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Add experimental code for biquad and low-pass filters.

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This commit is contained in:
David Reid
2020-01-09 11:27:57 +10:00
parent 45499c8bb8
commit 2b526f6945
5 changed files with 410 additions and 47 deletions
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research/ma_resampler.h
+50 -41
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@@ -3,49 +3,43 @@
#ifndef ma_resampler_h
#define ma_resampler_h
#include "ma_lpf.h"
typedef enum
{
ma_resample_algorithm_linear = 0, /* Fastest, lowest quality. */
ma_resample_algorithm_linear_lpf, /* Linear with a biquad low pass filter. */
ma_resample_algorithm_linear_lpf = 0, /* Linear with a biquad low pass filter. Default. */
ma_resample_algorithm_linear, /* Fastest, lowest quality. */
} ma_resample_algorithm;
typedef struct
{
ma_resample_algorithm algorithm;
ma_format format; /* Must be either ma_format_f32 or ma_format_s16. */
ma_uint32 channels;
ma_uint32 sampleRateIn;
ma_uint32 sampleRateOut;
ma_uint32 channels;
ma_format format; /* Must be either ma_format_f32 or ma_format_s16. */
ma_resample_algorithm algorithm;
struct
{
int _unused;
} linear;
struct
{
int _unused;
ma_uint32 cutoffFrequency;
} linearLPF;
} ma_resampler_config;
ma_resampler_config ma_resampler_config_init(ma_format format, ma_uint32 channels, ma_uint32 sampleRateIn, ma_uint32 sampleRateOut, ma_resample_algorithm algorithm);
typedef struct
{
ma_resampler_config config;
float timeX; /* Input time. */
float timeY; /* Output time. */
union
{
struct
{
float timeX; /* Input time. */
float timeY; /* Output time. */
struct
{
float yprev1; /* y-1 */
float yprev2; /* y-2 */
float a0;
float a1;
float a2;
float b0;
float b1;
float b2;
} lpf;
ma_lpf lpf;
} linear;
} state;
} ma_resampler;
@@ -75,7 +69,7 @@ It is an error for [pFramesOut] to be non-NULL and [pFrameCountOut] to be NULL.
It is an error for both [pFrameCountOut] and [pFrameCountIn] to be NULL.
*/
ma_result ma_resampler_process(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, void* pFramesIn);
ma_result ma_resampler_process(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, const void* pFramesIn);
/*
@@ -99,37 +93,52 @@ Implementation
#define MA_RESAMPLER_MAX_RATIO 48.0
#endif
ma_resampler_config ma_resampler_config_init(ma_format format, ma_uint32 channels, ma_uint32 sampleRateIn, ma_uint32 sampleRateOut, ma_resample_algorithm algorithm)
{
ma_resampler_config config;
MA_ZERO_OBJECT(&config);
config.format = format;
config.channels = channels;
config.sampleRateIn = sampleRateIn;
config.sampleRateOut = sampleRateOut;
config.algorithm = algorithm;
return config;
}
ma_result ma_resampler_init(const ma_resampler_config* pConfig, ma_resampler* pResampler)
{
ma_result result;
if (pConfig == NULL || pResampler == NULL) {
return MA_INVALID_ARGS;
}
MA_ZERO_OBJECT(pResampler);
pResampler->config = *pConfig;
pResampler->timeX = 0.0f;
pResampler->timeY = 0.0f;
switch (pConfig->algorithm)
{
case ma_resample_algorithm_linear:
{
pResampler->state.linear.timeX = 0.0f;
pResampler->state.linear.timeY = 0.0f;
} break;
case ma_resample_algorithm_linear_lpf:
{
pResampler->state.linear.timeX = 0.0f;
pResampler->state.linear.timeY = 0.0f;
pResampler->state.linear.lpf.yprev1 = 0.0f;
pResampler->state.linear.lpf.yprev2 = 0.0f;
ma_lpf_config lpfConfig;
lpfConfig = ma_lpf_config_init(pConfig->format, pConfig->channels, pConfig->sampleRateOut, pConfig->linearLPF.cutoffFrequency);
if (lpfConfig.cutoffFrequency == 0) {
lpfConfig.cutoffFrequency = ma_min(pConfig->sampleRateIn, pConfig->sampleRateOut) / 2;
