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-rw-r--r--src/pcm_utils.c18
1 files changed, 10 insertions, 8 deletions
diff --git a/src/pcm_utils.c b/src/pcm_utils.c
index a9706e019..bd7192acf 100644
--- a/src/pcm_utils.c
+++ b/src/pcm_utils.c
@@ -25,6 +25,12 @@
#include "audio_format.h"
#include "os_compat.h"
+static inline int
+pcm_dither(void)
+{
+ return (rand() & 511) - (rand() & 511);
+}
+
void pcm_volumeChange(char *buffer, int bufferSize,
const struct audio_format *format,
int volume)
@@ -46,8 +52,7 @@ void pcm_volumeChange(char *buffer, int bufferSize,
while (bufferSize > 0) {
temp32 = *buffer16;
temp32 *= volume;
- temp32 += rand() & 511;
- temp32 -= rand() & 511;
+ temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
*buffer16 = temp32 > 32767 ? 32767 :
@@ -60,8 +65,7 @@ void pcm_volumeChange(char *buffer, int bufferSize,
while (bufferSize > 0) {
temp32 = *buffer8;
temp32 *= volume;
- temp32 += rand() & 511;
- temp32 -= rand() & 511;
+ temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
*buffer8 = temp32 > 127 ? 127 :
@@ -92,8 +96,7 @@ static void pcm_add(char *buffer1, const char *buffer2, size_t bufferSize1,
temp32 =
(vol1 * (*buffer16_1) +
vol2 * (*buffer16_2));
- temp32 += rand() & 511;
- temp32 -= rand() & 511;
+ temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
*buffer16_1 =
@@ -111,8 +114,7 @@ static void pcm_add(char *buffer1, const char *buffer2, size_t bufferSize1,
while (bufferSize1 > 0 && bufferSize2 > 0) {
temp32 =
(vol1 * (*buffer8_1) + vol2 * (*buffer8_2));
- temp32 += rand() & 511;
- temp32 -= rand() & 511;
+ temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
*buffer8_1 =