Setting a very low maximum bitrate causes audio loss.
Using oggenc and libvorbis from CVS (2002-06-18), files encoded with a maximum
bitrate of 8 kbps are missing the first 30+ seconds of audio. Encoding with
-M 16 results in files that are missing small gaps of audio every so often.
The granulepos values are still in sync with the original, so it looks like
the encoder is not outputting certain packets.