Commit 81a86fde authored by Josh Coalson's avatar Josh Coalson
Browse files

move dithering into plugin_common library

parent b6c08cd0
......@@ -28,6 +28,7 @@
#include "in2.h"
#include "FLAC/all.h"
#include "plugin_common/all.h"
#ifdef max
#undef max
......@@ -93,134 +94,6 @@ HANDLE thread_handle = INVALID_HANDLE_VALUE; /* the handle to the decode thread
DWORD WINAPI __stdcall DecodeThread(void *b); /* the decode thread procedure */
/* 32-bit pseudo-random number generator */
static __inline FLAC__uint32 prng(FLAC__uint32 state)
{
return (state * 0x0019660dL + 0x3c6ef35fL) & 0xffffffffL;
}
/* dither routine derived from MAD winamp plugin */
typedef struct {
FLAC__int32 error[3];
FLAC__int32 random;
} dither_state;
static __inline FLAC__int32 linear_dither(unsigned source_bps, unsigned target_bps, FLAC__int32 sample, dither_state *dither, const FLAC__int32 MIN, const FLAC__int32 MAX)
{
unsigned scalebits;
FLAC__int32 output, mask, random;
FLAC__ASSERT(source_bps < 32);
FLAC__ASSERT(target_bps <= 24);
FLAC__ASSERT(target_bps <= source_bps);
/* noise shape */
sample += dither->error[0] - dither->error[1] + dither->error[2];
dither->error[2] = dither->error[1];
dither->error[1] = dither->error[0] / 2;
/* bias */
output = sample + (1L << (source_bps - target_bps - 1));
scalebits = source_bps - target_bps;
mask = (1L << scalebits) - 1;
/* dither */
random = (FLAC__int32)prng(dither->random);
output += (random & mask) - (dither->random & mask);
dither->random = random;
/* clip */
if(output > MAX) {
output = MAX;
if(sample > MAX)
sample = MAX;
}
else if(output < MIN) {
output = MIN;
if(sample < MIN)
sample = MIN;
}
/* quantize */
output &= ~mask;
/* error feedback */
dither->error[0] = sample - output;
/* scale */
return output >> scalebits;
}
static unsigned pack_pcm(FLAC__byte *data, FLAC__int32 *input, unsigned wide_samples, unsigned channels, unsigned source_bps, unsigned target_bps)
{
static dither_state dither[MAX_SUPPORTED_CHANNELS];
FLAC__byte * const start = data;
FLAC__int32 sample;
unsigned samples = wide_samples * channels;
const unsigned bytes_per_sample = target_bps / 8;
FLAC__ASSERT(MAX_SUPPORTED_CHANNELS == 2);
FLAC__ASSERT(channels > 0 && channels <= MAX_SUPPORTED_CHANNELS);
FLAC__ASSERT(source_bps < 32);
FLAC__ASSERT(target_bps <= 24);
FLAC__ASSERT(target_bps <= source_bps);
FLAC__ASSERT(source_bps & 7 == 0);
FLAC__ASSERT(target_bps & 7 == 0);
if(source_bps != target_bps) {
const FLAC__int32 MIN = -(1L << source_bps);
const FLAC__int32 MAX = ~MIN; /*(1L << (source_bps-1)) - 1 */
const unsigned dither_twiggle = channels - 1;
unsigned dither_source = 0;
while(samples--) {
sample = linear_dither(source_bps, target_bps, *input++, &dither[dither_source], MIN, MAX);
dither_source ^= dither_twiggle;
switch(target_bps) {
case 8:
data[0] = sample ^ 0x80;
break;
case 24:
data[2] = (FLAC__byte)(sample >> 16);
/* fall through */
case 16:
data[1] = (FLAC__byte)(sample >> 8);
data[0] = (FLAC__byte)sample;
}
data += bytes_per_sample;
}
}
else {
while(samples--) {
sample = *input++;
switch(target_bps) {
case 8:
data[0] = sample ^ 0x80;
break;
case 24:
data[2] = (FLAC__byte)(sample >> 16);
/* fall through */
case 16:
data[1] = (FLAC__byte)(sample >> 8);
data[0] = (FLAC__byte)sample;
}
data += bytes_per_sample;
}
}
return data - start;
}
#if 0
@@@@ incorporate this
static void do_vis(char *data, int nch, int resolution, int position)
......@@ -480,7 +353,7 @@ DWORD WINAPI __stdcall DecodeThread(void *b)
#endif
const unsigned n = min(wide_samples_in_reservoir_, 576);
const unsigned delta = n * channels;
int bytes = (int)pack_pcm(sample_buffer_, reservoir_, n, channels, bits_per_sample, target_bps);
int bytes = (int)FLAC__plugin_common__pack_pcm(sample_buffer_, reservoir_, n, channels, bits_per_sample, target_bps);
unsigned i;
for(i = delta; i < wide_samples_in_reservoir_ * channels; i++)
......
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