--- a/encrypted-media/encrypted-media-respec.html Fri Oct 10 14:40:35 2014 -0700
+++ b/encrypted-media/encrypted-media-respec.html Fri Oct 10 14:40:59 2014 -0700
@@ -111,19 +111,9 @@
<!-- Adds the '-> arrow in conditional steps. -->
dl.switch > dt:before { content: '\21AA'; padding: 0 0.5em 0 0; display: inline-block; width: 1em; text-align: right; line-height: 0.5em; }
- <!-- Adds underlining of non-normative <span>. -->
- p > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]),
- li > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]) { border-bottom: solid #9999CC; }
-
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.domintro:before { display: table; margin: -1em -0.5em -0.5em auto; width: auto; content: 'This box is non-normative. Implementation requirements are given below this box.'; color: black; font-style: italic; border: solid 2px; background: white; padding: 0 0.25em; }
</style>
- <style type="text/css">
- <!-- For inline non-normative text. -->
- .non-normative { font-style: italic; color: DarkSlateGrey; }
- .non-normative em { font-style: normal;}
- .non-normative var { font-style: normal;}
- </style>
</head>
<body>
@@ -169,12 +159,11 @@
<section id="definitions">
<h3>Definitions</h3>
- <p>Text in <span class="non-normative">this font and color</span> is non-normative.</p>
<section id="cdm">
<h4>Content Decryption Module (CDM)</h4>
<p>The Content Decryption Module (CDM) is a generic term for the client component that provides the functionality, including decryption, for one or more <a href="#key-system">Key Systems</a>.</p>
- <p class="non-normative">Implementations may or may not separate the implementations of CDMs or treat them as separate from the user agent.
+ <p class="note">Implementations may or may not separate the implementations of CDMs or treat them as separate from the user agent.
This is transparent to the API and application.
A user agent may support one or more CDMs.</p>
</section>
@@ -187,10 +176,11 @@
The <a href="#common-key-systems">Common Key Systems</a> are supported by all user agents. User agents may also provide additional CDMs with corresponding Key System strings.
</p>
- <p>A Key System string is always a reverse domain name. <span class="non-normative">For example, "com.example.somesystem".</span>
+ <p>A Key System string is always a reverse domain name.
Key System strings are compared using case-sensitive matching. It is recommended that CDMs use simple lower-case ASCII key system strings.</p>
+ <p class="note">For example, "com.example.somesystem".</p>
- <p class="non-normative">
+ <p class="note">
Within a given system ("somesystem" in the example), subsystems may be defined as determined by the key system provider.
For example, "com.example.somesystem.1" and "com.example.somesystem.1_5".
Key System providers should keep in mind that these will be used for comparison and discovery, so they should be easy to compare and the structure should remain reasonably simple.
@@ -211,15 +201,15 @@
<section id="session-id">
<h4>Session ID</h4>
- <p>A Session ID is a unique string identifier generated by the <a href="#cdm">CDM</a> that can be used by the application to identify <coderef>MediaKeySession</coderef> objects.
- <span class="non-normative">(The underlying content protection protocol does not necessarily need to support Session IDs.)</span>
- </p>
+ <p>A Session ID is a unique string identifier generated by the <a href="#cdm">CDM</a> that can be used by the application to identify <coderef>MediaKeySession</coderef> objects.</p>
<p>A new Session ID is generated each time the user agent and CDM successfully create a new session.</p>
<p>Each Session ID shall be unique within the browsing context in which it was created.
Session IDs for "<coderef prefix="sessiontype">persistent</coderef>" sessions must be unique within the <a href="http://www.w3.org/TR/html5/browsers.html#origin-0">origin</a> over time, including across browsing sessions.
</p>
+
+ <p class="note">The underlying content protection protocol does not necessarily need to support Session IDs.</p>
</section>
<section id="decryption-key">
@@ -230,7 +220,8 @@
Such keys may only be provided to the <a href="#cdm">CDM</a> via an <methodref>update</methodref> call. (They may later be loaded by <methodref>load</methodref> as part of the stored session data.)
