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Commit 2b526f69 authored by David Reid's avatar David Reid
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Add experimental code for biquad and low-pass filters.

parent 45499c8b
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research/ma_lpf.h 0 → 100644
View file @ 2b526f69
#ifndef ma_lpf_h
#define ma_lpf_h
/*
TODO:
- Document passthrough behaviour of the biquad filter and how it doesn't update previous inputs and outputs.
- Document how changing biquad constants requires reinitialization of the filter (due to issue above).
*/
typedef struct
{
ma_format format;
ma_uint32 channels;
float a0;
float a1;
float a2;
float b0;
float b1;
float b2;
} ma_biquad_config;
ma_biquad_config ma_biquad_config_init(ma_format format, ma_uint32 channels, float a0, float a1, float a2, float b0, float b1, float b2);
typedef struct
{
ma_biquad_config config;
ma_bool32 isPassthrough;
ma_uint32 prevFrameCount;
float x1[MA_MAX_CHANNELS]; /* x[n-1] */
float x2[MA_MAX_CHANNELS]; /* x[n-2] */
float y1[MA_MAX_CHANNELS]; /* y[n-1] */
float y2[MA_MAX_CHANNELS]; /* y[n-2] */
} ma_biquad;
ma_result ma_biquad_init(const ma_biquad_config* pConfig, ma_biquad* pBQ);
ma_result ma_biquad_process(ma_biquad* pBQ, void* pFramesOut, const void* pFramesIn, ma_uint64 frameCount);
typedef struct
{
ma_format format;
ma_uint32 channels;
ma_uint32 sampleRate;
ma_uint32 cutoffFrequency;
} ma_lpf_config;
ma_lpf_config ma_lpf_config_init(ma_format format, ma_uint32 channels, ma_uint32 sampleRate, ma_uint32 cutoffFrequency);
typedef struct
{
ma_biquad bq; /* The low-pass filter is implemented as a biquad filter. */
ma_lpf_config config;
} ma_lpf;
ma_result ma_lpf_init(const ma_lpf_config* pConfig, ma_lpf* pLPF);
ma_result ma_lpf_process(ma_lpf* pLPF, void* pFramesOut, const void* pFramesIn, ma_uint64 frameCount);
#endif /* ma_lpf_h */
#if defined(MINIAUDIO_IMPLEMENTATION)
ma_biquad_config ma_biquad_config_init(ma_format format, ma_uint32 channels, float a0, float a1, float a2, float b0, float b1, float b2)
{
ma_biquad_config config;
MA_ZERO_OBJECT(&config);
config.format = format;
config.channels = channels;
config.a0 = a0;
config.a1 = a1;
config.a2 = a2;
config.b0 = b0;
config.b1 = b1;
config.b2 = b2;
return config;
}
ma_result ma_biquad_init(const ma_biquad_config* pConfig, ma_biquad* pBQ)
{
if (pBQ == NULL) {
return MA_INVALID_ARGS;
}
MA_ZERO_OBJECT(pBQ);
if (pConfig == NULL) {
return MA_INVALID_ARGS;
}
if (pConfig->a0 == 0) {
return MA_INVALID_ARGS; /* Division by zero. */
}
/* Currently only supporting f32, but support for other formats will be added later. */
if (pConfig->format != ma_format_f32) {
return MA_INVALID_ARGS;
}
pBQ->config = *pConfig;
if (pConfig->a0 == 1 && pConfig->a1 == 0 && pConfig->a2 == 0 &&
pConfig->b0 == 1 && pConfig->b1 == 0 && pConfig->b2 == 0) {
pBQ->isPassthrough = MA_TRUE;
}
/* Normalize. */
pBQ->config.a1 /= pBQ->config.a0;
pBQ->config.a2 /= pBQ->config.a0;
pBQ->config.b0 /= pBQ->config.a0;
