Comment 2 for bug 329462

It is a Windows Mobile device, hence its playback capabilities depend on the software the user installs.

Anyway, the default MS Windows Media Player seem to struggle with MP4 and does not support OGG at all. Also, the individual folders are usually prepended with "My " string.

So it might be safer to enable just MP3s (plus possibly WMV and WMA - I have no such files to test). I have finally created a separate subset:

          <match key="@storage.originating_device:usb.product_id" int="0xc25">
             <addset key="portable_audio_player.access_method.protocols" type="strlist">storage</addset>
             <append key="portable_audio_player.output_formats" type="strlist">audio/mp3</append>
             <append key="portable_audio_player.audio_folders" type="strlist">My Music/</append>
          </match>