On Thu, 31 Mar 2022, Ben Avison wrote:
The VC1 decoder was missing lots of important fast paths for Arm, especially
for 64-bit Arm. This submission fills in implementations for all functions
where a fast path already existed and the fallback C implementation was
taking 1% or more of the runtime, and adds a new fast path to permit
vc1_unescape_buffer() to be overridden.
I've measured the playback speed on a 1.5 GHz Cortex-A72 (Raspberry Pi 4)
using `ffmpeg -i <bitstream> -f null -` for a couple of example streams:
Architecture: AArch32 AArch32 AArch64 AArch64
Stream: 1 2 1 2
Before speed: 1.22x 0.82x 1.00x 0.67x
After speed: 1.31x 0.98x 1.39x 1.06x
Improvement: 7.4% 20% 39% 58%
`make fate` passes on both AArch32 and AArch64.
Changes in v2:
* Refactor checkasm tests to convert some macros into functions.
* Remove cast-to-void of checked_call.
* Limit 16-bit values in idctdsp checkasm test to +/-0x100.
* Reinstate ff_add_pixels_clamped_arm.
* Adapt vc1 deblocking filters to specify stride as ptrdiff_t.
* Add align specifiers to a few VLD/VST instructions for AArch32 deblocking
filter, and adapt checkasm test not to test with tighter alignment than is
encountered in normal use.
* Correct unescape buffer memcmp length.
* Update benchmarks for AArch64 idctdsp.
Thanks! From a quick readthrough, this version of the patchset seems good
to me! I'll run it through some more testing, and push it if everything
seems to work fine (tomorrow or so).
// Martin
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