file has been created as fragmented mp4 with the mp4box tool from the gpac project while demuxing with ffmpeg it causes the following errors: [mov,mp4,m4a,3gp,3g2,mj2 @ 0x766c30]missing mandatory atoms, broken header [mov,mp4,m4a,3gp,3g2,mj2 @ 0x766c30]mov: header not found !!! (err:-1, moov:1, mdat:1) pos:79409