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275 lines
10 KiB
275 lines
10 KiB
/**
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* OpenAL cross platform audio library
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* Copyright (C) 2013 by Mike Gorchak
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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* Or go to http://www.gnu.org/copyleft/lgpl.html
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*/
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#include "config.h"
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#include <cmath>
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#include <cstdlib>
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#include <cmath>
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#include "alMain.h"
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#include "alcontext.h"
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#include "alAuxEffectSlot.h"
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#include "alError.h"
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#include "alu.h"
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#include "filters/biquad.h"
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namespace {
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struct DistortionState final : public EffectState {
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/* Effect gains for each channel */
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ALfloat mGain[MAX_OUTPUT_CHANNELS]{};
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/* Effect parameters */
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BiquadFilter mLowpass;
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BiquadFilter mBandpass;
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ALfloat mAttenuation{};
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ALfloat mEdgeCoeff{};
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ALfloat mBuffer[2][BUFFERSIZE]{};
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ALboolean deviceUpdate(const ALCdevice *device) override;
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void update(const ALCcontext *context, const ALeffectslot *slot, const EffectProps *props, const EffectTarget target) override;
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void process(ALsizei samplesToDo, const ALfloat (*RESTRICT samplesIn)[BUFFERSIZE], const ALsizei numInput, ALfloat (*RESTRICT samplesOut)[BUFFERSIZE], const ALsizei numOutput) override;
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DEF_NEWDEL(DistortionState)
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};
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ALboolean DistortionState::deviceUpdate(const ALCdevice *UNUSED(device))
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{
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mLowpass.clear();
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mBandpass.clear();
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return AL_TRUE;
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}
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void DistortionState::update(const ALCcontext *context, const ALeffectslot *slot, const EffectProps *props, const EffectTarget target)
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{
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const ALCdevice *device{context->Device};
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/* Store waveshaper edge settings. */
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const ALfloat edge{
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minf(std::sin(al::MathDefs<float>::Pi()*0.5f * props->Distortion.Edge), 0.99f)};
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mEdgeCoeff = 2.0f * edge / (1.0f-edge);
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ALfloat cutoff{props->Distortion.LowpassCutoff};
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/* Bandwidth value is constant in octaves. */
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ALfloat bandwidth{(cutoff / 2.0f) / (cutoff * 0.67f)};
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/* Multiply sampling frequency by the amount of oversampling done during
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* processing.
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*/
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auto frequency = static_cast<ALfloat>(device->Frequency);
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mLowpass.setParams(BiquadType::LowPass, 1.0f, cutoff / (frequency*4.0f),
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calc_rcpQ_from_bandwidth(cutoff / (frequency*4.0f), bandwidth)
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);
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cutoff = props->Distortion.EQCenter;
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/* Convert bandwidth in Hz to octaves. */
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bandwidth = props->Distortion.EQBandwidth / (cutoff * 0.67f);
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mBandpass.setParams(BiquadType::BandPass, 1.0f, cutoff / (frequency*4.0f),
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calc_rcpQ_from_bandwidth(cutoff / (frequency*4.0f), bandwidth)
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);
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ALfloat coeffs[MAX_AMBI_CHANNELS];
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CalcDirectionCoeffs({0.0f, 0.0f, -1.0f}, 0.0f, coeffs);
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mOutBuffer = target.Main->Buffer;
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mOutChannels = target.Main->NumChannels;
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ComputePanGains(target.Main, coeffs, slot->Params.Gain*props->Distortion.Gain, mGain);
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}
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void DistortionState::process(ALsizei samplesToDo, const ALfloat (*RESTRICT samplesIn)[BUFFERSIZE], const ALsizei /*numInput*/, ALfloat (*RESTRICT samplesOut)[BUFFERSIZE], const ALsizei numOutput)
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{
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ALfloat (*RESTRICT buffer)[BUFFERSIZE] = mBuffer;
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const ALfloat fc = mEdgeCoeff;
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ALsizei base;
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ALsizei i, k;
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for(base = 0;base < samplesToDo;)
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{
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/* Perform 4x oversampling to avoid aliasing. Oversampling greatly
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* improves distortion quality and allows to implement lowpass and
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* bandpass filters using high frequencies, at which classic IIR
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* filters became unstable.
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*/
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ALsizei todo{mini(BUFFERSIZE, (samplesToDo-base) * 4)};
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/* Fill oversample buffer using zero stuffing. Multiply the sample by
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* the amount of oversampling to maintain the signal's power.
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*/
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for(i = 0;i < todo;i++)
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buffer[0][i] = !(i&3) ? samplesIn[0][(i>>2)+base] * 4.0f : 0.0f;
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/* First step, do lowpass filtering of original signal. Additionally
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* perform buffer interpolation and lowpass cutoff for oversampling
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* (which is fortunately first step of distortion). So combine three
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* operations into the one.
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*/
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mLowpass.process(buffer[1], buffer[0], todo);
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/* Second step, do distortion using waveshaper function to emulate
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* signal processing during tube overdriving. Three steps of
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* waveshaping are intended to modify waveform without boost/clipping/
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* attenuation process.
