Re: [AVT] Question on RTP sequence number in RFC2833 and bis-02

[Eric Cheung <cheung@research.att.com>]

Hi, I am still hoping that I can get some clarification from the WG on 
this question.  Apologies if this was discussed before, but I could not 
find anything by searching on the archive.

Thanks
Eric

Eric Cheung wrote:
> Hi Henning, Scott
>
> Want to clarify a fine point.
>
> In RFC2833:
>
>    If there has been no new event
>    in the last interval, the event SHOULD be retransmitted three times
>    or until the next event is recognized.
>
> Q1: For a device conforming to RFC2833, should the RTP sequence number 
> in the 3 packets be incremented, or should they be the same?
>
>
> In RFC2833bis-02, this seems to be clarified:
>
>    If an event has ended and
>    there has been no new event in the last interval, the event SHOULD be
>    retransmitted three times at the interval used by the source for
>    updates.
>
>    In all cases, the RTP sequence number MUST be incremented by one in
>    each RTP packet.
>
> Q2: Can you confirm that if a device conforms to bis-02, the sequence 
> number in the 3 packets will be monotonically increasing?
>
> Q3: In writing this, I realize that I am not sure whether there should 
> be 4 packets (1 original transmission + 3 retransmission) or 3 packets. 
>  Can you clarify this?
>
>
> Sorry for the nit-picking, but when testing it seems many devices do 
> many different things when it comes to 2833.
>
> Thanks
> Eric

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