Subject: RE: [AVT] RE: Working group last call: draft-ietf-avt-ulp-14.txt

From: "Mark Watson" <[email-masked]>
Date: Thu, 19 Jan 2006 12:57:44 -0500

Magnus,

Good point - I had not thought of that. So, then we should leave the
timestamp as it is in RFC2733.

...Mark

-----Original Message-----
From: Magnus Westerlund [mailto:[email-masked]] 
Sent: Thursday, January 19, 2006 12:20 PM
To: Mark Watson; Adam Li
Cc: [email-masked]
Subject: Re: [AVT] RE: Working group last call:
draft-ietf-avt-ulp-14.txt

Thanks Mark,

The WGLC of this document has conclude and there is a need for 
addressing these comments and an update. A one week WGLC will held on 
these updates at that time the new version is addressed.

I also have a comment on the feedback:

Mark Watson wrote:
> C.5) Section 7.3: Timestamp: it is not clear to me what purpose it
serves to timestamp the FEC packet with the time it was sent, since
there are many strategies for timing the sending of the FEC packets
relative to the original stream. It might be more useful to timestamp it
with the same time as the last packet protected by this FEC packet,
since that is the time in the stream playout after which the FEC packet
is useless. However, this would not result in monotonically increasing
timestamps.

There is one good reason for timestamping with transmission time. It 
makes the RTCP reports on the FEC traffic very accurate and can be used 
to measure traffic characteristics better than for example a stream of 
video packets. To me there is no need to indicate the protected streams 
media TS corresponding to the last directly protected packet. That 
information is in most cases available from the buffer by looking into 
the payload of the received FEC packet. However it will provide 
information is some cases that is not directly available. So this would 
be a definite trade-off but probably not worth changing in this update 
to RFC 2733.

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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