.M2V

Introduction

An .m2v file holds MPEG-2 video on its own, with no audio and no container. MPEG-2 video, defined by ITU-T H.262 and ISO/IEC 13818-2, is the codec of DVD video and of standard-definition digital television. DVD authoring tools take the video as an .m2v file and the audio as separate files, then multiplex them into the disc’s VOB files.

MPEG-1 video streams have the same layout and are sometimes saved as .m1v.

Structure

The stream is made of headers and data, each header starting with a start code: the bytes 00 00 01 and a code byte. B3 is the sequence header, with the frame size, aspect ratio, frame rate and bit rate; B5 is an extension, which marks the stream as MPEG-2 rather than MPEG-1; B8 starts a group of pictures; 00 is a picture header; 01 to AF are slices of the picture; and B7 ends the sequence.

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