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Allow level-id to be different in codec match #3023

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11 changes: 11 additions & 0 deletions amendments.json
Original file line number Diff line number Diff line change
Expand Up @@ -1242,5 +1242,16 @@
"web-platform-tests/wpt#48361"
]
}
],
"codec-match-without-level-id": [
{
"description": "Two codecs are considered the same even if level-id is not",
"type": "correction",
"status": "candidate",
"difftype": "modify",
"id": 52,
"pr": 3023,
"testUpdates": "not-testable"
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Remote SDP is testable.

}
]
}
1 change: 1 addition & 0 deletions base-rec.html
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Expand Up @@ -11174,6 +11174,7 @@ <h4 id="methods-8">
</ol>
</div>
<div id="codecmatch-algorithm"><!-- added as anchor to new algo in revised spec --></div>
<div id="codec-match-without-level-id"><!-- amendment to the codecmatch-algorithm --></div>
<div class="note" role="note" id="issue-container-generatedID-47"><div role="heading" class="note-title marker" id="h-note-47" aria-level="5"><span>Note</span></div><p class="">
If set, the offerer's codec preferences will decide the order
of the codecs in the offer. If the answerer does not have any
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92 changes: 75 additions & 17 deletions webrtc.html
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Original file line number Diff line number Diff line change
Expand Up @@ -2818,9 +2818,9 @@ <h4>
<li>
<p>For each <var>encoding</var> in
<var>transceiver</var>.{{RTCRtpTransceiver/[[Sender]]}}.{{RTCRtpSender/[[SendEncodings]]}},
if <var>encoding</var>.{{RTCRtpEncodingParameters/codec}} does not
[= codec dictionary match | match =] any entry in <var>codecs</var>,
[=map/remove=] <var>encoding</var>[{{RTCRtpEncodingParameters/codec}}].</p>
if <var>encoding</var>.{{RTCRtpEncodingParameters/codec}} does not match any entry in
<var>codecs</var>, using the [= codec dictionary match =] algorithm with <var>ignoreLevels</var>
set to <code>true</code>, [=map/remove=] <var>encoding</var>.{{RTCRtpEncodingParameters/codec}}.</p>
</li>
</ol>
</li>
Expand Down Expand Up @@ -3748,7 +3748,9 @@ <h2>
or {{RTCRtpTransceiverDirection/"sendrecv"}},
exclude any codecs not included in the
[=RTCRtpSender/list of implemented send codecs=] for
<var>kind</var>.
<var>kind</var>, using the [= codec dictionary match =]
algorithm with <var>ignoreLevels</var> set to
<code>true</code>.</p>
</p>
</li>
<li>
Expand All @@ -3759,7 +3761,9 @@ <h2>
or {{RTCRtpTransceiverDirection/"sendrecv"}},
exclude any codecs not included in the
[=list of implemented receive codecs=] for
<var>kind</var>.
<var>kind</var>, using the [= codec dictionary match =]
algorithm with <var>ignoreLevels</var> set to
<code>true</code>.
</p>
</li>
</ol>
Expand Down Expand Up @@ -4031,7 +4035,9 @@ <h2>
or {{RTCRtpTransceiverDirection/"sendrecv"}},
exclude any codecs not included in the
[=RTCRtpSender/list of implemented send codecs=] for
<var>kind</var>.
<var>kind</var>, using the [= codec dictionary match =]
algorithm with <var>ignoreLevels</var> set to
<code>true</code>.
</p>
</li>
<li>
Expand All @@ -4042,7 +4048,9 @@ <h2>
or {{RTCRtpTransceiverDirection/"sendrecv"}},
exclude any codecs not included in the
[=list of implemented receive codecs=] for
<var>kind</var>.
<var>kind</var>, using the [= codec dictionary match =]
algorithm with <var>ignoreLevels</var> set to
<code>true</code>.
</p>
</li>
</ol>
Expand Down Expand Up @@ -9086,7 +9094,8 @@ <h2>
</li>
<li id="setparameters-codec-validation-4">
Any <var>encoding</var> in encodings [=map/exists|contains=] a codec
[= codec dictionary match | not found =] in <var>choosableCodecs</var>.
not found in <var>choosableCodecs</var>, using the [= codec dictionary match =]
algorithm with <var>ignoreLevels</var> set to <code>true</code>.
