[MPlayer-users] keyframes only returned extracting jpeg from WMV2 and 3 files

Marques Johansson marques at displague.com
Mon Sep 27 19:38:30 CEST 2004

I am making an interface for a webpage that would ask the person 
what second of the movie they would like to use as a thumbnail.

With a number of WMV2 and WMV3 files which I have, the following does not 
produce what mplayer's gui might show at the ss suplied time but 
returns, what i suspect as, the nearest keyframe.

The fifteen second movies I have been using seem to yield four unique 
jpegs when I try "-ss 1" .. "-ss 15".  With a 1 Keyframe/s movie I get 
about 15.

It also seems that I always get two jpegs for each frame request; the 
first of the two seems to be the first keyframe of the entire clip.

mplayer -vf scale=160:120  -vo jpeg -ss 2 -frames 1 -nosound somefile.wmv

I have also tried some combinations of -fps and framerate, but my best 
results are still keyframe jpegs.

I believe I could use some of the mencoder options (-ofps -endpos) to work 
around this, but I can't figure out how to produce simple jpegs from 
mencoder.  Should I use mencoder to  converting my wmvs to some other 
format with 1s keyframes and then extract the jpegs from it with mplayer, 
or is there a more sane option?
Marques Johansson
marques at displague.com

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