</p>
- <p>A key is considered <em>usable</em> if the CDM is certain the key is currently usable for decryption. <span class="non-normative">For example, a key is not usable if its license has expired.</span></p>
+ <p>A key is considered <em>usable</em> if the CDM is certain the key is currently usable for decryption.</p>
+ <p class="note">For example, a key is not usable if its license has expired.</p>
</section>
<section id="decryption-key-id">
@@ -250,7 +241,7 @@
<section id="initialization-data">
<h4>Initialization Data</h4>
- <p class="non-normative">
+ <p class="note">
<a href="#key-system">Key Systems</a> usually require a block of initialization data containing information about the stream to be decrypted before they can construct a license request message.
This block could be a simple key or content ID or a more complex structure containing such information.
It should always allow unique identification of the key(s) needed to decrypt the content.
@@ -342,8 +333,8 @@
</ol>
<p id="server-certificate">The <methoddfn name="setServerCertificate">setServerCertificate(<var title="true">serverCertificate</var>)</methoddfn> method provides a server certificate to be used to encrypt messages to the license server. It must run the following steps:</p>
- <p class="non-normative">The contents of <var title="true">serverCertificate</var> are <a href="#key-system">Key System</a>-specific.</p>
- <p class="non-normative">Key systems that use such certificates should also support requesting the certificate from the server via an additional round trip. This simplifies interoperability for applications that are not designed to provide certificates to specific key systems.</p>
+ <p class="note">The contents of <var title="true">serverCertificate</var> are <a href="#key-system">Key System</a>-specific.</p>
+ <p class="note">Key systems that use such certificates should also support requesting the certificate from the server via an additional round trip. This simplifies interoperability for applications that are not designed to provide certificates to specific key systems.</p>
<ol>
<li><p>If <var title="true">serverCertificate</var> is an empty array, return a promise rejected with a new <code><dom4ref name="exception-domexception">DOMException</dom4ref></code> whose name is <code><a href="#dfn-InvalidAccessError">"InvalidAccessError"</a></code>.</p></li>
@@ -410,8 +401,9 @@
<dl class="switch">
<dt>If <var title="true">keySystem</var> is a value that may be successfully passed to <methodref>create</methodref></dt>
<dd>Let <var title="true">probably result</var> be "<coderef prefix="istypesupportedresult">probably</coderef>".</dd>
- <dt>Otherwise <span class="non-normative">(as may be the case for strings that are only used for discovery)</span></dt>
+ <dt>Otherwise</dt>
<dd>Let <var title="true">probably result</var> be "<coderef prefix="istypesupportedresult">maybe</coderef>".</dd>
+ <p class="note">This may, for example, be the case for strings that are only used for discovery.</p>
</dl>
</li>
@@ -439,8 +431,12 @@
<li><p>If <var title="true">contentType</var> is an empty string or contains an invalid or unrecognized MIME type, return the <a href="#dom-istypesupportedresultempty">empty string</a> and abort these steps.</p></li>
<li><p>Let <var title="true">container</var> be the container type specified by <var title="true">contentType</var>.</p></li>
<li><p>Let <var title="true">parameters</var> be the <a href="http://tools.ietf.org/html/rfc6381">RFC 6381</a> parameters, if any, specified by <var title="true">contentType</var>.</p></li>
- <li><p>Let <var title="true">media types</var> be the set of media types specified by <var title="true">parameters</var>. <span class="non-normative">(For example, all of the codecs.)</span> It may be empty. The case-sensitivity of string comparisons is determined by the appropriate RFC or other specification. <span class="non-normative">(Case-sensitive string comparison is recommended because <a href="http://tools.ietf.org/html/rfc6381#section-3.3">RFC 6381</a> says, "Values are case sensitive" for some formats.)</span></p></li>
- <li><p>If the user agent does not support <var title="true">container</var>, return the <a href="#dom-istypesupportedresultempty">empty string</a> and abort these steps. The case-sensitivity of string comparisons is determined by the appropriate RFC. <span class="non-normative">(Per <a href="http://tools.ietf.org/html/rfc6838#section-4.2">RFC 6838</a>, "Both top-level type and subtype names are case-insensitive.")</span></p></li>
+ <li><p>Let <var title="true">media types</var> be the set of media types specified by <var title="true">parameters</var>. It may be empty. The case-sensitivity of string comparisons is determined by the appropriate RFC or other specification.</p>
+ <p class="note">For example, all of the codecs. Case-sensitive string comparison is recommended because <a href="http://tools.ietf.org/html/rfc6381#section-3.3">RFC 6381</a> says, "Values are case sensitive" for some formats.</p>
