Re: [AVT] I-D ACTION:draft-ietf-avt-variable-rate-audio-00.txt

[Qiaobing Xie <Qiaobing.Xie at motorola.com>]

Hi, Stephan/Colin,

I like this solution and the draft summaries the issue/benefits very well.

...
>   *  Is it a good idea to require ALL future I-Ds on audio (not only
>      the variable clock frequency ones) to use the uRTR?
>   *  Or only those that do not fit the uRTR (fit == subset of prime
>      factors)?
...

Or, we can make uRTR a standard _option_ to all payloads - e.g., whenever rate param is set
to 192kHz (or whatever value we end up with), it would mean that uRTR is in use, if rate is
set to any other value, it implies that the actual sampling rate is in use.

regards,
-Qiaobing


Internet-Drafts at ietf.org wrote:

> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Audio/Video Transport Working Group of the IETF.
>
> 	Title		: RTP Timestamp Frequency for Variable Rate Audio Codecs
> 	Author(s)	: S. Wenger, C. Perkins
> 	Filename	: draft-ietf-avt-variable-rate-audio-00.txt
> 	Pages		: 6
> 	Date		: 2004-10-19
> 	
> This memo discusses the problems of audio codecs with variable 
>    external sampling rates.  Historically, for audio codecs, the RTP 
>    timestamp frequency was chosen to match the sampling rate of the 
>    audio codec.  However, this choice is nowadays more difficult to 
>    justify, because of the advent of audio codecs (and, even more 
>    important, practical use cases) that support multiple sample rates 
>    and the switch between the sample rates during the lifetime of an 
>    RTP session.  This Internet draft addresses the problem by 
>    suggesting that RTP Payload RFCs for such codecs to utilize a 
>    single, high, unified RTP timestamp frequency.
>
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