Subject: [AVT] Common Format: draft-ietf-avt-evrc-07, draft-mathai-avt-smv-00, Purevoice, etc.

From: Magda <[email-masked]>
Date: Thu, 30 Aug 2001 15:12:23 -0700

There's been some discussion on a number of issues with the 
draft-ietf-avt-evrc-07. Also the SMV RTP proposal (draft-mathai-avt-smv-00) 
is up for discussion. The SMV proposal is very similar to the EVRC RTP 
proposal.

Given the similarities between the EVRC and SMV proposals with each other 
and also prior drafts (such as PureVoice), perhaps it would be useful to 
develop a more generic RTP payload format capable of supporting any of 
these vocoders.

By eliminating small differences between the formats, implementation 
complexity is reduced, while the common format is capable of supporting 
both EVRC and SMV (and likely PureVoice) as well as future vocoders.

-- magda.

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From: "Adam Li" <[email-masked]>
Date: Thu, 30 Aug 2001 19:10:07 -0700

Hi,

I suppose it would not be too hard to have a common format that works for
both EVRC and SMV. There is nothing in the current draft that is codec
specific which would prevent this. It does reduce the complexities of
protocols and implemenation. I am not sure if it is allright to design one
common RTP payload format for more than one codec. Have there been any such
case before? Are there any special issues need to pay additional attention
to?

Although based on RFC 2658 (for PureVoice), the current EVRC draft has some
significant difference from it already. There is an addition packet type, to
name one. Including the PureVoice in this draft may imply obsoleting RFC
2658 and possibly the devices that have implemented it. Maybe the Chairs and
Kyle (who authored RFC 2658, and is also an author for the EVRC draft) can
give us some more suggestion on what should we do.

Thanks,

Adam

----------
Adam H. Li
Image Communication Lab                    (310) 825-5178 (Lab)
University of California, Los Angeles      (310) 825-7928 (Fax)

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of Magda
Sent: Thursday, August 30, 2001 3:12 PM
To: [email-masked]
Subject: [AVT] Common Format: draft-ietf-avt-evrc-07,
draft-mathai-avt-smv-00, Purevoice, etc.

Given the similarities between the EVRC and SMV proposals with each other
and also prior drafts (such as PureVoice), perhaps it would be useful to
develop a more generic RTP payload format capable of supporting any of these
vocoders.

By eliminating small differences between the formats, implementation
complexity is reduced, while the common format is capable of supporting both
EVRC and SMV (and likely PureVoice) as well as future vocoders.

-- magda.

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
http://www1.ietf.org/mailman/listinfo/avt

---

From: Colin Perkins <[email-masked]>
Date: Fri, 31 Aug 2001 00:14:34 -0400

>case before? Are there any special issues need to pay additional attention

I would certainly encourage payload formats which are as similar - and as
simple - as possible, provided that doesn't adversely affect performance.
Each format will still need a separate MIME type registration and (dynamic) 
payload type identifier, though. 

If the formats really are identical, it might make sense to combine them 
in the same way we did for AMR and AMR-WB. The SMV format hasn't had much
discussion so far though, so we want to be sure that format is stable
before trying to merge it with another.

>give us some more suggestion on what should we do.

I don't think this is worth making the existing PureVoice format obsolete.

Colin