Subject: [MMUSIC] SDP Support for Multiple Packetisation Periods

From: Paul Beaumont <[email-masked]>
Date: Thu, 28 Jul 2011 20:19:43 +0100

All

Apologies, being first time to IETF and its mailing lists, if this is not the right mailing list to post this request to.

On initial inspection it looks like it is not possible to specify in SDP the specific packetisation period associated with a codec that is available through negotiation. Specific case I am concerned with is to support (1) G.711 @ PP=10ms and (2) G.711 @ PP=20ms; prioritised in that order. The ptime parameter would appear to apply to both.

Please can you advise where I should submit this question or if this is the right forum then whether the above observation is correct and any supplemental information/comments you may have?

Thanks
Paul Beaumont

---

From: Randell Jesup <[email-masked]>
Date: Thu, 28 Jul 2011 15:37:12 -0400

On 7/28/2011 3:19 PM, Paul Beaumont wrote:
> On initial inspection it looks like it is not possible to specify in 
> SDP the specific packetisation period associated with a codec that is 
> available through negotiation. Specific case I am concerned with is to 
> support (1) G.711 @ PP=10ms and (2) G.711 @ PP=20ms; prioritised in 
> that order. The ptime parameter would appear to apply to both.

You can't specify the packetization; you can merely specify a preferred 
ptime and a maxptime.  The
sender can use any packetization time they want up to maxptime.  The 
codec may limit it further (see iLBC), and the granularity will vary 
with codec.

-- 
Randell Jesup
[email-masked]