[FFmpeg-devel] [PATCH] avfilter: implement halve filter

[James Darnley]

On 2017-02-14 22:25, Mark Thompson wrote:
> 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?

I would be tempted to blame the lack of SIMD for the poor performance.


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