[FFmpeg-devel] [PATCH] swresample: add exact_rational option

Muhammad Faiz mfcc64 at gmail.com
Sun Jun 12 02:56:31 CEST 2016

give high quality resampling
as good as with linear_interp=on
as fast as without linear_interp=on
tested visually with ffplay
ffplay -f lavfi "aevalsrc='sin(10000*t*t)', aresample=osr=48000,
ffplay -f lavfi "aevalsrc='sin(10000*t*t)',
aresample=osr=48000:linear_interp=on, showcqt=gamma=5"
ffplay -f lavfi "aevalsrc='sin(10000*t*t)',
aresample=osr=48000:exact_rational=on, showcqt=gamma=5"

slightly speed improvement
for fair comparison with -cpuflags 0
audio.wav is ~ 1 hour 44100 stereo 16bit wav file
ffmpeg -i audio.wav -af aresample=osr=48000 -f null -
        old         new
real    13.498s     13.121s
user    13.364s     12.987s
sys      0.131s      0.129s

        old         new
real    23.035s     23.050s
user    22.907s     22.917s
sys      0.119s     0.125s

real    12.418s
user    12.298s
sys      0.114s

possibility to decrease memory usage if soft compensation is ignored

patch attached

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