Alliance for Open Media codecs

[benwaggoner]

Originally Posted by mzso

"Or it could be that we luckily hit upon the right essential transform that balances spatial and temporal prediction better than available alternatives."

I highly doubt it. I think it's more likely the illusion of familiarity and the blinders that come with it.

"Some of this could be because of the momentum of R&D around the traditional stuff."

It certainly seems like that alternatives got only limited efforts on them.

Yeah. It's really hard to disprove the hypothesis that there could be better fundamental ways of encoding.

That said, wavelets sure got a lot of attention for image and motion coding. Good for images, but no one figured out an efficient motion compensation strategy for it.

Daala had a lot of really intriguing notions, but the most interesting stuff in it never really got to a promising proof of concept. Sure, maybe with 10 years of 1000 engineers something could be found. Any alternative transforms have to compete with decades of refinement of block-based frequency coding.

A lot of promising ideas get figured out how to port into a block-based structure. For example, HEVC's transform skip mode can make anime, graphics, and text way easier to encode at low bitrates and high quality. So new features, like have been seen in VVC and AV1, can get included as tools. Arguably, once you have 64x64 or bigger blocks, you've pretty much got all the advantages of wavelet coding already, within a block based model. And intra-frame prediction brings a lot of the potential value of fractal encoding.

One exciting thing (to me at least) about Daala that didn't make it into AV1 was doing frequency-domain prediction, so there was no need to rasterize a frame that wasn't going to get displayed, and dithering didn't need to be included in quantization. It didn't work out for reasons I don't quite recall.