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Re: [rtcweb] Adding previously "discarded" codecs in SDP renegotiation

Christer Holmberg <christer.holmberg@ericsson.com> Tue, 29 March 2016 08:29 UTC

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From: Christer Holmberg <christer.holmberg@ericsson.com>
To: Iñaki Baz Castillo <ibc@aliax.net>, "rtcweb@ietf.org" <rtcweb@ietf.org>
Thread-Topic: [rtcweb] Adding previously "discarded" codecs in SDP renegotiation
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Date: Tue, 29 Mar 2016 08:29:22 +0000
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Subject: Re: [rtcweb] Adding previously "discarded" codecs in SDP renegotiation
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Hi,

I see no reason why one should not be allowed to add previously discarded
codecs. There can be many reasons why a codec is discarded at one point,
but might be accepted later.

Regards,

Christer



On 29/03/16 00:25, "rtcweb on behalf of Iñaki Baz Castillo"
<rtcweb-bounces@ietf.org on behalf of ibc@aliax.net> wrote:

>Hi, the scenario is the following:
>
>- Alice sends SDP offer to Bob by offering VP8 (PT 100) and H264
>packetization-mode=1 (PT 101).
>
>- Bob answers with just VP8 (let's say it sets PT 110) in the m= line,
>regardless he also supports H264.
>
>At this time Alice must send VP8 (PT 110) to Bob, and Bob must send
>VP8 (PT 100) to Alice. Fine.
>
>Later Bob wants to change to H264, so he sends a SDP reoffer to Alice
>by just offering H264 packetization-mode=1 (PT 111).
>
>Assuming this is valid (re-enabling a previously discarded codec),
>Alice answers the reoffer with just H264 (PT 101).
>
>
>Is this valid? And a more pragmatic questions: should I assume that
>current WebRTC implementations would support this scenario?
>
>Thanks a lot.
>
>
>-- 
>Iñaki Baz Castillo
><ibc@aliax.net>
>
>_______________________________________________
>rtcweb mailing list
>rtcweb@ietf.org
>https://www.ietf.org/mailman/listinfo/rtcweb

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