[FFmpeg-devel] [PATCH] avfilter: implement halve filter
Mark Thompson
sw at jkqxz.net
Tue Feb 14 23:25:03 EET 2017
On 14/02/17 19:44, Daniel Oberhoff wrote:
> filter strictly “halves” the image efficiently, which is often exactly what is needed
> likely much faster than using scale
Did you benchmark this? How?
$ time ./ffmpeg -f lavfi -i allyuv -vf 'scale=iw/2:ih/2' -vframes 400 -f null -
...
frame= 400 fps= 26 q=-0.0 Lsize=N/A time=00:00:16.00 bitrate=N/A speed=1.05x
...
real 0m15.365s
user 0m11.092s
sys 0m4.272s
$ time ./ffmpeg -f lavfi -i allyuv -vf 'halve' -vframes 400 -f null -
...
frame= 400 fps= 22 q=-0.0 Lsize=N/A time=00:00:16.00 bitrate=N/A speed=0.873x
...
real 0m18.392s
user 0m46.280s
sys 0m3.656s
So it uses four times as much CPU as swscale to be marginally slower?
(Skylake 6300; I admit the SMT could well be making it look a bit worse than it actually is on the CPU time.)
On a more general note, components that duplicate existing functionality are unlikely to be accepted without a compelling use-case for them to be included.
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