Subject: [Megaco] Question on defining bitrate of G.723.1

From: Manuel Poza <[email-masked]>
Date: Tue, 19 Feb 2002 11:31:21 +0100

Hi, all!

I have a question regarding to the G.723.1 codec.

In the call example in appendix A.1 in rfc 3015, the RTP profile chosen
for the RTP terminations is the number 4, that corresponds to G.723
(m=audio $ RTP/AVP 4). However, no bitrate is specified for it (5.3 and
6.3 kbps are possible for this codec). What's the reason for this?

    1) There is a default value (6.3 kbps?)
    2) G.723.1 codecs must be able  to decode any of the two modes with
no previous communication
    3) Other

Related to this, should a MG understand the following?
         m=audio $ RTP/AVP 4
         a=fmtp: 4 bitrate=6.3

Best regards and thank you in advance,

Manuel Poza

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From: Dan Elbert <[email-masked]>
Date: Tue, 19 Feb 2002 16:33:42 +0200

Can you use the ptime (packetization time) attribute in SDP to specify the
bitrate ?

Dan Elbert
RADVISION

-----Original Message-----
From: Manuel Poza [mailto:[email-masked]]
Sent: Tuesday, February 19, 2002 12:31 PM
To: [email-masked]
Subject: [Megaco] Question on defining bitrate of G.723.1

Hi, all!

Manuel Poza

---

From: "Tom-PT Taylor"<[email-masked]>
Date: Sun, 24 Feb 2002 18:40:33 -0500

You do use an attribute.  fmtp parameters are those registered when the
payload is defined as a MIME type.  The starting point is
draft-ietf-avt-rtp-mime-xx.txt.  This shows the following for the G723
payload type:

     Optional parameters:
          ptime, maxptime

          bitrate: the data rate in kb/s used or preferred for the audio
          bit stream, with permissible values 5.3 or 6.3.  If
          unspecified, the bitrate may change from frame to frame as
          indicated inband.

          annexa: indicates that Annex A, voice activity detection, is
          used or preferred.  Permissible values are "yes" and "no"
          (without the quotes); "yes" is implied if this parameter is
          omitted.

-----Original Message-----
From: Manuel Poza [mailto:[email-masked]]
Sent: Tuesday, February 19, 2002 5:31 AM
To: [email-masked]
Subject: [Megaco] Question on defining bitrate of G.723.1

Hi, all!

Manuel Poza

---

From: "Tom-PT Taylor"<[email-masked]>
Date: Sun, 24 Feb 2002 18:40:33 -0500

Optional parameters:
          ptime, maxptime

-----Original Message-----
From: Manuel Poza [mailto:[email-masked]]
Sent: Tuesday, February 19, 2002 5:31 AM
To: [email-masked]
Subject: [Megaco] Question on defining bitrate of G.723.1

Hi, all!

Manuel Poza