[vlc-devel] [RTP] timestamp decrease

Rémi Denis-Courmont rem at videolan.org
Tue Mar 10 21:24:54 CET 2009

Le mardi 10 mars 2009 22:03:59 vlc at sosend.de, vous avez écrit :
> The sequence number is incremented (to 19075) but the timestamp has
> decreased (to 1014202791) for payload type 96!
> This only happens for the video stream.  The audio RTP packets are OK.

The semantics of the RTP timestamps depends on the payload type. As a general 
rule it contains the Presentation Time Stamp (PTS) of the first block of data 
inside the packet. Also as a general rule, the packets are ordered by 
Decoding Time Stamp (DTS). In the presence of bi-directional predicted frames 
("B-frames"), the codec would logically send the later key frame ("I-frame") 
first, as it should have an earlier DTS inspite of the later PTS. It is hence 
perfectly normal to have a late timestamp before an earlier one, within short 
time intervals.

I do not think there is a bug anywhere.

Rémi Denis-Courmont

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