[FFmpeg-devel] [PATCH 2/2] swscale/aarch64: Add rgb24 to yuv implementation

[Zhao Zhili]

> On Jun 3, 2024, at 22:17, Rémi Denis-Courmont <remi at remlab.net> wrote:
> 
> Le maanantaina 3. kesäkuuta 2024, 16.11.15 EEST Zhao Zhili a écrit :
>>> See https://github.com/mstorsjo/FFmpeg/actions/runs/9346228714 for one
>>> example run of these actions with your patches.
>> Wow, it’s very helpful. This is the action result of the updated patch:
>> 
>> https://github.com/quink-black/FFmpeg/actions/runs/9350348848
>> 
>> https://ffmpeg.org/pipermail/ffmpeg-devel/2024-June/328786.html
>> 
>> The test still failed on x86, but success on all arm64 platform and
>> longarch. I have tried to call rgb24ToY_c and ff_rgb24ToY_avx
>> directly and compare the results, they don't match. I’m confused.
> 
> As Martin write, some x86 code is imprecise, or even wrong.

On x86:

With the following command:
./ffmpeg -bitexact -cpuflags 0  -f lavfi -i testsrc  -frames 1 -pix_fmt yuv420p -f framemd5 -
0,          0,          0,        1,   115200, d6b3abfc5280311c2758d5e4028c07b5

Without “-cpuflags 0”
./ffmpeg -bitexact -f lavfi -i testsrc  -frames 1 -pix_fmt yuv420p -f framemd5 -
0,          0,          0,        1,   115200, 1d302ce90bd5b6eec681730cc0868be4

It's indeed non bitexact.

On aarch64 with the neon implementation I can get the same result as
"-cpuflags 0":
./ffmpeg -bitexact  -f lavfi -i testsrc  -frames 1 -pix_fmt yuv420p -f framemd5 -
0,          0,          0,        1,   115200, d6b3abfc5280311c2758d5e4028c07b5

Now I can disable the test for x86 and continue the work on aarch64.

> 
> I would just disable the test on x86 until some x86 arcane magician fixes it.
> 
> -- 
> 雷米‧德尼-库尔蒙
> http://www.remlab.net/
> 
> 
> 
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