forked from w3c/encrypted-media
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathwebm-format.html
326 lines (214 loc) · 16.2 KB
/
webm-format.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
<!DOCTYPE html>
<html lang="en" dir="ltr" typeof="bibo:Document " prefix="bibo: http://purl.org/ontology/bibo/ w3p: http://www.w3.org/2001/02pd/rec54#">
<head><meta lang="" property="dc:language" content="en">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>WebM EME Stream Format and Initialization Data</title>
<!-- script to register bugs -->
<!-- Disabled unless/until it supports GitHub issues.
<script src="https://w3c.github.io/webcomponents/assets/scripts/bug-assist.js"></script>
<meta name="bug.product" content="HTML WG">
<meta name="bug.component" content="Encrypted Media Extensions">
-->
<link rel="stylesheet" href="eme.css">
<style>/*****************************************************************
* ReSpec 3 CSS
* Robin Berjon - http://berjon.com/
*****************************************************************/
/* --- INLINES --- */
em.rfc2119 {
text-transform: lowercase;
font-variant: small-caps;
font-style: normal;
color: #900;
}
h1 acronym, h2 acronym, h3 acronym, h4 acronym, h5 acronym, h6 acronym, a acronym,
h1 abbr, h2 abbr, h3 abbr, h4 abbr, h5 abbr, h6 abbr, a abbr {
border: none;
}
dfn {
font-weight: bold;
}
a.internalDFN {
color: inherit;
border-bottom: 1px solid #99c;
text-decoration: none;
}
a.externalDFN {
color: inherit;
border-bottom: 1px dotted #ccc;
text-decoration: none;
}
a.bibref {
text-decoration: none;
}
cite .bibref {
font-style: normal;
}
code {
color: #C83500;
}
/* --- TOC --- */
.toc a, .tof a {
text-decoration: none;
}
a .secno, a .figno {
color: #000;
}
ul.tof, ol.tof {
list-style: none outside none;
}
.caption {
margin-top: 0.5em;
font-style: italic;
}
/* --- TABLE --- */
table.simple {
border-spacing: 0;
border-collapse: collapse;
border-bottom: 3px solid #005a9c;
}
.simple th {
background: #005a9c;
color: #fff;
padding: 3px 5px;
text-align: left;
}
.simple th[scope="row"] {
background: inherit;
color: inherit;
border-top: 1px solid #ddd;
}
.simple td {
padding: 3px 10px;
border-top: 1px solid #ddd;
}
.simple tr:nth-child(even) {
background: #f0f6ff;
}
/* --- DL --- */
.section dd > p:first-child {
margin-top: 0;
}
.section dd > p:last-child {
margin-bottom: 0;
}
.section dd {
margin-bottom: 1em;
}
.section dl.attrs dd, .section dl.eldef dd {
margin-bottom: 0;
}
@media print {
.removeOnSave {
display: none;
}
}
</style><link rel="stylesheet" href="https://www.w3.org/StyleSheets/TR/W3C-ED"><!--[if lt IE 9]><script src='https://www.w3.org/2008/site/js/html5shiv.js'></script><![endif]--></head>
<body class="h-entry" role="document" id="respecDocument"><div class="head" role="contentinfo" id="respecHeader">
<p>
<a href="http://www.w3.org/"><img width="72" height="48" src="https://www.w3.org/Icons/w3c_home" alt="W3C"></a>
</p>
<h1 class="title p-name" id="title" property="dcterms:title">WebM EME Stream Format and Initialization Data</h1>
<h2 id="w3c-editor-s-draft-12-march-2015"><abbr title="World Wide Web Consortium">W3C</abbr> Editor's Draft <time property="dcterms:issued" class="dt-published" datetime="2015-03-12">12 March 2015</time></h2>
<dl>
<dt>This version:</dt>
<dd><a class="u-url" href="https://w3c.github.io/encrypted-media/cenc-format.html">https://w3c.github.io/encrypted-media/cenc-format.html</a></dd>
<dt>Latest published version:</dt>
<dd><a href="http://www.w3.org/TR/encrypted-media/">http://www.w3.org/TR/encrypted-media/</a></dd>
<dt>Latest editor's draft:</dt>
<dd><a href="https://w3c.github.io/encrypted-media/cenc-format.html">https://w3c.github.io/encrypted-media/cenc-format.html</a></dd>
<dt>Editors:</dt>
<dd class="p-author h-card vcard" property="bibo:editor" resource="_:editor0"><span property="rdf:first" typeof="foaf:Person"><span property="foaf:name" class="p-name fn">David Dorwin</span>, <a property="foaf:workplaceHomepage" class="p-org org h-org h-card" href="https://www.google.com/">Google Inc.</a></span>
<span property="rdf:rest" resource="_:editor1"></span>
</dd>
<dd class="p-author h-card vcard" resource="_:editor1"><span property="rdf:first" typeof="foaf:Person"><span property="foaf:name" class="p-name fn">Adrian Bateman</span>, <a property="foaf:workplaceHomepage" class="p-org org h-org h-card" href="https://www.microsoft.com/">Microsoft Corporation</a></span>
<span property="rdf:rest" resource="_:editor2"></span>
</dd>
<dd class="p-author h-card vcard" resource="_:editor2"><span property="rdf:first" typeof="foaf:Person"><span property="foaf:name" class="p-name fn">Mark Watson</span>, <a property="foaf:workplaceHomepage" class="p-org org h-org h-card" href="https://www.netflix.com/">Netflix Inc.</a></span>
<span property="rdf:rest" resource="rdf:nil"></span>
</dd>
<dt>Repository:</dt>
<dd>
<a href="https://github.com/w3c/encrypted-media/">https://github.com/w3c/encrypted-media/</a>
</dd>
</dl>
<p class="copyright">
<a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> ©
2015
<a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup>
(<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>,
<a href="http://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>,
<a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>).
