that are happening. Thomas wants to directly jump to the
'Alonso accident' listed next to the video as a section of interest in the
video. </p>
</div>
</div>
</div>

<div class="div2">
<h3><a id="uc3" name="uc3"></a>4.3 Recompositing Media Fragments </h3>

<p>As we enable direct linking to media fragments in a URI, we can also enable
simple recompositing of such media fragments. Note that because the media
fragments in a composition may possibly originate from different codecs and
very different files, we can not realistically expect smooth playback between
the fragments. </p>

<div class="div3">
<h4><a id="scenario3.1" name="scenario3.1"></a>4.3.1 Scenario 1: Reframing a
photo in a slideshow</h4>

<div class="exampleOuter">
<p>Erik has a collection of photos and wants to create a slide show of some of
the photos and wants to highlight specific areas in each image. He uses xspf to
define the slide show (playlist) using spatial fragment URIs to address the
photo fragments. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario3.2" name="scenario3.2"></a>4.3.2 Scenario 2: Mosaic</h4>

<div class="exampleOuter">
<p>Jack wants to create a mosaic for his website with all the image fragments
that Erik defined collated together. He uses SMIL 3.0 Tiny Profile and the
spatial fragment URIs to layout the image fragments and stitch them together as
a new "image". </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario3.3" name="scenario3.3"></a>4.3.3 Scenario 3: Video
Mashup</h4>

<div class="exampleOuter">
<p>Jack has a collection of videos and wants to create a mashup from segments
out of these videos without having to manually edit them together. He uses SMIL
3.0 Tiny Profile and temporal fragment URIs to address the clips out of the
videos and sequence them together. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario3.4" name="scenario3.4"></a>4.3.4 Scenario 4: Spatial Video
Navigation</h4>

<div class="exampleOuter">
<p>Elaine has recorded a video mosaic of all her 4 TV channels of an
international election day in a single video. She wants to keep the original
synchronised file, but now she wants to be able to play back each of the four
channels' recordings separately and in sequence. She creates a playlist of
media fragments URIs that each select a specific channel in the mosaic to play
each channel after one another. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario3.5" name="scenario3.5"></a>4.3.5 Scenario 5: Selective
previews</h4>

<p>Given an ability to link to media fragments through URIs, people will want
to decide whether they receive the full resource or just the data that relates
to the media fragment. This is particularly the case where the resource is
large, where the bandwidth is scarce or expensive, and/or where people have
limited time/patience to wait until the full resource is loaded. </p>

<div class="exampleOuter">
<p>Yves is a busy person. He doesn't have time to attend all meetings that he
is supposed to attend. He also uses his mobile device for accessing Web
resources while traveling, to make the most of his time. Some of the recent
meetings that Yves was supposed to attend have been recorded and published on
the Web. A colleague points out to Yves in an email which sections of the
meetings he should watch. While on his next trip, Yves goes back to this email
and watches the highlighted sections by simply clicking on them. The media
server of his company dynamically composes a valid media resource from the URIs
that Yves is sending it such that Yves' video player can play just the right
fragments. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario3.6" name="scenario3.6"></a>4.3.6 Scenario 6: Music
Samples</h4>

<div class="exampleOuter">
<p>Erik has a music collection. He creates an "audio podcast" in the form of an
RSS feed with URIs that link to samples from his music files. His friends can
play back the samples in their Web-attached music players. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario3.7" name="scenario3.7"></a>4.3.7 Scenario 7: Highlighting
regions (out-of-scope)</h4>

<div class="exampleOuter">
<p>Tim has discovered yet another alumni photo of his third school year class.
This time he doesn't want to crop his face but he wants to keep the photo in
the context of his classmates. He wants his region of the photo highlighted and
the rest grey scaled. </p>
</div>

<p>This scenario is out of scope for this Working Group because the display of
the highlighted region is up to the user agent and is not relevant to the
network interaction. This particular scenario is already possible with image
maps in HTML. </p>
</div>
</div>

<div class="div2">
<h3><a id="uc4" name="uc4"></a>4.4 Annotating Media Fragments</h3>

<p>Media resources typically don't just consist of the binary data. There is
often a lot of textual information available that relates to the media
resource. Enabling the addressing of media fragments ultimately creates a means
to attach annotations to media fragments, for example, using the <cite><a
href="#mediaont-10">Ontology for Media Resource 1.0</a></cite>. </p>

<div class="div3">
<h4><a id="scenario4.1" name="scenario4.1"></a>4.4.1 Scenario 1: Spatial
Tagging of Images</h4>

<div class="exampleOuter">
<p>Raphael systematically annotates some highlighted regions in his photos that
depict his friends, families, or the monuments he finds impressive. This
knowledge is represented by RDF descriptions that use spatial fragment URIs to
relate to the image fragments in his annotated collection. It makes it possible
later to search and retrieve all these media fragment URIs that relate to one
particular friend or monument. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario4.2" name="scenario4.2"></a>4.4.2 Scenario 2: Temporal
Tagging of Audio and Video</h4>

<div class="exampleOuter">
<p>Raphael also has a collection of audio and video files of all the
presentations he ever made. His RDF description collection extends to
describing all the temporal segments where he gave a demo of a software system
with structured details on the demo. </p>
</div>

<table border="1" summary="Editorial note: Silvia">
  <tbody>
    <tr>
      <td width="50%" valign="top" align="left"><b>Editorial note:
      Silvia</b></td>
      <td width="50%" valign="top" align="right"> </td>
    </tr>
    <tr>
      <td valign="top" align="left" colspan="2">Time-aligned text such as
        captions, subtitles in multiple languages, and audio descriptions for
        audio and video don't have to be created as separate documents and link
        to each segment through a temporal URI. Such text can be made part of
        the media resource by the media author or delivered as a separate, but
        synchronised data stream to the media player. In either case, when it
        comes to using these with the HTML5 &lt;video&gt; tag, they should be
        made accessible to the Web page through a javascript API for the
        video/audio/image element. This needs to be addressed in the HTML5
        working group. </td>
    </tr>
  </tbody>
</table>
</div>

<div class="div3">
<h4><a id="scenario4.3" name="scenario4.3"></a>4.4.3 Scenario 3: Named
Anchors</h4>

<p>Annotating media resources at the level of a complete resource is in certain
circumstances not enough. Support for annotating multimedia on the level of
fragments is often desired. The definition of "anchors" (or id tags) for
fragments of media resources will allow us to identify fragments by name. It
allows the creation of an author-defined segmentation of the resource - an
author-provided structure. </p>

<div class="exampleOuter">
<p>Raphael would like to attach an RDF-based annotation to a video fragment
that is specified through an "anchor". Identifying the media fragment by name
instead of through a temporal video fragment URI allows him to create a more
memorable URI than having to remember the time offsets. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario4.4" name="scenario4.4"></a>4.4.4 Scenario 4: Spatial and
Temporal Tagging</h4>

<div class="exampleOuter">
<p>Guillaume uses video fragment URIs in an MPEG-7 sign language profile to
describe a moving point of interest: he wants the focus region to be the
dominant hand in a Sign Language video. The series of video fragment URIs gives
the coordinates and timing of the trajectory followed by the hand, and by
naming them, can also describe the areas of changing hand-shapes. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario4.5" name="scenario4.5"></a>4.4.5 Scenario 5: Search
Engine</h4>

<div class="exampleOuter">
<p>Guillaume wants to retrieve the images of each bike present at a recent
cycling event. Group photos and general shots of the event have been published
online together with detailed RDF annotations. Thanks to a query in a search
engine that is able to parse the RDF annotations, Guillaume can now retrieve
multiple individual shots of each bike in the collection, where the URI is
created based on the RDF annotations. </p>
</div>
</div>
</div>

<div class="div2">
<h3><a id="uc5" name="uc5"></a>4.5 Adapting Media Resources</h3>

<p>When addressing a media resource as a user, one often has the desire not to
retrieve the full resource, but only a subpart of interest. This may be a
temporally or spatially consecutive subpart, but could also be e.g. a smaller
bandwidth version of the same resource, a lower framerate video, a image with
less colour depth or an audio file with a lower sampling rate. Media adaptation
is the general term used for such server-side created versions of media
resources. </p>

<div class="div3">
<h4><a id="scenario5.1" name="scenario5.1"></a>4.5.1 Scenario 1: Changing Video
quality (out-of-scope)</h4>

<div class="exampleOuter">
<p>Davy is looking for videos about allergies and would like to get previews at
a lower frame rate to decide whether to download and save them in his
collection. He would like to be able to specify in the URI a means of telling
the media server the adaptation that he is after. For video he would like to
adapt width, height, frame rate, colour depth, and temporal subpart selection.
Alternatively, he may want to get just a thumbnail of the video. </p>
</div>

<p>This scenario is out of scope for this Working Group because it requires
changes be made to the actual encoded data to retrieve a "fragment". URI based
media fragments should basically be achieved through cropping of one or more
byte sections. It is possible to develop in future a scheme for such transcoded
resources using a URI query (?) specification. </p>
</div>

<div class="div3">
<h4><a id="scenario5.2" name="scenario5.2"></a>4.5.2 Scenario 2: Selecting
Regions in Images </h4>

<div class="exampleOuter">
<p>Davy is interested to have precise coordinates on his browser address bar to
see and pan over large-size images maps. Through the same URI scheme he can now
generically address and locate different image subparts on his User Agent for
all image types. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario5.3" name="scenario5.3"></a>4.5.3 Scenario 3: Selecting an
Image from a multi-part document (out-of-scope)</h4>

<div class="exampleOuter">
<p>Davy is now interested in multi-resolution, multi-page medical images. He
wants to select the detailed image of the toe X-rays which appear on page 7 of
the TIFF document. </p>
</div>

<p>The support of particular media formats such as TIFF is out of scope - the
Working Group only deals with the specification of generic addressing
approaches, but support of particular file formats needs to be implemented by
the format developers. A spatial fragment URI to an image is, however, in
scope. </p>
</div>

<div class="div3">
<h4><a id="scenario5.4" name="scenario5.4"></a>4.5.4 Scenario 4: Retrieving an
Image embedded thumbnail (out-of-scope)</h4>

