I think you can (or should) use multi-line of "m=".

m=audio 5004 RTP/AVP 0
a=rtpmap:0 PCMU/8000
a=ptime:10

m=audio 5004 RTP/AVP 4 
a=rtpmap:4 G723/8000
a=ptime:30

m=audio 5004 RTP/AVP 18
a=rtpmap:18 G729/8000
a=ptime:20


Regards/Linda

-----Original Message-----
From: Danail Kirov [mailto:[EMAIL PROTECTED] 
Sent: Monday, November 01, 2004 4:14 PM
To: [EMAIL PROTECTED]
Subject: [Sip-implementors] Does RFC3264 allow different ptime for different
audio codecs?


Hi All,

Is it allowed to add 
a=ptime:xx
for every codec listed in a single m= line?
For example:

m=audio 5004 RTP/AVP 0 4 18
a=rtpmap:0 PCMU/8000
a=ptime:10
a=rtpmap:4 G723/8000
a=ptime:30
a=rtpmap:18 G729/8000
a=ptime:20

All the samples I've seen so far imply there is only one ptime per m= line,
but this does not describe the "real world" where one would want to use
different audio codecs with different packet times and different codecs
operate on different [ms] frames.
G.711   - 1ms
G.729   - 10ms
G.723   - 30ms
i.e - specifiying  10ms does not make any sense for G.723, but does for
G.729 and G.711. 

Regards,

Danail Kirov


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