diff options
| author | Ganesh Ajjanagadde <gajjanagadde@gmail.com> | 2015-11-24 13:00:54 -0500 |
|---|---|---|
| committer | Ganesh Ajjanagadde <gajjanagadde@gmail.com> | 2015-11-24 20:36:40 -0500 |
| commit | 990619968a40ff64f789ba7d004a118351695fa6 (patch) | |
| tree | 7b4f43bb6211650d05ce2048f822c7cf0b22acf8 /libavfilter | |
| parent | e9c7493f19a610f44690ef2f2f3737a3c6236fdf (diff) | |
| download | ffmpeg-990619968a40ff64f789ba7d004a118351695fa6.tar.gz | |
avfilter/vsrc_mandelbrot: change sin to sinf for color computation
lrintf is anyway used, suggesting we only care up to floating precision.
Rurthermore, there is a compat hack in avutil/libm for this function,
and it is used in avcodec/aacps_tablegen.h.
This yields a non-negligible speedup. Sample benchmark:
x86-64, Haswell, GNU/Linux:
old (draw_mandelbrot):
274635709 decicycles in draw_mandelbrot, 256 runs, 0 skips
300287046 decicycles in draw_mandelbrot, 512 runs, 0 skips
371819935 decicycles in draw_mandelbrot, 1024 runs, 0 skips
336663765 decicycles in draw_mandelbrot, 2048 runs, 0 skips
581851016 decicycles in draw_mandelbrot, 4096 runs, 0 skips
new (draw_mandelbrot):
269882717 decicycles in draw_mandelbrot, 256 runs, 0 skips
296359285 decicycles in draw_mandelbrot, 512 runs, 0 skips
370076599 decicycles in draw_mandelbrot, 1024 runs, 0 skips
331478354 decicycles in draw_mandelbrot, 2048 runs, 0 skips
571904318 decicycles in draw_mandelbrot, 4096 runs, 0 skips
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Diffstat (limited to 'libavfilter')
| -rw-r--r-- | libavfilter/vsrc_mandelbrot.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/libavfilter/vsrc_mandelbrot.c b/libavfilter/vsrc_mandelbrot.c index 91bf63fd42..063b7d1894 100644 --- a/libavfilter/vsrc_mandelbrot.c +++ b/libavfilter/vsrc_mandelbrot.c @@ -334,11 +334,11 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize, switch(s->outer){ case ITERATION_COUNT: zr = i; - c = lrintf((sin(zr)+1)*127) + lrintf((sin(zr/1.234)+1)*127)*256*256 + lrintf((sin(zr/100)+1)*127)*256; + c = lrintf((sinf(zr)+1)*127) + lrintf((sinf(zr/1.234)+1)*127)*256*256 + lrintf((sinf(zr/100)+1)*127)*256; break; case NORMALIZED_ITERATION_COUNT: zr = i + log2(log(s->bailout) / log(zr*zr + zi*zi)); - c = lrintf((sin(zr)+1)*127) + lrintf((sin(zr/1.234)+1)*127)*256*256 + lrintf((sin(zr/100)+1)*127)*256; + c = lrintf((sinf(zr)+1)*127) + lrintf((sinf(zr/1.234)+1)*127)*256*256 + lrintf((sinf(zr/100)+1)*127)*256; break; case WHITE: c = 0xFFFFFF; |