Subject: Fw: [AVT] No_data in the RFC3267

From: [email-masked]
Date: Fri, 23 Sep 2005 11:04:52 +0200

Hello,

Sorry to repeat my request but I'm not sure that my previous email has 
been correctly transmitted. 

I've put an example based on my understanding but it is not yet clear in 
my mind for the SN+5 and SN+6 packets. Could you confirm that this figure 
is correct and indicates the timestamp value for the SN+5 and SN+7 
packets? 

This example is based on a redundancy scheme (window=1). The first column 
is the RTP Sequence Number, the second column is the Timestamp value. The 
field between brackets correspond to the sample reference for the 
timestamp. "nd" is for no data and we consider in this example that 
"no_data" is not transmitted in the packet.
SIDf: SID first
SIDu: SID update

Best regards

Yannick STEPHAN

Magnus Westerlund <[email-masked]>
20/09/2005 10:49
 
        To:     Yannick STEPHAN/FR/ALCATEL@ALCATEL
        cc:     [email-masked]
        Subject:        Re: [AVT] No_data in the RFC3267

[email-masked] wrote:
> Hi Magnus,
> 
> thanks a lot for your answer. 
> 
> an additionnal question:
> 
> in the RFC3267, when the redundancy is enabled for a codec mode (window 
= 
> 1 for example) , what is the sample reference  used to insert the 
> timestamp  in the RTP header. Is it the first sample of the first block 
or 
> the first sample of the second one? 
> When there is no data, does this timestamp correspond to the single 
block 
> in the packet?
The timestamp always referes to the first sample of the first (oldest) 
frame-block (independent of frame type as it can be speech, sid or 
NO_DATA) in the payload. So when using redundancy it will reference the 
oldest of the redundnat frame-blocks included in the payload.

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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[email-masked]
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---

From: Magnus Westerlund <[email-masked]>
Date: Fri, 23 Sep 2005 13:53:42 +0200

> been correctly transmitted. 

Sorry but I didn't see your attached gif file so the mail was a bit unclear.

> is correct and indicates the timestamp value for the SN+5 and SN+7 

Yes, the figure is correct for a redundancy scheme repeating the last 
frame together with the current frame.

The timestamp of SN+5 will be TS(SIDu) and will only contain the SIDu 
frame, no no_data frame.

SN+7 will also only contain speech data frame N+10 and will have Ts(N+10).

Cheers

Magnus Westerlund