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Re: Need API to read the CSRC on received tracks (#4)

From: Harald Alvestrand <harald@alvestrand.no>
Date: Sat, 01 Aug 2015 11:26:12 +0200
Message-ID: <55BC90B4.4050507@alvestrand.no>
To: public-webrtc@w3.org
Thanks for bringing this to the list!

Speaking as contributor only:

CSRC is only useful for a single case: That of a media mixer at the
conference server, where the set of contributors changes over time.
(The audio volume extension, bug #6, is not the same thing.)

I don't regard this as an important use case, and think we can safely
put this off to the next revision of the specification, where the
RTCRtpReceiver does seem like the logical place to put it.

Note about the solution proposed:

If changes in CSRC are what interest people, rather than the absolute
values at a given time, there needs to be events firing for the CSRC
changes, and the timing relationships between data returned from
"getContributingSources" and the fired events need to be defined.


On 07/31/2015 07:26 PM, Bernard Aboba wrote:
>> It could extend RTCRtpReceiver, like this:
>>
>> Contributing Sources
>>
>> The getContributingSources method extends the RTCRtpReceiver object,
>> providing information on the sources contributing to an incoming
>> media stream.
>>
>> partial interface RTCRtpReceiver {
>>     sequence<RTCRtpContributingSource> getContributingSources ();
>> };
>>
>> Methods
>>
>> getContributingSources
>> Retrieve the sequence of contributing sources.
>>
>> No parameters.
>> Return type: sequence<RTCRtpContributingSource>
>>
>> dictionary RTCRtpContributingSource
>>
>> dictionary RTCRtpContributingSource {
>>              DOMHiResTimeStamp timestamp;
>>              unsigned long     csrc;
>>              byte              audioLevel;
>> };
>>
>> Dictionary RTCRtpContributingSource Members
>>
>> audioLevel of type byte,
>> The audio level of the contributing source. Value is between 0 and
>> -127 representing the contributing source dBov value, as described in
>> [RFC6465]
>>
>> csrc of type unsigned long,
>> The contributing source.
>>
>> timestamp of type DOMHiResTimeStamp,
>>
>>
>>
>>
>> On Jul 31, 2015, at 08:31, Cullen Jennings <notifications@github.com
>> <mailto:notifications@github.com>> wrote:
>>
>>> @alvestrand <https://github.com/alvestrand> - would stats be a
>>> reasonable place to put this or should it be RTCRtpReceiver ?
>>>
>>> 
>>> Reply to this email directly or view it on GitHub
>>> <https://github.com/w3c/webrtc-pc/issues/4#issuecomment-126725763>.
>>>


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Received on Saturday, 1 August 2015 09:26:45 UTC

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