Quote:
Originally Posted by benwaggoner
I'd expect that the limitation of VP9 would be based on single-core performance. Reducing frame size is the easiest way to improve performance,
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VP9's column-wise parallelism is effectively splitting a frame into several small frames. It's similar to and is about halfway between HEVC's tiles and slices. Like tiles, there's no signaling/encapsulation overhead for each element, but like slices, the long rectangular elements (as opposed to square'ish ones) result in more dependency breaks and decreased efficiency.
The weird thing, though, is that Google's (and therefore Chrome's, Opera's, Firefox's) VP9 decoder needs the
encoder to operate in `frame-parallel` mode, which additionally worsens entropy coding because that also disables the backward context update tool.