</li>
</ul>
</li>
Expand Down Expand Up @@ -9791,8 +9800,16 @@ <h2>
<dfn data-idl>codec</dfn> of type <span class="idlMemberType">RTCRtpCodec</span>
</dt>
<dd>
<p>Optional value selecting which codec is used for this encoding's
RTP stream. If absent, the user agent can chose to use any negotiated codec.</p>
<p>
Optional value selecting which codec is used for this encoding's
RTP stream. If absent, the user agent can chose to use any negotiated codec.
</p>
<p>
When {{codec}} is set and {{RTCRtpSender/[[SendCodecs]]}} have been negotiated,
the user agent SHOULD use the first {{RTCRtpSender/[[SendCodecs]]}} matching
{{codec}} for sending, according to the [= codec dictionary match =] algorithm
with <var>ignoreLevels</var> set to <code>true</code>.
</p>
</dd>
</div>
<div>
Expand Down Expand Up @@ -11466,10 +11483,13 @@ <h2>
</ol>
</div>
<div id="codecmatch-algorithm">
<p> The <dfn class="export">codec dictionary match</dfn> algorithm
given two {{RTCRtpCodec}} dictionaries
<var>first</var> and <var>second</var> is as follows:
<p>
The <dfn class="export">codec dictionary match</dfn> algorithm given two
{{RTCRtpCodec}} dictionaries <var>first</var> and <var>second</var>, and
an <var>ignoreLevels</var> boolean defaulting to <code>false</code> if not
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specified, is as follows:
</p>
</div>
<ol class=algorithm>
<li>
<p>
Expand Down Expand Up @@ -11497,18 +11517,56 @@ <h2>
<p>
If either (but not both) of <var>first</var>.{{RTCRtpCodec/sdpFmtpLine}}
and <var>second</var>.{{RTCRtpCodec/sdpFmtpLine}} are [= map/exist | missing =],
or if they both [=map/exist=] and <var>first</var>.{{RTCRtpCodec/sdpFmtpLine}}
is different from <var>second</var>.{{RTCRtpCodec/sdpFmtpLine}}, return
<code>false</code>.
return <code>false</code>.
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</p>
</li>
<li>
<p>
If both <var>first</var>.{{RTCRtpCodec/sdpFmtpLine}} and
<var>second</var>.{{RTCRtpCodec/sdpFmtpLine}} [=map/exist=], and are in key/value format, run the following
steps:
</p>
<ol>
<li>
<p>
Let <var>firstMediaFormat</var> be a key-value map of the media formats constructed
from <var>first</var>.{{RTCRtpCodec/sdpFmtpLine}} and <var>secondMediaFormat</var>
be a key-value map of the media formats constructed from
<var>second</var>.{{RTCRtpCodec/sdpFmtpLine}}.
</p>
<p class="note">
Which FMTP parameters make up the media format is codec specific. In some cases
a parameter can be omitted and still be inferred, in which case it is also a part
of the media format of that codec.
</p>
</li>
<li>
<p>
If <var>firstMediaFormat</var> is not equal to <var>secondMediaFormat</var>, return
<code>false</code>.
</p>
</li>
<li>
<div id="codec-match-without-level-id">
<p>
If <var>ignoreLevels</var> is <code>false</code> and the highest complying bitstream
levels inferred from <var>first</var>.{{RTCRtpCodec/sdpFmtpLine}} and
<var>second</var>.{{RTCRtpCodec/sdpFmtpLine}} are different, return <code>false</code>.
</p>
<p class="note">
Even if <var>ignoreLevels</var> is <code>true</code>, some codecs (such as H.264) include
levels in the media format, so that the level cannot be ignored in this algorithm.
</p>
</div>
</li>
</ol>
</li>
<li>
<p>
Return <code>true</code>.
</p>
</li>
</ol>
</div>
<p class="note">
If set, the offerer's receive codec preferences will decide the order
of the codecs in the offer. If the answerer does not have any
Expand Down