RE: [Sip] ptime attribute in Offer SDP

Hi,

The media line in your example is not allowed. The ptime attribute is
not codec specific, it is given per media description (m= line).

The possibility to provide a ptime value for a specific codec has been
discussed on the MMUSIC list. Different alternatives were discussed. One
proposal was to define a new attribute. Another proposal was to use the
"vsel" attribute, defined in RFC3108, which allows you to provide values
per codecs.

Regards,

Christer

________________________________

From: Udit_Goyal@3com.com [mailto:Udit_Goyal@3com.com] 
Sent: 2. toukokuuta 2006 12:01
To: sip list
Cc: sip@ietf.org
Subject: [Sip] ptime attribute in Offer SDP 

Hi, 

How can a UA publish its capabilities of supporting multiple
packetization time support for a particular codec, 

For example: 
For codec L8 if it supports both 20 and 30 ms ptime values, 
For codec L16, it supports 40 ms 

Is following media line is allowed? 

m=audio 49230 RTP/AVP 96 97 
a=rtpmap:96 L8/8000 
a=ptime: 20 
a=ptime:30 
a=rtpmap:97 L16/8000 
a=ptime:40 

And is ptime attribute a property of whole media lines or only for a
codec, I remember in earlier discussions it is a codec attribute. 

-Udit 