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swr: add a dither_scale parameter to tune the amplitude of the dither. 

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-04-11 13:44:48 +02:00
parent a2c92e6063
commit c1d404b9e4
3 changed files with 5 additions and 1 deletions
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2
libswresample/dither.c
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@ -36,6 +36,8 @@ void swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSa
if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<24;
if(in_fmt == AV_SAMPLE_FMT_S16 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<8;
scale *= s->dither_scale;
for(i=0; i<len + TMP_EXTRA; i++){
double v;
seed = seed* 1664525 + 1013904223;

3
libswresample/swresample.c
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@ -53,7 +53,8 @@ static const AVOption options[]={
{"rmvol", "rematrix volume" , OFFSET(rematrix_volume), AV_OPT_TYPE_FLOAT, {.dbl=1.0}, -1000, 1000, 0},
{"flags", NULL , OFFSET(flags) , AV_OPT_TYPE_FLAGS, {.dbl=0}, 0, UINT_MAX, 0, "flags"},
{"res", "force resampling", 0, AV_OPT_TYPE_CONST, {.dbl=SWR_FLAG_RESAMPLE}, INT_MIN, INT_MAX, 0, "flags"},
{"dither", "dither method" , OFFSET(dither_method), AV_OPT_TYPE_INT, {.dbl=0}, 0, SWR_DITHER_NB-1, 0, "dither_method"},
{"dither_scale" , "dither scale" , OFFSET(dither_scale ), AV_OPT_TYPE_FLOAT, {.dbl=1}, 0, INT_MAX, 0},
{"dither_method", "dither method" , OFFSET(dither_method), AV_OPT_TYPE_INT , {.dbl=0}, 0, SWR_DITHER_NB-1, 0, "dither_method"},
{"rectangular", "rectangular dither", 0, AV_OPT_TYPE_CONST, {.dbl=SWR_DITHER_RECTANGULAR}, INT_MIN, INT_MAX, 0, "dither_method"},
{"triangular" , "triangular dither" , 0, AV_OPT_TYPE_CONST, {.dbl=SWR_DITHER_TRIANGULAR }, INT_MIN, INT_MAX, 0, "dither_method"},
{"triangular_hp" , "triangular dither with high pass" , 0, AV_OPT_TYPE_CONST, {.dbl=SWR_DITHER_TRIANGULAR_HIGHPASS }, INT_MIN, INT_MAX, 0, "dither_method"},

1
libswresample/swresample_internal.h
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@ -51,6 +51,7 @@ struct SwrContext {
int used_ch_count; ///< number of used input channels (mapped channel count if channel_map, otherwise in.ch_count)
enum SwrDitherType dither_method;
int dither_pos;
float dither_scale;
int int_bps; ///< internal bytes per sample
int resample_first; ///< 1 if resampling must come first, 0 if rematrixing