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Optimize SINC resampler.

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Trade memory for performance. Avoid using linear interpolation
between phases.
This commit is contained in:
Themaister 2012-11-07 23:27:31 +01:00
parent ef418260de
commit 6421fe248b
1 changed files with 24 additions and 77 deletions
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101
audio/sinc.c
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@ -42,27 +42,16 @@
#include <immintrin.h>
#endif
#define PHASE_BITS 8
#define SUBPHASE_BITS 16
#define PHASE_BITS 16
#define PHASES (1 << PHASE_BITS)
#define PHASES_SHIFT (SUBPHASE_BITS)
#define SUBPHASES (1 << SUBPHASE_BITS)
#define SUBPHASES_SHIFT 0
#define SUBPHASES_MASK ((1 << SUBPHASE_BITS) - 1)
#define PHASES_WRAP (1 << (PHASE_BITS + SUBPHASE_BITS))
#define FRAMES_SHIFT (PHASE_BITS + SUBPHASE_BITS)
#define SIDELOBES 8
#define TAPS (SIDELOBES * 2)
#define CUTOFF 1.0
#define PHASE_INDEX 0
#define DELTA_INDEX 1
struct rarch_resampler
{
sample_t phase_table[PHASES][2][TAPS];
sample_t phase_table[PHASES][TAPS];
sample_t buffer_l[2 * TAPS];
sample_t buffer_r[2 * TAPS];
@ -94,31 +83,9 @@ static void init_sinc_table(rarch_resampler_t *resamp)
double sinc_phase = M_PI * (p + (SIDELOBES - 1 - j));
float val = CUTOFF * sinc(CUTOFF * sinc_phase) * lanzcos(sinc_phase / SIDELOBES);
resamp->phase_table[i][PHASE_INDEX][j] = val;
resamp->phase_table[i][j] = val;
}
}
// Optimize linear interpolation.
for (int i = 0; i < PHASES - 1; i++)
{
for (int j = 0; j < TAPS; j++)
{
resamp->phase_table[i][DELTA_INDEX][j] =
(resamp->phase_table[i + 1][PHASE_INDEX][j] - resamp->phase_table[i][PHASE_INDEX][j]) / SUBPHASES;
}
}
// Interpolation between [PHASES - 1] => [PHASES]
for (int j = 0; j < TAPS; j++)
{
double p = 1.0;
double sinc_phase = M_PI * (p + (SIDELOBES - 1 - j));
double phase = CUTOFF * sinc(CUTOFF * sinc_phase) * lanzcos(sinc_phase / SIDELOBES);
float result = (phase - resamp->phase_table[PHASES - 1][PHASE_INDEX][j]) / SUBPHASES;
resamp->phase_table[PHASES - 1][DELTA_INDEX][j] = result;
}
}
// No memalign() for us on Win32 ...
@ -171,25 +138,17 @@ static void process_sinc(rarch_resampler_t *resamp, float *out_buffer)
const float *buffer_l = resamp->buffer_l + resamp->ptr;
const float *buffer_r = resamp->buffer_r + resamp->ptr;
unsigned phase = resamp->time >> PHASES_SHIFT;
unsigned delta = (resamp->time >> SUBPHASES_SHIFT) & SUBPHASES_MASK;
__m256 delta_f = _mm256_set1_ps(delta);
const float *phase_table = resamp->phase_table[phase][PHASE_INDEX];
const float *delta_table = resamp->phase_table[phase][DELTA_INDEX];
unsigned phase = resamp->time;
const float *phase_table = resamp->phase_table[phase];
for (unsigned i = 0; i < TAPS; i += 8)
{
__m256 buf_l = _mm256_loadu_ps(buffer_l + i);
__m256 buf_r = _mm256_loadu_ps(buffer_r + i);
__m256 buf_l = _mm256_loadu_ps(buffer_l + i);
__m256 buf_r = _mm256_loadu_ps(buffer_r + i);
__m256 phases = _mm256_load_ps(phase_table + i);
__m256 deltas = _mm256_load_ps(delta_table + i);
__m256 sinc = _mm256_add_ps(phases, _mm256_mul_ps(deltas, delta_f));
sum_l = _mm256_add_ps(sum_l, _mm256_mul_ps(buf_l, sinc));
sum_r = _mm256_add_ps(sum_r, _mm256_mul_ps(buf_r, sinc));
__m256 sinc = _mm256_load_ps(phase_table + i);
sum_l = _mm256_add_ps(sum_l, _mm256_mul_ps(buf_l, sinc));
sum_r = _mm256_add_ps(sum_r, _mm256_mul_ps(buf_r, sinc));
}
// hadd on AVX is weird, and acts on low-lanes and high-lanes separately.
