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Make the compressor effect multichannel

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This commit is contained in:
Chris Robinson
2016-01-28 02:49:40 -08:00
parent c1f87414c5
commit 210b4c1fcd
1 changed files with 58 additions and 25 deletions
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Alc/effects/compressor.c
+58 -25
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@@ -31,7 +31,7 @@ typedef struct ALcompressorState {
DERIVE_FROM_TYPE(ALeffectState);
/* Effect gains for each channel */
ALfloat Gain[MAX_OUTPUT_CHANNELS];
ALfloat Gain[MAX_EFFECT_CHANNELS][MAX_OUTPUT_CHANNELS];
/* Effect parameters */
ALboolean Enabled;
@@ -57,73 +57,106 @@ static ALboolean ALcompressorState_deviceUpdate(ALcompressorState *state, ALCdev
static ALvoid ALcompressorState_update(ALcompressorState *state, const ALCdevice *device, const ALeffectslot *slot)
{
aluMatrixf matrix;
ALfloat scale;
ALuint i;
state->Enabled = slot->EffectProps.Compressor.OnOff;
ComputeAmbientGains(device->AmbiCoeffs, device->NumChannels, slot->Gain, state->Gain);
scale = device->AmbiScale;
aluMatrixfSet(&matrix,
1.0f, 0.0f, 0.0f, 0.0f,
0.0f, scale, 0.0f, 0.0f,
0.0f, 0.0f, scale, 0.0f,
0.0f, 0.0f, 0.0f, scale
);
for(i = 0;i < 4;i++)
ComputeBFormatGains(device->AmbiCoeffs, device->NumChannels,
matrix.m[i], slot->Gain, state->Gain[i]);
}
static ALvoid ALcompressorState_process(ALcompressorState *state, ALuint SamplesToDo, const ALfloat (*restrict SamplesIn)[BUFFERSIZE], ALfloat (*restrict SamplesOut)[BUFFERSIZE], ALuint NumChannels)
{
ALuint it, kt;
ALuint i, j, k;
ALuint base;
for(base = 0;base < SamplesToDo;)
{
ALfloat temps[256];
ALuint td = minu(256, SamplesToDo-base);
ALfloat temps[64][4];
ALuint td = minu(64, SamplesToDo-base);
/* Load samples into the temp buffer first. */
for(j = 0;j < 4;j++)
{
for(i = 0;i < td;i++)
temps[i][j] = SamplesIn[j][i+base];
}
if(state->Enabled)
{
ALfloat output, smp, amplitude;
ALfloat gain = state->GainCtrl;
ALfloat output, amplitude;
for(it = 0;it < td;it++)
for(i = 0;i < td;i++)
{
smp = SamplesIn[0][it+base];
amplitude = fabsf(smp);
/* Roughly calculate the maximum amplitude from the 4-channel
* signal, and attack or release the gain control to reach it.
*/
amplitude = fabsf(temps[i][0]);
amplitude = maxf(amplitude + fabsf(temps[i][1]),
maxf(amplitude + fabsf(temps[i][2]),
amplitude + fabsf(temps[i][3])));
if(amplitude > gain)
gain = minf(gain+state->AttackRate, amplitude);
else if(amplitude < gain)
gain = maxf(gain-state->ReleaseRate, amplitude);
output = 1.0f / clampf(gain, 0.5f, 2.0f);
temps[it] = smp * output;
/* Apply the inverse of the gain control to normalize/compress
* the volume. */
output = 1.0f / clampf(gain, 0.5f, 2.0f);
for(j = 0;j < 4;j++)
temps[i][j] *= output;
}
state->GainCtrl = gain;
}
else
{
ALfloat output, smp, amplitude;
ALfloat gain = state->GainCtrl;
ALfloat output, amplitude;
for(it = 0;it < td;it++)
for(i = 0;i < td;i++)
{
smp = SamplesIn[0][it+base];
/* Same as above, except the amplitude is forced to 1. This
* helps ensure smooth gain changes when the compressor is
* turned on and off.
*/
amplitude = 1.0f;
if(amplitude > gain)
gain = minf(gain+state->AttackRate, amplitude);
else if(amplitude < gain)
gain = maxf(gain-state->ReleaseRate, amplitude);
output = 1.0f / clampf(gain, 0.5f, 2.0f);
temps[it] = smp * output;
output = 1.0f / clampf(gain, 0.5f, 2.0f);
for(j = 0;j < 4;j++)
temps[i][j] *= output;
}
state->GainCtrl = gain;
}
for(kt = 0;kt < NumChannels;kt++)
/* Now mix to the output. */
for(j = 0;j < 4;j++)
{
ALfloat gain = state->Gain[kt];
if(!(fabsf(gain) > GAIN_SILENCE_THRESHOLD))
continue;
for(k = 0;k < NumChannels;k++)
{
ALfloat gain = state->Gain[j][k];
if(!(fabsf(gain) > GAIN_SILENCE_THRESHOLD))
continue;
for(it = 0;it < td;it++)
SamplesOut[kt][base+it] += gain * temps[it];
for(i = 0;i < td;i++)
SamplesOut[k][base+i] += gain * temps[i][j];
}
}
base += td;