[FFmpeg-devel] [RFC/PATCH] bitpacked_dec: Optimization for bitpacked_dec decoder performance

[Paul B Mahol]

On Fri, May 12, 2023 at 12:20 AM Marton Balint <cus at passwd.hu> wrote:

>
>
> On Wed, 10 May 2023, Lance Wang wrote:
>
> > On Sat, May 6, 2023 at 8:41 PM Devin Heitmueller <
> > devin.heitmueller at ltnglobal.com> wrote:
> >
> >> On Sat, May 6, 2023 at 8:16 AM James Almer <jamrial at gmail.com> wrote:
> >> > Can you bench with the START_TIMER and STOP_TIMER macros in timer.h?
> >> > Also, define CACHED_BITSTREAM_READER in bitpacked_dec.c before
> including
> >> > git_bits.h and test the actual implementation again, to see if it
> makes
> >> > any difference.
> >>
> >> Original code:
> >> 671661910 decicycles in bitpacked_dec,       1 runs,      0 skips
> >> 669736380 decicycles in bitpacked_dec,       1 runs,      0 skips
> >> 669370700 decicycles in bitpacked_dec,       1 runs,      0 skips
> >>
> >> Original code with CACHED_BITSTREAM_READER defined
> >> 352599030 decicycles in bitpacked_dec,       1 runs,      0 skips
> >> 336163810 decicycles in bitpacked_dec,       1 runs,      0 skips
> >> 344628350 decicycles in bitpacked_dec,       1 runs,      0 skips
> >>
> >> My proposed versioned:
> >> 257353330 decicycles in bitpacked_dec,       1 runs,      0 skips
> >> 271527000 decicycles in bitpacked_dec,       1 runs,      0 skips
> >> 252701500 decicycles in bitpacked_dec,       1 runs,      0 skips
> >>
> >>
> > Yes, it's show better performance, so LGTM if nobody have plan to
> optimize
> > the bitstream
> > function.
>
> Actually the cached bitstream reader was faster here than the manual
> approach:
>
> ./ffmpeg -stream_loop 128 -threads 1 -f bitpacked -pix_fmt yuv422p10le -s
> 3840x2160 -c:v bitpacked -i source.yuv -pix_fmt yuv422p10le -f null none
> -loglevel error
>
> Old code:
>
> 821050920 decicycles in bitpacked,       1 runs,      0 skips
> 815402160 decicycles in bitpacked,       2 runs,      0 skips
> 814108410 decicycles in bitpacked,       4 runs,      0 skips
> 814213800 decicycles in bitpacked,       8 runs,      0 skips
> 815048325 decicycles in bitpacked,      16 runs,      0 skips
> 812866713 decicycles in bitpacked,      32 runs,      0 skips
> 809186523 decicycles in bitpacked,      64 runs,      0 skips
> 808317601 decicycles in bitpacked,     128 runs,      0 skips
>
> With the patch:
>
> 379879920 decicycles in bitpacked,       1 runs,      0 skips
> 387491580 decicycles in bitpacked,       2 runs,      0 skips
> 397720260 decicycles in bitpacked,       4 runs,      0 skips
> 389581560 decicycles in bitpacked,       8 runs,      0 skips
> 381820635 decicycles in bitpacked,      16 runs,      0 skips
> 379791675 decicycles in bitpacked,      32 runs,      0 skips
> 379246303 decicycles in bitpacked,      64 runs,      0 skips
> 379221671 decicycles in bitpacked,     128 runs,      0 skips
>
> Old code and #defined CACHED_BITSTREAM_READER 1
>
> 345122280 decicycles in bitpacked,       1 runs,      0 skips
> 343663020 decicycles in bitpacked,       2 runs,      0 skips
> 343372680 decicycles in bitpacked,       4 runs,      0 skips
> 342554535 decicycles in bitpacked,       8 runs,      0 skips
> 340816522 decicycles in bitpacked,      16 runs,      0 skips
> 340225672 decicycles in bitpacked,      32 runs,      0 skips
> 340283520 decicycles in bitpacked,      64 runs,      0 skips
> 339643105 decicycles in bitpacked,     128 runs,      0 skips
>

Could someone send patch for this ?


>
> Regards,
> Marton
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