<div class="exampleOuter">
<p>Davy is also interested to have the kind of preview functionality for
pictures, in particular these large 10 mega-pixel JPEG files that have embedded
thumbnails in them. He can now provide a fast preview by selecting the embedded
thumbnail in the original image without even having to resize or create a new
separate file! </p>
</div>

<p>This particular scenario is out of scope for a media fragment URI, since it
creates a resource of a different mime type to the original resource. This
cannot be done using the URI fragment specifier, but only using the query
specifier. This is left as a future exercise. </p>
</div>

<div class="div3">
<h4><a id="scenario5.5" name="scenario5.5"></a>4.5.5 Scenario 5: Switching of
Video Transmission</h4>

<div class="exampleOuter">
<p>Davy has a blind friend called Katrina. Katrina would also like to watch the
videos that Davy has found, and is lucky that the videos have additional
alternative audio tracks, which describe to blind users what is happening in
the videos. Her Internet connection is of lower bandwidth and she would like to
switch off the video track, but receive the two audio tracks (original audio
plus audio annotations). She would like to do this track selection through
simple changes to the URI. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario5.6" name="scenario5.6"></a>4.5.6 Scenario 6: Toggle All
Audio OFF</h4>

<div class="exampleOuter">
<p>Sebo is Deaf and enjoys watching videos on the Web. Her friend sent her a
link to a new music video but she doesn't want to waste time and bandwidth
receiving any sounds. So when she enters the URI in her browser's address bar,
she also adds an extra parameter to select the video track only. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario5.7" name="scenario5.7"></a>4.5.7 Scenario 7: Toggle
specific Audio tracks</h4>

<div class="exampleOuter">
<p>Davy's girlfriend is a fan of Karaoke. She loves to be able to play back
videos from the Web that have a karaoke text, and two audio tracks, one each
for the music and for the singer. She practices the songs by playing back the
complete video with all tracks, but uses the video in Karaoke parties with
friends where she turns off the singer's audio track through a simple selection
of tracks in the User Agent. </p>
</div>
</div>

<div class="div3">
<h4><a id="scenario5.8" name="scenario5.8"></a>4.5.8 Scenario 8: Video aspect
ratio (out-of-scope)</h4>

<div class="exampleOuter">
<p>Silvia's television is brand new and with a display in 16:9, however she has
video on her media server that are in 3:2 format. To avoid paying a premium in
network fees, she would like the television to request only what can be
displayed to avoid wasting bandwidth. </p>
</div>

<p>This particular scenario is out of scope for a media fragment URI, since it
is unclear what a server should do with a request that has a different aspect
ratio. It is a display issue rather than a bandwidth or clipping issue. In
general, a user agent would create black borders around the video with a
diverging aspect ratio. However, it is up to the user agent what to do in such
a situation of diverging aspect ratio between what the server supplies and what
the user agent is requested to display. For example, HTML5 has specifications
for what to do in such a situation. </p>
</div>
</div>
</div>

<div class="div1">
<h2><a id="media-fragment-requirements"
name="media-fragment-requirements"></a>5 Requirements for Media Fragment
URIs</h2>

<p>This section describes the list of required media fragment addressing
dimensions that have resulted from the use case analysis.</p>

<p>It further analyses what format requirements the media resources has to
adhere to in order to allow the extraction of the data that relates to that
kind of addressing.</p>

<div class="div2">
<h3><a id="req_temporal" name="req_temporal"></a>5.1 Requirement r01: Temporal
fragments</h3>

<p>A temporal fragment of a media resource is a clipping along the time
dimension from a start to an end time that are within the duration of the media
resource. </p>

<p>Whether a media resource supports temporal fragment extraction is in the
first place dependent on the coding format and more specifically how encoding
parameters were set. For video coding formats, temporal fragments can be
extracted if the video stream provides random access points (i.e., a point that
is not dependent on previously encoded video data, typically corresponding to
an intra-coded frame) on a regular basis. The same holds true for audio coding
formats, i.e., the audio stream needs to be accessible at a point where the
decoder can start decoding without the need of previous coded data. </p>
</div>

<div class="div2">
<h3><a id="req_spatial" name="req_spatial"></a>5.2 Requirement r02: Spatial
fragments</h3>

<p>A spatial fragment of a media resource is a clipping of an image region. For
media fragment addressing we only regard rectangular regions. </p>

<p>Support for extraction of spatial fragments from a media resource in the
compressed domain depends on the coding format. The coding format must allow to
encode spatial regions independently from each other in order to support the
extraction of these regions in the compressed domain. Note that there are
currently two variants: region extraction and interactive region extraction. In
the first case, the regions (i.e., Regions Of Interest, ROI) are known at
encoding time and coded independently from each other. In the second case, ROIs
are not known at encoding time and can be chosen by a user agent. In this case,
the media resource is divided in a number of tiles, each encoded independently
from each other. Subsequently, the tiles covering the desired region are
extracted from the media resource. </p>
</div>

<div class="div2">
<h3><a id="req_tracks" name="req_tracks"></a>5.3 Requirement r03: Track
fragments</h3>

<p>A typical media resource consists of multiple tracks of data multiplexed
together into the media resource. A media resource could for example consist of
several audio, several video, and several textual annotation or metadata
tracks. Their individual extraction / addressing is desirable in particular
from a media adaptation point of view. </p>

<p>Whether the extraction of tracks from a media resource is supported or not
depends on the container format of the media resource. Since a container format
only defines a syntax and does not introduce any compression, it is always
possible to describe the structures of a container format. Hence, if a
container format allows the encapsulation of multiple tracks, then it is
possible to describe the tracks in terms of byte ranges. Examples of such
container formats are Ogg <cite><a href="#ogg">RFC 3533</a></cite> and MP4.
Note that it is possible that the tracks are multiplexed, implying that a
description of one track consists of a list of byte ranges. Also note that the
extraction of tracks (and fragments in general) from container formats often
introduces the necessity of syntax element modifications in the headers. </p>
</div>

<div class="div2">
<h3><a id="req_named" name="req_named"></a>5.4 Requirement r04: Named
fragments</h3>

<p>A named fragment of a media resource is a media fragment - either a track, a
time section, or a spatial region - that has been given a name through some
sort of annotation mechanism. Through this name, the media fragment can be
addressed in a more human-readable form. </p>

<p>No coding format provides support for named fragments, since naming is not
part of the encoding/decoding process. Hence, we have to consider container
formats for this feature. In general, if a container format allows the
insertion of metadata describing the named fragments, then the container format
supports named fragments, if the fragment class is also supported. For example,
you can include a CMML <cite><a href="#cmml">CMML</a></cite> or TimedText
description in an MP4 or Ogg <cite><a href="#ogg">RFC 3533</a></cite> container
and interpret this description to extract temporal fragments based on a name
given to them in the description. </p>
</div>

<div class="div2">
<h3><a id="fitness_req" name="fitness_req"></a>5.5 Fitness Conditions on Media
Containers/Resources</h3>

<p>There is a large number of media codecs and encapsulation formats that we
need to take into account as potential media resources on the Web. This section
analyses the general conditions for media formats that make them fit for
supporting the different types of fragment URIs. </p>

<p>Media resources should fulfill the following conditions to allow extraction
of fragments: </p>
<ul>
  <li><p>The media fragments can be extracted in the compressed domain.</p>
  </li>
  <li><p>No syntax element modifications in the bitstream are needed to perform
    the extraction.</p>
  </li>
</ul>

<p>Not all media formats will be compliant with these two conditions. Hence, we
distinguish the following categories: </p>
<ul>
  <li><p><b>Fit</b>: The media resource meets the two conditions (i.e.,
    fragments can be extracted in the compressed domain and no syntax element
    modifications are necessary). In this case, caching media fragments of such
    media resources on the byte level is possible.</p>
  </li>
  <li><p><b>Conditionally fit</b>: Media fragments can be extracted in the
    compressed domain, but syntax element modifications are required. These
    media fragments provide cacheable byte ranges for the data, but syntax
    element modifications are needed in headers applying to the whole media
    resource/fragment. In this case, these headers could be sent to the client
    in the first response of the server.</p>
  </li>
  <li><p><b>Unfit</b>: Media fragments cannot be extracted in the compressed
    domain as byte ranges. In this case, transcoding operations are necessary
    to extract media fragments. Since these media fragments do not create
    reproducible bytes, it is not possible to cache these media fragments. Note
    that media formats which enable extracting fragments in the compressed
    domain, but are not compliant with category 2 (i.e., syntax element
    modifications are not only applicable to the whole media resource), also
    belong to this category.</p>
  </li>
</ul>

<p>Those media types that are capable of doing what server-side media fragments
require are of interest to us. For those that aren't, the fall-back case
applies (i.e. full download and then offsetting). Appendix <a
href="#fitness-table"><b>B Evaluation of fitness per media formats</b></a>
lists a large number of typical formats and determines which we see fit,
conditionally fit, or currently unfit for supporting the different types of
media fragment URIs. </p>

<table border="1" summary="Editorial note: Silvia">
  <tbody>
    <tr>
      <td width="50%" valign="top" align="left"><b>Editorial note:
      Silvia</b></td>
      <td width="50%" valign="top" align="right"> </td>
    </tr>
    <tr>
      <td valign="top" align="left" colspan="2"><p>We ask for further input
        into the table in the attachment, in particular where there are
        question marks.</p>
      </td>
    </tr>
  </tbody>
</table>
</div>
</div>
</div>

