I'm a little bit of a newbie when it comes to Mencoder and Linux in general, so I've been having trouble finding the "best" settings to encode small video files to play on the GP2X. This is the best I've been able to do:
mencoder input.avi -oac copy -ovc xvid -xvidencopts bitrate=192 -vf scale=320:240 -o output.avi
And for dual-audio (change the aid appropriately):
mencoder input.avi -oac mp3lame -aid 1 -lameopts vbr=2 -ovc xvid -xvidencopts bitrate=192 -vf scale=320:240 -o output.avi
The main problem with these settings is that in anime, things get a little choppy in action scenes. I think it's because setting the bitrate like that makes it somewhat constant. Replacing "bitrate=192" with "pass=2" seems to just make an error, and the other option (I can't think of it off the top of my head) seems a little weird to me. Oh, also, I set the bitrate to 192 because I don't really know what people tend to use for video, and it let me store two and a half hours of anime on a single 256MB SD card.
mencoder input.avi -oac copy -ovc xvid -xvidencopts bitrate=192 -vf scale=320:240 -o output.avi
And for dual-audio (change the aid appropriately):
mencoder input.avi -oac mp3lame -aid 1 -lameopts vbr=2 -ovc xvid -xvidencopts bitrate=192 -vf scale=320:240 -o output.avi
The main problem with these settings is that in anime, things get a little choppy in action scenes. I think it's because setting the bitrate like that makes it somewhat constant. Replacing "bitrate=192" with "pass=2" seems to just make an error, and the other option (I can't think of it off the top of my head) seems a little weird to me. Oh, also, I set the bitrate to 192 because I don't really know what people tend to use for video, and it let me store two and a half hours of anime on a single 256MB SD card.