From f8a237a3074b444a8d88d92d9fcce10508479d35 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Wed, 11 Apr 2012 13:27:22 +0200
Subject: [PATCH] swr: add triangular highpass dither
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
---
libswresample/dither.c | 23 ++++++++++++++++++++++-
libswresample/swresample.c | 1 +
libswresample/swresample.h | 1 +
3 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/libswresample/dither.c b/libswresample/dither.c
index 663e2007ba5..88f788066e7 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);
}
diff --git a/libswresample/swresample.c b/libswresample/swresample.c
index 715a446456c..78b0355c4f0 100644
--- a/libswresample/swresample.c
+++ b/libswresample/swresample.c
@@ -56,6 +56,7 @@ static const AVOption options[]={
{"dither", "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"},
{0}
};
diff --git a/libswresample/swresample.h b/libswresample/swresample.h
index 3a54c8eed97..137517d6d29 100644
--- a/libswresample/swresample.h
+++ b/libswresample/swresample.h
@@ -49,6 +49,7 @@ enum SwrDitherType {
SWR_DITHER_NONE = 0,
SWR_DITHER_RECTANGULAR,
SWR_DITHER_TRIANGULAR,
+ SWR_DITHER_TRIANGULAR_HIGHPASS,
SWR_DITHER_NB, ///< not part of API/ABI
};
--
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