<div class="back">

<div class="div1">
<h2><a id="references-normative" name="references-normative"></a>A
References</h2>
<dl>
  <dt class="label"><a name="cmml"></a>[CMML] </dt>
    <dd><a
      href="http://www.annodex.net/TR/draft-pfeiffer-cmml-03.txt"><cite>Continuous
      Media Markup Language (CMML), Version 2.1</cite></a>. IETF
      Internet-Draft, March 2006. </dd>
  <dt class="label"><a name="html40"></a>[HTML 4.0] </dt>
    <dd>D. Ragett, A. Le Hors and I. Jacobs. <a
      href="http://www.w3.org/TR/REC-html40/intro/intro.html#fragment-uri"><cite>HTML
      Fragment identifiers</cite></a>. W3C Recommendation, December 1999.
      Available at <a
      href="http://www.w3.org/TR/REC-html40/intro/intro.html#fragment-uri">http://www.w3.org/TR/REC-html40/intro/intro.html#fragment-uri</a>.
    </dd>
  <dt class="label"><a name="isoBaseMediaFF"></a>[ISO Base Media File Format]
  </dt>
    <dd><a
      href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c051533_ISO_IEC_14496-12_2008.zip"><cite>Information
      technology - Coding of audio-visual objects - Part 12: ISO base media
      file format</cite></a>. April 2009. </dd>
  <dt class="label"><a name="mf-spec"></a>[Media Fragments URI 1.0] </dt>
    <dd><a
      href="http://www.w3.org/2008/WebVideo/Fragments/WD-media-fragments-spec/"><cite>Media
      Fragments URI 1.0</cite></a>. W3C Working Draft, October 2009. </dd>
  <dt class="label"><a name="mpeg-7"></a>[MPEG-7] </dt>
    <dd><cite>Information Technology - Multimedia Content Description Interface
      (MPEG-7)</cite>. Standard No. ISO/IEC 15938:2001, International
      Organization for Standardization(ISO), 2001. </dd>
  <dt class="label"><a name="mpeg21"></a>[MPEG-21] </dt>
    <dd><cite>Information Technology - Multimedia Framework (MPEG-21)</cite>.
      Standard No. ISO/IEC 21000:2002, International Organization for
      Standardization(ISO), 2002. Available at <a
      href="http://www.chiariglione.org/mpeg/working_documents/mpeg-21/fid/fid-is.zip">http://www.chiariglione.org/mpeg/working_documents/mpeg-21/fid/fid-is.zip</a>.
    </dd>
  <dt class="label"><a name="mediaont-10"></a>[Ontology for Media Resource 1.0]
  </dt>
    <dd>W. Lee, T. Bürger, F. Sasaki, V. Malaisé, F. Stegmaier and Joakim
      Söderberg. <a
      href="http://www.w3.org/TR/2009/WD-mediaont-10-20090618/"><cite>Ontology
      for Media Resource 1.0</cite></a>. W3C Working Draft, June 2009.
      Available at <a
      href="http://www.w3.org/TR/mediaont-10">http://www.w3.org/TR/mediaont-10</a>.
    </dd>
  <dt class="label"><a name="rfc2119"></a>[RFC 2119] </dt>
    <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
      Words for use in RFCs to Indicate Requirement Levels</cite></a>. IETF RFC
      2119, March 1997. Available at <a
      href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>.
    </dd>
  <dt class="label"><a name="ogg"></a>[RFC 3533] </dt>
    <dd>S. Pfeiffer. <cite>The Ogg Encapsulation Format Version 0</cite>. IETF
      RFC 3533, May 2003. Available at <a
      href="http://www.ietf.org/rfc/rfc3533.txt">http://www.ietf.org/rfc/rfc3533.txt</a>.
    </dd>
  <dt class="label"><a name="rfc3986"></a>[RFC 3986] </dt>
    <dd>T. Berners-Lee, R. Fielding and L. Masinter. <a
      href="http://www.ietf.org/rfc/rfc3986.txt"><cite>Uniform Resource
      Identifier (URI): Generic Syntax</cite></a>. IETF RFC 3986, January 2005.
      Available at <a
      href="http://www.ietf.org/rfc/rfc3986.txt">http://www.ietf.org/rfc/rfc3986.txt</a>.
    </dd>
  <dt class="label"><a name="rfc5147"></a>[RFC 5147] </dt>
    <dd>E. Wilde and M. Duerst. <a
      href="http://tools.ietf.org/html/rfc5147"><cite>URI Fragment Identifiers
      for the text/plain Media Type</cite></a>. IETF RFC 5147, April 2008.
      Available at <a
      href="http://tools.ietf.org/html/rfc5147">http://tools.ietf.org/html/rfc5147</a>.
    </dd>
  <dt class="label"><a name="abnf"></a>[RFC 5234] </dt>
    <dd>D. Crocker. <a
      href="http://tools.ietf.org/html/rfc5234"><cite>Augmented BNF for Syntax
      Specifications: ABNF</cite></a>, IETF RFC 5234, January 2008. Available
      at <a
      href="http://tools.ietf.org/html/rfc5234">http://tools.ietf.org/html/rfc5234</a>.
    </dd>
  <dt class="label"><a name="roe"></a>[ROE] </dt>
    <dd><a href="http://wiki.xiph.org/index.php/ROE"><cite>Rich Open multitrack
      media Exposition (ROE)</cite></a>. Xiph.org Wiki, April 2009. </dd>
  <dt class="label"><a name="skeleton"></a>[Skeleton] </dt>
    <dd><a href="http://wiki.xiph.org/OggSkeleton"><cite>Ogg
      Skeleton</cite></a>. Xiph .org Wiki, April 2009. </dd>
  <dt class="label"><a name="smpte"></a>[SMPTE] </dt>
    <dd><cite>SMPTE RP 136 Time and Control Codes for 24, 25 or 30
      Frame-Per-Second Motion-Picture Systems</cite> </dd>
  <dt class="label"><a name="svg"></a>[SVG] </dt>
    <dd>J. Ferraiolo. <a
      href="http://www.w3.org/TR/2001/REC-SVG-20010904/linking#FragmentIdentifiersSVG"><cite>SVG
      Fragment identifiers</cite></a>. W3C Recommendation, September 2001.
      Available at <a
      href="http://www.w3.org/TR/2001/REC-SVG-20010904/linking#FragmentIdentifiersSVG">http://www.w3.org/TR/2001/REC-SVG-20010904/linking#FragmentIdentifiersSVG</a>.
    </dd>
  <dt class="label"><a name="temporalURI"></a>[Temporal URI] </dt>
    <dd>S. Pfeiffer, C. Parker and A. Pang. <a
      href="http://annodex.net/TR/draft-pfeiffer-temporal-fragments-03.html"><cite>Specifying
      time intervals in URI queries and fragments of time-based Web
      resources</cite></a>. Internet Draft, March 2005. Available at <a
      href="http://annodex.net/TR/draft-pfeiffer-temporal-fragments-03.html">http://annodex.net/TR/draft-pfeiffer-temporal-fragments-03.html</a>.
      IETF Internet-Draft, March 2005. </dd>
  <dt class="label"><a name="xpointer"></a>[XPointer Framework] </dt>
    <dd>P. Grosso, E. Maler, J. Marsh and N. Walsh. <a
      href="http://www.w3.org/TR/xptr-framework/"><cite>XPointer
      Framework</cite></a>. W3C Recommendation, March 2003. Available at <a
      href="http://www.w3.org/TR/xptr-framework/">http://www.w3.org/TR/xptr-framework/</a>.
    </dd>
</dl>
</div>

<div class="div1">
<h2><a id="fitness-table" name="fitness-table"></a>B Evaluation of fitness per
media formats</h2>

<p>In order to get a view on which media formats belong to which fitness
category, an overview is provided for key media formats. In the following
tables, the 'X' symbol indicates that the media format does not support a
particular fragment axis. The tables are separated by video/audio/image codecs
and container formats. </p>

<table border="1">
  <tbody>
    <tr>
      <th>Video Codec</th>
      <th>Track</th>
      <th>Temporal</th>
      <th>Spatial</th>
      <th>Name</th>
      <th>Remark</th>
    </tr>
    <tr>
      <td>H.261</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>MPEG-1 Video</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>H.262/MPEG-2 Video</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>H.263</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>MPEG-4 Visual</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>H.264/MPEG-4 AVC</td>
      <td>n/a</td>
      <td>fit</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>Spatial fragment extraction is possible with Flexible Macroblock
        Ordening (FMO)</td>
    </tr>
    <tr>
      <td>AVS</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>Motion JPEG</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>Motion JPEG2000</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td>Spatial fragment extraction is possible in the compressed domain, but
        syntax element modifications are needed for every frame.</td>
    </tr>
    <tr>
      <td>VC-1</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>Dirac</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td>When Dirac is stored in the Ogg <cite><a href="#ogg">RFC
        3533</a></cite> container using Skeleton <cite><a
        href="#skeleton">Skeleton</a></cite>, ROE <cite><a
        href="#roe">ROE</a></cite> and CMML <cite><a
        href="#cmml">CMML</a></cite>, track, temporal and named fragments are
        supported. </td>
    </tr>
    <tr>
      <td>Theora</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td>When Theora is stored in the Ogg <cite><a href="#ogg">RFC
        3533</a></cite> container using Skeleton <cite><a
        href="#skeleton">Skeleton</a></cite>, ROE <cite><a
        href="#roe">ROE</a></cite> and CMML <cite><a
        href="#cmml">CMML</a></cite>, track, temporal and named fragments are
        supported. </td>
    </tr>
    <tr>
      <td>RealVideo</td>
      <td>n/a</td>
      <td>fit(?)</td>
      <td>unfit(?)</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>DV</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>Betacam</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>OMS</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>SNOW</td>
      <td>n/a</td>
      <td>fit</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
  </tbody>
</table>

