Dima353/openal-soft
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Avoid multiple sin, cos, and sqrt calls for filter calculations

Browse Source
This commit is contained in:
Chris Robinson
2015-10-11 10:21:37 -07:00
parent db22465c1d
commit b859f1bdc3
1 changed files with 35 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files
OpenAL32/alFilter.c
+35 -31
View File
@@ -338,70 +338,74 @@ void ALfilterState_clear(ALfilterState *filter)
void ALfilterState_setParams(ALfilterState *filter, ALfilterType type, ALfloat gain, ALfloat freq_mult, ALfloat bandwidth)
{
ALfloat alpha;
ALfloat w0;
ALfloat alpha, sqrtgain_alpha_2;
ALfloat w0, sin_w0, cos_w0;
// Limit gain to -100dB
gain = maxf(gain, 0.00001f);
w0 = F_TAU * freq_mult;
sin_w0 = sinf(w0);
cos_w0 = cosf(w0);
/* Calculate filter coefficients depending on filter type */
switch(type)
{
case ALfilterType_HighShelf:
alpha = sinf(w0)/2.0f*sqrtf((gain + 1.0f/gain)*(1.0f/0.75f - 1.0f) + 2.0f);
filter->b[0] = gain*((gain+1.0f) + (gain-1.0f)*cosf(w0) + 2.0f*sqrtf(gain)*alpha);
filter->b[1] = -2.0f*gain*((gain-1.0f) + (gain+1.0f)*cosf(w0) );
filter->b[2] = gain*((gain+1.0f) + (gain-1.0f)*cosf(w0) - 2.0f*sqrtf(gain)*alpha);
filter->a[0] = (gain+1.0f) - (gain-1.0f)*cosf(w0) + 2.0f*sqrtf(gain)*alpha;
filter->a[1] = 2.0f* ((gain-1.0f) - (gain+1.0f)*cosf(w0) );
filter->a[2] = (gain+1.0f) - (gain-1.0f)*cosf(w0) - 2.0f*sqrtf(gain)*alpha;
alpha = sin_w0/2.0f*sqrtf((gain + 1.0f/gain)*(1.0f/0.75f - 1.0f) + 2.0f);
sqrtgain_alpha_2 = 2.0f * sqrtf(gain) * alpha;
filter->b[0] = gain*((gain+1.0f) + (gain-1.0f)*cos_w0 + sqrtgain_alpha_2);
filter->b[1] = -2.0f*gain*((gain-1.0f) + (gain+1.0f)*cos_w0 );
filter->b[2] = gain*((gain+1.0f) + (gain-1.0f)*cos_w0 - sqrtgain_alpha_2);
filter->a[0] = (gain+1.0f) - (gain-1.0f)*cos_w0 + sqrtgain_alpha_2;
filter->a[1] = 2.0f* ((gain-1.0f) - (gain+1.0f)*cos_w0 );
filter->a[2] = (gain+1.0f) - (gain-1.0f)*cos_w0 - sqrtgain_alpha_2;
break;
case ALfilterType_LowShelf:
alpha = sinf(w0)/2.0f*sqrtf((gain + 1.0f/gain)*(1.0f/0.75f - 1.0f) + 2.0f);
filter->b[0] = gain*((gain+1.0f) - (gain-1.0f)*cosf(w0) + 2.0f*sqrtf(gain)*alpha);
filter->b[1] = 2.0f*gain*((gain-1.0f) - (gain+1.0f)*cosf(w0) );
filter->b[2] = gain*((gain+1.0f) - (gain-1.0f)*cosf(w0) - 2.0f*sqrtf(gain)*alpha);
filter->a[0] = (gain+1.0f) + (gain-1.0f)*cosf(w0) + 2.0f*sqrtf(gain)*alpha;
filter->a[1] = -2.0f* ((gain-1.0f) + (gain+1.0f)*cosf(w0) );
filter->a[2] = (gain+1.0f) + (gain-1.0f)*cosf(w0) - 2.0f*sqrtf(gain)*alpha;
alpha = sin_w0/2.0f*sqrtf((gain + 1.0f/gain)*(1.0f/0.75f - 1.0f) + 2.0f);
sqrtgain_alpha_2 = 2.0f * sqrtf(gain) * alpha;
filter->b[0] = gain*((gain+1.0f) - (gain-1.0f)*cos_w0 + sqrtgain_alpha_2);
filter->b[1] = 2.0f*gain*((gain-1.0f) - (gain+1.0f)*cos_w0 );
filter->b[2] = gain*((gain+1.0f) - (gain-1.0f)*cos_w0 - sqrtgain_alpha_2);
filter->a[0] = (gain+1.0f) + (gain-1.0f)*cos_w0 + sqrtgain_alpha_2;
filter->a[1] = -2.0f* ((gain-1.0f) + (gain+1.0f)*cos_w0 );
filter->a[2] = (gain+1.0f) + (gain-1.0f)*cos_w0 - sqrtgain_alpha_2;
break;
case ALfilterType_Peaking:
alpha = sinf(w0) * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sinf(w0));
alpha = sin_w0 * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sin_w0);
filter->b[0] = 1.0f + alpha * gain;
filter->b[1] = -2.0f * cosf(w0);
filter->b[1] = -2.0f * cos_w0;
filter->b[2] = 1.0f - alpha * gain;
filter->a[0] = 1.0f + alpha / gain;
filter->a[1] = -2.0f * cosf(w0);
filter->a[1] = -2.0f * cos_w0;
filter->a[2] = 1.0f - alpha / gain;
break;
case ALfilterType_LowPass:
alpha = sinf(w0) * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sinf(w0));
filter->b[0] = (1.0f - cosf(w0)) / 2.0f;
filter->b[1] = 1.0f - cosf(w0);
filter->b[2] = (1.0f - cosf(w0)) / 2.0f;
alpha = sin_w0 * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sin_w0);
filter->b[0] = (1.0f - cos_w0) / 2.0f;
filter->b[1] = 1.0f - cos_w0;
filter->b[2] = (1.0f - cos_w0) / 2.0f;
filter->a[0] = 1.0f + alpha;
filter->a[1] = -2.0f * cosf(w0);
filter->a[1] = -2.0f * cos_w0;
filter->a[2] = 1.0f - alpha;
break;
case ALfilterType_HighPass:
alpha = sinf(w0) * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sinf(w0));
filter->b[0] = (1.0f + cosf(w0)) / 2.0f;
filter->b[1] = -(1.0f + cosf(w0));
filter->b[2] = (1.0f + cosf(w0)) / 2.0f;
alpha = sin_w0 * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sin_w0);
filter->b[0] = (1.0f + cos_w0) / 2.0f;
filter->b[1] = -(1.0f + cos_w0);
filter->b[2] = (1.0f + cos_w0) / 2.0f;
filter->a[0] = 1.0f + alpha;
filter->a[1] = -2.0f * cosf(w0);
filter->a[1] = -2.0f * cos_w0;
filter->a[2] = 1.0f - alpha;
break;
case ALfilterType_BandPass:
alpha = sinf(w0) * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sinf(w0));
alpha = sin_w0 * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sin_w0);
filter->b[0] = alpha;
filter->b[1] = 0;
filter->b[2] = -alpha;
filter->a[0] = 1.0f + alpha;
filter->a[1] = -2.0f * cosf(w0);
filter->a[1] = -2.0f * cos_w0;
filter->a[2] = 1.0f - alpha;
break;
}