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Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp-00.txt

Randell Jesup <randell-ietf@jesup.org> Mon, 15 August 2011 14:53 UTC

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Date: Mon, 15 Aug 2011 10:52:25 -0400
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Subject: Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp-00.txt
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On 8/15/2011 4:20 AM, Harald Alvestrand wrote:

> On 08/12/11 17:24, Paul Kyzivat wrote:
>> That brings up another peculiar case. Suppose the m-lines in question
>> were, in order, video, audio, and timed text, and the answerer again
>> only wanted to use audio and timed text. In that case, will it still
>> want to use the port offered for video??? How would the answer be
>> constructed, and where would the answering port be placed?
> That is a strong argument in favour of "just don't give any codecs". I'm
> adding that too.

If you're suggesting "m=video 4321 RTP/AVP" as an SDP line, it's illegal to
not have a payload listed, I'm afraid (though many implementations will 
accept
it).  That includes when you reject an m= line with port 0.

>> It occurs to me that there is another "special" port that might be
>> co-opted for use here: port 9, the discard port.
> Magic numbers are bad for technological health. I don't think I'd like
> to see that.

Agreed, though occasionally it's ok, even if not optimal (port 0 for 
reject for example).


-- 
Randell Jesup
randell-ietf@jesup.org

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