mp4 to avi/mpeg conversion I'm trying to convert an mp4 video to play on a digital photo frame. The photo frame (Living Image Li1210) manual states: 

The digital photo frame can playback MPEG1, MPEG2, MPEG4, and AVI (dependant upon codec) video formats.

And in the FAQs: The device only works with the avi/mpeg4 files taken by most digital cameras. It is also capable of playing some compressed AVI files, such as DivX and XviD videos... The best supported resolution of a photo or video is 480x234.

I've tried various options with ffmpeg such as

ffmpeg -i in.mp4 -vcodec mpeg4 -vf scale=480x234 out.avi


but can't seem to get anything but a blank screen on the photo frame.

Any help or advice would be greatly appreciated.

Thanks
Apologies I'd being faffing with different scaling settings and must have got my files mixed up. The following (quoted in the question) does in fact work on this product - Living Images Li1210.

ffmpeg -i in.mp4 -vcodec mpeg4 -vf scale=480x234 out.avi


However the following scaling seemed to produce better results when converting from 1280x720 (youtube standard download)

ffmpeg -i in.mp4 -vcodec mpeg4 -vf scale=416x234 out.avi


And I think this addition from this question produced a slight improvement

ffmpeg -i in.mp4 -q:v 6 -vcodec mpeg4 -vf scale=416x234 out.avi