<p></p>

<table border="1">
  <tbody>
    <tr>
      <th>Audio Codec</th>
      <th>Track</th>
      <th>Temporal</th>
      <th>Spatial</th>
      <th>Name</th>
      <th>Remark</th>
    </tr>
    <tr>
      <td>MPEG-1 Audio</td>
      <td>n/a</td>
      <td>fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>AAC</td>
      <td>n/a</td>
      <td>fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>Vorbis</td>
      <td>n/a</td>
      <td>fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>When Vorbis is stored in the Ogg <cite><a href="#ogg">RFC
        3533</a></cite> container using Skeleton <cite><a
        href="#skeleton">Skeleton</a></cite>, ROE <cite><a
        href="#roe">ROE</a></cite> and CMML <cite><a
        href="#cmml">CMML</a></cite>, track, temporal and named fragments are
        supported. </td>
    </tr>
    <tr>
      <td>FLAC</td>
      <td>n/a</td>
      <td>fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>When FLAC is stored in the Ogg <cite><a href="#ogg">RFC
        3533</a></cite> container using Skeleton <cite><a
        href="#skeleton">Skeleton</a></cite>, ROE <cite><a
        href="#roe">ROE</a></cite> and CMML <cite><a
        href="#cmml">CMML</a></cite>, track, temporal and named fragments are
        supported. </td>
    </tr>
    <tr>
      <td>Speex</td>
      <td>n/a</td>
      <td>fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>When Speex is stored in the Ogg <cite><a href="#ogg">RFC
        3533</a></cite> container using Skeleton <cite><a
        href="#skeleton">Skeleton</a></cite>, ROE <cite><a
        href="#roe">ROE</a></cite> and CMML <cite><a
        href="#cmml">CMML</a></cite>, track, temporal and named fragments are
        supported. </td>
    </tr>
    <tr>
      <td>AC-3/Dolby Digital</td>
      <td>n/a</td>
      <td>fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>TTA</td>
      <td>n/a</td>
      <td>fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>WMA</td>
      <td>n/a</td>
      <td>fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>MLP</td>
      <td>n/a</td>
      <td>fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td></td>
    </tr>
  </tbody>
</table>

<p></p>

<table border="1">
  <tbody>
    <tr>
      <th>Image Codec</th>
      <th>Track</th>
      <th>Temporal</th>
      <th>Spatial</th>
      <th>Name</th>
      <th>Remark</th>
    </tr>
    <tr>
      <td>JPEG</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>JPEG2000</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>JPEG LS</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>HD Photo</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>GIF</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
    <tr>
      <td>PNG</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>unfit</td>
      <td>n/a</td>
      <td></td>
    </tr>
  </tbody>
</table>

<p></p>

<table border="1">
  <tbody>
    <tr>
      <th>Container Formats</th>
      <th>Track</th>
      <th>Temporal</th>
      <th>Spatial</th>
      <th>Name</th>
      <th>Remark</th>
    </tr>
    <tr>
      <td>MOV</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td><a title="http://www.apple.com/quicktime/tutorials/texttracks.html"
        class="external text"
        href="http://www.apple.com/quicktime/tutorials/texttracks.html">QTText</a>
        provides named chapters </td>
    </tr>
    <tr>
      <td>MP4</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td><a title="http://en.wikipedia.org/wiki/MPEG-4_Part_17"
        class="external text"
        href="http://en.wikipedia.org/wiki/MPEG-4_Part_17">MPEG-4 TimedText</a>
        provides named sections </td>
    </tr>
    <tr>
      <td>3GP</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td><a title="http://en.wikipedia.org/wiki/MPEG-4_Part_17"
        class="external text"
        href="http://en.wikipedia.org/wiki/MPEG-4_Part_17">3GPP TimedText</a>
        provides named sections </td>
    </tr>
    <tr>
      <td>MPEG-21 FF</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td><a
        title="http://www.chiariglione.org/mpeg/technologies/mpeg-21/mp21-did/index.htm"
        class="external text"
        href="http://www.chiariglione.org/mpeg/technologies/mpeg-21/mp21-did/index.htm">MPEG-21
        Digital Item Declaration</a> provides named sections </td>
    </tr>
    <tr>
      <td>OGG</td>
      <td>conditionally fit (1)</td>
      <td>fit</td>
      <td>n/a</td>
      <td>conditionally fit (2)</td>
      <td>(1) Using ROE <cite><a href="#roe">ROE</a></cite> and Skeleton
        <cite><a href="#skeleton">Skeleton</a></cite>, track selection is
        possible; (2) Using ROE, CMML <cite><a href="#cmml">CMML</a></cite> and
        Skeleton, named addressing of temporal and track fragments is possible
      </td>
    </tr>
    <tr>
      <td>Matroska</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td></td>
    </tr>
    <tr>
      <td>MXF</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td></td>
    </tr>
    <tr>
      <td>ASF</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td>Marker objects provide named anchor points</td>
    </tr>
    <tr>
      <td>AVI</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>X</td>
      <td></td>
    </tr>
    <tr>
      <td>FLV</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td><a
        title="http://help.adobe.com/en_US/Soundbooth/2.0/WSA5A1DDFB-6BE2-4486-BE0C-A10CEEF119ADa.html"
        class="external text"
        href="http://help.adobe.com/en_US/Soundbooth/2.0/WSA5A1DDFB-6BE2-4486-BE0C-A10CEEF119ADa.html">cue
        points</a> provide named anchor points </td>
    </tr>
    <tr>
      <td>RMFF</td>
      <td>fit or conditionally fit(?)</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>?</td>
      <td></td>
    </tr>
    <tr>
      <td>WAV</td>
      <td>X</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>X</td>
      <td></td>
    </tr>
    <tr>
      <td>AIFF</td>
      <td>X</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>X</td>
      <td></td>
    </tr>
    <tr>
      <td>XMF</td>
      <td>?</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>?</td>
      <td></td>
    </tr>
    <tr>
      <td>AU</td>
      <td>X</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>X</td>
      <td></td>
    </tr>
    <tr>
      <td>TIFF</td>
      <td>conditionally fit</td>
      <td>n/a</td>
      <td>n/a</td>
      <td>conditionally fit</td>
      <td>Can store multiple images (i.e., tracks) in one file, possibility to
        insert "private tags" (i.e., proprietary information)</td>
    </tr>
  </tbody>
</table>
</div>

<div class="div1">
<h2><a id="technologies-survey" name="technologies-survey"></a>C Technologies
Survey</h2>

<div class="div2">
<h3><a id="ExistingSchemes" name="ExistingSchemes"></a>C.1 Existing URI
fragment schemes</h3>

<p>Some existing URI schemes define semantics for fragment identifiers. In this
section, we list these URI schemes and provide examples of their fragment
identifiers. </p>

<div class="div3">
<h4><a id="GeneralURISchemes" name="GeneralURISchemes"></a>C.1.1 General
specification of URI fragments</h4>
<ul>
  <li>
    <div>
    <em>URI Fragment</em><cite><a href="#rfc3986">RFC 3986</a></cite> 

    <div class="exampleInner">
    <pre>http://www.w3.org/2008/WebVideo/Fragments/wiki/Main_Page#Preparation_of_Working_Draft</pre>
    </div>
    cited from RFC3986: "The fragment identifier component of a URI allows
    indirect identification of a secondary resource by reference to a primary
    resource and additional identifying information. The identified secondary
    resource may be some portion or subset of the primary resource, some view
    on representations of the primary resource, or some other resource defined
    or described by those representations. A fragment identifier component is
    indicated by the presence of a number sign ("#") character and terminated
    by the end of the URI." </div>
  </li>
</ul>
</div>

<div class="div3">
<h4><a id="NonAudioVideoURISchemes" name="NonAudioVideoURISchemes"></a>C.1.2
Fragment specifications not for audio/video</h4>
<ul>
  <li>
    <div>
    <em>HTML named anchors </em><cite><a href="#html40">HTML 4.0</a></cite> 

    <div class="exampleInner">
    <pre>http://www.w3.org/2008/WebVideo/Fragments/wiki/Main_Page#Preparation_of_Working_Draft</pre>
    </div>
    refers to a specific named anchor within the resource
    http://www.w3.org/2008/WebVideo/Fragments/wiki/Main_Page </div>
  </li>
  <li>
    <div>
    <em>XPointer named elements </em><cite><a href="#xpointer">XPointer
    Framework</a></cite> 

    <div class="exampleInner">
    <pre>http://www.w3schools.com/xlink/dogbreeds.xml#xpointer(id("Rottweiler"))</pre>
    </div>
    refers to the element with id equal to 'Rottweiler' in the target XML
    document http://www.w3schools.com/xlink/dogbreeds.xml </div>
  </li>
  <li>
    <div>
    <em>text (plain) </em><cite><a href="#rfc5147">RFC 5147</a></cite> 

    <div class="exampleInner">
    <pre>http://example.com/text.txt#line=10,20</pre>
    </div>
    identifies lines 11 to 20 of the text.txt MIME entity </div>
  </li>
  <li>
    <div>
    <em>SVG </em><cite><a href="#svg">SVG</a></cite> 

    <div class="exampleInner">
    <pre>http://example.com/wiki/File:Yalta_summit_1945_with_Churchill,_Roosevelt,_Stalin.svg#svgView(14.64,15.73,146.98,147.48)
                </pre>
    </div>
    specifies the region to be viewed of the SVG image
    http://example.com/wiki/File:Yalta_summit_1945_with_Churchill,_Roosevelt,_Stalin.svg
    </div>
  </li>
</ul>
</div>

<div class="div3">
<h4><a id="AudioVideoURISchemes" name="AudioVideoURISchemes"></a>C.1.3 Fragment
specifications for audio/video</h4>
<ul>
  <li>
    <div>
    <em>Temporal URI/Ogg technologies </em><cite><a
    href="#temporalURI">Temporal URI</a></cite> 

    <div class="exampleInner">
    <pre>http://example.com/video.ogv#t=12.3/21.16</pre>
    </div>
    specifies a temporal fragment of the OGG Theora video
    http://example.com/video.ogv starting at 12.3 s and and ending at 21.16 s
    </div>
  </li>
  <li>
    <div>
    <em>MPEG-21 </em><cite><a href="#mpeg21">MPEG-21</a></cite> 

    <div class="exampleInner">
    <pre>http://www.example.com/myfile.mp4#mp(/~time('npt','10','30'))</pre>
    </div>
    specifies a temporal fragment of the MP4 resource
    http://www.example.com/myfile.mp4 starting at 10 s and and ending at 30 s
    </div>
  </li>
</ul>
</div>
</div>

<div class="div2">
<h3><a id="ExistingApplications" name="ExistingApplications"></a>C.2 Existing
applications using proprietary temporal media fragment URI schemes</h3>

<p>In this section, we list a number of proprietary URI schemes which are able
to identify media fragments. Note that all of these schemes only provide
support for addressing temporal media fragments.</p>
<ul>
  <li>
    <div>
    <em>Google Video</em> (<a
    href="http://lists.w3.org/Archives/Public/public-media-fragment/2008Oct/0067.html">announcement</a>) 

