Topic on Extension talk:TimedMediaHandler
MP3 player vanishes
$wgEnabledAudioTranscodeSet  = WebVideoTranscode::ENC_MP3; is not enough to make an MP3 player appear. It needs a handler and I didn't find it in handlers directory, so I wrote one.
Ok maybe you could upload the patch to gerrit where users can look at it and find errors. and tell you if you need to edit other files to get it working.
You could try this
$wgMediaHandlers['audio/mpeg'] = 'Mp4Handler'; $wgFileExtensions = 'mp3';
Thank you, Mp4Handler really can handle MP3, and even under IE 10.
There is also a problem when your Mp3Handler writes an <audio> tag then it gets automatically rewritten and the tag may vanish too. But there is a setting in TimedMediaHandler/MwEmbedModules/EmbedPlayer/EmbedPlayer.config.php this can then be modified to not rewrite <audio> tag:
$wgMwEmbedModuleConfig['EmbedPlayer.RewriteSelector' ] = 'video,playlist';
In my case Mp4Handler did not work