I am running MediaTomb on my Mac Mini g4 to serve my audio library to my Orange LiveRadio. Most files are mp3 and they play fine, but some are Ogg Vorbis which the device cannot play. So I added this section to the config to deal with them:
<transcoding enabled="yes">
<mimetype-profile-mappings>
<transcode mimetype="audio/ogg" using="oggmpeg"/>
<transcode mimetype="audio/x-vorbis+ogg" using="oggmpeg"/>
</mimetype-profile-mappings>
<profiles>
<profile name="oggmpeg" enabled="yes" type="external">
<mimetype>audio/mpeg</mimetype>
<accept-url>no</accept-url>
<first-resource>yes</first-resource>
<hide-original-resource>yes</hide-original-resource>
<agent command="sox" arguments="%in -t mp3 %out"/>
<buffer size="1048576" chunk-size="131072" fill-size="262144"/>
</profile>
</profiles>
</transcoding>
It works, but the sound has the 'blips' typical of corrupt .mp3 files. I have tried various settings for the buffering, and the smaller the chunk_size the more frequent the blips. I also tried an alternative agent -- a shell script that piped ogg123 to lame -- with the same results. I startedMediaTomb with the --debug switch but could not see anything in the output that indicated a problem.
Software is all newly built with MacPorts. Some problem related to the powerpc architecture perhaps?