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Use a single delay line for chorus feedback on a fixed tap

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The outputs themselves use a variale-delay tap, but using a separate fixed-
delay tap on the feedback helps improve the perceived "wobble" with sustained
notes. This also applies to the flanger effect.
This commit is contained in:
Chris Robinson 2017-12-18 13:41:12 -08:00
parent eee4aca40b
commit 661bd054aa
2 changed files with 110 additions and 84 deletions
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97
Alc/effects/chorus.c
View File

@ -38,7 +38,7 @@ enum ChorusWaveForm {
typedef struct ALchorusState {
DERIVE_FROM_TYPE(ALeffectState);
ALfloat *SampleBuffer[2];
ALfloat *SampleBuffer;
ALsizei BufferLength;
ALsizei offset;
@ -72,8 +72,7 @@ static void ALchorusState_Construct(ALchorusState *state)
SET_VTABLE2(ALchorusState, ALeffectState, state);
state->BufferLength = 0;
state->SampleBuffer[0] = NULL;
state->SampleBuffer[1] = NULL;
state->SampleBuffer = NULL;
state->offset = 0;
state->lfo_offset = 0;
state->lfo_range = 1;
@ -82,9 +81,8 @@ static void ALchorusState_Construct(ALchorusState *state)
static ALvoid ALchorusState_Destruct(ALchorusState *state)
{
al_free(state->SampleBuffer[0]);
state->SampleBuffer[0] = NULL;
state->SampleBuffer[1] = NULL;
al_free(state->SampleBuffer);
state->SampleBuffer = NULL;
ALeffectState_Destruct(STATIC_CAST(ALeffectState,state));
}
@ -99,21 +97,17 @@ static ALboolean ALchorusState_deviceUpdate(ALchorusState *state, ALCdevice *Dev
if(maxlen != state->BufferLength)
{
void *temp = al_calloc(16, maxlen * sizeof(ALfloat) * 2);
void *temp = al_calloc(16, maxlen * sizeof(ALfloat));
if(!temp) return AL_FALSE;
al_free(state->SampleBuffer[0]);
state->SampleBuffer[0] = temp;
state->SampleBuffer[1] = state->SampleBuffer[0] + maxlen;
al_free(state->SampleBuffer);
state->SampleBuffer = temp;
state->BufferLength = maxlen;
}
for(it = 0;it < state->BufferLength;it++)
{
state->SampleBuffer[0][it] = 0.0f;
state->SampleBuffer[1][it] = 0.0f;
}
state->SampleBuffer[it] = 0.0f;
return AL_TRUE;
}
@ -144,7 +138,7 @@ static ALvoid ALchorusState_update(ALchorusState *state, const ALCcontext *Conte
/* Offset the delay so that the center point remains the same with the LFO
* ranging from 0...2 instead of -1...+1.
*/
state->delay = fastf2i(delay - state->depth + 0.5f);
state->delay = fastf2i(delay-state->depth + 0.5f);
state->feedback = props->Chorus.Feedback;
@ -218,49 +212,68 @@ static ALvoid ALchorusState_process(ALchorusState *state, ALsizei SamplesToDo, c
{
const ALsizei bufmask = state->BufferLength-1;
const ALfloat feedback = state->feedback;
const ALsizei avgdelay = (state->delay+fastf2i(state->depth) + (FRACTIONONE>>1)) >>
FRACTIONBITS;
ALfloat *restrict delaybuf = state->SampleBuffer;
ALsizei i, c;
ALsizei base;
for(base = 0;base < SamplesToDo;)
{
const ALsizei todo = mini(256, SamplesToDo-base);
ALfloat temps[256];
ALint moddelays[2][256];
ALfloat temps[2][256];
ALsizei offset;
for(c = 0;c < 2;c++)
if(state->waveform == CWF_Triangle)
{
ALfloat *restrict sampbuf = state->SampleBuffer[c];
ALint disp_offset = state->lfo_disp*c;
ALint moddelays[256];
ALsizei offset;
GetTriangleDelays(moddelays[0], state->lfo_offset, state->lfo_range, state->lfo_scale,
state->depth, state->delay, todo);
GetTriangleDelays(moddelays[1], (state->lfo_offset+state->lfo_disp)%state->lfo_range,
state->lfo_range, state->lfo_scale, state->depth, state->delay,
todo);
}
else /*if(state->waveform == CWF_Sinusoid)*/
{
GetSinusoidDelays(moddelays[0], state->lfo_offset, state->lfo_range, state->lfo_scale,
state->depth, state->delay, todo);
GetSinusoidDelays(moddelays[1], (state->lfo_offset+state->lfo_disp)%state->lfo_range,
state->lfo_range, state->lfo_scale, state->depth, state->delay,
todo);
}
if(state->waveform == CWF_Triangle)
GetTriangleDelays(moddelays, (state->lfo_offset+disp_offset)%state->lfo_range,
state->lfo_range, state->lfo_scale, state->depth, state->delay,
todo);
else /*if(state->waveform == CWF_Sinusoid)*/
GetSinusoidDelays(moddelays, (state->lfo_offset+disp_offset)%state->lfo_range,
state->lfo_range, state->lfo_scale, state->depth, state->delay,
todo);
offset = state->offset;
for(i = 0;i < todo;i++)
{
ALint delay;
ALfloat mu;
offset = state->offset;
for(i = 0;i < todo;i++)
{
ALint delay = moddelays[i] >> FRACTIONBITS;
ALfloat mu = (moddelays[i]&FRACTIONMASK) * (1.0f/FRACTIONONE);
// Feed the buffer's input first (necessary for delays < 1).
