Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in the API?
Adam Bergkvist <adam.bergkvist@ericsson.com> Fri, 22 February 2013 09:43 UTC
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Date: Fri, 22 Feb 2013 10:43:41 +0100
From: Adam Bergkvist <adam.bergkvist@ericsson.com>
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To: Magnus Westerlund <magnus.westerlund@ericsson.com>
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>, "public-webrtc@w3.org" <public-webrtc@w3.org>
Subject: Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in the API?
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On 2013-02-22 10:19, Magnus Westerlund 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. Reading CSRC info: Right now, the SSRC(s) of a track is only exposed via the Stats API. I think that's the right level if we were to support reading CSRC info as well. Updating CSRC info: IMO, we shouldn't add anything in the MediaStream API for this. If it's needed, it should be supported by the API that initiates the mixing. /Adam
- [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in the… Magnus Westerlund
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Adam Bergkvist
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Magnus Westerlund
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Harald Alvestrand
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Stefan Håkansson LK
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Adam Bergkvist
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Adam Bergkvist
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Magnus Westerlund
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Cullen Jennings (fluffy)
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Emil Ivov
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Cullen Jennings
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Justin Uberti
- Re: [rtcweb] draft-ietf-rtcweb-rtp-usage: CSRC in… Emil Ivov