scott wrote:

> It's not surprising that mpeg2 and 4 are much more complex than this.

On the contrary, it would be surprising if MPEG2 was *not* more complex 
than this... ;-)

> The key concept is how to describe the current frame fairly accurately 
> with the minimum amount of data, given some data from previous (and in 
> some cases future) frames.  Commonly motion is detected, as often blocks 
> of pixels hardly change, but are shifted in space from one frame to the 
> next.

...so they added motion prediction then?

> Obviously then 
> there is more than one possible bitstream depending on how good your 
> motion detection code is, which frames you reference, what tolerance you 
> use for detecting motion, etc etc.

Indeed.

> And of course at some point you need 
> to consider the CPU power needed to encode the video.

I'm usually more interested in how much CPU power is required to 
*decode* the video. Let's face it, no codec on Earth is as slow as 
POV-Ray. ;-)

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