    <div class="exampleInner">
    <pre>http://video.google.com/videoplay?docid=4776181634656145640#&amp;ei=MCH-SNfJD5HS2gKirMD2Dg&amp;q=%22that%27s+a+tremendous+gift%22#50m16s</pre>
    </div>
    Syntax: <code>#50m16s</code></div>
  </li>
  <li>
    <div>
    <em>YouTube</em> (<a
    href="http://www.techcrunch.com/2008/10/25/youtube-enables-deep-linking-within-videos/">announcement</a>) 

    <div class="exampleInner">
    <pre>http://www.youtube.com/watch?v=1bibCui3lFM#t=1m45s</pre>
    </div>
    Syntax: <code>#t=1m45s</code> 
    <p>YouTube also does click-throughs on their embedded videos to time
    offsets (see <a
    href="http://googlesystem.blogspot.com/2009/08/clicking-on-youtube-video.html">announcement</a>),
    and returns to time offsets when people browse away from a video they half
    watched (see <a
    href="">http://youtube-global.blogspot.com/2009/09/release-notes-91709.html</a>).
    </p>
    </div>
  </li>
  <li>
    <div>
    <em>Archive.org</em> (uses the temporalURI specification <cite><a
    href="#temporalURI">Temporal URI</a></cite>) 

    <div class="exampleInner">
    <pre>http://www.archive.org/download/to-SF/toSF_512kb.mp4?t=74.5</pre>
    </div>
    Syntax: <code>?t=74.5</code></div>
  </li>
  <li>
    <div>
    <em>Videosurf</em> (<a
    href="http://solution.allthingsd.com/20081118/a-search-engine-with-a-real-eye-for-videos/">announcement</a>) 

    <div class="exampleInner">
    <pre>http://www.videosurf.com/video/michael-jordan-1989-playoffs-gm-5-vs-cavs-the-shot-904591?t=140&amp;e=184</pre>
    </div>
    Syntax: <code>?t=140&amp;e=184</code> (with t=start, e=end) </div>
  </li>
</ul>
</div>

<div class="div2">
<h3><a id="MediaFragmentApproaches" name="MediaFragmentApproaches"></a>C.3
Media fragment specification approaches</h3>

<table border="1">
  <tbody>
    <tr>
      <th>Media fragment Approach</th>
      <th>Temporal</th>
      <th>Spatial</th>
      <th>Track</th>
      <th>Name</th>
    </tr>
    <tr>
      <td colspan="5"><em>URI based</em> </td>
    </tr>
    <tr>
      <td>SVG</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
      <td>No</td>
    </tr>
    <tr>
      <td>Temporal URI/Ogg technologies</td>
      <td>Yes</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>MPEG-21</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td colspan="5"><em>Non-URI-based</em> </td>
    </tr>
    <tr>
      <td>SMIL</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>No?</td>
      <td>No?</td>
    </tr>
    <tr>
      <td>MPEG-7</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>SVG</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
      <td>?</td>
    </tr>
    <tr>
      <td>TV-Anytime</td>
      <td>Yes</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>ImageMaps</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
      <td>?</td>
    </tr>
  </tbody>
</table>

<div class="div3">
<h4><a id="URI-based" name="URI-based"></a>C.3.1 URI based</h4>

<div class="div4">
<h5><a id="SVG_URI" name="SVG_URI"></a>C.3.1.1 SVG</h5>

<div class="div5">
<h6><a id="Spatial_SVG_URI" name="Spatial_SVG_URI"></a>C.3.1.1.1 Spatial</h6>

<p>Possible via SVG 1.1 Fragment Identifiers. Only rectangular spatial regions
are supported:</p>

<div>

<div class="exampleInner">
<pre>http://example.com/wiki/File:Yalta_summit_1945_with_Churchill,_Roosevelt,_Stalin.svg#svgView(14.64,15.73,146.98,147.48)</pre>
</div>
</div>
</div>
</div>

<div class="div4">
<h5><a id="TemporalURI" name="TemporalURI"></a>C.3.1.2 Temporal URI/Ogg
technologies</h5>

<div class="div5">
<h6><a id="Temporal_TemporalURI" name="Temporal_TemporalURI"></a>C.3.1.2.1
Temporal</h6>

<p>A Temporal URI <cite><a href="#temporalURI">Temporal URI</a></cite> is being
used to play back temporal fragments in Annodex. The clip's begin and end are
specified directly in the URI. When using "#" the URI fragment identfier, it is
expected that the media fragment is played after downloading the complete
resource, while using "?" URI query parameters, it is expected that the media
fragment is extracted on the server and downloaded as a new resource to the
client. Linking to such a resource looks as follows: </p>

<div class="exampleInner">
<pre>                &lt;a href="http://example.com/video.ogv#t=12.3/21.16" /&gt;
                &lt;a href="http://example.com/video.ogv?t=12.3/21.16" /&gt;
              </pre>
</div>

<p>It it possible to use different temporal schemes, which give frame-accurate
clipping when used correctly:</p>

<div class="exampleInner">
<pre>                &lt;a href="http://example.com/video.ogv?t=npt:12.3/21.16" /&gt;
                &lt;a href="http://example.com/video.ogv?t=smpte-25:00:12:33:06/00:21:16:00" /&gt;
                &lt;a href="http://example.com/audio.ogv?t=clock:20021107T173045.25Z" /&gt;
              </pre>
</div>
</div>

<div class="div5">
<h6><a id="Track_TemporalURI" name="Track_TemporalURI"></a>C.3.1.2.2 Track</h6>

<p>Tracks are an orthogonal concept to time-aligned annotations. Therefore,
Xiph/Annodex have invented another way of describing/annotating these. It's
only new (since January 2008) and is called: ROE (for Rich Open multitrack
media Encapsulation) <cite><a href="#roe">ROE</a></cite>. With ROE you would
describe the composition of your media resource on the server. This file can
also be downloaded to a client to find out about the "capabilities" of the
file. It is however mainly used for authoring-on-the-fly. Depending on what a
client requires, the ROE file can be used to find the different tracks and
multiplex them together. Here is an example file: </p>

<div class="exampleInner">
<pre>                &lt;ROE&gt;
                &lt;head&gt;
                &lt;link rel="alternate" type="text/html" href="http://example.com/complete_video.html" /&gt;
                &lt;/head&gt;
                &lt;body&gt;
                &lt;track id="v" provides="video"&gt;
                &lt;seq&gt;
                &lt;mediaSource id="v0" src="http://example.com/video.ogv" content-type="video/ogg" /&gt;
                &lt;mediaSource id="v1" src="http://example.com/theora.ogv?track=v1" content-type="video/theora" /&gt;
                &lt;/seq&gt;
                &lt;/track&gt;
                &lt;track id="a" provides="audio"&gt;
                &lt;mediaSource id="a1" src="http://example.com/theora.ogv?track=a1" content-type="audio/vorbis" /&gt;
                &lt;/track&gt;
                &lt;track id="c1" provides="caption"&gt;
                &lt;mediaSource src="http://example.com/cmml1.cmml" content-type="text/cmml" /&gt;
                &lt;/track&gt;
                &lt;track id="c2" provides="ticker"&gt;
                &lt;mediaSource src="http://example.com/cmml2.cmml" content-type="text/cmml" /&gt;
                &lt;/track&gt;
                &lt;/body&gt;
                &lt;/ROE&gt;
              </pre>
</div>

<p>This has not completely been worked through and implemented, but Metavid is
using ROE as an export format to describe the different resources available as
subpart to one media resource. Note that ROE is also used to create an Ogg
Skeleton <cite><a href="#skeleton">Skeleton</a></cite> in a final multiplexed
file. Thus, the information inherent in ROE goes into the file (at least in
theory) and can be used to extract tracks in a URI: </p>

<div class="exampleInner">
<pre>&lt;video src="http://example.com/video.ogv?track=a/v/c1"/&gt;</pre>
</div>
</div>

<div class="div5">
<h6><a id="Named_TemporalURI" name="Named_TemporalURI"></a>C.3.1.2.3 Named</h6>

<p>To include outgoing hyperlinks into video, you have to define the
time-aligned markup of your video (or audio) stream. For this purpose, Annodex
uses CMML <cite><a href="#cmml">CMML</a></cite>. Here is an example CMML file
that can be used to include out-going hyperlinks next to or into Ogg <cite><a
href="#ogg">RFC 3533</a></cite> streams. ("next to" means here that the CMML
file is kept separate of the Ogg file, but that the client-side player knows to
synchronise the two, "into" means that CMML is multiplexed as a timed text
codec into the Ogg physical bitstream creating only one file that has to be
exchanged). The following defines a CMML clip that has an outgoing hyperlink
(this is a partial document extracted from a CMML file): </p>

<div class="exampleInner">
<pre>                &lt;clip id="tic1" start="npt:12.3" end="npt:21.16" title="Introduction"&gt;
                &lt;a href="http://example.com/fish.ogv?t=5" &gt;Watch another fish video.&lt;/a&gt;
                &lt;meta name="author" content="Frank"/&gt;
                &lt;img src="fish.png"/&gt;
                &lt;body&gt;This is the introduction to the film Joe made about fish.&lt;/body&gt;
                &lt;/clip&gt;
              </pre>
</div>

<p>Note how there is also the possibility of naming a thumbnail, providing
metadata, and giving a full description of the clip in the body tag.
Interestingly, you can also address into temporal fragments of a CMML <cite><a
href="#cmml">CMML</a></cite> file, since it is a representation of a
time-continuous data resource: </p>

<div class="exampleInner">
<pre>&lt;a href="http://example.com/sample.cmml?t=npt:4" /&gt;</pre>
</div>

<p>With CMML and ROE you can address into named temporal regions of a CMML file
itself: </p>

<div class="exampleInner">
<pre>&lt;a href="http://example.com/sample.cmml?id="tic1" /&gt;</pre>
</div>
</div>
</div>

