Elison,
IMO, it looks fine to me.
I also find a draft, though expires, which might be similar to your
case.
draft-foster-mmusic-vbdformat-01
5. Proposed representation in SDP
Note that it is possible to specify multiple
"vbd" payload types, each with a different "fmtp" value and, therefore,
a
different audio encoding.
An example media description in SDP might be:
m=audio 3456 RTP/AVP 15 98 99
a=rtpmap:98 vbd/8000
a=fmtp:98 0
a=rtpmap:99 vbd/8000
a=fmtp:99 8
-Rockson
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
Elison Niven
Sent: Wednesday, June 25, 2008 7:54 PM
To: [email protected]
Subject: Re: [Sip-implementors] G.723.1 sdp negotiation
I got it that I can't override the static payload type even if I am not
using it. Right?
And then is the following offer valid?
m = audio 8000 RTP/AVP 4 100
m = rtpmap:4 G723/8000
m = fmtpmap:4 bitrate=6.3
m = rtpmap:100 G723/8000
m = fmtpmap:100 bitrate=5.3
Or can I assign dynamic payload types to both of them - for example
99&100?
-Elison
-----Original Message-----
From: Rockson Li (zhengyli) [mailto:[EMAIL PROTECTED]
Sent: Wednesday, June 25, 2008 3:38 PM
To: Elison Niven; [email protected]
Subject: RE: [Sip-implementors] G.723.1 sdp negotiation
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
Elison Niven
Sent: Wednesday, June 25, 2008 5:22 PM
To: [email protected]
Subject: [Sip-implementors] G.723.1 sdp negotiation
_____
From: Elison Niven [mailto:[EMAIL PROTECTED]
Sent: Wednesday, June 25, 2008 9:30 AM
To: '[email protected]'
Subject: G.723.1 sdp negotiation
Hi list,
I am again sending this mail as I did not find it listed on the official
archives.
I apologize for any inconvenience caused.
Elison
_____
From: Elison Niven [mailto:[EMAIL PROTECTED]
Sent: Tuesday, June 24, 2008 3:35 PM
To: '[email protected]'
Cc: '[EMAIL PROTECTED]'; '[EMAIL PROTECTED]'
Subject: G.723.1 sdp negotiation
Hi List,
I know this question has been addressed before but it still isn't very
clear.
If I send an offer with an SDP like:
m = audio 8000 RTP/AVP 4
m = rtpmap:4 G723/8000
And if the answer also does not specify the bitrate in an fmtpmap line
for the G723 codec, what codec should be used?
Should it be G.723.1 High rate or Low rate?
RFC3555 says on G723: "If unspecified, the bitrate may change from frame
to frame as indicated inband."
The remote end may start sending RTP as either High rate (6.3 Kb/s) or
Low rate (5.3 kb/s).
How to go about if there is no facility to detect the RTP data received
- Is it High rate or Low rate?
(Ex: The DSP etc. does not have such support)
In that case, I need to know which codec to use from the SDP negotiation
itself.
I want to show that I support for both G.723.1 6.3 kb/s (High rate) and
5.3 Kb/s (Low rate) in the offer I send.
In that case, is the following SDP in the offer valid?
m = audio 8000 RTP/AVP 4 5
m = rtpmap:4 G723/8000
m = fmtpmap:4 bitrate=6.3
m = rtpmap:5 G723/8000
m = fmtpmap:5 bitrate = 5.3
(Is it alright to override static payload 5 here?) [Rockson] you cannot
do this , you'd better use dynamic payload type, and "a=" for rtpmap and
fmtp attribute.
Best Regards,
Elison
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