[MPlayer-dev-eng] [RFC] rc2

Nico Sabbi nicola_sabbi at fastwebnet.it
Wed Apr 11 21:44:41 CEST 2007

Matthias Hopf wrote:
> On Apr 11, 07 17:37:17 +0200, Nico Sabbi wrote:
>>>- native MPEG2 TS demuxer adds offset to PTS, lavf works on most (*)
>>no, it doesn't add any offset, but since lavf uses a frame parser
>>every packet has 1 complete frame with a correct pts
> I don't think that is all. An ac3 frame has a length of 32ms for 48k
> audio, and I found (per-file constant) offsets of -200 to 200ms with the
> native TS demuxer.

there's usually an initial preload in broadcast transmissions
(audio transmitted somewhat ahead of time wrt to video), that is:
"near" packet N there's a video packet with Vpts(N) and an audio 
packet with Apts(N)=Vpts(N)-K.
Mplayer will initially play them as if they corresponded to the same
pts, but after few seconds the sync stabilizes.
IIUC  lavf seems to discard the initial packets corresponding to the 
pre-loaded stream

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