Re: [MMUSIC] Scope of RTP payload types in BUNDLE?

Colin Perkins <csp@csperkins.org> Mon, 27 May 2013 18:10 UTC

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Date: Mon, 27 May 2013 19:10:48 +0100
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To: Christer Holmberg <christer.holmberg@ericsson.com>
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Subject: Re: [MMUSIC] Scope of RTP payload types in BUNDLE?
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On 27 May 2013, at 18:55, Christer Holmberg wrote:
>>>>> v=0
>>>>> o=alice 2890844526 2890844526 IN IP4 host.anywhere.com s= c=IN IP4
>>>>> host.anywhere.com
>>>>> t=0 0
>>>>> m=audio 49170 RTP/AVP 96
>>>>> a=rtpmap:96 AMR-WB/16000
>>>>> m=audio 49170 RTP/AVP ???
>>>>> a=rtpmap:??? AMR-WB/16000
>>>> 
>>>> Not sure I get your point. You can have two different payload types that map to the same payload format in a single RTP session, since
>>>> you can always distinguish what payload format is intended. You can't have the same payload type mapping to two different payload
>>>> formats in a single RTP session, since you can't then infer what payload format was meant.
>>> 
>>> Please not that both PTs map to the SAME payload format :)
>> 
>> I thought I addressed that in my reply.
> 
> I am not sure you did - at least I didn't get it :)
> 
> Again, my understanding of what you said is that, for any payload format within an RTP session, the PT value has to be unique.

Correct.

> In the example above the same payload format, within the same RTP session, is used in two separate m- lines. But, I still can't use the same PT value for both m- lines, even if the payload format is the same, can I?


Why not? I don't see any problem mapping the same payload type to the exact same payload format in two different m= lines. Mapping the same payload type to two different payload formats is the problem.

-- 
Colin Perkins
http://csperkins.org/