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| author | Michael Niedermayer <michaelni@gmx.at> | 2012-04-11 13:27:22 +0200 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2012-04-11 13:27:22 +0200 |
| commit | f8a237a3074b444a8d88d92d9fcce10508479d35 (patch) | |
| tree | 06f53bfb00674b57b04bec3fefa4832e45c77111 /libswresample/dither.c | |
| parent | 1fc4ff2205cdad4fbb7225f0f32cb7e32edc1eec (diff) | |
| download | ffmpeg-f8a237a3074b444a8d88d92d9fcce10508479d35.tar.gz | |
swr: add triangular highpass dither
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Diffstat (limited to 'libswresample/dither.c')
| -rw-r--r-- | libswresample/dither.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/libswresample/dither.c b/libswresample/dither.c index 663e2007ba..88f788066e 100644 --- a/libswresample/dither.c +++ b/libswresample/dither.c @@ -23,6 +23,8 @@ void swri_get_dither(void *dst, int len, unsigned seed, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt, enum SwrDitherType method) { double scale = 0; +#define TMP_EXTRA 2 + double *tmp = av_malloc((len + TMP_EXTRA) * sizeof(double)); int i; if(in_fmt == AV_SAMPLE_FMT_FLT || in_fmt == AV_SAMPLE_FMT_DBL){ @@ -34,19 +36,36 @@ void swri_get_dither(void *dst, int len, unsigned seed, enum AVSampleFormat out_ 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; - for(i=0; i<len; i++){ + for(i=0; i<len + TMP_EXTRA; i++){ double v; seed = seed* 1664525 + 1013904223; switch(method){ case SWR_DITHER_RECTANGULAR: v= ((double)seed) / UINT_MAX - 0.5; break; case SWR_DITHER_TRIANGULAR : + case SWR_DITHER_TRIANGULAR_HIGHPASS : v = ((double)seed) / UINT_MAX; seed = seed*1664525 + 1013904223; v-= ((double)seed) / UINT_MAX; break; default: av_assert0(0); } + tmp[i] = v; + } + + for(i=0; i<len; i++){ + double v; + + switch(method){ + case SWR_DITHER_RECTANGULAR: + case SWR_DITHER_TRIANGULAR : + v = tmp[i]; + break; + case SWR_DITHER_TRIANGULAR_HIGHPASS : + v = (- tmp[i] + 2*tmp[i+1] - tmp[i+2]) / sqrt(6); + break; + default: av_assert0(0); + } v*= scale; @@ -58,4 +77,6 @@ void swri_get_dither(void *dst, int len, unsigned seed, enum AVSampleFormat out_ default: av_assert0(0); } } + + av_free(tmp); } |