+ </li>
+ <li><p>If the user agent does not support <var title="true">container</var>, return the <a href="#dom-istypesupportedresultempty">empty string</a> and abort these steps. The case-sensitivity of string comparisons is determined by the appropriate RFC.</p>
+ <p class="note">Per <a href="http://tools.ietf.org/html/rfc6838#section-4.2">RFC 6838</a>, "Both top-level type and subtype names are case-insensitive.")</p>
+ </li>
<li><p>If the user agent and <var title="true">keySystem</var> implementation do not support playback of encrypted <videoanchor name="media-data">media data</videoanchor> for all <var title="true">media types</var>, return the <a href="#dom-istypesupportedresultempty">empty string</a> and abort these steps.</p></li>
<li><p>If <var title="true">capability</var> was not provided, follow the steps for the first matching condition from the following list and abort these steps:</p>
<dl class="switch">
@@ -511,8 +507,8 @@
<p>The steps of an algorithm are always aborted when resolving or rejecting a promise.</p>
<p>The <methoddfn name="generateRequest">generateRequest(<var title="true">initDataType</var>, <var title="true">initData</var>)</methoddfn> method generates a request based on the <var title="true">initData</var>. It must run the following steps:</p>
- <p class="non-normative">The contents of <var title="true">initData</var> are container-specific <a href="#initialization-data">Initialization Data</a>.
- <var title="true">initDataType</var> is the <a href="#initialization-data-type">initialization data type</a> that indicates how to interpret <var title="true">initData</var>.
+ <p><var title="true">initData</var> is <a href="#initialization-data">Initialization Data</a>, and
+ <var title="true">initDataType</var> is an <a href="#initialization-data-type">initialization data type</a> that indicates how to interpret <var title="true">initData</var>.
</p>
<ol>
@@ -546,17 +542,22 @@
<li><p>Follow the steps for the first matching condition from the following list:</p>
<dl class="switch">
<dt>If <var title="true">session type</var> is "<coderef prefix="sessiontype">temporary</coderef>"</dt>
- <dd>Let <var title="true">requested session type</var> be a temporary non-persisted session. <span class="non-normative">(The returned license must not be persistable.)</span></dd>
+ <dd>Let <var title="true">requested session type</var> be a temporary non-persisted session.</p>
+ <p class="note">The returned license must not be persistable.</p>
+ </dd>
<dt>If <var title="true">session type</var> is "<coderef prefix="sessiontype">persistent</coderef>"</dt>
- <dd>Let <var title="true">requested session type</var> be a persistable session. <span class="non-normative">(The returned license may be persistable.)</span></dd>
+ <dd>Let <var title="true">requested session type</var> be a persistable session.<p>
+ <p class="note">The returned license may be persistable.)</p>
+ </dd>
</dl>
- <p class="non-normative">Note: The license server determines the type of license that is returned, either persistent or non-persistent. A persistent license cannot be added to a non-persistable session.</p>
+ <p class="note">The license server determines the type of license that is returned, either persistent or non-persistent. A persistent license cannot be added to a non-persistable session.</p>
</li>
<li><p>Let <var title="true">session id</var> be a unique <a href="#session-id">Session ID</a> string.</p>
<p>If <var title="true">session type</var> is "<coderef prefix="sessiontype">persistent</coderef>", the ID must be unique within the the <a href="http://www.w3.org/TR/html5/browsers.html#origin-0">origin</a> of this object's <code><dom4ref name="document">Document</dom4ref></code> over time, including across Documents and browsing sessions.</p>
</li>
- <li><p>Let <var title="true">message</var> be a request <span class="non-normative">(e.g. a license request)</span> for the <var title="true">requested session type</var> generated based on the <var>init data</var>, which is interpreted per <var title="true">initDataType</var>.</p>
+ <li><p>Let <var title="true">message</var> be a request for the <var title="true">requested session type</var> generated based on the <var>init data</var>, which is interpreted per <var title="true">initDataType</var>.</p>
+ <p class="note">For example, a license request.</p>
<p>The <var title="true">cdm</var> must not use any stream-specific data, including <videoanchor name="media-data">media data</videoanchor>, not provided via the <var>init data</var>.</p>
<p>The <var title="true">cdm</var> should <em>not</em> store session data, including the session ID, at this point. See <a href="#session-storage">Session Storage and Persistence</a>.</p>
</li>
@@ -601,7 +602,7 @@
<li><p>Let <var title="true">session data</var> be the data stored for the <var>sanitized session ID</var> in the <var title="true">origin</var>.
