VC-1 vs. AVC HP: History and differences..

[MfA]

One thing not mentioned in AVC uses CABAC which is significantly more expensive than the entropy coding in VC-1.

As far as decoding is concerned I wouldn't really call it expensive. It takes less than a mm2 of die space. That's what? A couple of cents? The cost of H.264 is in the licensing, not the hardware. Same goes for the interpolation filter, it's FUD.

Modern formats use very large runs of predicted frames, subtle changes in the DCT transform were enough to screw up mpeg-4 decoders ... I don't think changing the loop filter is realistic.

 

[Blazkowicz]

I don't want to dig into the technical details, I don't know much shit about them, but generally :
I believe in the law of diminishing returns for compression, and I want to think about the power required by the decoding. A more power hungry codec == millons tons more coal burned.