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

Avoid recalculating the same coefficient

Browse Source
This commit is contained in:
Chris Robinson
2013-05-19 03:18:21 -07:00
parent 78e7c1c27b
commit 1976d64814
1 changed files with 9 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Alc/alcDistortion.c
+9 -11
View File
@@ -58,7 +58,7 @@ typedef struct ALdistortionState {
ALEQFilter lowpass;
ALfloat frequency;
ALfloat attenuation;
ALfloat edge;
ALfloat edge_coeff;
/* Oversample data */
ALfloat oversample_buffer[BUFFERSIZE][4];
@@ -89,6 +89,7 @@ static ALvoid DistortionUpdate(ALeffectState *effect, ALCdevice *Device, const A
ALfloat alpha;
ALfloat bandwidth;
ALfloat cutoff;
ALfloat edge;
for(it = 0; it < Device->NumChan; it++)
{
@@ -100,7 +101,8 @@ static ALvoid DistortionUpdate(ALeffectState *effect, ALCdevice *Device, const A
state->attenuation = Slot->effect.Distortion.Gain;
/* Store waveshaper edge settings */
state->edge = Slot->effect.Distortion.Edge;
edge = sinf(Slot->effect.Distortion.Edge * (F_PI/2.0f));
state->edge_coeff = 2.0f * edge / (1.0f-edge);
/* Lowpass filter */
cutoff = Slot->effect.Distortion.LowpassCutoff;
@@ -136,7 +138,6 @@ static ALvoid DistortionProcess(ALeffectState *effect, ALuint SamplesToDo, const
ALfloat tempsmp;
ALuint it;
ALuint kt;
ALuint st;
/* Perform 4x oversampling to avoid aliasing. */
/* Oversampling greatly improves distortion */
@@ -177,18 +178,15 @@ static ALvoid DistortionProcess(ALeffectState *effect, ALuint SamplesToDo, const
for(it = 0; it < SamplesToDo * 4; it++)
{
ALfloat smp = oversample_buffer[it];
ALfloat edge = sinf(state->edge * (F_PI / 2.0f));
ALfloat fc = state->edge_coeff;
/* Second step, do distortion using waveshaper function */
/* to emulate signal processing during tube overdriving. */
/* Three steps of waveshaping are intended to modify */
/* waveform without boost/clipping/attenuation process. */
for(st = 0; st < 3; st++)
{
smp = (1.0f + 2.0f * edge / (1.0f - edge)) * smp / (1.0f + 2.0f * edge / (1.0f - edge) * fabsf(smp));
if((st & 0x00000001) == 0x00000001)
smp *= -1.0f;
}
smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp));
smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp)) * -1.0f;
smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp));
/* Third step, do bandpass filtering of distorted signal */
tempsmp = state->bandpass.b[0] / state->bandpass.a[0] * smp +
@@ -205,7 +203,7 @@ static ALvoid DistortionProcess(ALeffectState *effect, ALuint SamplesToDo, const
/* Fourth step, final, do attenuation and perform decimation, */
/* store only one sample out of 4. */
if(!(it & 0x00000003))
if(!(it&3))
{
smp *= state->attenuation;
for(kt = 0; kt < MaxChannels; kt++)