_____
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?)
Best Regards,
Elison
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