This file contains a silent audio stream. This is special because all of the
AAC frames are 7 bytes long, which means that rather than there being a sample
length table, trak -> samplesize is set to 7.

The demuxer then complains 'WARNING! Samplesize(7) != 1', and only a
small number of the frames are actually passed to the codec. Although
this more-or-less works in mplayer, mencoder fares much less well. For
instance,

mencoder -oac copy -ovc copy silent-mp4.mp4 -o silent-mp4.avi

produces a file with a corrupt video stream.


I'm going to submit a patch to mplayer-dev-eng.

Oh, and, uh, sorry about the slightly adult video content... I think
it's vaguely within the bounds of good taste though.