[FFmpeg-devel] [PATCH 0/2] ARM64 HEVC QPEL/EPEL

Josh Dekker josh at itanimul.li
Wed Apr 28 22:50:24 EEST 2021

This is a patch originally, submitted in 2017 (author/date info left
intact). At the time, it didn't get much attention I assume due to the
sheer size of it. I have split the patch into only its QPEL/EPEL parts,
rebasing, and doing some cleaning of the patches as much is reasonable
for a 9001 line diff. I also have SAO band (non-working) and 32x32 IDCT
(working but honestly in a worse state than these patches).

This patch gives a large overall speedup roughly 30% in my testing. The
only problem is that (as previously stated), 1) it's a lot of code, the
original author didn't make use of macros. 2) it's only 8-bit. I will be
writing 10-bit assembly, and whilst I do that will clean-up/macro-ify
the current 8-bit assembly. Though there is still lots to be done.

Our current IDCTs for HEVC aren't great either, I had a 40% speedup on
the 16x16 one in testing. The assembly is far from 'done' but we're
getting closer slowly at least.

There were some suggestions for smaller improvements in the previous
reviews and I have not applied those. The first course of action is to
refractor it so that it is possible to work on the code without going
insane. I think it's fine to use it whilst I'm working on refractoring
it due to the large speedup: the code-weight in the binary should be
relatively similar even after that anyway.

Also, updated kperf patch as per Lynne's request.


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