This must not include data from other origin(s) or that is not associated with an origin.</p></li>
<li><p>If there is an unclosed "<coderef prefix="sessiontype">persistent</coderef>" session in any <dom4ref name="document">Document</dom4ref> representing the <var title="true">session data</var>, reject <var>promise</var> with a new <code><dom4ref name="exception-domexception">DOMException</dom4ref></code> whose name is <code><a href="#dfn-QuotaExceededError">"QuotaExceededError"</a></code>.</p>
- <p class="non-normative">In other words, do not create a session if a non-closed persistent session already exists for this <var>sanitized session ID</var> in any browsing context.</p>
+ <p class="note">In other words, do not create a session if a non-closed persistent session already exists for this <var>sanitized session ID</var> in any browsing context.</p>
</li>
<li><p>Load the <var title="true">session data</var>.</p></li>
<li><p>If the <var title="true">session data</var> indicates an expiration time for the session, let <var title="true">expiration time</var> be the expiration time in milliseconds since 01 January 1970 UTC.</p></li>
@@ -628,7 +629,7 @@
</ol>
<p>The <methoddfn name="update">update(<var title="true">response</var>)</methoddfn> method provides messages, including licenses, to the CDM. It must run the following steps:</p>
- <p class="non-normative">The contents of <var title="true">response</var> are <var title="true"><a href="#key-system">keySystem</a></var>-specific.</p>
+ <p class="note">The contents of <var title="true">response</var> are <var title="true"><a href="#key-system">keySystem</a></var>-specific.</p>
<ol>
<li><p>If this object's <var title="true">callable</var> value is false, return a promise rejected with a new <code><dom4ref name="exception-domexception">DOMException</dom4ref></code> whose name is <code><a href="#dfn-InvalidStateError">"InvalidStateError"</a></code>.</p></li>
@@ -663,10 +664,10 @@
<dd>Reject <var>promise</var> with a new <code><dom4ref name="exception-domexception">DOMException</dom4ref></code> whose name is <code><a href="#dfn-InvalidAccessError">"InvalidAccessError"</a></code>.</dd>
</dl>
<p>See also <a href="#session-storage">Session Storage and Persistence</a>.</p>
- <p class="non-normative">Note: When <var>sanitized response</var> contains key(s) and/or related data, <var title="true">cdm</var> will likely cache the key and related data indexed by key ID.</p>
- <p class="non-normative">Note: The replacement algorithm within a session is <a href="#key-system">Key System</a>-dependent.</p>
- <p class="non-normative">Note: Keys from different sessions should be cached independently such that closing one session does not affect keys in other sessions, even if they have overlapping key IDs.</p>
- <p class="non-normative">Note: It is recommended that CDMs support a standard and reasonably high minimum number of keys per <coderef>MediaKeySession</coderef> object, including a standard replacement algorithm, and a standard and reasonably high minimum number of <coderef>MediaKeySession</coderef> objects.
+ <p class="note">When <var>sanitized response</var> contains key(s) and/or related data, <var title="true">cdm</var> will likely cache the key and related data indexed by key ID.</p>
+ <p class="note">The replacement algorithm within a session is <a href="#key-system">Key System</a>-dependent.</p>
+ <p class="note">Keys from different sessions should be cached independently such that closing one session does not affect keys in other sessions, even if they have overlapping key IDs.</p>
+ <p class="note">It is recommended that CDMs support a standard and reasonably high minimum number of keys per <coderef>MediaKeySession</coderef> object, including a standard replacement algorithm, and a standard and reasonably high minimum number of <coderef>MediaKeySession</coderef> objects.
This enables a reasonable number of key rotation algorithms to be implemented across user agents and may reduce the likelihood of playback interruptions in use cases that involve various streams in the same element (i.e. adaptive streams, various audio and video tracks) using different keys.
</p>
</li>
@@ -690,9 +691,9 @@
<li><p>Return <var>promise</var>.</p></li>
</ol>
- <p>The <methoddfn name="close">close()</methoddfn> method allows an application to indicate that it no longer needs the session and the CDM should release any resources associated with this object and close it.
