Re: [AVTCORE] Query: Reporting SSRC when you send no streams?
Magnus Westerlund <magnus.westerlund@ericsson.com> Mon, 01 June 2015 09:19 UTC
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Date: Mon, 01 Jun 2015 11:19:32 +0200
From: Magnus Westerlund <magnus.westerlund@ericsson.com>
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To: Harald Alvestrand <harald@alvestrand.no>, avt@ietf.org, pbos@google.com
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Subject: Re: [AVTCORE] Query: Reporting SSRC when you send no streams?
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Harald Alvestrand skrev den 2015-06-01 10:59: > This came up in a WebRTC-related context: > > If you send no streams, what SSRC should you be using in receiver reports? You obviously need one, and if there are no known intention to send a stream later, then one have to pick one value at random. > > If you start sending streams, should your reporting SSRC(s) change? I think it is okay for one (first) of the streams that will be sent to use the reporting SSRC. If one consider the multiple clock rates RFC (https://datatracker.ietf.org/doc/rfc7160/) one would in most cases require a new SSRC. But, the reporting SSRC has no known RTP timestamp rate bound to it, prior to picking it. Thus, I don't see a requirement to force to use a new SSRC. However, I also don't see that it would be wrong to use a new SSRC and then stop using the previous reporting one. This will of course have the down side of reducing the per SSRC bit-rate during the 25+ seconds of timeout period for the old reporting. > > If you stop sending streams, what should happen? Keep reporting from the > stream(s) that are gone, or switch to a new (old?) non-sending SSRC? I think you should maintain at least one of the SSRCs as reporting SSRC. If that has to be replaced if one re-adds streams would depend on the timestamp rate, media type and other context associated with the SSRC. > > I'm looking at draft-ietf-avtcore-rtp-multi-stream (and -optimization), > and they seem to offer plenty of advice for the case where there is more > than one stream (report on them all in -multi-stream, add them to a > group in -optimization), but not specifically for the 0->1, 1->0 > transitions. > > Of course, I may have overlooked something... No, I don't think you have overlooked anything. From my perspective this could be fit into the draft-ietf-avtcore-rtp-multi-stream set of clarifications to ensure consistent behaviours. However, I think we need to agree on what the recommended behaviour is, and if we make clear that several behaviours may occur. Cheers Magnus Westerlund ---------------------------------------------------------------------- Services, Media and Network features, Ericsson Research EAB/TXM ---------------------------------------------------------------------- Ericsson AB | Phone +46 10 7148287 Färögatan 6 | Mobile +46 73 0949079 SE-164 80 Stockholm, Sweden | mailto: magnus.westerlund@ericsson.com ----------------------------------------------------------------------
- [AVTCORE] Query: Reporting SSRC when you send no … Harald Alvestrand
- Re: [AVTCORE] Query: Reporting SSRC when you send… Magnus Westerlund
- Re: [AVTCORE] Query: Reporting SSRC when you send… Harald Alvestrand
- Re: [AVTCORE] Query: Reporting SSRC when you send… Simon Perreault
- Re: [AVTCORE] Query: Reporting SSRC when you send… Simon Perreault
- Re: [AVTCORE] Query: Reporting SSRC when you send… Magnus Westerlund
- Re: [AVTCORE] Query: Reporting SSRC when you send… Simon Perreault
- Re: [AVTCORE] Query: Reporting SSRC when you send… Magnus Westerlund
- Re: [AVTCORE] Query: Reporting SSRC when you send… Simon Perreault
- Re: [AVTCORE] Query: Reporting SSRC when you send… Harald Alvestrand
- Re: [AVTCORE] Query: Reporting SSRC when you send… Simon Perreault
- Re: [AVTCORE] Query: Reporting SSRC when you send… Magnus Westerlund