Generally, the recommendation for avi is 400x240 video, bitrates no higher than 1200 and mp3 audio bitrate of 192. This is the "mplayer" setting in tablet-encode which does a good job for most of the stuff I throw at it. While no compatibility with osso-media-player is guaranteed at this setting most stuff will play in the regular media player. The "best" setting of tablet encode which does guarantee playability in osso-media-player is the same as mplayer with a video bitrate of 768 instead of 1200.