If not be able to support then when will mp3 support added?
Topic on Extension talk:TimedMediaHandler
That format is not a priority for this extension (The primary goal is to support a/v formats used by Wikimedia. For political reasons its very unlikely Wikimedia will be using this format)
If you put the following at the bottom of LocalSettings.php, it might work, no guarantees:
$wgMediaHandlers['audio/mpeg'] = 'Mp4Handler';
$wgFileExtensions[] = 'mp3';
You may want to consider something like mw:Extension:Mp3Handler
Well, in fact setting wgMediaHandlers & wgFileExtensions like you wrote in reply generate lots of strange buggy problem. Such as existing mp3 file become not exist on both File: page and [[File: ]] link. (at least in MW 1.27.1)
It work awhile in test environment but generate numerous problem in production. So this work around is not recommend for mw users.
Here is the error message:
MediaHandler::getHandler: no handler found for audio/mp3.
Linker::makeImageLink: File:Aa5ba7ca70265445_0..mp3 does not allow inline display
LocalFile::upgradeRow: file does not exist, aborting
ForeignAPIRepo: HTTP GET: https://commons.wikimedia.org/w/api.php?titles=File%3AKancollebgmB12.mp3&iiprop=timestamp%7Cuser%7Ccomment%7Curl%7Csize%7Csha1%7Cmetadata%7Cmime%7Cmediatype%7Cextmetadata&prop=imageinfo&iimetadataversion=2&iiextmetadatamultilang=1&format=json&action=query&redirects=true&uselang=zh
File::transform transformation deferred.
File::transform transformation deferred.
File::transform transformation deferred.
I can confirm the mp3 file will not be load with both $wgForeignFileRepos ForeignDBRepo class and ForeignDBViaLBRepo class. Loading mp3 locally work in most of case as well as using ForeignAPIRepo class.
There is another bug which prevent ogg from loading if ForeignDBRepo class were used. Using ForeignDBViaLBRepo can by pass that ogg bug. Unfortunately, this is not the case for MP3. Moreover, due to the political reasons , this bug is not like to be fixed.