/** * OpenAL cross platform audio library * Copyright (C) 2013 by Anis A. Hireche, Nasca Octavian Paul * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, * Boston, MA 02111-1307, USA. * Or go to http://www.gnu.org/copyleft/lgpl.html */ #include #include "config.h" #include "alu.h" #include "alFilter.h" #include "alError.h" #include "alMain.h" #include "alAuxEffectSlot.h" /* Auto-wah is simply a low-pass filter with a cutoff frequency that shifts up * or down depending on the input signal, and a resonant peak at the cutoff. * * Currently, we assume a cutoff frequency range of 500hz (no amplitude) to * 3khz (peak gain). Peak gain is assumed to be in normalized scale. */ typedef struct ALautowahState { DERIVE_FROM_TYPE(ALeffectState); /* Effect gains for each channel */ ALfloat Gain[MaxChannels]; /* Effect parameters */ ALfloat AttackRate; ALfloat ReleaseRate; ALfloat Resonance; ALfloat PeakGain; ALfloat GainCtrl; ALfloat Frequency; /* Samples processing */ ALfilterState LowPass; } ALautowahState; static ALvoid ALautowahState_Destruct(ALautowahState *UNUSED(state)) { } static ALboolean ALautowahState_deviceUpdate(ALautowahState *state, ALCdevice *device) { state->Frequency = (ALfloat)device->Frequency; return AL_TRUE; } static ALvoid ALautowahState_update(ALautowahState *state, ALCdevice *device, const ALeffectslot *slot) { ALfloat attackTime, releaseTime; ALfloat gain; attackTime = slot->EffectProps.Autowah.AttackTime * state->Frequency; releaseTime = slot->EffectProps.Autowah.ReleaseTime * state->Frequency; state->AttackRate = 1.0f / attackTime; state->ReleaseRate = 1.0f / releaseTime; state->PeakGain = slot->EffectProps.Autowah.PeakGain; state->Resonance = slot->EffectProps.Autowah.Resonance; gain = sqrtf(1.0f / device->NumChan) * slot->Gain; SetGains(device, gain, state->Gain); } static ALvoid ALautowahState_process(ALautowahState *state, ALuint SamplesToDo, const ALfloat *SamplesIn, ALfloat (*SamplesOut)[BUFFERSIZE]) { ALuint it, kt; ALuint base; for(base = 0;base < SamplesToDo;) { ALfloat temps[64]; ALuint td = minu(SamplesToDo-base, 64); ALfloat gain = state->GainCtrl; for(it = 0;it < td;it++) { ALfloat smp = SamplesIn[it+base]; ALfloat alpha, w0; ALfloat amplitude; ALfloat cutoff; /* Similar to compressor, we get the current amplitude of the * incoming signal, and attack or release to reach it. */ amplitude = fabsf(smp); if(amplitude > gain) gain = minf(gain+state->AttackRate, amplitude); else if(amplitude < gain) gain = maxf(gain-state->ReleaseRate, amplitude); gain = maxf(gain, GAIN_SILENCE_THRESHOLD); /* FIXME: What range does the filter cover? */ cutoff = lerp(20.0f, 20000.0f, minf(gain/state->PeakGain, 1.0f)); /* The code below is like calling ALfilterState_setParams with * ALfilterType_LowPass. However, instead of passing a bandwidth, * we use the resonance property for Q. This also inlines the call. */ w0 = F_2PI * cutoff / state->Frequency; /* FIXME: Resonance controls the resonant peak, or Q. How? Not sure * that Q = resonance*0.1. */ alpha = sinf(w0) / (2.0f * state->Resonance*0.1f); state->LowPass.b[0] = (1.0f - cosf(w0)) / 2.0f; state->LowPass.b[1] = 1.0f - cosf(w0); state->LowPass.b[2] = (1.0f - cosf(w0)) / 2.0f; state->LowPass.a[0] = 1.0f + alpha; state->LowPass.a[1] = -2.0f * cosf(w0); state->LowPass.a[2] = 1.0f - alpha; state->LowPass.b[2] /= state->LowPass.a[0]; state->LowPass.b[1] /= state->LowPass.a[0]; state->LowPass.b[0] /= state->LowPass.a[0]; state->LowPass.a[2] /= state->LowPass.a[0]; state->LowPass.a[1] /= state->LowPass.a[0]; state->LowPass.a[0] /= state->LowPass.a[0]; temps[it] = ALfilterState_processSingle(&state->LowPass, smp); } state->GainCtrl = gain; for(kt = 0;kt < MaxChannels;kt++) { ALfloat gain = state->Gain[kt]; if(!