Re: [rtcweb] Clarification on simulcast and RID and RepairedRtpStreamId

Sergio Garcia Murillo <sergio.garcia.murillo@gmail.com> Tue, 04 December 2018 09:35 UTC

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To: =?UTF-8?Q?I=c3=b1aki_Baz_Castillo?= <ibc@aliax.net>
Cc: Magnus Westerlund <magnus.westerlund@ericsson.com>, rtcweb@ietf.org
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From: Sergio Garcia Murillo <sergio.garcia.murillo@gmail.com>
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Date: Tue, 4 Dec 2018 10:39:04 +0100
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Subject: Re: [rtcweb] Clarification on simulcast and RID and RepairedRtpStreamId
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On 03/12/2018 22:26, Iñaki Baz Castillo wrote:
> On Mon, 3 Dec 2018 at 22:22, Sergio Garcia Murillo
> <sergio.garcia.murillo@gmail.com> wrote:
>> My point is that there is a single source in the transceiver/MID why
>> should we add default RID and waste 2 more bytes in each media and rtx
>> packet?
> Regardless what browsers do today, both MID and RID headers should be
> just included in the first packets. The receiver is supposed to update
> its ssrc table for faster matching.
>
> NOTE: The sender should also resend MID and RID if the SSRC changed
> because some RFCs state that SSRCs may conflict and things that
> absolutely never happen.
>
Kind of agree, but from a theoretical point of view remember that we 
introduced MIDs/RIDs to cover rtp proxing/switching scenarios in which 
ssrc conflicts may happen, so in order to cover those scenarios the 
MIDs/RIDs values must be included in every packet. If we ignore that, 
then could just go back to ssrc signaling and avoid mids/rids 
completely, which I would be in favor of.

Best regards

Sergio