Subject: [AVT] question on DTX for AMR

From: Faerber Tobias ICM MP PO8 RD MCH83 <[email-masked]>
Date: Mon, 21 Jan 2002 17:12:26 +0100

1) in DTX mode: do you transmit a ToC in case a NO_DATA AMR frame is at the
end of a payload frame ?
e.g. you have {7,7,8,15,15} in one RTP frame ?
so is ther a ToC for the last two AMR frames? I guess not because you can
get the loss from the next timestamp info.

2) what happens if you send lots of NO_DATA frames, e.g. only NO_DATA frames
within one RTP payload. is there any ToC ?
e.g. 15,15,15,15,15 => 5 ToC s? or no one and backmapping through time stamp
of next RTP packet ?

best regards,
Tobi

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From: Magnus Westerlund <[email-masked]>
Date: Mon, 21 Jan 2002 18:37:43 +0100

Hi,

I think both of these questions is answered in the sixth paragraph of section 2.
in draft-ietf-avt-rtp-amr-10.txt.

> get the loss from the next timestamp info.

No you is recommended to exclude all NO_DATA in the end of packets. The
exception is interleaving.

> e.g. 15,15,15,15,15 => 5 ToC s? or no one and backmapping through time stamp

No you should also never begin a packet with a NO_DATA frame, with the exception
of interleaving.

Cheers

Magnus Westerlund

Audio Technology, Ericsson Research
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