- <span class="non-normative">The returned promise is resolved when the request has been processed, and the <coderef>closed</coderef> attribute promise is resolved when the session is closed.</span>
- It must run the following steps:</p>
+ <p>The <methoddfn name="close">close()</methoddfn> method allows an application to indicate that it no longer needs the session and the CDM should release any resources associated with this object and close it.</p>
+ <p class="note">The returned promise is resolved when the request has been processed, and the <coderef>closed</coderef> attribute promise is resolved when the session is closed.</p>
+ <p>It must run the following steps:</p>
<ol>
<li><p>If this object's <var title="true">callable</var> value is false, return a promise rejected with a new <code><dom4ref name="exception-domexception">DOMException</dom4ref></code> whose name is <code><a href="#dfn-InvalidStateError">"InvalidStateError"</a></code>.</p></li>
@@ -732,9 +733,8 @@
<li>
<p>Process the remove request.</p>
<p>This may involve exchanging message(s) with the application.</p>
- <p>Unless this step fails, the CDM must have cleared all stored session data associated with this object, including the <coderef>sessionId</coderef>, before proceeding to the next step.
- <span class="non-normative">(A subsequent call to <methodref>load</methodref> with <coderef>sessionId</coderef> would fail because there is no data stored for that session ID.)</span>
- </p>
+ <p>Unless this step fails, the CDM must have cleared all stored session data associated with this object, including the <coderef>sessionId</coderef>, before proceeding to the next step.</p>
+ <p class="note">A subsequent call to <methodref>load</methodref> with <coderef>sessionId</coderef> would fail because there is no data stored for that session ID.)</p>
</li>
</ol>
</li>
@@ -799,7 +799,7 @@
</dd>
<dt><var title="">event</var> . <coderef>message</coderef></dt>
<dd>
- <p>Returns the message <span class="non-normative">(i.e. license request)</span> to send.</p>
+ <p>Returns the message to send.</p>
</dd>
</dl>
<div class="impl">
@@ -812,7 +812,7 @@
<section id="mediakeysession-events" class="informative">
<h3>Event Summary</h3>
- <p>Note: In some implementations, <coderef>MediaKeySession</coderef> objects may not fire any events until the <coderef>MediaKeys</coderef> object is associated with a media element using <methodref>setMediaKeys</methodref>.</p>
+ <p class="note">In some implementations, <coderef>MediaKeySession</coderef> objects may not fire any events until the <coderef>MediaKeys</coderef> object is associated with a media element using <methodref>setMediaKeys</methodref>.</p>
<table>
<thead>
@@ -870,7 +870,8 @@
<li><p>Let the <var title="true">session</var> be the associated <coderef>MediaKeySession</coderef> object.</p></li>
<li><p><Queue-a-task/> to <fire-a-simple-event/> named <coderef prefix="event">keyschange</coderef> at the <var title="true">session</var>.</p></li>
<li><p><Queue-a-task/> to run the <a href="#algorithms-resume-playback">Attempt to Resume Playback If Necessary</a> algorithm on each of the <a href="#media-element">media element(s)</a> whose <coderef prefix="attr">mediaKeys</coderef> attribute is the MediaKeys object that created the <var title="true">session</var>.</p>
- <p>The user agent may choose to skip this step if it knows resuming will fail <span class="non-normative">(i.e. no additional keys became available)</span>.</p>
+ <p>The user agent may choose to skip this step if it knows resuming will fail.</p>
+ <p class="note">For example, the user agenet may skip this step if no additional keys became available.</p>
</li>
</ol>
</section>
@@ -893,7 +894,7 @@
<section id="algorithms-session-close">
<h4>Session Close</h4>
<p>The Session Close algorithm is run when the CDM closes the session associated with a <coderef>MediaKeySession</coderef> object.</p>
- <p class="non-normative">The CDM may close a session at any point, such as in response to a <methodref>close</methodref> call, when the session is no longer needed, or when system resources are lost.
+ <p class="note">The CDM may close a session at any point, such as in response to a <methodref>close</methodref> call, when the session is no longer needed, or when system resources are lost.
Keys in other sessions should be unaffected, even if they have overlapping key IDs.
</p>
<p>The following steps are run:</p>
@@ -980,7 +981,7 @@
<p>An application that creates a "<coderef prefix="sessiontype">persistent</coderef>" session should later remove the stored data using <methodref>remove</methodref>.