}
/* TODO: Biquad LPF filter coefficients. */
pResampler->state.linear.lpf.a0 = 0.0f;
pResampler->state.linear.lpf.a1 = 0.0f;
pResampler->state.linear.lpf.a2 = 0.0f;
pResampler->state.linear.lpf.b0 = 0.0f;
pResampler->state.linear.lpf.b1 = 0.0f;
pResampler->state.linear.lpf.b2 = 0.0f;
result = ma_lpf_init(&lpfConfig, &pResampler->state.linear.lpf);
if (result != MA_SUCCESS) {
return result;
}
} break;
default: return MA_INVALID_ARGS;
@@ -138,7 +147,7 @@ ma_result ma_resampler_init(const ma_resampler_config* pConfig, ma_resampler* pR
return MA_SUCCESS;
}
static ma_result ma_resampler_process__seek__linear(ma_resampler* pResampler, ma_uint64* pFrameCountOut, ma_uint64* pFrameCountIn, void* pFramesIn)
static ma_result ma_resampler_process__seek__linear(ma_resampler* pResampler, ma_uint64* pFrameCountOut, ma_uint64* pFrameCountIn, const void* pFramesIn)
{
MA_ASSERT(pResampler != NULL);
@@ -163,13 +172,13 @@ static ma_result ma_resampler_process__seek__linear(ma_resampler* pResampler, ma
return MA_SUCCESS;
}
static ma_result ma_resampler_process__seek__linear_lpf(ma_resampler* pResampler, ma_uint64* pFrameCountOut, ma_uint64* pFrameCountIn, void* pFramesIn)
static ma_result ma_resampler_process__seek__linear_lpf(ma_resampler* pResampler, ma_uint64* pFrameCountOut, ma_uint64* pFrameCountIn, const void* pFramesIn)
{
/* TODO: Proper linear LPF implementation. */
return ma_resampler_process__seek__linear(pResampler, pFrameCountOut, pFrameCountIn, pFramesIn);
}
static ma_result ma_resampler_process__seek(ma_resampler* pResampler, ma_uint64* pFrameCountOut, ma_uint64* pFrameCountIn, void* pFramesIn)
static ma_result ma_resampler_process__seek(ma_resampler* pResampler, ma_uint64* pFrameCountOut, ma_uint64* pFrameCountIn, const void* pFramesIn)
{
MA_ASSERT(pResampler != NULL);
@@ -190,7 +199,7 @@ static ma_result ma_resampler_process__seek(ma_resampler* pResampler, ma_uint64*
}
static ma_result ma_resampler_process__read__linear(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, void* pFramesIn)
static ma_result ma_resampler_process__read__linear(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, const void* pFramesIn)
{
MA_ASSERT(pResampler != NULL);
MA_ASSERT(pFramesOut != NULL);
@@ -205,13 +214,13 @@ static ma_result ma_resampler_process__read__linear(ma_resampler* pResampler, ma
return MA_SUCCESS;
}
static ma_result ma_resampler_process__read__linear_lpf(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, void* pFramesIn)
static ma_result ma_resampler_process__read__linear_lpf(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, const void* pFramesIn)
{
/* TODO: Proper linear LPF implementation. */
return ma_resampler_process__read__linear(pResampler, pFrameCountOut, pFramesOut, pFrameCountIn, pFramesIn);
}
static ma_result ma_resampler_process__read(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, void* pFramesIn)
static ma_result ma_resampler_process__read(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, const void* pFramesIn)
{
MA_ASSERT(pResampler != NULL);
MA_ASSERT(pFramesOut != NULL);
@@ -237,13 +246,13 @@ static ma_result ma_resampler_process__read(ma_resampler* pResampler, ma_uint64*
}
}
ma_result ma_resampler_process(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, void* pFramesIn)
ma_result ma_resampler_process(ma_resampler* pResampler, ma_uint64* pFrameCountOut, void* pFramesOut, ma_uint64* pFrameCountIn, const void* pFramesIn)
{
if (pResampler == NULL) {
return MA_INVALID_ARGS;
}
if (pFrameCountOut != NULL && pFrameCountIn == NULL) {
if (pFrameCountOut == NULL && pFrameCountIn == NULL) {
return MA_INVALID_ARGS;
}