pBQ->config.b1 /= pBQ->config.a0;
pBQ->config.b2 /= pBQ->config.a0;
return MA_SUCCESS;
}
ma_result ma_biquad_process(ma_biquad* pBQ, void* pFramesOut, const void* pFramesIn, ma_uint64 frameCount)
{
ma_uint32 n;
ma_uint32 c;
float a1 = pBQ->config.a1;
float a2 = pBQ->config.a2;
float b0 = pBQ->config.b0;
float b1 = pBQ->config.b1;
float b2 = pBQ->config.b2;
if (pBQ == NULL || pFramesOut == NULL || pFramesIn == NULL) {
return MA_INVALID_ARGS;
}
/* Fast path for passthrough. */
if (pBQ->isPassthrough) {
ma_copy_memory_64(pFramesOut, pFramesIn, frameCount * ma_get_bytes_per_frame(pBQ->config.format, pBQ->config.channels));
return MA_SUCCESS;
}
/* Currently only supporting f32. */
if (pBQ->config.format == ma_format_f32) {
float* pY = ( float*)pFramesOut;
const float* pX = (const float*)pFramesIn;
for (n = 0; n < frameCount; n += 1) {
for (c = 0; c < pBQ->config.channels; c += 1) {
float x2 = pBQ->x2[c];
float x1 = pBQ->x1[c];
float x0 = pX[n*pBQ->config.channels + c];
float y2 = pBQ->y2[c];
float y1 = pBQ->y1[c];
float y0 = b0*x0 + b1*x1 + b2*x2 - a1*y1 - a2*y2;
pY[n*pBQ->config.channels + c] = y0;
pBQ->x2[c] = x1;
pBQ->x1[c] = x0;
pBQ->y2[c] = y1;
pBQ->y1[c] = y0;
}
}
} else {
return MA_INVALID_ARGS; /* Format not supported. Should never hit this because it's checked in ma_biquad_init(). */
}
return MA_SUCCESS;
}
ma_lpf_config ma_lpf_config_init(ma_format format, ma_uint32 channels, ma_uint32 sampleRate, ma_uint32 cutoffFrequency)
{
ma_lpf_config config;
MA_ZERO_OBJECT(&config);
config.format = format;
config.channels = channels;
config.sampleRate = sampleRate;
config.cutoffFrequency = cutoffFrequency;
return config;
}
ma_result ma_lpf_init(const ma_lpf_config* pConfig, ma_lpf* pLPF)
{
ma_result result;
ma_biquad_config bqConfig;
double q;
double w;
double s;
double c;
double a;
if (pLPF == NULL) {
return MA_INVALID_ARGS;
}
MA_ZERO_OBJECT(pLPF);
if (pConfig == NULL) {
return MA_INVALID_ARGS;
}
pLPF->config = *pConfig;
q = 1 / sqrt(2);
w = 2 * MA_PI_D * pConfig->cutoffFrequency / pConfig->sampleRate;
s = sin(w);
c = cos(w);
a = s / (2*q);
bqConfig.a0 = (float)( 1 + a);
bqConfig.a1 = (float)(-2 * c);
bqConfig.a2 = (float)( 1 - a);
bqConfig.b0 = (float)((1 - c) / 2);
bqConfig.b1 = (float)( 1 - c);
bqConfig.b2 = (float)((1 - c) / 2);
bqConfig.format = pConfig->format;
bqConfig.channels = pConfig->channels;
result = ma_biquad_init(&bqConfig, &pLPF->bq);
if (result != MA_SUCCESS) {
return result;
}
return MA_SUCCESS;
}
ma_result ma_lpf_process(ma_lpf* pLPF, void* pFramesOut, const void* pFramesIn, ma_uint64 frameCount)
{
if (pLPF == NULL) {
return MA_INVALID_ARGS;
}
return ma_biquad_process(&pLPF->bq, pFramesOut, pFramesIn, frameCount);
}
#endif
\ No newline at end of file
research/ma_resampler.h
View file @ 2b526f69
......@@ -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;
/* 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;
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;
}
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;
}
......
