Re: [AVTCORE] [Technical Errata Reported] RFC4733 (3451)

[Magnus Westerlund <[e-mail]>]

Hi,

(As Individual)

Are we certain that the RTP payload format will never be sent over two
different but linked SSRCs to the original audio. There is such a use
case (See RFC 3388) where DTMF and original audio are sent in two
different RTP sessions and thus with different SSRCs (although, they
could have the same number for binding reasons). I fear the proposed
corrected text is to restrictive.

Cheers

Magnus

On 2013-01-11 14:24, RFC Errata System wrote:
> 
> The following errata report has been submitted for RFC4733,
> "RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals".
> 
> --------------------------------------
> You may review the report below and at:
> http://www.rfc-editor.org/errata_search.php?rfc=4733&eid=3451
> 
> --------------------------------------
> Type: Technical
> Reported by: Xavier Marjou <[e-mail]>
> 
> Section: 2.1
> 
> Original Text
> -------------
> Named telephone events are carried as part of the audio stream and
> MUST use the same sequence number and timestamp base as the regular
> audio channel to simplify the generation of audio waveforms at a 
> gateway.
> 
> Corrected Text
> --------------
> Named telephone events are carried as part of the audio stream and
> MUST use the same SSRC (therefore the same timing and sequence
> number space) and the same timestamp clock rate as the regular
> audio channel to simplify the generation of audio waveforms at a
> gateway.
> 
> Notes
> -----
> RFC4733 was written in a way to avoid the multiple clock-rate problem by mandating the use of the same SSRC for DTMF and audio. However it's not explicitly written, which brings an ambiguity. It was commented that RFC4733 needs to be updated. (c.f. http://tools.ietf.org/wg/avtext/minutes?item=minutes-85-avtext.html)
> 
> Instructions:
> -------------
> This errata is currently posted as "Reported". If necessary, please
> use "Reply All" to discuss whether it should be verified or
> rejected. When a decision is reached, the verifying party (IESG)
> can log in to change the status and edit the report, if necessary. 
> 
> --------------------------------------
> RFC4733 (draft-ietf-avt-rfc2833bis-15)
> --------------------------------------
> Title               : RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals
> Publication Date    : December 2006
> Author(s)           : H. Schulzrinne, T. Taylor
> Category            : PROPOSED STANDARD
> Source              : Audio/Video Transport
> Area                : Real-time Applications and Infrastructure
> Stream              : IETF
> Verifying Party     : IESG
> _______________________________________________
> Audio/Video Transport Core Maintenance
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> 


-- 

Magnus Westerlund

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