Hi, 2016-01-20 15:27 GMT+01:00 John Cox <j...@kynesim.co.uk>: > The by22 code gained me an overall factor of two in the abs level decode > - the gains do depend a lot on the quantity of residual - you gain a lot > more on I-frames than you do otherwise as they tend to have much longer > residuals. The higher the bitrate the more useful this code is. But as > you note it didn't use vast amounts of time relative to everything else > anyway. > > The reworking / simplification of the loop(s) around the abs level > decode and the scaling gave me the biggest single improvement.
The thing is, it provided no gain on no Win64 system I had at hand. Or very minor, once I switched off things. The amount of new/changed code would make it worth discussing, were it not for actual gains on arm. > After that the reworking of get_sig_ceoff_flag_idxs was a useful gain Yes, this is the most agreeable part of the non-applied parts. > Special caseing the single coeff path gave a similar gain This is a big slowdown on Win64 and UHD-bluray like sequences, but that can be switched off in that case. > After that the scale rework - now probably 75% faster than it was > previously but it wasn't taking a huge amount of time. The work is done, I don't mind. > And after that all the other bits - my experience with optimising this > sort of code (I did a lot of work on a TI H.264 implementation in the > past) is that no single change is going to do everything, you just have > to polish everything until it goes fast enough. Sure. There may be positive interactions, but my own figures showed the sigmap/greater than flags were the only ones worth optimizing on Win64. > Sorry - I don't quite understand what you've said here. Doesn't matter anymore, I think I have just laid out the parts actually mattering, and for haswell/Win64 (ie x86_64). I'll reply more in depth to the new patchset, but not until you're on holidays. Which should leave me more time for reviewing it, so all the better. Best regards, -- Christophe _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel