Hi Raghul,
I believe that the 'm' line can contain multiple offered or answered
codecs:
m=audio 56514 RTP/AVP 107 0 8 18 101
>From reading through the mentioned RFC 3261 and 3264, I think that it is
viable to have an offer of:
m=audio 56514 RTP/AVP 0 8
and an answer of:
m=audio 56514 RTP/AVP 0 8 18
There is a corresponding 'm' line to the one offered, but the responder is
indicating that it is capable of additional codecs than those requested.
Importantly, if supported, both ends should use the first codec in the
list, but I've seen in practice that some clients don't always follow this
(e.g trying to pick the best codec for a given bandwidth).
John
From: Raghul Prasanna <raghul82 at yahoo.co.uk>
To: Cesar Fiestas <fiestas.cesar at gmail.com>,
discussion at sipforum.org
Date: 20/05/2011 15:53
Subject: Re: [SIPForum-discussion] Offer Answer Model
Sent by: discussion-bounces at sipforum.org
HI Cesar,
I did some investigation myself and here is the snippet from RFC 3264 - Offer Answer model for SDP
For each "m=" line in the offer, there MUST be a corresponding "m="
line in the answer. The answer MUST contain exactly the same number
of "m=" lines as the offer. This allows for streams to be matched up
based on their order. This implies that if the offer contained zero
"m=" lines, the answer MUST contain zero "m=" lines.
This seems to be contradicting what you have just said, or I am I getting it wrong?
Raghul
--- On Thu, 19/5/11, Cesar Fiestas <fiestas.cesar at gmail.com> wrote:
From: Cesar Fiestas <fiestas.cesar at gmail.com>
Subject: Re: [SIPForum-discussion] Offer Answer Model
To: "Raghul Prasanna" <raghul82 at yahoo.co.uk>
Date: Thursday, 19 May, 2011, 18:03
Well when A send a request to B....is sending a request with a preference codec of g711alaw....B then says yeah cool..but you know what i can also
do g729 if you want on top of G711alaw...but A since it can only handle g711alaw .....B says ok G711alaw it is...although I want you know that i
can do g729 as well. :) hope that helps
On Thu, May 19, 2011 at 3:40 AM, Raghul Prasanna <raghul82 at yahoo.co.uk> wrote:
Hello All,
I have a scenario where, the Invite message has just one code - G.711 A law, but the 200 OK from the other end has g.711 A law and G.729.
Actually this happens in Reinvite when putting the call onhold.
The A end sent invite with G.711 alaw and G.729 codec which was answered with G.711 A law by B end, call got connected.
Now A end receives Reinvite from B end to put call on hold, with just G.711 A law and the A end sends 200 OK to Reinvite but with G.711 and G.729
(as seen in the initial Invite).
Is this valid, should the answer always contain only the codecs mentioned in Offer (Invite) which is G.711 A law? Please explain.
If someone can paste any rfc snippet showing how it should behave, it will be very helpful.
Thanks,
Raghul
_______________________________________________
This is the SIP Forum discussion mailing list
TO UNSUBSCRIBE, or edit your delivery options, please visit http://sipforum.org/mailman/listinfo/discussion
Post to the list at discussion at sipforum.org
--
Cesar Fiestas
join my Linkedin Network
http://www.linkedin.com/in/cesarfiestas
Telephone 843 606 1600
sor:cfiestas at voip-labs.com
_______________________________________________
This is the SIP Forum discussion mailing list
TO UNSUBSCRIBE, or edit your delivery options, please visit
http://sipforum.org/mailman/listinfo/discussion
Post to the list at discussion at sipforum.org
This email and any attachments are confidential and may also be privileged. If you are not the addressee, do not disclose, copy, circulate or in any other way use or rely on the information contained in this email or any attachments. If received in error, notify the sender immediately and delete this email and any attachments from your system. Emails cannot be guaranteed to be secure or error free as the message and any attachments could be intercepted, corrupted, lost, delayed, incomplete or amended. JT Group Limited and its subsidiaries do not accept liability for damage caused by this email or any attachments and may monitor email traffic.
JT Group Limited is incorporated in Jersey with limited liability under company number 84230 and has its registered office at No.1 The Forum, Grenville Street, St Helier, JE4 8PB.
Jersey Telecom Limited is incorporated in Jersey with limited liability under company number 83487 and has its registered office at No.1 The Forum, Grenville Street, St Helier, JE4 8PB.
Wave Telecom Limited is incorporated in Guernsey with limited liability under company number 39971 and has its registered office at Suite 7, Havilland Street, St Peter Port, GY1 2QE.
Newtel Data Services Limited is incorporated in Guernsey with limited liability under company number 47458 and has its registered office at Suite 7,Havilland Street, St Peter Port, GY1 2QE.
Newtel (Guernsey) Limited is incorporated in Guernsey with limited liability
under company number 22722 and has its registered office at Suite 7,
Havilland Street, St Peter Port, GY1 2QE.
Guernsey.Net Limited is incorporated in Guernsey with limited liability under company number 30030 and has its registered office at Suite 7, Provident House, Havilland Street, St Peter Port, Guernsey, GY1 2QE.
Jersey Telecom Limited and Wave Telecom Limited are subsidiary companies of JT Group Limited.
Navitas Telecom and JT Global are trading brands of Jersey Telecom Limited.
Newtel (Guernsey)Limited and Guernsey.Net are subsidiaries of Wave Telecom Limited.