I transcode video and specify mimetype in config.xml as:
<mimetype>video/mp4</mimetype>
On the player, the mimetype shows as:
"video/mp4;rate=44100;channels=1"
rate and channels seem to come from the metadata of the original video. mediatomb should not add this subtype to the transcoded video since the transcoded video could have another audio format then the original video.
(Also, in this specific case channels=1 is wrong also for the original video.)
Seen on mediatomb 0.12.1 running on Ubuntu 10.10