I use the iPhone. Before upgrading iTunes and the iPhone firmware I was able to load video on the iPhone using iTunes. Now I have problems getting the same video to sync to the iPhone. I also have problems getting some video podcasts to sync to the iPhone that used to sync just fine.
I did some research using ffmpeg -i on some of the files that synced and some of the ones that wouldn't sync. I found that the video that wouldn't sync all had something in common. The aspect ratio was showing up as 0:1 (for DAR and PAR).
I googled some iPhone video conversion parameters and found an ffmpeg parameter that gets any video to sync, -aspect 16:9. Now I just need to come up with a set of ffmpeg video conversion parameters that play for more than a few seconds before the audio drops out and the video stops playing.
Gonna try doing an ffmpeg copy and report back the results.
I found out a lot. The 0.49 version of ffmpeg that comes with ffmpegX works fine. It was either patched to deal with the QuickTime mpeg4 issues or uses default setting that work with QuickTime. Turns out QuickTime needs square pixels for mpeg4 and the harddup video filter to avoid a frame copy problem when it converts to the mpeg4 format as the duplicate frame flag gets lost in the translation. I haven't figured out how to do this with ffmpeg. But all the info on this issue is dealt with in a section of the mencorder documentation under the heading QuickTime. Mencoder uses ffmpeg under the "-lavc" flag.
I'll update with the details after I perform some tests.