[adicoto]

Step 1. Just downloaded an .m4a file. BSPlayer failed to play the file and requiered for a codec. Found Haali and FFDshow. Neither of this one is my prefered, so I've closed the codec manager window. File won't play. So, tested with MPC (wich use the very same codecs/filters I have installed on my computers). File play OK.
Step 2. Renamed the file as MP4. File play ok in BSPlayer, using, as normally should do, Gabest MP4 splitter and CoreAAC audio decoder.

Codec management problem ? Or the extension just mixed up BSPlayer's capabilities ? But even after adding M4A as extension in BSplayer's preferencies, the file failed to play using this extension.