MPEG-4

Differently from MPEG-2, which is a very simple and beautiful video codec, MPEG-4 is a huge and ugly beast.

It added support for Global Motion Compenstion, Direct Mode Motion Compensation, Quarter Sample Mode Interpolation, Grayscale Alpha planes, Sprites, 3D Mesh Objects, Face and Body Animation (yes, you can encode faces and bodies in MPEG-4), Wavelet transform, N-bit (whatever that means), and a bunch of things more.

It didn’t really reflect the reality of what was needed for codec technology at the time, and it still doesn’t reflect reality of what would be needed for codec technology today. MPEG-4 is kind of like what Dr. Henry Wu says in Jurassic World:

This added an enormous amount of complexity to the codec. Even things that used to be simple to understand, such as the concept of a video frame, was rebranded as a Video Object Plane, or VOP. And there are four types of VOPs: I, P, B, and S(GMC), where GMC stands for Global Motion Compensation. I don’t like the expression VOP, I’ll just keep calling them frames.

Most decoders don’t support most of the features that should have gone into MPEG-4. But that’s ok, we kind of settled on a subset of features that make sense.

There are many different well-known implementations of MPEG-4. Remember DivX ;-), with its watermarked logo ruining a bunch of videos? Remember Xvid, which was very confusing in the beginning because we’d ask ourselves “wait, what? wasn’t it spelled the other way around?”? They were MPEG-4 too (and not MPEG-2 for </pun>). Remember RealVideo? That shit was based on MPEG-4 (well, mostly H.263, which was a saner codec, and mostly interoperable with MPEG-4). RealVideo, on the other hand, was not sane, and definitely not interoperable with anything.

Anyways…