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Re: [rtcweb] JSEP: Issues with a=ssrc and RTP payload type switching

Simon Perreault <sperreault@jive.com> Mon, 08 June 2015 15:16 UTC

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Date: Mon, 08 Jun 2015 09:15:04 -0600
From: Simon Perreault <sperreault@jive.com>
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To: Harald Alvestrand <harald@alvestrand.no>, Magnus Westerlund <magnus.westerlund@ericsson.com>, Roman Shpount <roman@telurix.com>
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Subject: Re: [rtcweb] JSEP: Issues with a=ssrc and RTP payload type switching
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Le 2015-06-08 09:09, Harald Alvestrand a écrit :
> This has another implication:
> 
> When doing PT switching for comfort noise, you MUST have a CN with the
> same clock rate as your normal audio codec.
> 
> CN is exactly the type of PT-switching that, if it occurs at all, occurs
> very frequently.

I'm not following. We're discussing generating a new SSRC on clock
rate-switching, not on PT-switching. For the CN example, you would
typically include in your SDP one CN payload type per possible clock
type so that you can switch payload types without switching the clock rate.

Simon

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