You are right, they are contained in some container.. but my task is not to bother abt container format...

My part comes into picture ater the video is moved out of container, so it's now a video stream compressed either in MPEG4 or H.264 ... Well checking a few files reveal that for MPEG4 it is 00 00 01 BX... and for H264 it is 00 00 01 mostly...

Btw, Thanks all for help..

Edesign