delaybuf[offset&bufmask] = SamplesIn[0][base+i];
sampbuf[offset&bufmask] = SamplesIn[0][base+i];
temps[i] = sampbuf[(offset-delay) & bufmask]*(1.0f-mu) +
sampbuf[(offset-(delay+1)) & bufmask]*mu;
sampbuf[offset&bufmask] += temps[i] * feedback;
offset++;
}
// Tap for the left output.
delay = moddelays[0][i] >> FRACTIONBITS;
mu = (moddelays[0][i]&FRACTIONMASK) * (1.0f/FRACTIONONE);
temps[0][i] = delaybuf[(offset-delay) & bufmask]*(1.0f-mu) +
delaybuf[(offset-(delay+1)) & bufmask]*mu;
MixSamples(temps, NumChannels, SamplesOut, state->Gain[c], state->Gain[c],
0, base, todo);
// Tap for the right output.
delay = moddelays[1][i] >> FRACTIONBITS;
mu = (moddelays[1][i]&FRACTIONMASK) * (1.0f/FRACTIONONE);
temps[1][i] = delaybuf[(offset-delay) & bufmask]*(1.0f-mu) +
delaybuf[(offset-(delay+1)) & bufmask]*mu;
// Accumulate feedback from the average delay of the taps.
delaybuf[offset&bufmask] += delaybuf[(offset-avgdelay) & bufmask] * feedback;
offset++;
}
state->offset += todo;
state->lfo_offset = (state->lfo_offset+todo) % state->lfo_range;
for(c = 0;c < 2;c++)
MixSamples(temps[c], NumChannels, SamplesOut, state->Gain[c], state->Gain[c],
0, base, todo);
base += todo;
}
}

97
Alc/effects/flanger.c
View File

@ -38,7 +38,7 @@ enum FlangerWaveForm {
typedef struct ALflangerState {
DERIVE_FROM_TYPE(ALeffectState);
ALfloat *SampleBuffer[2];
ALfloat *SampleBuffer;
ALsizei BufferLength;
ALsizei offset;
@ -72,8 +72,7 @@ static void ALflangerState_Construct(ALflangerState *state)
SET_VTABLE2(ALflangerState, ALeffectState, state);
state->BufferLength = 0;
state->SampleBuffer[0] = NULL;
state->SampleBuffer[1] = NULL;
state->SampleBuffer = NULL;
state->offset = 0;
state->lfo_offset = 0;
state->lfo_range = 1;
@ -82,9 +81,8 @@ static void ALflangerState_Construct(ALflangerState *state)
static ALvoid ALflangerState_Destruct(ALflangerState *state)
{
al_free(state->SampleBuffer[0]);
state->SampleBuffer[0] = NULL;
state->SampleBuffer[1] = NULL;
al_free(state->SampleBuffer);
state->SampleBuffer = NULL;
ALeffectState_Destruct(STATIC_CAST(ALeffectState,state));
}
@ -99,21 +97,17 @@ static ALboolean ALflangerState_deviceUpdate(ALflangerState *state, ALCdevice *D
if(maxlen != state->BufferLength)
{
void *temp = al_calloc(16, maxlen * sizeof(ALfloat) * 2);
void *temp = al_calloc(16, maxlen * sizeof(ALfloat));
if(!temp) return AL_FALSE;
al_free(state->SampleBuffer[0]);
state->SampleBuffer[0] = temp;
state->SampleBuffer[1] = state->SampleBuffer[0] + maxlen;
al_free(state->SampleBuffer);
state->SampleBuffer = temp;
state->BufferLength = maxlen;
}
for(it = 0;it < state->BufferLength;it++)
{
state->SampleBuffer[0][it] = 0.0f;
state->SampleBuffer[1][it] = 0.0f;
}
state->SampleBuffer[it] = 0.0f;
return AL_TRUE;
}
@ -144,7 +138,7 @@ static ALvoid ALflangerState_update(ALflangerState *state, const ALCcontext *con
/* Offset the delay so that the center point remains the same with the LFO
* ranging from 0...2 instead of -1...+1.
