Subject: Re: [AVT] FW: New Version Notification fordraft-schmidt-avt-rfc3016bis-01

From: "Jaehwan Kim" <[email-masked]>
Date: Thu, 5 Mar 2009 17:45:45 +0900

Hi Frans,
Thank you for the good document. It is what we wanted.

BTW, I found one issue from 3016 and 3016bis. There was no number of
channel information in SDP examples.

>From RFC4566,
For audio streams, <encoding parameters> indicates the number
         of audio channels.  This parameter is OPTIONAL and may be
         omitted if the number of channels is one, provided that no
         additional parameters are needed.

But also I found some examples from your draft-ietf-avt-rtp-mps-02.txt

In case of stereo, 
 a=rtpmap:96 mpeg4-generic/48000/2

In case of 5.1 using MPEG Surround,
a=rtpmap:97 mpeg4-generic/48000/6

Looks good.

BTW, this issue reminds me of HE-AACv2 which is actually used in 3GPP.
If the AAC uses PS implicitly, i.e. object=2, the number of channel
should be always 1 for old AAC only decoder. Of course, a relevant text
should be prepared for HE-AACv2. I might be able to help that case.

Regards,
Jaehwan

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---

From: "Bont, Frans de" <[email-masked]>
Date: Thu, 5 Mar 2009 16:41:28 +0100

Hi Jaehwan,

Thanks for your feedback. See some comments inline.

> -----Original Message-----
> From: Jaehwan Kim [mailto:[email-masked]]
> Sent: 2009 Mar 05 9:46 AM
> To: Bont, Frans de; IETF AVT WG
> Subject: RE: [AVT] FW: New Version Notification fordraft-schmidt-avt-
> rfc3016bis-01
>
> Hi Frans,

You are right! Some of the examples are not mono so the number of
channels MUST be provided by the OPTIONAL encoding parameter.

> should be prepared for HE-AACv2. I might be able to help that case.

Indeed, the main use in 3GPP is of HE-AACv2. Therefore, it is a good
suggestion to include HE-AACv2 in this update. We can either add a new
example for this purpose or extend one of the recently added examples.

Your help is very much appreciated.

Best regards,
Frans

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