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Filter codecs preferences on transceiver direction
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@henbos
henbos committed Nov 7, 2024
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15 changes: 15 additions & 0 deletions amendments.json
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Expand Up @@ -891,6 +891,21 @@
"id": 42
}
],
"setcodecpreferences-filter-direction": [
{
"description": "setCodecPreferences takes both send and receive codecs which get filtered at negotiation based on transceiver direction",
"pr": 1337,
"type": "correction",
"status": "candidate",
"tests": [
"webrtc/RTCRtpTransceiver-setCodecPreferences-direction.html"
],
"testUpdates": [
"web-platform-tests/wpt#1337"
],
"id": 50
}
],
"internalslot-jitterbuffertarget": [
{
"description": "Add control for the receiver's jitter buffer",
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80 changes: 47 additions & 33 deletions webrtc.html
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Expand Up @@ -3729,14 +3729,11 @@ <h2>
</li>
<li>
<p>
The <i>codec preferences</i> of a [= media
description =]'s [= associated =] transceiver,
<var>transceiver</var>, is said to be the value of
<var>transceiver</var>.{{RTCRtpTransceiver/[[PreferredCodecs]]}}
with the following filtering applied (or said not
to be set if
<var>transceiver</var>.{{RTCRtpTransceiver/[[PreferredCodecs]]}}
is empty):
Let <var>filteredCodecs</var> be the result of
applying the following filter on
<var>transceiver</var>.{{RTCRtpTransceiver/[[PreferredCodecs]]}}.
The filtering MUST NOT change the order of the codec
preferences:
</p>
<ol>
<li>
Expand Down Expand Up @@ -3769,8 +3766,11 @@ <h2>
</li>
</ol>
<p>
The filtering MUST NOT change the order of the
codec preferences.
The <i>codec preferences</i> of a [= media
description =]'s [= associated =] transceiver,
<var>transceiver</var>, is said to be the value of
<var>filteredCodecs</var> if non-empty and said to
be unset otherwise.
</p>
</li>
<li>
Expand Down Expand Up @@ -4012,14 +4012,11 @@ <h2>
<ol id="create-answer-restrictions">
<li>
<p>
The <i>codec preferences</i> of an m= section's
[= associated =] transceiver,
<var>transceiver</var>, is said to be the value of
<var>transceiver</var>.{{RTCRtpTransceiver/[[PreferredCodecs]]}}
with the following filtering applied (or said not
to be set if
<var>transceiver</var>.{{RTCRtpTransceiver/[[PreferredCodecs]]}}
is empty):
Let <var>filteredCodecs</var> be the result of
applying the following filter on
<var>transceiver</var>.{{RTCRtpTransceiver/[[PreferredCodecs]]}}.
The filtering MUST NOT change the order of the
codec preferences:
</p>
<ol>
<li>
Expand Down Expand Up @@ -4052,8 +4049,11 @@ <h2>
</li>
</ol>
<p>
The filtering MUST NOT change the order of the
codec preferences.
The <i>codec preferences</i> of a [= media
description =]'s [= associated =] transceiver,
<var>transceiver</var>, is said to be the value of
<var>filteredCodecs</var> if non-empty and said to
be unset otherwise.
</p>
</li>
<li>
Expand Down Expand Up @@ -11325,31 +11325,40 @@ <h2>
<dfn data-idl="">setCodecPreferences</dfn>
</dt>
<dd>
<div id="setcodecpreferences-receive">
<div id="setcodecpreferences-receive"><!-- kept for candidate amendments management purposes --></div>
<div id="setcodecpreferences-filter-direction">
<p>
The {{setCodecPreferences}} method overrides the default
receive codec preferences used by the <a>user agent</a>. When
codec preferences used by the <a>user agent</a>. When
generating a session description using either
{{RTCPeerConnection/createOffer}} or
{{RTCPeerConnection/createAnswer}}, the <a>user agent</a>
MUST use the indicated codecs, in the order specified in the
<var>codecs</var> argument, for the media section
corresponding to this {{RTCRtpTransceiver}}.
{{RTCPeerConnection/createAnswer}}, the <a>user agent</a> MUST
filter the preferred codecs on {{RTCRtpTransceiver/direction}}
and, if this results in a non-empty list, it MUST use the
specified codecs in the order of the <var>codecs</var>
argument, for the media section corresponding to this
{{RTCRtpTransceiver}}.
</p>
<p>
This method allows applications to disable the negotiation of
specific codecs (including RTX/RED/FEC). It also allows an
application to cause a remote peer to prefer the codec that
appears first in the list for sending.
application to affect the remote peer's default codecs;
influencing both what they should send by default and the
default codec order of subsequently generated remote SDP. But
just like the local peer can override its defaults, so can the
remote peer. The local peer MUST be prepared to receive any
codec that it has been negotiated, even ones not first in the
list.
</p>
<!-- 'until this method is called again' is not clear. Ditto for 'any default value' -->
<p class="needs-test">
Codec preferences remain in effect for all calls to
{{RTCPeerConnection/createOffer}} and
{{RTCPeerConnection/createAnswer}} that include this
{{RTCRtpTransceiver}} until this method is called again.
Setting <var>codecs</var> to an empty sequence resets codec
preferences to any default value.
Setting <var>codecs</var> to an empty sequence, or one that
becomes empty after {{RTCRtpTransceiver/direction}} filtering,
resets codec preferences to any default value.
</p>
<p class="note">
Codecs have their payload types listed under each m= section
Expand All @@ -11364,8 +11373,11 @@ <h2>
be removed from the mapping of payload types in the SDP.
</p>
<p>
{{setCodecPreferences}} will reject attempts to set <var>codecs</var>
[= codec dictionary match | not matching =] codecs found in
{{setCodecPreferences}} will reject attempts to set
<var>codecs</var> [= codec dictionary match | not matching =]
codecs found in either
{{RTCRtpSender}}.{{RTCRtpSender/getCapabilities}}(<var>kind</var>)
or
{{RTCRtpReceiver}}.{{RTCRtpReceiver/getCapabilities}}(<var>kind</var>),
where <var>kind</var> is the kind of the
{{RTCRtpTransceiver}} on which the method is called.
Expand Down Expand Up @@ -11407,7 +11419,9 @@ <h2>
</li>
<li class="no-test-needed">
<p>
Let <var>codecCapabilities</var> be
Let <var>codecCapabilities</var> be the union of
{{RTCRtpSender}}.{{RTCRtpSender/getCapabilities}}(<var>kind</var>).{{RTCRtpParameters/codecs}}
and
{{RTCRtpReceiver}}.{{RTCRtpReceiver/getCapabilities}}(<var>kind</var>).{{RTCRtpParameters/codecs}}.
</p>
</li>
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