[FFmpeg-devel] [PATCH] Request for adding XPSNR avfilter

[Helmrich, Christian]

Hi,


> So its better to use that instead of human written assembly? Does clang generate faster code without this asm?


I'm not sure I fully understand your questions, but I hope the following answers it. The reason why we auto-converted our intrinsics code to asm is not a technical one, we unfortunately just don't have the knowledge or resources to manually write asm code. If I remember correctly, the SIMD optimized code runs about twice as fast as the C code, especially on UHD input.


> Please remove SLICE_THREADS related flag as there is no call to execute to filter in slices. Please remove stdbool.h header and adapt code to compile without it.


Done, please find attached a second version (v1) of the XPSNR avfilter patch.


Thanks and best,


Christian Helmrich

Fraunhofer HHI, Video Coding and Analytics Department


________________________________
Von: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> im Auftrag von Paul B Mahol <onemda at gmail.com>
Gesendet: Dienstag, 10. Januar 2023 21:43
An: FFmpeg development discussions and patches
Cc: Stoffers, Christian
Betreff: Re: [FFmpeg-devel] [PATCH] Request for adding XPSNR avfilter

On 1/10/23, Helmrich, Christian <christian.helmrich at hhi.fraunhofer.de> wrote:
> Hi,
>
> please find attached a patch (relative to FFmpeg master as of early January
> 10, 2023)
> adding avfilter support for extended perceptually weighted peak
> signal-to-noise ratio
> (XPSNR) measurements for videos, as described in the related addition to
> filters.texi.
>
> The XPSNR code was originally vectorized using SIMD intrinsics, but we
> concluded that
> FFmpeg code requires asm instead of such intrinsics, so we let gcc
> auto-convert these

So its better to use that instead of human written assembly?
Does clang generate faster code without this asm?

> instructions to pure assembly; see the vf_xpsnr.asm file. If the added asm
> code is too
> lengthy, intrinsics would be possible, or something else is missing, please
> let us know.
>

Please remove SLICE_THREADS related flag as there is no call to
execute to filter in slices.
Please remove stdbool.h header and adapt code to compile without it.

> Best,
>
> Christian Helmrich and Christian Stoffers
> Fraunhofer HHI
>
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