(gain > GAIN_SILENCE_THRESHOLD)) continue; for(it = 0;it < td;it++) SamplesOut[kt][base+it] += gain * temps[it]; } base += td; } } static void ALautowahState_Delete(ALautowahState *state) { free(state); } DEFINE_ALEFFECTSTATE_VTABLE(ALautowahState); typedef struct ALautowahStateFactory { DERIVE_FROM_TYPE(ALeffectStateFactory); } ALautowahStateFactory; static ALeffectState *ALautowahStateFactory_create(ALautowahStateFactory *UNUSED(factory)) { ALautowahState *state; state = malloc(sizeof(*state)); if(!state) return NULL; SET_VTABLE2(ALautowahState, ALeffectState, state); state->AttackRate = 0.0f; state->ReleaseRate = 0.0f; state->Resonance = 0.0f; state->PeakGain = 1.0f; state->GainCtrl = 1.0f; ALfilterState_clear(&state->LowPass); return STATIC_CAST(ALeffectState, state); } DEFINE_ALEFFECTSTATEFACTORY_VTABLE(ALautowahStateFactory); ALeffectStateFactory *ALautowahStateFactory_getFactory(void) { static ALautowahStateFactory AutowahFactory = { { GET_VTABLE2(ALautowahStateFactory, ALeffectStateFactory) } }; return STATIC_CAST(ALeffectStateFactory, &AutowahFactory); } void ALautowah_setParami(ALeffect *UNUSED(effect), ALCcontext *context, ALenum UNUSED(param), ALint UNUSED(val)) { SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); } void ALautowah_setParamiv(ALeffect *effect, ALCcontext *context, ALenum param, const ALint *vals) { ALautowah_setParami(effect, context, param, vals[0]); } void ALautowah_setParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val) { ALeffectProps *props = &effect->Props; switch(param) { case AL_AUTOWAH_ATTACK_TIME: if(!(val >= AL_AUTOWAH_MIN_ATTACK_TIME && val <= AL_AUTOWAH_MAX_ATTACK_TIME)) SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE); props->Autowah.AttackTime = val; break; case AL_AUTOWAH_RELEASE_TIME: if(!(val >= AL_AUTOWAH_MIN_RELEASE_TIME && val <= AL_AUTOWAH_MAX_RELEASE_TIME)) SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE); props->Autowah.ReleaseTime = val; break; case AL_AUTOWAH_RESONANCE: if(!(val >= AL_AUTOWAH_MIN_RESONANCE && val <= AL_AUTOWAH_MAX_RESONANCE)) SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE); props->Autowah.Resonance = val; break; case AL_AUTOWAH_PEAK_GAIN: if(!(val >= AL_AUTOWAH_MIN_PEAK_GAIN && val <= AL_AUTOWAH_MAX_PEAK_GAIN)) SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE); props->Autowah.PeakGain = val; break; default: SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); } } void ALautowah_setParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals) { ALautowah_setParamf(effect, context, param, vals[0]); } void ALautowah_getParami(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum UNUSED(param), ALint *UNUSED(val)) { SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); } void ALautowah_getParamiv(const ALeffect *effect, ALCcontext *context, ALenum param, ALint *vals) { ALautowah_getParami(effect, context, param, vals); } void ALautowah_getParamf(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val) { const ALeffectProps *props = &effect->Props; switch(param) { case AL_AUTOWAH_ATTACK_TIME: *val = props->Autowah.AttackTime; break; case AL_AUTOWAH_RELEASE_TIME: *val = props->Autowah.ReleaseTime; break; case AL_AUTOWAH_RESONANCE: *val = props->Autowah.Resonance; break; case AL_AUTOWAH_PEAK_GAIN: *val = props->Autowah.PeakGain; break; default: SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); } } void ALautowah_getParamfv(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals) { ALautowah_getParamf(effect, context, param, vals); } DEFINE_ALEFFECT_VTABLE(ALautowah);