I have a lumia 640 (snapdragon 400) phone which refuses to play any MKV/AVC (h.264) files, with a very unhelpful error message. I'd like to know why the file can't be played - windows 8.1 update 2 has introduced support for the matroska container and I believe the snapdragon 400 processor supports most h.264 profiles. If it is somehow a codec issue, can it be fixed?
Edit: seems to be related to the lack of AC3 support. Can this codec be added to the phone for use with any application?