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Reimplement the compressor to work per-sample

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This commit is contained in:
Chris Robinson 2013-11-06 23:39:41 -08:00
parent 414a9edc6e
commit e0fecdcaaa
1 changed files with 52 additions and 38 deletions
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90
Alc/effects/compressor.c
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@ -35,10 +35,9 @@ typedef struct ALcompressorState {
/* Effect parameters */
ALboolean Enabled;
ALfloat Envelope;
ALfloat EnvGain;
ALfloat Attack;
ALfloat Release;
ALfloat AttackRate;
ALfloat ReleaseRate;
ALfloat GainCtrl;
} ALcompressorState;
static ALvoid ALcompressorState_Destruct(ALcompressorState *UNUSED(state))
@ -47,10 +46,11 @@ static ALvoid ALcompressorState_Destruct(ALcompressorState *UNUSED(state))
static ALboolean ALcompressorState_deviceUpdate(ALcompressorState *state, ALCdevice *device)
{
state->Attack = expf(-1.0f / (device->Frequency * 0.0001f));
state->Release = expf(-1.0f / (device->Frequency * 0.3f));
state->Envelope = 0.0f;
state->EnvGain = 1.0f;
const ALfloat attackTime = device->Frequency * 0.2f; /* 200ms Attack */
const ALfloat releaseTime = device->Frequency * 0.4f; /* 400ms Release */
state->AttackRate = 1.0 / attackTime;
state->ReleaseRate = 1.0 / releaseTime;
return AL_TRUE;
}
@ -60,9 +60,6 @@ static ALvoid ALcompressorState_update(ALcompressorState *state, ALCdevice *Devi
ALfloat gain;
state->Enabled = Slot->EffectProps.Compressor.OnOff;
/* FIXME: Could maybe use the compressor's attack/release to move the gain to 1? */
if(!state->Enabled)
state->EnvGain = 1.0f;
gain = sqrtf(1.0f / Device->NumChan) * Slot->Gain;
SetGains(Device, gain, state->Gain);
@ -70,46 +67,61 @@ static ALvoid ALcompressorState_update(ALcompressorState *state, ALCdevice *Devi
static ALvoid ALcompressorState_process(ALcompressorState *state, ALuint SamplesToDo, const ALfloat *SamplesIn, ALfloat (*SamplesOut)[BUFFERSIZE])
{
ALfloat env = state->Envelope;
ALfloat envgain = state->EnvGain;
ALfloat tattack = state->Attack;
ALfloat trelease = state->Release;
ALuint it, kt;
ALuint base;
ALfloat theta;
ALfloat rms;
for(base = 0;base < SamplesToDo;)
{
ALfloat temps[64];
ALuint td = minu(SamplesToDo-base, 64);
ALfloat summ = 0.0f;
for(it = 0;it < td;it++)
{
ALfloat smp = SamplesIn[it+base] * 0.5f;
summ += smp * smp;
temps[it] = smp;
}
if(state->Enabled)
{
const ALfloat threshold = 0.5f;
const ALfloat slope = 0.5f;
ALfloat output, smp, amplitude;
ALfloat gain = state->GainCtrl;
/* computing rms and envelope */
rms = sqrtf(summ / td);
theta = ((rms > env) ? tattack : trelease);
env = (1.0f - theta)*rms + theta*env;
for(it = 0;it < td;it++)
{
smp = SamplesIn[it+base];
/* applying a hard-knee rms based compressor */
if(env > threshold)
envgain = envgain - (env - threshold) * slope;
amplitude = fabs(smp);
if(amplitude > gain)
gain = minf(gain+state->AttackRate, amplitude);
else if(amplitude < gain)
gain = maxf(gain-state->ReleaseRate, amplitude);
output = 1.0 / clampf(gain, 0.5f, 2.0f);
temps[it] = smp * output;
}
state->GainCtrl = gain;
}
else
{
ALfloat output, smp, amplitude;
ALfloat gain = state->GainCtrl;
for(it = 0;it < td;it++)
{
smp = SamplesIn[it+base];
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;
}
state->GainCtrl = gain;
}
for(kt = 0;kt < MaxChannels;kt++)
{
ALfloat gain = state->Gain[kt] * envgain * 2.0f;
ALfloat gain = state->Gain[kt];
if(!(gain > GAIN_SILENCE_THRESHOLD))
continue;
@ -119,9 +131,6 @@ static ALvoid ALcompressorState_process(ALcompressorState *state, ALuint Samples
base += td;
}
state->Envelope = env;
state->EnvGain = envgain;
}
static void ALcompressorState_Delete(ALcompressorState *state)
@ -144,6 +153,11 @@ static ALeffectState *ALcompressorStateFactory_create(ALcompressorStateFactory *
if(!state) return NULL;
SET_VTABLE2(ALcompressorState, ALeffectState, state);
state->Enabled = AL_TRUE;
state->AttackRate = 0.0f;
state->ReleaseRate = 0.0f;
state->GainCtrl = 1.0f;
return STATIC_CAST(ALeffectState, state);
}