me/portaudio
Watch
1
0
Fork
You've already forked portaudio
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

corrected Int24_To_Int16_Dither and implemented Int24_To_Int8_Dither, Float32_To_Int24 to use all 'double' types for optimal code generation (not mixing double with floats)

Browse source
This commit is contained in:
dmitrykos 2010-12-26 15:58:30 +00:00
commit db36090a98
1 changed files with 42 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

72
src/common/pa_converters.c
View file

@ -459,7 +459,7 @@ static void Float32_To_Int24(
while( count-- )
{
/* convert to 32 bit and drop the low 8 bits */
double scaled = *src * 0x7FFFFFFF;
double scaled = (double)(*src) * 2147483647.0;
temp = (PaInt32) scaled;
#if defined(PA_LITTLE_ENDIAN)
@ -1163,39 +1163,33 @@ static void Int24_To_Int16_Dither(
void *sourceBuffer, signed int sourceStride,
unsigned int count, struct PaUtilTriangularDitherGenerator *ditherGenerator )
{
#define _PA_CNV_RESCALE(__max_from,__max_to,g) ((1.0f/(float)(__max_from/2+1))*((float)((__max_to/2+1)+g)))
#ifndef PA_BIG_ENDIAN
#define _PA_INT24_TO_INT32(v) ((int)(((int)v[2] << 24)|((int)v[1] << 16)|((int)v[0] << 8)) >> 8)
#else
#define _PA_INT24_TO_INT32(v) ((int)(((int)v[0] << 24)|((int)v[1] << 16)|((int)v[2] << 8)) >> 8)
#endif
#define _PA_INT24_TO_FLOAT(v,g) ((float)(_PA_INT24_TO_INT32(v)) * _PA_CNV_RESCALE(0xffffff,0xffff,g))
unsigned char *src = (unsigned char*)sourceBuffer;
PaInt16 *dest = (PaInt16*)destinationBuffer;
unsigned char *src = (unsigned char *)sourceBuffer;
PaInt16 *dest = (PaInt16 *)destinationBuffer;
float dither, dithered;
PaInt32 temp, dither;
while( count-- )
{
dither = PaUtil_GenerateFloatTriangularDither( ditherGenerator );
/* downscale 24-bit int to 16-bit int placed into 32-bit float container,
16-bit scaler is decreased by 2 to leave space for dither in order not to overflow
*/
dithered = _PA_INT24_TO_FLOAT(src, -2.0f) + dither;
#ifdef PA_USE_C99_LRINTF
*dest = lrintf(dithered-0.5f);
#else
*dest = (PaInt16) dithered;
#if defined(PA_LITTLE_ENDIAN)
temp = (((PaInt32)src[0]) << 8);
temp = temp | (((PaInt32)src[1]) << 16);
temp = temp | (((PaInt32)src[2]) << 24);
#elif defined(PA_BIG_ENDIAN)
temp = (((PaInt32)src[0]) << 24);
temp = temp | (((PaInt32)src[1]) << 16);
temp = temp | (((PaInt32)src[2]) << 8);
#endif
src += sourceStride * 3;
/* REVIEW */
dither = PaUtil_Generate16BitTriangularDither( ditherGenerator );
*dest = (PaInt16) (((temp >> 1) + dither) >> 15);
src += sourceStride * 3;
dest += destinationStride;
}
}
/* -------------------------------------------------------------------------- */
static void Int24_To_Int8(
@ -1233,13 +1227,31 @@ static void Int24_To_Int8_Dither(
void *sourceBuffer, signed int sourceStride,
unsigned int count, struct PaUtilTriangularDitherGenerator *ditherGenerator )
{
(void) destinationBuffer; /* unused parameters */
(void) destinationStride; /* unused parameters */
(void) sourceBuffer; /* unused parameters */
(void) sourceStride; /* unused parameters */
(void) count; /* unused parameters */
(void) ditherGenerator; /* unused parameters */
/* IMPLEMENT ME */
unsigned char *src = (unsigned char*)sourceBuffer;
signed char *dest = (signed char*)destinationBuffer;
PaInt32 temp, dither;
while( count-- )
{
#if defined(PA_LITTLE_ENDIAN)
temp = (((PaInt32)src[0]) << 8);
temp = temp | (((PaInt32)src[1]) << 16);
temp = temp | (((PaInt32)src[2]) << 24);
#elif defined(PA_BIG_ENDIAN)
temp = (((PaInt32)src[0]) << 24);
temp = temp | (((PaInt32)src[1]) << 16);
temp = temp | (((PaInt32)src[2]) << 8);
#endif
/* REVIEW */
dither = PaUtil_Generate16BitTriangularDither( ditherGenerator );
*dest = (signed char) (((temp >> 1) + dither) >> 23);
src += sourceStride * 3;
dest += destinationStride;
}
}
/* -------------------------------------------------------------------------- */