[Standards-JIG] XEP-0167: Jingle audio payload extensions

Sean Egan seanegan at gmail.com
Mon Oct 30 22:17:09 UTC 2006


On 10/30/06, Peter Saint-Andre <stpeter at jabber.org> wrote:
> For example, as described in draft-ietf-avt-rtp-speex, the "ptime",
> "sr", "ebw", "vbr", "eng", and "mode" parameters may be specified in
> relation to usage of the Speex codec. In SDP these parameters are
> represented in the "fmtp" line. I think that in Jingle we would
> represent these in XML, such as:

A few of us here at Google discussed this exact issue last week. Our
consensus was that codecs specified on the fmtp line should be
specified more like:

<payload-type id='96' name='speex' clockrate='16000'>
  <parameter name='vbr' value='on'/>
  <parameter name='cmg' value='on'/>
</payload-type>

This allows you to negotiate codec parameters and easily translate
them to SDP without maintaining and understanding a vast namespace
registry of every possible codec.

Non-codec-specific attributes (those defined in the SDP RFC itself)
should be attributes of the <payload-type/> element. So you'd have:

<payload-type id='96' name='speex' clockrate='16000' ptime='30' >
  <parameter name='vbr' value='on'/>
  <parameter name='cmg' value='on'/>
</payload-type>

-s.



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