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*/
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for(i = 0;i < todo;i++)
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{
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ALfloat smp = buffer[1][i];
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smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp));
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smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp)) * -1.0f;
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smp = (1.0f + fc) * smp/(1.0f + fc*fabsf(smp));
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buffer[0][i] = smp;
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}
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/* Third step, do bandpass filtering of distorted signal. */
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mBandpass.process(buffer[1], buffer[0], todo);
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todo >>= 2;
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for(k = 0;k < numOutput;k++)
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{
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/* Fourth step, final, do attenuation and perform decimation,
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* storing only one sample out of four.
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*/
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const ALfloat gain{mGain[k]};
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if(!(std::fabs(gain) > GAIN_SILENCE_THRESHOLD))
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continue;
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for(i = 0;i < todo;i++)
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samplesOut[k][base+i] += gain * buffer[1][i*4];
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}
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base += todo;
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}
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}
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void Distortion_setParami(EffectProps*, ALCcontext *context, ALenum param, ALint)
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{ alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer property 0x%04x", param); }
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void Distortion_setParamiv(EffectProps*, ALCcontext *context, ALenum param, const ALint*)
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{ alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer-vector property 0x%04x", param); }
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void Distortion_setParamf(EffectProps *props, ALCcontext *context, ALenum param, ALfloat val)
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{
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switch(param)
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{
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case AL_DISTORTION_EDGE:
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if(!(val >= AL_DISTORTION_MIN_EDGE && val <= AL_DISTORTION_MAX_EDGE))
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SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion edge out of range");
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props->Distortion.Edge = val;
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break;
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case AL_DISTORTION_GAIN:
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if(!(val >= AL_DISTORTION_MIN_GAIN && val <= AL_DISTORTION_MAX_GAIN))
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SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion gain out of range");
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props->Distortion.Gain = val;
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break;
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case AL_DISTORTION_LOWPASS_CUTOFF:
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if(!(val >= AL_DISTORTION_MIN_LOWPASS_CUTOFF && val <= AL_DISTORTION_MAX_LOWPASS_CUTOFF))
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SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion low-pass cutoff out of range");
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props->Distortion.LowpassCutoff = val;
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break;
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case AL_DISTORTION_EQCENTER:
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if(!(val >= AL_DISTORTION_MIN_EQCENTER && val <= AL_DISTORTION_MAX_EQCENTER))
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SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion EQ center out of range");
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props->Distortion.EQCenter = val;
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break;
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case AL_DISTORTION_EQBANDWIDTH:
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if(!(val >= AL_DISTORTION_MIN_EQBANDWIDTH && val <= AL_DISTORTION_MAX_EQBANDWIDTH))
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SETERR_RETURN(context, AL_INVALID_VALUE,, "Distortion EQ bandwidth out of range");
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props->Distortion.EQBandwidth = val;
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break;
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default:
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alSetError(context, AL_INVALID_ENUM, "Invalid distortion float property 0x%04x",
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param);
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}
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}
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void Distortion_setParamfv(EffectProps *props, ALCcontext *context, ALenum param, const ALfloat *vals)
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{ Distortion_setParamf(props, context, param, vals[0]); }
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void Distortion_getParami(const EffectProps*, ALCcontext *context, ALenum param, ALint*)
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{ alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer property 0x%04x", param); }
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void Distortion_getParamiv(const EffectProps*, ALCcontext *context, ALenum param, ALint*)
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{ alSetError(context, AL_INVALID_ENUM, "Invalid distortion integer-vector property 0x%04x", param); }
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void Distortion_getParamf(const EffectProps *props, ALCcontext *context, ALenum param, ALfloat *val)
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{
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switch(param)
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{
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case AL_DISTORTION_EDGE:
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*val = props->Distortion.Edge;
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break;
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case AL_DISTORTION_GAIN:
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*val = props->Distortion.Gain;
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break;
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case AL_DISTORTION_LOWPASS_CUTOFF:
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*val = props->Distortion.LowpassCutoff;
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break;
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case AL_DISTORTION_EQCENTER:
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*val = props->Distortion.EQCenter;
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break;
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case AL_DISTORTION_EQBANDWIDTH:
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*val = props->Distortion.EQBandwidth;
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break;
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default:
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alSetError(context, AL_INVALID_ENUM, "Invalid distortion float property 0x%04x",
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param);
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}
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}
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void Distortion_getParamfv(const EffectProps *props, ALCcontext *context, ALenum param, ALfloat *vals)
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{ Distortion_getParamf(props, context, param, vals); }
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DEFINE_ALEFFECT_VTABLE(Distortion);
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struct DistortionStateFactory final : public EffectStateFactory {
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EffectState *create() override { return new DistortionState{}; }
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EffectProps getDefaultProps() const noexcept override;
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const EffectVtable *getEffectVtable() const noexcept override { return &Distortion_vtable; }
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};
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EffectProps DistortionStateFactory::getDefaultProps() const noexcept
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{
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EffectProps props{};
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props.Distortion.Edge = AL_DISTORTION_DEFAULT_EDGE;
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props.Distortion.Gain = AL_DISTORTION_DEFAULT_GAIN;
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props.Distortion.LowpassCutoff = AL_DISTORTION_DEFAULT_LOWPASS_CUTOFF;
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props.Distortion.EQCenter = AL_DISTORTION_DEFAULT_EQCENTER;
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props.Distortion.EQBandwidth = AL_DISTORTION_DEFAULT_EQBANDWIDTH;
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return props;
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}
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} // namespace
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EffectStateFactory *DistortionStateFactory_getFactory()
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{
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static DistortionStateFactory DistortionFactory{};
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return &DistortionFactory;
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}
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