@FLX90
As a quick test for what gets packed into an .mp4 container and whether your playback device will play it you may want to try:
Code:
ffmpeg.exe -i "yoursource.mkv" -c:a copy -c:v copy "output.mp4"
It should pack your VC-1 untouched (=original quality) plus the first acceptable audio stream into an .mp4 container. Then try to play the file "output.mp4" with your player. What do you get?