<div class="div4">
<h5><a id="MPEG-21" name="MPEG-21"></a>C.3.1.3 MPEG-21</h5>

<p>Four different schemes are specified in MPEG-21 Part 17 <cite><a
href="#mpeg21">MPEG-21</a></cite> to address parts of media resources: ffp(),
offset(), mp(), and mask(): </p>
<ul>
  <li><p><em>ffp()</em> is applicable for file formats conforming to the ISO
    Base Media File Format (aka MPEG-4 part 12 or ISO/IEC 14496-12) and is able
    to identifiy tracks via track_ID located in the iloc and tkhd box
    respectively </p>
  </li>
  <li><p><em>offset()</em> is applicable to any digital resource and identifies
    a range of bytes in a data stream (similar functionality as the HTTP byte
    range mechanism). </p>
  </li>
  <li><p><em>mp()</em> is applicable for media resources whose Internet media
    type (or MIME type) is equal to audio/mpeg, video/mpeg, video/mp4,
    audio/mp4, or application/mp4 and provides two complementary mechanisms for
    identifying fragments in a multimedia resource via: </p>
    <ul>
      <li><p>a set of so-called dimensions (i.e., temporal, spatial or
        spatiotemporal) which are independent of the coding/container format:
        for the temporal dimension, the following time schemes are supported:
        NPT, SMPTE, MPEG-7, and UTC.</p>
      </li>
      <li><p>a hierarchical logical model of the resource. Such a logical model
        is dependent on the underlying container format (e.g., audio CD
        contains a list of tracks). The structures defined in these logical
        models are accessed with a syntax based on XPath.</p>
      </li>
    </ul>
  </li>
  <li><p><em>mask()</em> is applicable for media resources whose Internet media
    type (or MIME type) is equal to video/mp4 or video/mpeg and addresses a
    binary mask defined in a resource (binary masks can be achieved through
    MPEG-4 shape coding). Note that this mask is meant to be applied to a video
    resource and that the video resource may itself be the resource that
    contains the mask. </p>
  </li>
</ul>

<p>Note that hierarchical combinations of addressing schemes are also possible.
The '*' operator is used for this purpose. When two consecutive pointer parts
are separated by the '*' operator, the fragments located by the first pointer
part (to the left of the '*' operator) are used as a context for evaluating the
second pointer part (to the right of the '*' operator). </p>

<div class="div5">
<h6><a id="Temporal_MPEG-21" name="Temporal_MPEG-21"></a>C.3.1.3.1 Temporal</h6>

<p>Supported by the mp() scheme: </p>
<ul>
  <li>
    <div>
    Select the first sixty seconds: 

    <div class="exampleInner">
    <pre>http://www.example.com/myfile.mp4#mp(~time('npt','0','60'))</pre>
    </div>
    </div>
  </li>
</ul>
</div>

<div class="div5">
<h6><a id="Spatial_MPEG-21" name="Spatial_MPEG-21"></a>C.3.1.3.2 Spatial</h6>

<p>Supported by the mp() scheme: </p>
<ul>
  <li>
    <div>
    locates a 20x20 square region of an image: 

    <div class="exampleInner">
    <pre>http://www.example.com/myfile.mp4#mp(~region(rect(20,20,40,40)))</pre>
    </div>
    </div>
  </li>
  <li>
    <div>
    address a moving region which is restricted to the time interval between 10
    and 30 seconds NPT: 

    <div class="exampleInner">
    <pre>http://www.example.com/myfile.mp4#mp(/~time('npt','10','30')/~moving-region(rect(0,0,5,5),pt(10,10,t(5)),pt(20,20)))</pre>
    </div>
    </div>
  </li>
</ul>
</div>

<div class="div5">
<h6><a id="Track_MPEG-21" name="Track_MPEG-21"></a>C.3.1.3.3 Track</h6>

<p>Supported by the mp() and ffp() schemes: </p>
<ul>
  <li>
    <div>
    Select the first track of a CD: 

    <div class="exampleInner">
    <pre>http://www.example.com/myfile.mp4#mp(/CD/track[position()=1])</pre>
    </div>
    </div>
  </li>
  <li>
    <div>
    Select a track based on its id: 

    <div class="exampleInner">
    <pre>http://www.example.com/myfile.mp4#ffp(track_ID=101)</pre>
    </div>
    </div>
  </li>
</ul>
</div>

<div class="div5">
<h6><a id="Named_MPEG-21" name="Named_MPEG-21"></a>C.3.1.3.4 Named</h6>

<p>Supported by the ffp() and mask() schemes: </p>
<ul>
  <li>
    <div>
    Select the fragment with item ID equal to 1: 

    <div class="exampleInner">
    <pre>http://www.example.com/myfile.mp4#ffp(item_ID=1)</pre>
    </div>
    </div>
  </li>
  <li>
    <div>
    Selects a portion of an MPEG-4 video, myVideo.mp4, using a mask defined in
    the first track of the same MPEG-4 video: 

    <div class="exampleInner">
    <pre>http://www.example.com/myVideo.mp4#mask(%23ffp(item_ID=1),mpeg)</pre>
    </div>
    </div>
  </li>
</ul>
</div>
</div>
</div>

<div class="div3">
<h4><a id="Non-URI-based" name="Non-URI-based"></a>C.3.2 Non-URI-based</h4>

<div class="div4">
<h5><a id="SMIL" name="SMIL"></a>C.3.2.1 SMIL</h5>

<div class="div5">
<h6><a id="Temporal_SMIL" name="Temporal_SMIL"></a>C.3.2.1.1 Temporal</h6>

<p><em>Playing temporal fragments out-of-context</em> </p>

<p>SMIL allows you to play only a fragment of the video by using the clipBegin
and clipEnd atributes. How this is implemented, though, is out of scope for the
SMIL spec (and for http-based URLs it may well mean that implementations get
the whole media item and cut it up locally): </p>

<div class="exampleInner">
<pre>&lt;video xml:id="toc1" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" clipBegin="12.3s" clipEnd="21.16s" /&gt;</pre>
</div>

<p>It is possible to use different time schemes, which give frame-accurate
clipping when used correctly:</p>

<div class="exampleInner">
<pre>                &lt;video xml:id="toc2" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" clipBegin="npt=12.3s" clipEnd="npt=21.16s" /&gt;
                &lt;video xml:id="toc3" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" clipBegin="smpte=00:00:12:09" clipEnd="smpte=00:00:21:05" /&gt;
              </pre>
</div>

<p>Adding metadata to such a fragment is supported since SMIL 3.0: </p>

<div class="exampleInner">
<pre>                &lt;video xml:id="toc4" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" clipBegin="12.3s" clipEnd="21.16s"&gt;
                &lt;metadata&gt;
                &lt;rdf:.... xmlns:rdf="...."&gt;
                ....
                &lt;/rdf:...&gt;
                &lt;/metadata&gt;
                &lt;/video&gt;
              </pre>
</div>

<p><em>Referring to temporal fragments in-context</em> </p>

<p>The following piece of code will play back the whole video, and during the
interesting section of the video allow clicking on it to follow a link:</p>

<div class="exampleInner">
<pre>                &lt;video xml:id="tic1" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" &gt;
                &lt;area begin="12.3s" end="21.16s" href="http://www.example.com" /&gt;
                &lt;/video&gt;
              </pre>
</div>

<p>It is also possible to have a link to the relevant section of the video.
Suppose the following SMIL code is located in
http://www.example.com/smilpresentation:</p>

<div class="exampleInner">
<pre>                &lt;video xml:id="tic2" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" &gt;
                &lt;area xml:id="tic2area" begin="12.3s" end="21.16s"/&gt;
                &lt;/video&gt;
              </pre>
</div>

<p>Now, we can link to the media fragment using the following URI:</p>

<div class="exampleInner">
<pre>http://www.example.com/smilpresentation#tic2area</pre>
</div>

<p>Jumping to #tic2area will start the video at the beginning of the
interesting section. The presentation will not stop at the end, however, it
will continue. </p>
</div>

<div class="div5">
<h6><a id="Spatial_SMIL" name="Spatial_SMIL"></a>C.3.2.1.2 Spatial</h6>

<p><em>Playing spatial fragments out-of-context</em> </p>

<p>SMIL 3.0 allows playing back only a specific rectangle of the media. The
following construct will play back the center quarter of the video: </p>

<div class="exampleInner">
<pre>&lt;video xml:id="soc1" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" panZoom="25%, 25%, 50%, 50%"/&gt;</pre>
</div>

<p>Assuming the source video is 640x480, the following line plays back the
same: </p>

<div class="exampleInner">
<pre>&lt;video xml:id="soc2" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" panZoom="160, 120, 320, 240" /&gt;</pre>
</div>

<p>This construct can be combined with the temporal clipping.</p>

<p>It is possible to change the panZoom rectangle over time. The following code
fragment will show the full video for 10 seconds, then zoom in on the center
quarter over 5 seconds, then show that for the rest of the duration. The video
may be scaled up or centered, or something else, depending on SMIL layout, but
this is out of scope for the purpose of this investigation. </p>

<div class="exampleInner">
<pre>                &lt;video xml:id="soc3" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" panZoom="0, 0, 640, 480" /&gt;
                &lt;animate begin="10s" dur="5s" fill="freeze" attributeName="panZoom" to="160, 120, 320, 240 /&gt;
                &lt;/video&gt;
              </pre>
</div>

<p><em>Referring to spatial fragments in-context</em> </p>

<p>The following bit of code will enable the top-right quarter of the video to
be clicked to follow a link. Note the difference in the way the rectangle is
specified (left, top, right, bottom) when compared to panZoom (left, top,
width, height). This is an unfortunate side-effect of this attribute being
compatible with HTML and panZoom being compatible with SVG. </p>

<div class="exampleInner">
<pre>                &lt;video xml:id="tic1" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" &gt;
                &lt;area shape="rect" coords="50%, 0%, 100%, 50%" href="http://www.example.com" /&gt;
                &lt;/video&gt;
              </pre>
</div>

<p>Other shapes are possible, as in HTML and CSS. The spatial and temporal
constructs can be combined. The spatial coordinates can be animated, as for
panZoom. </p>
</div>

<div class="div5">
<h6><a id="Track_SMIL" name="Track_SMIL"></a>C.3.2.1.3 Track</h6>

