This is https://bugs.launchpad.net/ubuntu/+source/gstreamer0.10/+bug/921071

"After upgrading to 12.04, rhythmbox will sometimes stop playing daap files, only to after a few minutes start playing a different file again.

Ie, if I connect to a mt-daapd server running lucid with rhythmbox on precise, I can play individual files fine. I have selected to have songs play in random order, and rhythmbox will continue to the next song fine. Occassionally audio will stop in one of the songs and then minutes later it will start up again (with no user interaction) in another song. When it does stop, I can click to fast forward to another song and it works ok. This does not seem to happen with local files (I played them for hours with no interruption), only daap served files.

I have tried to correlate this with a problem with networking in precise, but do not see any messages problems in /var/log/syslog that would indicate a problem. Rhythmbox can play a mixture of ogg and mp3 files fine (ie, it is not a codecs issue). There is nothing in .xsession-errors when this occurs. I tried to strace rhythmbox at the time of the problem, but couldn't figure out what was happening.

This worked fine in 11.10 and earlier."

I narrowed this down to a simple reproducer-- moving from mp3 to ogg results in the ogg not playing for several seconds and then starting somewhere within the ogg (presumably the number of seconds that there was no sound output). This seems to be related to transcoding by the mt-daapd server. If I add 'never_transcode = ogg,mpeg' to mt-daapd.conf the problem presents itself in rhythmbox. If I remove it, it works fine.

Attached is updated debug output when using:
$ GST_DEBUG=:5 rhythmbox --debug > /tmp/lp-921071_debug-with-gst_debug5.log

Specifically, playing 2834.mp3 works fine, but when it transitions to 790.ogg, there is a gap in playback.