The CDM may also remove sessions as appropriate, but applications should not rely on this.
</p>
- <p class="non-normative">See the <a href="#security">Security Considerations</a> and <a href="#privacy">Privacy Considerations</a> sections for additional considerations when supporting persistent storage.</p>
+ <p class="note">See the <a href="#security">Security Considerations</a> and <a href="#privacy">Privacy Considerations</a> sections for additional considerations when supporting persistent storage.</p>
</section>
</section>
@@ -1030,7 +1031,9 @@
<li><p>If the <coderef prefix="attr">mediaKeys</coderef> attribute is not null, run the following steps:</p>
<ol>
<li><p>If the user agent or CDM do not support removing the association, let this object's <var title="true">attaching media keys</var> value be false and reject <var>promise</var> with a new <code><dom4ref name="exception-domexception">DOMException</dom4ref></code> whose name is <code><a href="#dfn-NotSupportedError">"NotSupportedError"</a></code>.</p></li>
- <li><p>If the association cannot currently be removed <span class="non-normative">(i.e. during playback)</span>, let this object's <var title="true">attaching media keys</var> value be false and reject <var>promise</var> with a new <code><dom4ref name="exception-domexception">DOMException</dom4ref></code> whose name is <code><a href="#dfn-InvalidStateError">"InvalidStateError"</a></code>.</p></li>
+ <li><p>If the association cannot currently be removed, let this object's <var title="true">attaching media keys</var> value be false and reject <var>promise</var> with a new <code><dom4ref name="exception-domexception">DOMException</dom4ref></code> whose name is <code><a href="#dfn-InvalidStateError">"InvalidStateError"</a></code>.</p>
+ <p class="note">For example, some implementations may not allow removal during playback.</p>
+ </li>
<li><p>Stop using the CDM instance represented by the <coderef prefix="attr">mediaKeys</coderef> attribute to decrypt <videoanchor name="media-data">media data</videoanchor> and remove the association with the media element.</p></li>
<li><p>If the preceding step failed, let this object's <var title="true">attaching media keys</var> value be false and reject <var>promise</var> with a new <code><dom4ref name="exception-domexception">DOMException</dom4ref></code> whose name is the appropriate <a href="#error-names">error name</a>.</p></li>
</ol>
@@ -1046,7 +1049,8 @@
</ol>
</li>
<li><p><Queue-a-task/> to run the <a href="#algorithms-resume-playback">Attempt to Resume Playback If Necessary</a> algorithm on the media element.</p>
- <p>The user agent may choose to skip this step if it knows resuming will fail <span class="non-normative">(i.e. <var>mediaKeys</var> has no sessions)</span>.</p>
+ <p>The user agent may choose to skip this step if it knows resuming will fail.<p>
+ <p class="note">For example, the user agenet may skip this step if <var>mediaKeys</var> has no sessions.</p>
</li>
</ol>
</li>
@@ -1058,8 +1062,8 @@
<li><p>Return <var>promise</var>.</p></li>
</ol>
- <p class="non-normative">Note: Support for clearing or replacing the associated <coderef>MediaKeys</coderef> object during playback is a quality of implementation issue. In many cases it will result in a bad user experience or rejected promise.</p>
- <p class="non-normative">Note: As a best practice, applications should create a MediaKeys object and call <methodref>setMediaKeys</methodref> before providing <videoanchor name="media-data">media data</videoanchor> (for example, setting the src attribute of the <a href="#media-element">media element</a>). This avoids potential delays in some implementations.</p>
+ <p class="note">Support for clearing or replacing the associated <coderef>MediaKeys</coderef> object during playback is a quality of implementation issue. In many cases it will result in a bad user experience or rejected promise.</p>
+ <p class="note">As a best practice, applications should create a MediaKeys object and call <methodref>setMediaKeys</methodref> before providing <videoanchor name="media-data">media data</videoanchor> (for example, setting the src attribute of the <a href="#media-element">media element</a>). This avoids potential delays in some implementations.</p>
</section>
<section id="htmlmediaelement-event-definitions">
@@ -1112,7 +1116,7 @@
<td><coderef>MediaEncryptedEvent</coderef></td>
<td>The user agent encounters <a href="#initialization-data">Initialization Data</a> in the <videoanchor name="media-data">media data</videoanchor>.</td>
<td><readystate/> is equal to <have-metadata/> or greater.
