[MPlayer-users] How to grab two different frames at 1 and 2 seconds.

[PaulM]

Hi,

I need to extract two or more different jpeg frames from a video file.
I'm trying to run this:

mplayer -frames 2 -vo jpeg -ss 00:00:01 -nosound  video.avi
this:
mplayer -frames 2 -vo jpeg -ss 00:00:02 -nosound  video.avi
this: 
mplayer -frames 2 -vo jpeg -ss 00:00:03 -nosound  video.avi
and this: 
mplayer -frames 2 -vo jpeg -ss 00:00:04 -nosound  video.avi

I assume I should get 4 different frames at positions 1,2,3 and 4. But that's wrong. For some reason I got the same frames which are absolutely equal. I got a different frame starting from 5th second only. Why is it so? Why mplayer generates identical frames for the first 4 seconds?  How can I get different frames?

Thanks a lot.

Paul