@ -214,25 +173,17 @@ static void process_sinc(rarch_resampler_t *resamp, float *out_buffer)
const float *buffer_l = resamp->buffer_l + resamp->ptr;
const float *buffer_r = resamp->buffer_r + resamp->ptr;
unsigned phase = resamp->time >> PHASES_SHIFT;
unsigned delta = (resamp->time >> SUBPHASES_SHIFT) & SUBPHASES_MASK;
__m128 delta_f = _mm_set1_ps(delta);
const float *phase_table = resamp->phase_table[phase][PHASE_INDEX];
const float *delta_table = resamp->phase_table[phase][DELTA_INDEX];
unsigned phase = resamp->time;
const float *phase_table = resamp->phase_table[phase];
for (unsigned i = 0; i < TAPS; i += 4)
{
__m128 buf_l = _mm_loadu_ps(buffer_l + i);
__m128 buf_r = _mm_loadu_ps(buffer_r + i);
__m128 buf_l = _mm_loadu_ps(buffer_l + i);
__m128 buf_r = _mm_loadu_ps(buffer_r + i);
__m128 phases = _mm_load_ps(phase_table + i);
__m128 deltas = _mm_load_ps(delta_table + i);
__m128 sinc = _mm_add_ps(phases, _mm_mul_ps(deltas, delta_f));
sum_l = _mm_add_ps(sum_l, _mm_mul_ps(buf_l, sinc));
sum_r = _mm_add_ps(sum_r, _mm_mul_ps(buf_r, sinc));
__m128 sinc = _mm_load_ps(phase_table + i);
sum_l = _mm_add_ps(sum_l, _mm_mul_ps(buf_l, sinc));
sum_r = _mm_add_ps(sum_r, _mm_mul_ps(buf_r, sinc));
}
// Them annoying shuffles :V
@ -264,16 +215,12 @@ static void process_sinc(rarch_resampler_t *resamp, float *out_buffer)
const float *buffer_l = resamp->buffer_l + resamp->ptr;
const float *buffer_r = resamp->buffer_r + resamp->ptr;
unsigned phase = resamp->time >> PHASES_SHIFT;
unsigned delta = (resamp->time >> SUBPHASES_SHIFT) & SUBPHASES_MASK;
float delta_f = (float)delta;
const float *phase_table = resamp->phase_table[phase][PHASE_INDEX];
const float *delta_table = resamp->phase_table[phase][DELTA_INDEX];
unsigned phase = resamp->time;
const float *phase_table = resamp->phase_table[phase];
for (unsigned i = 0; i < TAPS; i++)
{
float sinc_val = phase_table[i] + delta_f * delta_table[i];
float sinc_val = phase_table[i];
sum_l += buffer_l[i] * sinc_val;
sum_r += buffer_r[i] * sinc_val;
}
@ -288,7 +235,7 @@ void resampler_process(rarch_resampler_t *re, struct resampler_data *data)
// If data->ratio is < 1, we are downsampling.
// The sinc table is not set up for this, as it always assumes upsampling.
// Downsampling will work, but with some added noise due to aliasing might be present.
uint32_t ratio = PHASES_WRAP / data->ratio;
uint32_t ratio = PHASES / data->ratio;
const sample_t *input = data->data_in;
sample_t *output = data->data_out;
@ -297,17 +244,17 @@ void resampler_process(rarch_resampler_t *re, struct resampler_data *data)
while (frames)
{
while (frames && re->time >= PHASES_WRAP)
while (frames && re->time >= PHASES)
{
re->buffer_l[re->ptr + TAPS] = re->buffer_l[re->ptr] = *input++;
re->buffer_r[re->ptr + TAPS] = re->buffer_r[re->ptr] = *input++;
re->ptr = (re->ptr + 1) & (TAPS - 1);
re->time -= PHASES_WRAP;
re->time -= PHASES;
frames--;
}
if (re->time >= PHASES_WRAP)
if (re->time >= PHASES)
break;
process_sinc(re, output);