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Resampling and LPF work.

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This commit is contained in:
David Reid
2020-01-18 14:36:12 +10:00
parent df2903a0bc
commit 7d37789418
2 changed files with 129 additions and 83 deletions
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research/ma_lpf.h
+54 -30
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@@ -5,21 +5,45 @@
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).
- Document how ma_biquad_process() and ma_lpf_process() supports in-place filtering by passing in the same buffer for both the input and output.
*/
typedef struct
{
ma_format format;
ma_uint32 channels;
float a0;
float a1;
float a2;
float b0;
float b1;
float b2;
double a0;
double a1;
double a2;
double b0;
double b1;
double b2;
#if 0
union
{
struct
{
double a0;
double a1;
double a2;
double b0;
double b1;
double b2;
} f32;
struct
{
ma_int32 a0;
ma_int32 a1;
ma_int32 a2;
ma_int32 b0;
ma_int32 b1;
ma_int32 b2;
} s16;
} constants;
#endif
} 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);
ma_biquad_config ma_biquad_config_init(ma_format format, ma_uint32 channels, double a0, double a1, double a2, double b0, double b1, double b2);
typedef struct
{
@@ -62,7 +86,7 @@ ma_result ma_lpf_process(ma_lpf* pLPF, void* pFramesOut, const void* pFramesIn,
#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 ma_biquad_config_init(ma_format format, ma_uint32 channels, double a0, double a1, double a2, double b0, double b1, double b2)
{
ma_biquad_config config;
@@ -121,11 +145,11 @@ ma_result ma_biquad_process(ma_biquad* pBQ, void* pFramesOut, const void* pFrame
{
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;
double a1 = pBQ->config.a1;
double a2 = pBQ->config.a2;
double b0 = pBQ->config.b0;
double b1 = pBQ->config.b1;
double b2 = pBQ->config.b2;
if (pBQ == NULL || pFramesOut == NULL || pFramesIn == NULL) {
return MA_INVALID_ARGS;
@@ -149,18 +173,18 @@ ma_result ma_biquad_process(ma_biquad* pBQ, void* pFramesOut, const void* pFrame
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;
double x2 = pBQ->x2[c];
double x1 = pBQ->x1[c];
double x0 = pX[n*pBQ->config.channels + c];
double y2 = pBQ->y2[c];
double y1 = pBQ->y1[c];
double 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;
pY[n*pBQ->config.channels + c] = (float)y0;
pBQ->x2[c] = (float)x1;
pBQ->x1[c] = (float)x0;
pBQ->y2[c] = (float)y1;
pBQ->y1[c] = (float)y0;
}
}
} else {
@@ -212,12 +236,12 @@ ma_result ma_lpf_init(const ma_lpf_config* pConfig, ma_lpf* pLPF)
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.a0 = (double)( 1 + a);
bqConfig.a1 = (double)(-2 * c);
bqConfig.a2 = (double)( 1 - a);
bqConfig.b0 = (double)((1 - c) / 2);
bqConfig.b1 = (double)( 1 - c);
bqConfig.b2 = (double)((1 - c) / 2);
bqConfig.format = pConfig->format;
bqConfig.channels = pConfig->channels;