<abbr title="World Wide Web Consortium">W3C</abbr> <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>
<hr>
</div>
<section id="abstract" class="introductory" property="dc:abstract"><h2 id="h-abstract" resource="#h-abstract"><span property="xhv:role" resource="xhv:heading">Abstract</span></h2>
<p>This specification defines the stream format and initialization data for using WebM [<cite><a class="bibref" href="#bib-WebM">WebM</a></cite>] with the <a href="index.html#">Encrypted Media Extensions</a>.</p>
</section><section id="sotd" class="introductory"><h2 id="h-sotd" resource="#h-sotd"><span property="xhv:role" resource="xhv:heading">Status of This Document</span></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 <abbr title="World Wide Web Consortium">W3C</abbr> publications and the
latest revision of this technical report can be found in the <a href="http://www.w3.org/TR/"><abbr title="World Wide Web Consortium">W3C</abbr> technical reports index</a> at
http://www.w3.org/TR/.</em>
</p>
<p>The working group maintains <a href="https://github.com/w3c/encrypted-media/issues">a list of all bug reports that the editors have not yet tried to address</a>.</p>
<p>Implementors should be aware that this specification is not stable. <strong>Implementors who are not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways.</strong> Vendors interested in implementing this specification before it eventually reaches the Candidate Recommendation stage should join the mailing list mentioned below and take part in the discussions.</p>
<p>
This document was published by the <a href="http://www.w3.org/html/wg/">HTML Working Group</a> as an Editor's Draft.
If you wish to make comments regarding this document, please send them to
<a href="mailto:public-html-media@w3.org">public-html-media@w3.org</a>
(<a href="mailto:public-html-media-request@w3.org?subject=subscribe">subscribe</a>,
<a href="http://lists.w3.org/Archives/Public/public-html-media/">archives</a>).
All comments are welcome.
</p>
<p>
Publication as an Editor's Draft does not imply endorsement by the <abbr title="World Wide Web Consortium">W3C</abbr>
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>
This document was produced by a group operating under the
<a id="sotd_patent" property="w3p:patentRules" href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 <abbr title="World Wide Web Consortium">W3C</abbr> Patent
Policy</a>.
<abbr title="World Wide Web Consortium">W3C</abbr> maintains a <a href="https://www.w3.org/2004/01/pp-impl/40318/status" rel="disclosure">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 <abbr title="World Wide Web Consortium">W3C</abbr> Patent Policy</a>.
</p>
<p>This document is governed by the <a id="w3c_process_revision" href="http://www.w3.org/2014/Process-20140801/">1 August 2014 <abbr title="World Wide Web Consortium">W3C</abbr> Process Document</a>.
</p>
</section><section id="toc"><h2 class="introductory" id="h-toc" resource="#h-toc"><span property="xhv:role" resource="xhv:heading">Table of Contents</span></h2><ul class="toc" role="directory" id="respecContents"><li class="tocline"><a href="#stream-format" class="tocxref"><span class="secno">1. </span>Stream Format </a></li><li class="tocline"><a href="#detect-encrypt" class="tocxref"><span class="secno">2. </span>Detecting Encryption</a></li><li class="tocline"><a href="#init-data" class="tocxref"><span class="secno">3. </span>Initialization Data and Events</a></li><li class="tocline"><a href="#references" class="tocxref"><span class="secno">A. </span>References</a><ul class="toc"><li class="tocline"><a href="#normative-references" class="tocxref"><span class="secno">A.1 </span>Normative references</a></li></ul></li></ul></section>
<section id="stream-format" typeof="bibo:Chapter" resource="#stream-format" property="bibo:hasPart">
<!--OddPage--><h2 id="h-stream-format" resource="#h-stream-format"><span property="xhv:role" resource="xhv:heading"><span class="secno">1. </span>Stream Format </span></h2>
<p>Encrypted WebM streams [<cite><a class="bibref" href="#bib-WebM-Encryption">WebM-Encryption</a></cite>] are encrypted at the block level with AES-128 CTR encryption.
