Re: [rtcweb] Mapping of media streams to RTP (Re: Query: What does "context" mean in the context (sic) of requirement A15? [ACTION-6])

Randell Jesup <randell-ietf@jesup.org> Thu, 25 August 2011 14:41 UTC

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Date: Thu, 25 Aug 2011 10:39:52 -0400
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Subject: Re: [rtcweb] Mapping of media streams to RTP (Re: Query: What does "context" mean in the context (sic) of requirement A15? [ACTION-6])
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On 8/25/2011 3:50 AM, Elwell, John wrote:
> Randell,
>
> Good point - if the first RTCP packet gets dropped, it will be a long time before the next one arrives, and in the meantime no CSRC to SSRC mapping will be available.

Well, we are looking at AVPF which allows (though does not mandate) faster RTCP,
and I think we're suggesting the "fast sync" rfc as well, so that might cover it
- but there still can be a delay before the RTCP gets through successfully.


>> -----Original Message-----
>> From: public-webrtc-request@w3.org
>> [mailto:public-webrtc-request@w3.org] On Behalf Of Randell Jesup
>> Sent: 24 August 2011 21:13
>> To: public-webrtc@w3.org
>> Subject: Re: Mapping of media streams to RTP (Re: Query: What
>> does "context" mean in the context (sic) of requirement A15?
>> [ACTION-6])
>>
>> On 8/24/2011 11:47 AM, Elwell, John wrote:
>>>> RTCP doesn't have a delay if a SR is the first thing sent on
>>>> a session,
>>>> as recommended in draft-perkins-avt-rapid-rtp-sync-03
>> section 2.1.1 -
>>>> this is permitted by RFC 3550 too, it notes.
>>> [JRE] OK, so CNAME can be used to map an RTP stream to a
>> given media description in SDP. CNAME alone does not indicate
>> the purpose of an RTP stream - it would still need something
>> else to map it to "game" or "agent", and that is where
>> a=content comes in.
>>
>> Don't count on RTCP getting received...  Start of a session
>> might even
>> be the worst place for it.
>>
-- 
Randell Jesup
randell-ietf@jesup.org