[FFmpeg-devel] [PATCH] avfilter/vf_deshake: replace qsort with AV_QSORT
gajjanag at mit.edu
Sat Oct 31 13:47:37 CET 2015
On Sat, Oct 31, 2015 at 6:19 AM, Nicolas George <george at nsup.org> wrote:
> Le nonidi 9 brumaire, an CCXXIV, Ganesh Ajjanagadde a écrit :
>> Sample benchmark (x86-64, Haswell, GNU/Linux):
>> File: original from https://trac.ffmpeg.org/ticket/1430
>> command: ffmpeg -stream_loop 8 -i file.webm -vf deshake=rx=64:ry=64 -f null -
>> Timer truncated at 1024 runs.
>> 39676 decicycles in qsort, 1024 runs, 0 skips
>> 86783 decicycles in qsort, 1024 runs, 0 skips
> What was inside the start/stop_timer block? I see that the qsort call is
> after a very expensive loop, I suspect those few thousand cycles may be
> completely negligible in front of the loop itself.
Entirely possible. I just did this as a low hanging fruit. I highly
suspect that the algorithm can be improved (see Michael's comment).
The start/stop was just around the qsort statement. Since you asked
this, I will add it to the commit message.
> Nicolas George
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> ffmpeg-devel at ffmpeg.org
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