If DIVX is mpeg4,why the AVI extension?

[wulf109]

DIVX=mpeg4=avi?????

Nero Recode=mp4=mp4

Are they both mpeg4?

[andkiich]

AVI file extension has been bastardized lately for a lot of things that work on AVI files with different compression codecs. So while the AVI extension might be used, it could be one of many different compression codecs or non at all.

[lordsmurf]

MPEG4 is not a format, it's a codec.
This differs fromMPEG1 and MPEG2 which are both format and codec.

[sterno]

DivX and MPEG-4 aren't the same thing. DivX 5 is an MPEG-4 implementation, and MPEG-4 was largely based on the same compression techniques used in DivX.

A modern AVI file is just a "container", which may hold audio and video streams in a variety of codecs. A divx file is typically an AVI container with a divx-encoded video stream, but MPEG-4 also defines a container format of its own. Your "mp4" files may be using real MPEG-4 containers. The MPEG-4 container format has been largely irrelevant so far.