Yesterday I read the docs on my cell SonyEricsson W300i at the Multimedia Docs and Tools page and probably found the best options for me. Since the screen is 128×160 with about 200000 colors, the best format for movies is 128×96 (no, I cannot turn it on the side and use the higher resolution since it has no fullscreen mode). It can also read QCIF 176×144 but it (has to) scale it and I think I see jaggies on cartoons, very disturbing. Anyway, the lower resolution has the perk that I can use less bitrate to get the same quality. It can read 3GP files, but it’s better to use the more standard MP4, for example using Avidemux, and MPEG4 Part 2 Simple profile, i.e., no b-frames at all. I have not yet run into any variable frame rate limitation, but for such a small video, 128kbs is probably a waste of bits, maybe around 64kbps is better, or fixed quantiser 6 (or something less, i.e., higher quantizer). For audio, MP4 was ideally created to contain AAC and the cell supports the AAC-LC variant, so 48kbps stereo is fine (altough for music 64kbps is more appropriate) or donwmix to 32kbps mono.