Thread:Extension talk:TimedMediaHandler/How to enable transcoding to H.264 ?/reply (2)

Once you change any transcode setting you should clear out all your transcodes. ( see maintenance/cleanupTranscodes.php )

Also you should check that the commands being run will work to generate your mp4 files. i.e run the maintenance/WebVideoJobRunner.php job on the command line and observer the ffmpeg commands being called and confirm they are are successfully being executed.