<p>SMIL has no way to selectively enable or disable tracks in the video. It
only provides a general parameter mechanism which could conceivaby be used to
comminucate this information to a renderer, but this would make the document
non-portable. Moreover, no such implementations are known. </p>

<div class="exampleInner">
<pre>                &lt;video xml:id="st1" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" &gt;
                &lt;param name="jacks-remove-track" value="audio" /&gt;
                &lt;/video&gt;
              </pre>
</div>
</div>

<div class="div5">
<h6><a id="Named_SMIL" name="Named_SMIL"></a>C.3.2.1.4 Named</h6>

<p>SMIL has no way to show named fragments in the base material out-of-context.
It has no support for referring to named fragments in-context either, but it
does have support for referring to "media markers" (named points in time in the
media) if the underlying media formats supports them. Yet, no such
implementations are known: </p>

<div class="exampleInner">
<pre>                &lt;video xml:id="nf1" src="http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4" &gt;
                &lt;area begin="nf1.marker(jack-frag-begin)" end="nf1.marker(jack-frag-end)" href="http://www.example.com" /&gt;
                &lt;/video&gt;
              </pre>
</div>
</div>
</div>

<div class="div4">
<h5><a id="MPEG-7" name="MPEG-7"></a>C.3.2.2 MPEG-7</h5>

<div class="div5">
<h6><a id="Temporal_MPEG-7" name="Temporal_MPEG-7"></a>C.3.2.2.1 Temporal</h6>

<table border="1" summary="Editorial note: Raphaël">
  <tbody>
    <tr>
      <td width="50%" valign="top" align="left"><b>Editorial note:
      Raphaël</b></td>
      <td width="50%" valign="top" align="right"> </td>
    </tr>
    <tr>
      <td valign="top" align="left" colspan="2">For all dimensions covered by
        MPEG-7 the use of indirection should not forgotten.
        http://www.example.com/mpeg7file.mp7#speaker refers to the "speaker"
        xml element of this resource. The UA needs to parse this element in
        order to actually point to this fragment. </td>
    </tr>
  </tbody>
</table>

<p>A video is divided into VideoSegments that can be described by a timestamp.
MediaTimes are described using a MediaTimePoint and MediaDuration, which are
the starting time and shot duration respectively. The MediaTimePoint is defined
as follows: YYYY-MM-DDThh:mm:ss:nnnFNNN (Y: year, M: month, D: day, T: a
separation sign between date and time, h: hours, m: minutes, s: seconds, F:
separation sign between n and N, n: number of fractions, N: number of fractions
in a second). The MediaDuration is defined as follows: PnDTnHnMnSnNnF with nD
number of days, nH number of hours, nM number of minutes, nS number of seconds,
nN number of fractions and nF fractions per second. The temporal fragments can
also be defined in Time Units or relative compared to a defined time. This
MPEG-7 example describes a 'shot1' starting at 6sec 2002/2500 sec and lasts for
9sec 13389/25000 sec.</p>

<div class="exampleInner">
<pre>                &lt;VideoSegment id=”video” &gt;
                &lt;MediaLocator&gt;
                &lt;MediaUri&gt;http://www.w3.org/2008/WebVideo/Fragments/media/fragf2f.mp4&lt;/MediaUri&gt;
                &lt;/MediaLocator&gt;
                &lt;TemporalDecomposition&gt;
                &lt;VideoSegment id=”shot1”&gt;
                &lt;TextAnnotation&gt;
                &lt;KeywordAnnotation&gt;
                &lt;Keyword&gt;…&lt;/Keyword&gt;
                &lt;/KeywordAnnotation&gt;
                &lt;/TextAnnotation&gt;
                &lt;MediaTime&gt;
                &lt;MediaTimePoint&gt;T00:00:06:2002F25000&lt;/MediaTimePoint&gt;
                &lt;MediaDuration&gt;PT9S13389N25000F&lt;/MediaDuration&gt;
                &lt;/MediaTime&gt;
                &lt;/VideoSegment&gt;
                &lt;/TemporalDecomposition&gt;
                &lt;/VideoSegment&gt;
              </pre>
</div>
</div>

<div class="div5">
<h6><a id="Spatial_MPEG-7" name="Spatial_MPEG-7"></a>C.3.2.2.2 Spatial</h6>

<p>Selecting a spatial fragment of the video is also possible, using a
SpatialDecomposition-element. This MPEG-7 example describes a spatial
(polygonal) mask called "speaker" which is given by the coordinates of the
polygon: (40, 300), (40,210), ..., (320,300).</p>

<div class="exampleInner">
<pre>                &lt;VideoSegment&gt;
                &lt;SpatialDecomposition&gt;
                &lt;StillRegion id = “speaker”&gt;
                &lt;TextAnnotation&gt;
                &lt;FreeTextAnnotation&gt; Journalist&lt;/FreeTextAnnotation&gt;
                &lt;/TextAnnotation&gt;
                &lt;Mask xsi:type="SpatialMaskType"&gt;
                &lt;SubRegion&gt;
                &lt;Poly&gt;
                &lt;Coords&gt; 40 300, 40 210, ..., 320 300&lt;/Coords&gt;
                &lt;/Poly&gt;
                &lt;SubRegion&gt;
                &lt;/Mask&gt;
                &lt;/StillRegion&gt;
                &lt;/SpatialDecomposition&gt;
                &lt;/VideoSegment&gt;
              </pre>
</div>

<p>The spatial video fragment can be combined with temporal information thus
creating a SpatialTemporalDecomposition-element. </p>

<div class="exampleInner">
<pre>                &lt;VideoSegment&gt;
                &lt;SpatialTemporalDecomposition&gt;
                &lt;MovingRegion&gt;
                &lt;SpatioTemporalLocator&gt;
                &lt;MediaTime&gt;
                &lt;MediaTimePoint&gt;T00:00:06:2002F25000&lt;/MediaTimePoint&gt;
                &lt;MediaDuration&gt;PT9S13389N25000F&lt;/MediaDuration&gt;
                &lt;/MediaTime&gt;
                &lt;/SpatioTemporalLocator&gt;
                &lt;SpatioTemporalMask&gt;
                &lt;Mask xsi:type="SpatialMaskType"&gt;
                &lt;SubRegion&gt;
                &lt;Poly&gt;
                &lt;Coords&gt; 40 300, 105 210, ..., 320 240&lt;/Coords&gt;
                &lt;/Poly&gt;
                &lt;SubRegion&gt;
                &lt;/Mask&gt;
                &lt;/SpatioTemporalMask&gt;
                &lt;/MovingRegion&gt;
                &lt;/ SpatialTemporalDecomposition &gt;
                &lt;/VideoSegment&gt;
              </pre>
</div>

<p>A region of an image can also be described in MPEG-7</p>

<div class="exampleInner">
<pre>                &lt;Image id="image_yalta"&gt;           &lt;!-- whole image --&gt;
                &lt;MediaLocator&gt;
                &lt;MediaUri&gt;http://example.com/wiki/File:Yalta_summit_1945_with_Churchill,_Roosevelt,_Stalin.jpg&lt;/MediaUri&gt;
                &lt;/MediaLocator&gt;
                [...]
                &lt;SpatialDecomposition&gt;
                &lt;StillRegion id="SR1"&gt;          &lt;!-- still region --&gt;
                &lt;SpatialMask&gt;
                &lt;SubRegion&gt;
                &lt;Box&gt;14.64 15.73 161.62 163.21&lt;/Box&gt;
                &lt;SubRegion&gt;
                &lt;/SpatialMask&gt;
                &lt;/StillRegion&gt;
                &lt;/SpatialDecomposition&gt;
                &lt;/Image&gt;
              </pre>
</div>
</div>

<div class="div5">
<h6><a id="Track_MPEG-7" name="Track_MPEG-7"></a>C.3.2.2.3 Track</h6>

<p>Tracks can be described using the <em>MediaSourceDecompositionType</em>: </p>

<div class="exampleInner">
<pre>                &lt;Mpeg7&gt;
                &lt;Description xsi:type="ContentEntityType"&gt;
                &lt;MultimediaContent xsi:type="MultimediaType"&gt;
                &lt;Multimedia&gt;
                &lt;MediaSourceDecomposition gap="false" overlap="false"&gt;
                &lt;Segment xsi:type="VideoSegmentType"&gt;
                &lt;TextAnnotation&gt;
                &lt;FreeTextAnnotation&gt;video&lt;/FreeTextAnnotation&gt;
                &lt;/TextAnnotation&gt;
                &lt;MediaTime&gt;
                &lt;MediaTimePoint&gt;T00:00:00&lt;/MediaTimePoint&gt;
                &lt;MediaDuration&gt;PT0M15S&lt;/MediaDuration&gt;
                &lt;/MediaTime&gt;
                &lt;/Segment&gt;
                &lt;Segment xsi:type="AudioSegmentType"&gt;
                &lt;TextAnnotation&gt;
                &lt;FreeTextAnnotation&gt;audio&lt;/FreeTextAnnotation&gt;
                &lt;/TextAnnotation&gt;
                &lt;/Segment&gt;
                &lt;/MediaSourceDecomposition&gt;
                &lt;/Multimedia&gt;
                &lt;/MultimediaContent&gt;
                &lt;/Description&gt;
                &lt;/Mpeg7&gt;
              </pre>
</div>
</div>

<div class="div5">
<h6><a id="Named_MPEG-7" name="Named_MPEG-7"></a>C.3.2.2.4 Named</h6>

<p>Media fragments can be identified by their id.</p>

<div class="exampleInner">
<pre>                &lt;StillRegion id="speaker"&gt;
                ...
                &lt;/StillRegion&gt;
              </pre>
</div>

<p>The description of this media fragment can then be retrieved using the
following URI:</p>

<div class="exampleInner">
<pre>http://www.example.com/mpeg7file.mp7#speaker</pre>
</div>
</div>
</div>

<div class="div4">
<h5><a id="SVG" name="SVG"></a>C.3.2.3 SVG</h5>

<div class="div5">
<h6><a id="Temporal_SVG" name="Temporal_SVG"></a>C.3.2.3.1 Temporal</h6>

