Problem is, some of the songs are encoded in FLAC format, and they are not recognized by the above setup.
The fix is easy:
1. Install MacPorts, if you haven't done so already
2. Using MacPorts, install ffmpeg, which is a command line audio/video transcoder. Open Utilities/Terminal, and enter
sudo port install ffmpeg
3. Tell TwonkyServer, where to find ffmpeg. Still from the terminal, enter the following commands:
cd /Applications/TwonkyMediaServer.app/MediaServer/cgi-binsudo chmod a+rw ffmpeg.locationopen -a TextEdit ffmpeg.location
When TextEdit opens, replace the the file's current contents to this single line:
Save the file, close TextEdit
4. Tell TwonkyServer how to use ffmpeg to transcode FLAC to LPCM audio (which is the lossless audio format the PlayStation understands). This can be accomplished by creating and editing another file. Still in the terminal, enter these commands:
cd /Applications/TwonkyMediaServer.app/MediaServer/cgi-binsudo touch ffmpeg-flac-lpcm.descsudo chmod a+rw ffmpeg-flac-lpcm.descopen -a TextEdit ffmpeg-flac-lpcm.desc
In TextEdit, enter these four lines:
exec: ffmpeg -i $infile -f s16be $outfilefrom=audio/x-flacto=audio/L16dlnaprofile=LPCM
Save the file, close TextEdit.
Finally, restart TwonkyServer by clicking on Applications/TwonkyMediaServer. FLAC music files should be accessible now from the PlayStation.