*/
state->delay = fastf2i(delay - state->depth + 0.5f);
state->delay = fastf2i(delay-state->depth + 0.5f);
state->feedback = props->Flanger.Feedback;
@ -217,49 +211,68 @@ static ALvoid ALflangerState_process(ALflangerState *state, ALsizei SamplesToDo,
{
const ALsizei bufmask = state->BufferLength-1;
const ALfloat feedback = state->feedback;
const ALsizei avgdelay = (state->delay+fastf2i(state->depth) + (FRACTIONONE>>1)) >>
FRACTIONBITS;
ALfloat *restrict delaybuf = state->SampleBuffer;
ALsizei i, c;
ALsizei base;
for(base = 0;base < SamplesToDo;)
{
const ALsizei todo = mini(256, SamplesToDo-base);
ALfloat temps[256];
ALint moddelays[2][256];
ALfloat temps[2][256];
ALsizei offset;
for(c = 0;c < 2;c++)
if(state->waveform == FWF_Triangle)
{
ALfloat *restrict sampbuf = state->SampleBuffer[c];
ALint disp_offset = state->lfo_disp*c;
ALint moddelays[256];
ALsizei offset;
GetTriangleDelays(moddelays[0], state->lfo_offset, state->lfo_range, state->lfo_scale,
state->depth, state->delay, todo);
GetTriangleDelays(moddelays[1], (state->lfo_offset+state->lfo_disp)%state->lfo_range,
state->lfo_range, state->lfo_scale, state->depth, state->delay,
todo);
}
else /*if(state->waveform == FWF_Sinusoid)*/
{
GetSinusoidDelays(moddelays[0], state->lfo_offset, state->lfo_range, state->lfo_scale,
state->depth, state->delay, todo);
GetSinusoidDelays(moddelays[1], (state->lfo_offset+state->lfo_disp)%state->lfo_range,
state->lfo_range, state->lfo_scale, state->depth, state->delay,
todo);
}
if(state->waveform == FWF_Triangle)
GetTriangleDelays(moddelays, (state->lfo_offset+disp_offset)%state->lfo_range,
state->lfo_range, state->lfo_scale, state->depth, state->delay,
todo);
else /*if(state->waveform == FWF_Sinusoid)*/
GetSinusoidDelays(moddelays, (state->lfo_offset+disp_offset)%state->lfo_range,
state->lfo_range, state->lfo_scale, state->depth, state->delay,
todo);
offset = state->offset;
for(i = 0;i < todo;i++)
{
ALint delay;
ALfloat mu;
offset = state->offset;
for(i = 0;i < todo;i++)
{
ALint delay = moddelays[i] >> FRACTIONBITS;
ALfloat mu = (moddelays[i]&FRACTIONMASK) * (1.0f/FRACTIONONE);
// Feed the buffer's input first (necessary for delays < 1).
delaybuf[offset&bufmask] = SamplesIn[0][base+i];
sampbuf[offset&bufmask] = SamplesIn[0][base+i];
temps[i] = sampbuf[(offset-delay) & bufmask]*(1.0f-mu) +
sampbuf[(offset-(delay+1)) & bufmask]*mu;
sampbuf[offset&bufmask] += temps[i] * feedback;
offset++;
}
// Tap for the left output.
delay = moddelays[0][i] >> FRACTIONBITS;
mu = (moddelays[0][i]&FRACTIONMASK) * (1.0f/FRACTIONONE);
temps[0][i] = delaybuf[(offset-delay) & bufmask]*(1.0f-mu) +
delaybuf[(offset-(delay+1)) & bufmask]*mu;
MixSamples(temps, NumChannels, SamplesOut, state->Gain[c], state->Gain[c],
0, base, todo);
// Tap for the right output.
delay = moddelays[1][i] >> FRACTIONBITS;
mu = (moddelays[1][i]&FRACTIONMASK) * (1.0f/FRACTIONONE);
temps[1][i] = delaybuf[(offset-delay) & bufmask]*(1.0f-mu) +
delaybuf[(offset-(delay+1)) & bufmask]*mu;
// Accumulate feedback from the average delay.
delaybuf[offset&bufmask] += delaybuf[(offset-avgdelay) & bufmask] * feedback;
offset++;
}
state->offset += todo;
state->lfo_offset = (state->lfo_offset+todo) % state->lfo_range;
for(c = 0;c < 2;c++)
MixSamples(temps[c], NumChannels, SamplesOut, state->Gain[c], state->Gain[c],
0, base, todo);
base += todo;
}
}