Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in the API?

[Emil Ivov <[e-mail]>]

On 27.02.13, 20:25, Emil Ivov wrote:
> +1 again. It would also if such an API would also the possibility to

Awfully sorry! This was supposed to say:

"It would also *be great* if such an API would also *provide* the
possibility to retrieve audio levels.

(Coffee deficiency!)

Emil

> retrieve audio levels from the RTP (Magnus already mentioned RFC6465)
> so that applications can render such information.
> 
> (Like this for example: http://goo.gl/QTaqy )
> 
> Cheers,
> Emil
>>
>>
>> On Feb 22, 2013, at 1:19 AM, Magnus Westerlund
>> <[e-mail]> wrote:
>>
>>> WebRTC WG,
>>>
>>> As editor of the RTP usage specification in RTCWEB WG, we have had
>>> a noted issue in our draft specification 
>>> (https://datatracker.ietf.org/doc/draft-ietf-rtcweb-rtp-usage/).
>>> In Section 12.5. of version 05 (Contributing Sources) we had the
>>> following:
>>>
>>> (tbd: does the API need to provide the ability to add a CSRC list
>>> to an outgoing packet? this is only useful if the sender is mixing 
>>> content)
>>>
>>> This is clearly an API question. We intended to remove it. However,
>>> I like to hand it over to you in W3C to consider on the impact on
>>> the API this has.
>>>
>>> From my personal view point this has two aspects:
>>>
>>> Exposing when a received MediaStreamTrack is actually the mix (or 
>>> switch) of other MediaStreamTracks, a mix performed by a WebRTC
>>> endpoint or RTP middlebox (Mixer). Applications that like to know
>>> who are currently seen or audible needs this information mapping.
>>> We also have specified an optional to support RTP header extension
>>> (RFC6465) that provide energy levels for each contributing source.
>>> If that is used, that information would be something an application
>>> would like to render somehow.
>>>
>>> The other aspect is when an WebRTC endpoint mixes media to produce
>>> a new MediaStreamTrack, for example with the Web Audio API, then
>>> one need to consider if and how the CSRC list is populated.
>>>
>>> Cheers
>>>
>>> Magnus Westerlund
>>>
>>> ----------------------------------------------------------------------
>>>
>>>
> Multimedia Technologies, Ericsson Research EAB/TVM
>>> ----------------------------------------------------------------------
>>>
>>>
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>>>
>>>
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>>> https://www.ietf.org/mailman/listinfo/rtcweb
>>
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>>
> 

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