<p>SVG relies either on SMIL or HTML5 as a foreign object to introduce temporal
media fragmentation. It has no temporal fragmentation of its own. One can add a
video to a scene (as can be seen in example 2). Although it is possible to add
a foreign object within SVG wherein HTML5 video elements can be added. This is
(at the moment) not a solution for temporal segmentation as HTML does not
support it either. </p>

<div class="exampleInner">
<pre>                &lt;foreignObject&gt;
                &lt;div xmlns="http://www.w3.org/1999/xhtml"&gt;
                &lt;video src="myvideo.ogg"/&gt;
                &lt;/div&gt;
                &lt;/foreignObject&gt;
              </pre>
</div>

<p>Here's an example of a video that starts at second 5 and has a duration of
20 seconds:</p>

<div class="exampleInner">
<pre>                &lt;svg xmlns="http://www.w3.org/2000/svg" version="1.2" xmlns:xlink="http://www.w3.org/1999/xlink" width="320" height="240" viewBox="0 0 320 240"&gt;
                &lt;desc&gt;SVG 1.2 video example&lt;/desc&gt;
                &lt;g&gt;
                &lt;video xlink:href="test.avi" volume=".8" type="video/x-msvideo" width="320" height="240" x="50" y="50" begin=”5s” dur=”20.0s” repeatCount="indefinite"/&gt;
                &lt;/g&gt;
                &lt;/svg&gt;
              </pre>
</div>
</div>

<div class="div5">
<h6><a id="Spatial_SVG" name="Spatial_SVG"></a>C.3.2.3.2 Spatial</h6>

<p>XML snippet specifying a region of an image within SVG: </p>

<div class="exampleInner">
<pre>                &lt;svg xmlns:svg="http://www.w3.org/2000/svg" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"&gt;
                &lt;g id="layer1"&gt;
                &lt;"image" id="image_yalta" x="-0.34" y="0.20" width="400" height="167"
                xlink:href="http://example.com/wiki/File:Yalta_summit_1945_with_Churchill,_Roosevelt,_Stalin.jpg"/&gt;
                &lt;"rect" id="SR1" x="14.64" y="15.73" width="146.98" height="147.48"
                style="opacity:1;stroke:#ff0000;stroke-opacity:1"/&gt;
                &lt;/g&gt;
                &lt;/svg&gt;
              </pre>
</div>
</div>
</div>

<div class="div4">
<h5><a id="TV-Anytime" name="TV-Anytime"></a>C.3.2.4 TV-Anytime</h5>

<div class="div5">
<h6><a id="Temporal_TV-Anytime" name="Temporal_TV-Anytime"></a>C.3.2.4.1
Temporal</h6>

<p>Within TV-Anytime, programmes can be divided in segments. Segmentation
refers to the ability to define, access, and manipulate temporal intervals
(i.e. segments) within an AV stream. The following excerpt of a TV-Anytime
description illustrates the use of segments:</p>

<div class="exampleInner">
<pre>                &lt;TVAMain&gt;
                &lt;ProgramDescription&gt;
                &lt;ProgramInformationTable&gt;
                ...
                &lt;/ProgramInformationTable&gt;
                &lt;ProgramLocationTable&gt;
                ...
                &lt;/ProgramLocationTable&gt;
                &lt;SegmentInformationTable&gt;
                &lt;SegmentList&gt;
                &lt;SegmentInformation segmentId="segment_2"&gt;
                ...
                &lt;SegmentLocator&gt;
                &lt;MediaRelTimePoint&gt;T00:00:06:2002F25000&lt;/MediaRelTimePoint&gt;
                &lt;MediaDuration&gt;PT9S13389N25000F&lt;/MediaDuration&gt;
                &lt;/SegmentLocator&gt;
                ...
                &lt;/SegmentInformation&gt;
                &lt;/SegmentList&gt;
                &lt;/SegmentInformationTable&gt;
                &lt;/ProgramDescription&gt;
                &lt;/TVAMain&gt;
              </pre>
</div>

<p><em>SegmentLocator</em> locates the segment within a programme (instance) in
terms of start time and duration (optional). If the duration is not specified,
the segment ends at the end of the programme. Note that the types of
<em>MediaRelTimePoint</em> and <em>MediaDuration</em> correspond to the MPEG-7
types <em>MediaRelTimePointType</em> and <em>MediaDurationType</em>
respectively. </p>
</div>

<div class="div5">
<h6><a id="Named_TV-Anytime" name="Named_TV-Anytime"></a>C.3.2.4.2 Named</h6>

<p>Supported by the <em>segmentId</em> attribute of the
<em>SegmentInformationType</em>. The description of the media fragment can be
retrieved as follows: </p>

<div class="exampleInner">
<pre>http://www.example.com/tv_anytime_description.tva#xpointer(//*[@segmentId="segment_2"])</pre>
</div>
</div>
</div>

<div class="div4">
<h5><a id="ImageMaps" name="ImageMaps"></a>C.3.2.5 ImageMaps</h5>

<div class="div5">
<h6><a id="Spatial_ImageMaps" name="Spatial_ImageMaps"></a>C.3.2.5.1
Spatial</h6>

<p><em>Client-side image maps</em>: The MAP element specifies a client-side
image map. An image map is associated with an element via the element's usemap
attribute. The MAP element content model includes then either AREA elements or
A elements for specifying the geometric regions and the link associated with
them. Possible shapes are: rectangle (rect), circle (circle) or arbitrary
polygon (poly) </p>

<div class="exampleInner">
<pre>                &lt;img src="image.gif" usemap="#my_map"/&gt;
                &lt;map name="my_map"&gt;
                &lt;a href="guide.html" shape="rect" coords="0,0,118,28"&gt;Access Guide&lt;/a&gt; |
                &lt;a href="shortcut.html" shape="rect" coords="118,0,184,28"&gt;Go&lt;/A&gt; |
                &lt;a href="search.html" shape="circle" coords="184,200,60"&gt;Search&lt;/A&gt; |
                &lt;a href="top10.html" shape="poly" coords="276,0,276,28,100,200,50,50,276,0"&gt;Top Ten&lt;/A&gt;
                &lt;/map&gt;
              </pre>
</div>

<div class="exampleInner">
<pre>                &lt;map name="my_map"&gt;
                &lt;area href="guide.html" alt="Access Guide" shape="rect" coords="0,0,118,28"&gt;
                &lt;area href="search.html" alt="Search" shape="rect" coords="184,0,276,28"&gt;
                &lt;area href="shortcut.html" alt="Go" shape="circle"coords="184,200,60"&gt;
                &lt;area href="top10.html" alt="Top Ten" shape="poly" coords="276,0,276,28,100,200,50,50,276,0"&gt;
                &lt;/map&gt;
              </pre>
</div>

<p><em>Server-side image maps</em>: When the user activates the link by
clicking on the image, the screen coordinates are sent directly to the server
where the document resides. Screen coordinates are expressed as screen pixel
values relative to the image. The user agent derives a new URI from the URI
specified by the href attribute of the A element, by appending ? followed by
the x and y coordinates, separated by a comma. For instance, if the user clicks
at the location x=10, y=27 then the derived URI is:
http://www.example.com/images?10,27 </p>

<div class="exampleInner">
<pre>                &lt;a href="http://www.example.com/images" &gt;
                &lt;img src="image.gif" ismap alt="target"/&gt;
                &lt;/a&gt;
              </pre>
</div>
</div>
</div>

<div class="div4">
<h5><a id="HTML5" name="HTML5"></a>C.3.2.6 HTML 5</h5>

<table border="1" summary="Editorial note: Silvia">
  <tbody>
    <tr>
      <td width="50%" valign="top" align="left"><b>Editorial note:
      Silvia</b></td>
      <td width="50%" valign="top" align="right"> </td>
    </tr>
    <tr>
      <td valign="top" align="left" colspan="2">Currently, HTML5 relies on the
        abilities of the used media format for providing media fragment
        addressing. In future, HTML5 is planning to adopt the fragment URI
        specifications of this document for providing fragment addressing.
        Input from the WHAT and HTML working groups is requested. </td>
    </tr>
  </tbody>
</table>
</div>
</div>
</div>
</div>

<div class="div1">
<h2><a id="acknowledgments" name="acknowledgments"></a>D Acknowledgements
(Non-Normative)</h2>

<p>This document is the work of the <a
href="http://www.w3.org/2008/WebVideo/Fragments/">W3C Media Fragments Working
Group</a>. Members of the Working Group are (at the time of writing, and in
alphabetical order): Eric Carlson (Apple, Inc.), Michael Hausenblas (DERI
Galway at the National University of Ireland, Galway, Ireland), Jack Jansen
(CWI), Yves Lafon (W3C), Wonsuk Lee (Electronics and Telecommunications
Research Institute), Erik Mannens (IBBT), Thierry Michel (W3C), Guillaume
(Jean-Louis) Olivrin (Meraka Institute), Soohong Daniel Park (Samsung
Electronics Co., Ltd.), Conrad Parker (W3C Invited Experts), Silvia Pfeiffer
(W3C Invited Experts), David Singer (Apple, Inc.), Raphaël Troncy (EURECOM),
Vassilis Tzouvaras (K-Space), Davy Van Deursen (IBBT) </p>

<p>The people who have contributed to <a
href="http://lists.w3.org/Archives/Public/public-media-fragment/">discussions
on public-media-fragment@w3.org</a> are also gratefully acknowledged. In
particular: Olivier Aubert, Werner Bailer, Pierre-Antoine Champin, Cyril
Concolato, Franck Denoual, Martin J. Dürst, Jean Pierre Evain, Ken
Harrenstien, Kilroy Hughes, Philip Jägenstedt, Ryo Kawaguchi, Véronique
Malaisé, Henrik Nordstrom, Yannick Prié, Yves Raimond, Julian Reschke,
Geoffrey Sneddon, Felix Sasaki, Philip Taylor, Christian Timmerer, Jorrit
Vermeiren and Munjo Yu. </p>
</div>

<div class="div1">
<h2><a id="change-log" name="change-log"></a>E Change Log (Non-Normative)</h2>

<p>@@This paragraph will be replaced by the change log.@@</p>
</div>
</div>
</body>
</html>