research/tests/ma_lpf_test_0.c 0 → 100644
View file @ 2b526f69
#define DR_FLAC_IMPLEMENTATION
#include "../../extras/dr_flac.h" /* Enables FLAC decoding. */
#define DR_MP3_IMPLEMENTATION
#include "../../extras/dr_mp3.h" /* Enables MP3 decoding. */
#define DR_WAV_IMPLEMENTATION
#include "../../extras/dr_wav.h" /* Enables WAV decoding. */
#define MA_DEBUG_OUTPUT
#define MINIAUDIO_IMPLEMENTATION
#include "../../miniaudio.h"
#include "../ma_lpf.h"
ma_lpf g_lpf;
void data_callback(ma_device* pDevice, void* pOutput, const void* pInput, ma_uint32 frameCount)
{
ma_uint32 framesProcessed = 0;
ma_decoder* pDecoder = (ma_decoder*)pDevice->pUserData;
if (pDecoder == NULL) {
return;
}
/* We need to read into a temporary buffer and then run it through the low pass filter. */
while (framesProcessed < frameCount) {
float tempBuffer[4096];
ma_uint32 framesToProcessThisIteration;
framesToProcessThisIteration = frameCount - framesProcessed;
if (framesToProcessThisIteration > ma_countof(tempBuffer)/pDecoder->internalChannels) {
framesToProcessThisIteration = ma_countof(tempBuffer)/pDecoder->internalChannels;
}
#if 0
ma_decoder_read_pcm_frames(pDecoder, ma_offset_ptr(pOutput, framesProcessed * ma_get_bytes_per_frame(pDevice->playback.format, pDevice->playback.channels)), framesToProcessThisIteration);
#else
ma_decoder_read_pcm_frames(pDecoder, tempBuffer, framesToProcessThisIteration);
/* Out the results from the low pass filter straight into our output buffer. */
ma_lpf_process(&g_lpf, ma_offset_ptr(pOutput, framesProcessed * ma_get_bytes_per_frame(pDevice->playback.format, pDevice->playback.channels)), tempBuffer, framesToProcessThisIteration);
#endif
framesProcessed += framesToProcessThisIteration;
}
(void)pInput;
}
int main(int argc, char** argv)
{
ma_result result;
ma_decoder_config decoderConfig;
ma_decoder decoder;
ma_lpf_config lpfConfig;
ma_device_config deviceConfig;
ma_device device;
if (argc < 2) {
printf("No input file.\n");
return -1;
}
decoderConfig = ma_decoder_config_init(ma_format_f32, 0, 0);
result = ma_decoder_init_file(argv[1], &decoderConfig, &decoder);
if (result != MA_SUCCESS) {
return -2;
}
lpfConfig.format = decoderConfig.format;
lpfConfig.channels = decoder.internalChannels;
lpfConfig.sampleRate = decoder.internalSampleRate;
lpfConfig.cutoffFrequency = lpfConfig.sampleRate / 4;
result = ma_lpf_init(&lpfConfig, &g_lpf);
if (result != MA_SUCCESS) {
return -100;
}
deviceConfig = ma_device_config_init(ma_device_type_playback);
deviceConfig.playback.format = decoder.outputFormat;
deviceConfig.playback.channels = decoder.outputChannels;
deviceConfig.sampleRate = decoder.outputSampleRate;
deviceConfig.dataCallback = data_callback;
deviceConfig.pUserData = &decoder;
if (ma_device_init(NULL, &deviceConfig, &device) != MA_SUCCESS) {
printf("Failed to open playback device.\n");
ma_decoder_uninit(&decoder);
return -3;
}
if (ma_device_start(&device) != MA_SUCCESS) {
printf("Failed to start playback device.\n");
ma_device_uninit(&device);
ma_decoder_uninit(&decoder);
return -4;
}
printf("Press Enter to quit...");
getchar();
ma_device_uninit(&device);
ma_decoder_uninit(&decoder);
return 0;
}
tests/ma_test_0.vcxproj
View file @ 2b526f69
......@@ -327,13 +327,14 @@
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|x64'">true</ExcludedFromBuild>
</ClCompile>
<ClCompile Include="..\examples\simple_playback_emscripten.c">
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">false</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">false</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|ARM'">false</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|ARM'">false</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">false</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|x64'">false</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">true</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">true</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|ARM'">true</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|ARM'">true</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">true</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|x64'">true</ExcludedFromBuild>
</ClCompile>
<ClCompile Include="..\research\tests\ma_lpf_test_0.c" />
<ClCompile Include="..\research\tests\ma_resampler_test_0.c">
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">true</ExcludedFromBuild>
<ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">true</ExcludedFromBuild>
......@@ -409,6 +410,7 @@
</ItemGroup>
<ItemGroup>
<ClInclude Include="..\miniaudio.h" />
<ClInclude Include="..\research\ma_lpf.h" />
<ClInclude Include="..\research\ma_resampler.h" />
</ItemGroup>
<Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
......
tests/ma_test_0.vcxproj.filters
View file @ 2b526f69
......@@ -69,6 +69,9 @@
<ClCompile Include="..\examples\fixed_size_callback.c">
<Filter>Source Files</Filter>
</ClCompile>
<ClCompile Include="..\research\tests\ma_lpf_test_0.c">
<Filter>Source Files</Filter>
</ClCompile>
</ItemGroup>
<ItemGroup>
<ClInclude Include="..\miniaudio.h">
......@@ -77,5 +80,8 @@
<ClInclude Include="..\research\ma_resampler.h">
<Filter>Source Files</Filter>
</ClInclude>
<ClInclude Include="..\research\ma_lpf.h">
<Filter>Source Files</Filter>
</ClInclude>
</ItemGroup>
</Project>
\ No newline at end of file
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