MP4Box is a popular MP4 multiplexer that can easily and quickly import MPEG-4 video, DivX, XviD, h264, 3ivx, etc audio streams and subtitles into the .mp4 container.The end result will be a compliant MP4 stream. MP4Box can also easily extract streams from a .mp4. MP4Box is a command line utility but can be used with graphical user interfaces such as YAMB.