Subject: AW: [AVT] Working group last call: draft-ietf-avt-rtp-clearmode-02.txt - random comments

From: "Kreuter Ruediger" <[email-masked]>
Date: Fri, 19 Sep 2003 14:08:32 +0200

Thanks for your comments
1 and 3 is simple (see below),
but the 2nd one needs some discussion in the working group (see below)
 
Regards,
Ruediger

	-----Ursprüngliche Nachricht----- 
	Von: [email-masked] [mailto:[email-masked]] 
	Gesendet: Mi 17.09.2003 14:54 
	An: Magnus Westerlund; Kreuter Ruediger 
	Cc: 
	Betreff: Re: [AVT] Working group last call: draft-ietf-avt-rtp-clearmode-02.txt - random comments

	Random comments: 
	
	- I guess many people have already pointed it out before, but in section 3, "combinded" should be replaced by "combined" 

	Ruediger: will be fixed

	- Are 56kbps ISDN connections specifically excluded from this draft?  It seems to imply that you can use the 64kbps for anything you want as long as use use all 64kbps.  Would it be useful to indicate that lower rate data + padding can be passed by mutual agreement, or will that just blow up into a whole mess about how to define mutual agreement. 

	Ruediger: Well !

	- I would like to here a comment from the US members in the working group. Is it necessary to support 56kbps, 48kbps, ... at all ? These bitrates are not supported in RFC 3551 for PCMA/PCMU.

	- Are there other applications that need a 56 kbps (or lower) channel ?

	- If necessary, is the use of fill bits the appropriate method ?

	- Would we start to conflict here with the N x 64 kbps work in PWE3 ?

	- If support of "64 - (N x 8; where 1 <= N <= ?) kbps" is necessary and should be supported by the Clearmode draft, then we have at least two possibilities:

	1) different MIME subtypes for each bitrate (e.g. Clearmode-64, Clearmode-56, etc.), as e.g. with G.726 in RFC3551

	2) introduction of an optional bitrate parameter (in kbps), with "64" as default  -> this should be synchronized with the N x 64 kbps work in PWE3  

	BTW: I am not a member of the PWE3 discussion list. Any answer of PWE3 members should be sent to [email-masked] too.

	- Would it be useful to define where the most and least signficant bits are for each sample, or is that already defined in one of the references? 

	Ruediger: this makes sense; I will copy the regarding sentence from RFC3551, chapter 4.5.14 (RTP Profile for PCMA/PCMU)

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---

From: "Kreuter Ruediger" <[email-masked]>
Date: Wed, 24 Sep 2003 10:59:08 +0200

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