[MEncoder-users] -ss seek position?

[R.L. Horn]

On Mon, 9 Jun 2008, jthompson wrote:

> mencoder -ss 00:00:00 -endpos 00:00:05 -nosound -ovc copy 
> SOURCE_FILE.mpg -of mpeg -o OUT_FILE.mpg

> The behavior is quite odd. With start / stop :00/:05 mencoder returns 
> 5.005 secs and 150 frames writtenm, :01/:05 returns the same 5.005 secs 
> and 150 frames, :02/:05 returns 4.505 secs and 135 frames, :03/:05 
> returns 3.505 secs and 105 frames, :04/:05 returns 3.003 secs and 90 
> frames and :05/:05 returns 2.002 secs and 60 frames. My .mpg test clip 
> is only 6 seconds but I have tried longer clips.

The -ss option isn't all that well documented.  At best, I believe it can 
only seek to the nearest keyframe.  If you need better resolution, the 
only choice appears to be to write an EDL file and use -hr-edl-seek 
(though not with -ovc copy unless the input is raw or MJPEG or some other 
format where every frame is a complete picture).