- <span class="non-normative">It is possible that the element is playing or has played.</span>
+ <p class="note">It is possible that the element is playing or has played.</p>
</td>
</tr>
</tbody>
@@ -1144,8 +1148,8 @@
<coderef>initDataType</coderef> = <var title="">initDataType</var><br></br>
<coderef>initData</coderef> = <var title="">initData</var>
</li></ul>
- <p class="non-normative">Note that <readystate/> is <em>not</em> changed and no algorithms are aborted. This event merely provides information.</p>
- <p class="non-normative">Note that the <coderef>initData</coderef> attribute will be null if the media data is <em>not</em> <cors-same-origin/> or is <a href="#mixed-content">mixed content</a>.
+ <p class="note"><readystate/> is <em>not</em> changed and no algorithms are aborted. This event merely provides information.</p>
+ <p class="note">The <coderef>initData</coderef> attribute will be null if the media data is <em>not</em> <cors-same-origin/> or is <a href="#mixed-content">mixed content</a>.
Applications may retrieve the Initialization Data from an alternate source.
</p>
</li>
@@ -1156,7 +1160,7 @@
<section id="algorithms-encrypted-block">
<h4>Encrypted Block Encountered</h4>
- <p>The following steps are run when the <a href="#media-element">media element</a> encounters a block <span class="non-normative">(i.e. frame)</span> of encrypted <videoanchor name="media-data">media data</videoanchor> during the <resource-fetch-algorithm/>:</p>
+ <p>The following steps are run when the <a href="#media-element">media element</a> encounters a block of encrypted <videoanchor name="media-data">media data</videoanchor> during the <resource-fetch-algorithm/>:</p>
<ol>
<li><p>If the media element's <coderef prefix="attr">mediaKeys</coderef> attribute is not null, run the following steps:</p>
@@ -1164,9 +1168,11 @@
<li><p>Let <var title="true">media keys</var> be the <coderef>MediaKeys</coderef> object referenced by that atribute.</p></li>
<li><p>Let <var title="true">cdm</var> be the CDM loaded during the <a href="#dom-create">initialization</a> of the <var title="true">media keys</var>.</p></li>
<li><p>If there is at least one <coderef>MediaKeySession</coderef> created by the <var title="true">media keys</var> on which the <a href="#algorithms-session-close">Session Close</a> algorithm has not been run, run the following steps:</p>
- <p class="non-normative">This check ensures the <var title="true">cdm</var> has finished loading and is a prequisite for a matching key being available.</p>
+ <p class="note">This check ensures the <var title="true">cdm</var> has finished loading and is a prequisite for a matching key being available.</p>
<ol>
- <li><p>Let the <var title="true">block key ID</var> be the key ID of the current block <span class="non-normative">(as specified by the container)</span>.</p></li>
+ <li><p>Let the <var title="true">block key ID</var> be the key ID of the current block.</p>
+ <p class="note">The key ID is generally specified by the container.</p>
+ </li>
<li><p>Use the <var title="true">cdm</var> to execute the following steps:</p>
<ol>
<li><p>Let <var title="true">available keys</var> be the union of keys in sessions that were created by the <var title="true">media keys</var>.</p></li>
@@ -1176,7 +1182,7 @@
<dd>Run the following steps:
<ol>
<li><p>Let <var title="">block key</var> be the matching key.</p>
- <p class="non-normative">Note: If multiple sessions contain a <em>usable</em> key for the <var title="">block key ID</var>, which key to use is <a href="#key-system">Key System</a>-dependent.</p>
+ <p class="note">If multiple sessions contain a <em>usable</em> key for the <var title="">block key ID</var>, which key to use is <a href="#key-system">Key System</a>-dependent.</p>
</li>
<li><p>Use the <var title="true">cdm</var> to decrypt the block using <var title="">block key</var>.</p></li>
<li><p>Follow the steps for the first matching condition from the following list:</p>
@@ -1187,11 +1193,13 @@
<dd>Run the following steps:
<ol>
<li><p>If the <coderef>waitingFor</coderef> attribute on the media element is "<coderef prefix="waitingfor">key</coderef>", set the <coderef>waitingFor</coderef> attribute on the media element to "<coderef prefix="waitingfor">none</coderef>".</p></li>
- <li><p>Abort these steps and process the decrypted block as normal. <span class="non-normative">(Decode the block.)</span></p></li>
+ <li><p>Abort these steps and process the decrypted block as normal.</p>
+ <p class="note">In other words, decode the block.</p>
+ </li>
</ol>
</dd>
</dl>
- <p class="non-normative">Note: Not all decryption problems (i.e. using the wrong key) will result in a decryption failure. In such cases, no error is fired here but one may be fired during decode.</p>
