[MPlayer-G2-dev] bypassing PTS in video filter layer

Arpi arpi at thot.banki.hu
Sat Aug 2 22:59:24 CEST 2003


> > - it's not completely true that I frames are keyframes in mpeg2. there are
> >   streams (actually most of them i've seen) using partial update in I
> > frames, ie. you need to decode 2 or more I frames to get the complete
> > picture, otherwise you'll see checkboard-liek thing. just try to seek in
> > some mpeg2 streams... (mostly true for DVD and DVB files). I frames don't
> > use prediction (ie. reference frames), so you can seek to them, but also
> > don't always cover the whole image area, so you can't simply skip them.
> hmm, do u say that there are streams which have skiped MBs / skiped slices in 
> I frames? the syntax would allow that but i thought thats not allowed in the 

yes, skipped MBs. it looks like a checkboard, every 2nd or 3rd MB is
skipped, so you need 2 or 3 I/P frames to get the whole picture.

try any VOB (i've tried matrix.vob and
apollo_440_-_lost_in_space(jason_nevis_lunar_landing).vob, the later is on
mphq too) with mplayer file.vob -nosound -fps 2 and then seek.

> standard or did u mean I field pictures, for these 2 are needed and the 


> btw, mplayer should call AVCodec.flush() before seeking to avoid trashed B 
> frames, as the "future" refrence frame is wrong immediately after seeking

hmm. does it also flush internal buffers/states when using 'truncated' mode?
(i mean passing mpeg frame data by small chunks instead as whole frame ?)

A'rpi / Astral & ESP-team

Developer of MPlayer G2, the Movie Framework for all - http://www.MPlayerHQ.hu

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