The container shall include appropriate values within the <a href="http://matroska.org/technical/specs/index.html#ContentEncryption">ContentEncryption</a> [<cite><a class="bibref" href="#bib-Matroska">Matroska</a></cite>] element.
</p>
<p>WebM streams may be partially encrypted, both at the <a href="http://matroska.org/technical/specs/index.html#LevelTrack">Track</a> level and the block level.
In the former case, a subset of Tracks in the stream have a <a href="http://matroska.org/technical/specs/index.html#ContentEncryption">ContentEncryption</a> element.
In the latter case, a subset of the blocks within a Track containing a <a href="http://matroska.org/technical/specs/index.html#ContentEncryption">ContentEncryption</a> element are marked as encrypted.
</p>
</section>
<section id="detect-encrypt" typeof="bibo:Chapter" resource="#detect-encrypt" property="bibo:hasPart">
<!--OddPage--><h2 id="h-detect-encrypt" resource="#h-detect-encrypt"><span property="xhv:role" resource="xhv:heading"><span class="secno">2. </span>Detecting Encryption</span></h2>
<p>When a WebM <a href="http://matroska.org/technical/specs/index.html#LevelTrack">Track</a> [<cite><a class="bibref" href="#bib-Matroska">Matroska</a></cite>] is parsed, the presence of a <a href="http://matroska.org/technical/specs/index.html#ContentEncKeyID">ContentEncKeyID</a> element indicates that blocks in the track may be encrypted.
</p><p>For the purposes of the <a href="index.html#encrypted-block-encountered">encrypted block encountered</a>, encrypted blocks are those marked encrypted by the <a href="http://www.webmproject.org/docs/webm-encryption/#46-signal-byte-format">Signal Byte.</a> [<cite><a class="bibref" href="#bib-WebM-Encryption">WebM-Encryption</a></cite>]</p>
</section>
<section id="init-data" typeof="bibo:Chapter" resource="#init-data" property="bibo:hasPart">
<!--OddPage--><h2 id="h-init-data" resource="#h-init-data"><span property="xhv:role" resource="xhv:heading"><span class="secno">3. </span>Initialization Data and Events</span></h2>
<p><a href="index.html#initialization-data">Initialization Data</a> is always a single <a href="index.html#decryption-key-id">key ID</a>, as defined by the <a href="http://matroska.org/technical/specs/index.html#ContentEncKeyID">ContentEncKeyID</a> [<cite><a class="bibref" href="#bib-Matroska">Matroska</a></cite>] element of the <a href="http://matroska.org/technical/specs/index.html#LevelTrack">Track</a>.</p>
<p>Each time a <a href="http://matroska.org/technical/specs/index.html#ContentEncKeyID">ContentEncKeyID</a> element is encountered, the <a href="index.html#initdata-encountered">Initialization Data encountered</a> algorithm shall be invoked with <var title="">initDataType</var> = "webm" and <var title="">initData</var> = the value in that element.</p>
</section>
<section id="references" class="appendix" typeof="bibo:Chapter" resource="#references" property="bibo:hasPart"><!--OddPage--><h2 id="h-references" resource="#h-references"><span property="xhv:role" resource="xhv:heading"><span class="secno">A. </span>References</span></h2><section id="normative-references" typeof="bibo:Chapter" resource="#normative-references" property="bibo:hasPart"><h3 id="h-normative-references" resource="#h-normative-references"><span property="xhv:role" resource="xhv:heading"><span class="secno">A.1 </span>Normative references</span></h3><dl class="bibliography" resource=""><dt id="bib-Matroska">[Matroska]</dt><dd><a href="http://matroska.org/technical/specs/index.html" property="dc:requires"><cite>Matroska Specifications</cite></a>. 9 January 2014. URL: <a href="http://matroska.org/technical/specs/index.html" property="dc:requires">http://matroska.org/technical/specs/index.html</a>
</dd><dt id="bib-WebM">[WebM]</dt><dd><a href="http://www.webmproject.org/code/specs/container/" property="dc:requires"><cite>WebM Container Guidelines</cite></a>. 28 April 2014. URL: <a href="http://www.webmproject.org/code/specs/container/" property="dc:requires">http://www.webmproject.org/code/specs/container/</a>
</dd><dt id="bib-WebM-Encryption">[WebM-Encryption]</dt><dd>Frank Galligan. <a href="http://www.webmproject.org/docs/webm-encryption/" property="dc:requires"><cite>WebM Encryption</cite></a>. 4 March 2015. URL: <a href="http://www.webmproject.org/docs/webm-encryption/" property="dc:requires">http://www.webmproject.org/docs/webm-encryption/</a>
</dd></dl></section></section></body></html>