[MPlayer-users] play or encode only range of frames

[Adam Nielsen]

> You can use -ss to specify time from where to begin encoding. So I
> guess if you know original movie framerate, you can calculate the
> right value using formula:
> desired_start_frame / fps = desired_start_time

-ss will take decimal values (10.5) so you should be able to get it fairly 
accurate.  I'm still not sure how well it works though, because mplayer 
doesn't seek nicely with it (although mencoder seems ok.)  So far I prefer to 
allow a little extra on the front of the encoding, and trim it off afterwards 
with avidemux2 (which can be automated - you could even use avidemux2 in a 
script solely for cutting an AVI, assuming the AVI is using a supported 
codec.)

> And then use -frames

-frames is very accurate, assuming you can get the start time exact enough.

Cheers,
Adam.