I changed the mencoder command line to use -ovc xvid instead of lavc. I think this uses official xvid instead of ffmpeg's libxvid. Anyway, it's a bit smoother in Canola now (watchable). I'm still not entirely satisfied because I've seen how good it *can* look (Nokia Media Player, mpeg4, flawless, as above). Maybe I'll just statically transcode it before I watch anything, because that worked the best (besides being really annoying).

You could also try to get the bitrate down a bit. 768 kps seems a little high.

Like I said before, the choppiness is independent of bitrate. I've tried all the presets that tablet-encode offers, all the way down to 80 kbps. That's why I think I might have a problem with mplayer, possibly with its use of the framebuffer?

And again, the full 768kbps quality videos play perfectly in Nokia's Media Player, so the hardware is easily capable of it.

UPDATE: Issue solved thanks to a comment from attila77:

YES!! THANK YOU!! That solved my problem. Now my mediatomb on-the-fly transcoding setup works with Canola flawlessly! All it took was setting the audio to resample to 44100 (was 48k). I knew it had to be something simple.

hey spock,

so did you find the fix for mplayer choppiness?
I am having the exact same problems with the exact same mplayer version.
some videos play fine a couple of seconds and then get really choppy.
other videos play fine, but the playback isn't smooth comparing to built in player.

driving me crazy...