Video Encoding with mplayer

[lovalixir]

I am still a pretty much newbie with mplayer. I wish to do the followings and I am not too sure what kind of command to issue to get the result.

1. Encode the first 10 seconds of a movie file to another movie file (in same format. i.e avi to avi, mpg to mpg)

2. Detect the duration of the movie file (5 mins or 10 mins etc)

3. Change the resolution of the movie file (1024x768 to 640x480 etc)

I think mplayer can do all these features. I read up the mplayer manual. But I am still not too sure how to do these.