Summary: Fix the sound distortions for S24_3LE stream in alsa-lib softvol.
This patch fixes sound distortions in alsa-lib "softvol" for S24_3LE sound stream, when softvol slider isn't at 0.0dB position.
Signed-off-by: CannibalZerg cnb_zerg@yahoo.com --- src/pcm/pcm_softvol.c | 22 ++++++++++++++++++++-- 1 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/src/pcm/pcm_softvol.c b/src/pcm/pcm_softvol.c index 637e5cb..2c7c006 100644 --- a/src/pcm/pcm_softvol.c +++ b/src/pcm/pcm_softvol.c @@ -107,7 +107,8 @@ static inline int MULTI_DIV_32x16(int a, unsigned short b) v.i = a; y.i = 0; #if __BYTE_ORDER == __LITTLE_ENDIAN - x.i = (unsigned int)v.s[0] * b; + x.i = (unsigned short)v.s[0]; + x.i *= b; y.s[0] = x.s[1]; y.i += (int)v.s[1] * b; #else @@ -135,6 +136,23 @@ static inline int MULTI_DIV_int(int a, unsigned int b, int swap) return swap ? (int)bswap_32(fraction) : fraction; }
+/* always little endian */ +static inline int MULTI_DIV_24(int a, unsigned int b) +{ + unsigned int gain = b >> VOL_SCALE_SHIFT; + int fraction; + fraction = MULTI_DIV_32x16(a, b & VOL_SCALE_MASK); + if (gain) { + long long amp = (long long)a * gain + fraction; + if (amp > (int)0x7fffff) + amp = (int)0x7fffff; + else if (amp < (int)0x800000) + amp = (int)0x800000; + return (int)amp; + } + return fraction; +} + static inline short MULTI_DIV_short(short a, unsigned int b, int swap) { unsigned int gain = b >> VOL_SCALE_SHIFT; @@ -223,7 +241,7 @@ static inline short MULTI_DIV_short(short a, unsigned int b, int swap) tmp = src[0] | \ (src[1] << 8) | \ (((signed char *) src)[2] << 16); \ - tmp = MULTI_DIV_int(tmp, vol_scale, 0); \ + tmp = MULTI_DIV_24(tmp, vol_scale); \ dst[0] = tmp; \ dst[1] = tmp >> 8; \ dst[2] = tmp >> 16; \ -- 1.6.5.6