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List:       sip-implementors
Subject:    Re: [Sip-implementors] PAYLOAD TYPE FOR G729 A and G729B
From:       Brett Tate <brett () broadsoft ! com>
Date:       2013-11-13 12:02:03
Message-ID: 576A8B541C219D4E9CEB1DF8C19C7B881A068BEF () MBX08 ! citservers ! local
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Hi,

I don't claim to be an expert on SDP.  If you don't obtain your answer here, you \
might want to try the mmusic email list.

For payload types which have a static number, vendors typically use the static number \
(unless reason to do otherwise) although I'm not aware of the related normative \
statements. RFC 3551 section 1 indicates "Only the binding of some of the payload \
formats to static payload type numbers in Tables 4 and 5 is normative"; however I \
doubt that it means if there is a static mapping, it MUST be used (instead of \
dynamic) unless altering some aspect of it (such as the PCMU example within RFC 3551 \
section 6).

The following are a few links of potential interest.

http://tools.ietf.org/html/rfc3551 

http://tools.ietf.org/html/draft-ietf-mmusic-sdp-g723-g729-04

http://www.iana.org/assignments/rtp-parameters/rtp-parameters.xml 

http://tools.ietf.org/html/draft-ietf-mmusic-rfc4566bis-09 

> -----Original Message-----
> From: sampat patnaik [mailto:sam_east@yahoo.co.in]
> Sent: Wednesday, November 13, 2013 5:10 AM
> To: Brett Tate
> Cc: sip-implementors@lists.cs.columbia.edu
> Subject: Fw: PAYLOAD TYPE FOR G729 A and G729B
> 
> 
> Hi Brett,
> 
> Can you please throw light on a query regarding the usage of PAYLOAD
> TYPE in SDP media descriptor line. For G729,G729A and G729B , can you
> please specify whether we can use the dynamic payload types supported
> by necessary attributes i.e a parmeter that would  from an RTP payload
> type number (as used inan "m=" line) to an encoding name denoting the
> payload format to be used.  It also provides information on the clock
> rate and encoding parameters.  It is a media-level attribute that is
> not dependent on charset.
> 
> For Ex:
> 
> m=audio 1564 RTP/AVP 96 8 18 97 98
> 
> a=rtpmap:97 G729/8000
> 
> a=fmtp:97 annexb=no...  Can 97 be used as PT for g729a.
> 
> 
> 
> m_east@yahoo.co.in> wrote:
> 
> > From: sampat patnaik <sam_east@yahoo.co.in>
> > Subject: PAYLOAD TYPE FOR G729 A and G729B
> > To: "sip-implementors@lists.cs.columbia.edu" <sip-
> implementors@lists.cs.columbia.edu>
> > Date: Wednesday, 13 November, 2013, 12:26 AM
> > Hi
> > Experts,
> > I
> > have a query regarding this PAYLOAD type in MEDIA DESCRIPTOR
> > line of SDP which goes like this ..
> > As
> > per IANA , the PAYLOAD type for codec type G729 is static and is
> assigned as
> > 18.However i would like take a confirmation on my doubt that
> > the same static value is used for G729ANNEX A and G729 ANNEX
> > B as well
> > or it is dynamic allocation.
> > Can any of our experts throw light
> > on this and it would be great if u can support your reply
> > along with IANA/UNIVERSAL standards of numbering
> > plan.
> > RegardsSam
> > 

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