[FFmpeg-devel] [PATCH] lavc/lpc: exploit even symmetry of window function

Moritz Barsnick barsnick at gmx.net
Wed Mar 9 23:09:20 CET 2016

On Tue, Mar 08, 2016 at 22:16:50 -0500, Ganesh Ajjanagadde wrote:
> ffmpeg -i sin.flac -acodec aac -y sin_new.aac  5.22s user 0.03s system 105% cpu 4.970 total

Just wondering: Is this the sin.flac from
ffmpeg -f lavfi -i aevalsrc="sin(440*2*PI*t):s=48000" -t 300 -y sin.flac

Is a sinusoidal signal good enough to benchmark an audio encoder? It
only requires one very narrow frequency band, after all, no
psychoacoustics, ...

I don't see differences in general encoding speed of sine vs. noise,
but I didn't check the influence on your code improvements. Agreed,
noise doesn't do much for psychoacoustics probably either.

(BTW, if just inspecting ffmpeg runtime without use of benchmarking
start/stop markers, I use lavfi directly, to avoid the overhead of flac
decoding. And not aevalsrc - sine and even anoisesrc are 10x faster.)


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