Subject: [AVT] Comments on draft-ietf-avt-dsr-02.txt

From: Magnus Westerlund <[email-masked]>
Date: Tue, 09 Jul 2002 16:04:29 +0200

Hi Qiaobing and others,

Here is a few comments:

Section 4.
Second paragraph: A note that the padding of the payload not is the one 
that uses the P bit may be appropriate.

Isn't better to padd each individual frame pair to an octet boundary? It 
will result in 4 bit overhead per frame which is around 4.5 % increase 
in payload size compared to the cases having no padding at all. It will 
definitely make the payload format easier to implement and remove the 
need to shift every second frame pair four bits.

Section 6.
Shouldn't ptime be a optional parameter in the RTP case?

I am also lacking a section on how to map the parameters to SDP. 
Something very similar to RFC 3267's section 8.3.

Regards

Magnus Westerlund 

Multimedia Technologies, Ericsson Research ERA/TVA/A
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From: Qiaobing Xie <[email-masked]>
Date: Wed, 10 Jul 2002 14:28:08 -0500

Hi, Magnus,

Thank you for the comments.. Please see my responses in-line.

> that uses the P bit may be appropriate.

Good point. I will add text to clarify this.

> need to shift every second frame pair four bits.

You are not the only one to make this suggestion. I am consulting with my
co-authors on this.

> Shouldn't ptime be a optional parameter in the RTP case?

Yes. But I think, by default, this fact is provided and covered by SDP. Do you
think it would help if we mention it explicitly in this document?

> Something very similar to RFC 3267's section 8.3.

Good idea. I think it will be helpful. I will consider adding such a section. 

Thanks and regards,
-Qiaobing

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From: Magnus Westerlund <[email-masked]>
Date: Thu, 11 Jul 2002 09:49:32 +0200

Hi Qiaobing!

>think it would help if we mention it explicitly in this document?
It may seem to be so but in SDP it is only a suggested parameter. The 
MIME type registration does specify which parameter that are available 
for the codec. Therefore you should include ptime as an optional 
parameter in the registration. If you look at 
draft-ietf-avt-rtp-mime-06.txt you can see that all the audio codecs 
registrations contain the ptime as optional parameter and nothing is 
today done by default.

Regards

Magnus Westerlund

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From: Qiaobing Xie <[email-masked]>
Date: Thu, 11 Jul 2002 10:50:49 -0500

Hi, Magnus,

This sounds very reasonable. I will add it to the draft.

regards,
-Qiaobing

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From: Qiaobing Xie <[email-masked]>
Date: Tue, 16 Jul 2002 11:20:04 -0500

Hi, Magnus,

Magnus Westerlund wrote:
....
> need to shift every second frame pair four bits.

After consulting with my co-authors, we will make this change (I think many
implementors will be happy to see this change :)

regards,
-Qiaobing