Creates a stream transform for piping a fmp4 (fragmented mp4) from ffmpeg.
Can be used to generate a fmp4 m3u8 HLS playlist and compatible file fragments.
Can be used for storing past segments of the mp4 video in a buffer for later access.
Must use the following ffmpeg args -movflags +frag_keyframe+empty_moov+default_base_moof to generate
a valid fmp4 with a compatible file structure : ftyp+moov -> moof+mdat -> moof+mdat ...