+ <p class="note">Not all decryption problems (i.e. using the wrong key) will result in a decryption failure. In such cases, no error is fired here but one may be fired during decode.</p>
</li>
</ol>
</dd>
@@ -1199,8 +1207,7 @@
<dd>
<p class="issue"><a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=26372">Bug 26372</a> - It is TBD whether anything should happen in this case.</p>
</dd>
- <dt class="non-normative">Otherwise (there is no key for the <var title="true">block key ID</var> in any session)</dt>
- <dd class="non-normative">Continue.</dd>
+ <p class="note">Otherwise, there is no key for the <var title="true">block key ID</var> in any session so continue.</p>
</dl>
</li>
</ol>
@@ -1210,9 +1217,8 @@
</ol>
</li>
<li>
- <p><span class="non-normative">There is no usable key for the block.</span>
- Run the following steps:
- </p>
+ <p>Run the following steps:</p>
+ <p class="note">These steps are reached when there is no usable key for the block.</p>
<ol>
<li><p>Run the <a href="#algorithms-queue-waiting">Queue a "waiting" Event</a> algorithm on the media element.</p></li>
<li><p>Wait for a signal to resume playback.</p></li>
@@ -1220,7 +1226,7 @@
</li>
</ol>
- <div class="non-normative">
+ <div class="note">
<p>For frame-based encryption, this may be implemented as follows when the media element attempts to decode a frame as part of the <resource-fetch-algorithm/>:</p>
<ol>
<li><p>Let <var title="">encrypted</var> be false.</p></li>
@@ -1300,9 +1306,9 @@
<section id="common-key-systems">
<h2>Common Key Systems</h2>
- <p>All user agents must support the common key systems described in this section.
- <span class="non-normative">This ensures that there is a common baseline level of protection that is guaranteed to be supported in all user agents, including those that are entirely open source.
- Thus, content providers that need only basic protection can build simple applications that will work on all platforms without needing to work with any content protection providers.</span>
+ <p>All user agents must support the common key systems described in this section.<p>
+ <p class="note">This ensures that there is a common baseline level of protection that is guaranteed to be supported in all user agents, including those that are entirely open source.
+ Thus, content providers that need only basic protection can build simple applications that will work on all platforms without needing to work with any content protection providers.
</p>
<span id="simple-decryption-clear-key"></span> <!-- Legacy anchor name. -->
@@ -1448,7 +1454,7 @@
Applications should determine the URLs to use. The <coderef>type</coderef> attribute of the <coderef prefix="event">message</coderef> event can be used by the application to select among a set of URLs if applicable.
</p>
<p>User Agents are responsible for providing users with a secure way to browse the web. Since User Agents may integrate with third party CDM implementations, CDM implementers must provide sufficient information and controls to user agent implementers to enable them to properly asses the security implications of integrating with the Key System.</p>
- <p>Note: Unsandboxed CDMs (or CDMs that use platform features) and UAs that use them must be especially careful in all areas of security, including parsing of key and media data, etc. due to the potential for compromises to provide access to OS/platform features, interact with or run as root, access drivers, kernel, firmware, hardware, etc., all of which may not be written to be robust against hostile software or web-based attacks. Additionally, CDMs may not be updated with security fixes as frequently, especially when part of the OS, platform or hardware.</p>
+ <p>Unsandboxed CDMs (or CDMs that use platform features) and UAs that use them must be especially careful in all areas of security, including parsing of key and media data, etc. due to the potential for compromises to provide access to OS/platform features, interact with or run as root, access drivers, kernel, firmware, hardware, etc., all of which may not be written to be robust against hostile software or web-based attacks. Additionally, CDMs may not be updated with security fixes as frequently, especially when part of the OS, platform or hardware.</p>
<p>User agents may choose to only support the EME APIs and/or specific Key Systems (i.e. based on privacy and security risks) on secure origins.
This is especially important if a user agent chooses to support a Key System implementation that cannot be sufficiently sandboxed or otherwise secured.