- From: Bernard Aboba <Bernard.Aboba@microsoft.com>
- Date: Wed, 22 Feb 2017 19:44:53 +0000
- To: Varun Singh <varun@callstats.io>
- CC: "public-webrtc@w3.org" <public-webrtc@w3.org>
Varun said:
"I'd like to be able to change ptime for an audio codec, if I am able
to set it, it would be reasonable to know what is the maxptime and to
not set it higher."
[BA] Looking at JSEP Section 5.2.1 (initial Offers):
o If this m= section is for media with configurable durations of
media per packet, e.g., audio, an "a=maxptime" line, indicating
the maximum amount of media, specified in milliseconds, that can
be encapsulated in each packet, as specified in [RFC4566],
Section 6. This value is set to the smallest of the maximum
duration values across all the codecs included in the m= section.
Section 5.3.1 (Initial Answers) says:
o If this m= section is for media with configurable durations of
media per packet, e.g., audio, an "a=maxptime" line, as described
in Section 5.2.
Section 5.7.2 (Media Section Parsing) says:
o If present, a single "a=ptime" line MUST be parsed as described in
[RFC4566], Section 6, and its value stored.
o If present, a single "a=maxptime" line MUST be parsed as described
in [RFC4566], Section 6, and its value stored.
Section 5.9 (Applying a Remote Description) says:
* If the media section is of type audio:
+ For any specified "ptime" value, configure the available
media formats to use the specified packet size. If the
specified size is not supported for a media format, use the
next closest value instead.
[BA] Together this suggests that a single value of maxptime or ptime is provided per m-line.
However, currently the object model only provides the ability to expose capabilities such as maxptime at codec-level granularity within RTCRtpCodecCapability or settings such as ptime at codec-level granularity within RTCRtpCodecParameters.
Received on Wednesday, 22 February 2017 19:45:31 UTC