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https://github.com/love2d/megasource.git
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Update OpenAL Soft to 1.18.2
This commit is contained in:
Alex Szpakowski
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#include "config.h"
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#include <math.h>
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#include "alu.h"
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#include "almalloc.h"
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#define RMS_WINDOW_SIZE (1<<7)
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#define RMS_WINDOW_MASK (RMS_WINDOW_SIZE-1)
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#define RMS_VALUE_MAX (1<<24)
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#define LOOKAHEAD_SIZE (1<<13)
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#define LOOKAHEAD_MASK (LOOKAHEAD_SIZE-1)
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static_assert(RMS_VALUE_MAX < (UINT_MAX / RMS_WINDOW_SIZE), "RMS_VALUE_MAX is too big");
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typedef struct Compressor {
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ALfloat PreGain;
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ALfloat PostGain;
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ALboolean SummedLink;
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ALfloat AttackMin;
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ALfloat AttackMax;
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ALfloat ReleaseMin;
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ALfloat ReleaseMax;
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ALfloat Ratio;
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ALfloat Threshold;
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ALfloat Knee;
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ALuint SampleRate;
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ALuint RmsSum;
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ALuint *RmsWindow;
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ALsizei RmsIndex;
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ALfloat Envelope[BUFFERSIZE];
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ALfloat EnvLast;
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} Compressor;
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/* Multichannel compression is linked via one of two modes:
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*
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* Summed - Absolute sum of all channels.
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* Maxed - Absolute maximum of any channel.
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*/
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static void SumChannels(Compressor *Comp, const ALsizei NumChans, const ALsizei SamplesToDo,
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ALfloat (*restrict OutBuffer)[BUFFERSIZE])
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{
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ALsizei c, i;
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for(i = 0;i < SamplesToDo;i++)
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Comp->Envelope[i] = 0.0f;
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for(c = 0;c < NumChans;c++)
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{
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for(i = 0;i < SamplesToDo;i++)
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Comp->Envelope[i] += OutBuffer[c][i];
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}
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for(i = 0;i < SamplesToDo;i++)
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Comp->Envelope[i] = fabsf(Comp->Envelope[i]);
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}
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static void MaxChannels(Compressor *Comp, const ALsizei NumChans, const ALsizei SamplesToDo,
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ALfloat (*restrict OutBuffer)[BUFFERSIZE])
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{
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ALsizei c, i;
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for(i = 0;i < SamplesToDo;i++)
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Comp->Envelope[i] = 0.0f;
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for(c = 0;c < NumChans;c++)
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{
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for(i = 0;i < SamplesToDo;i++)
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Comp->Envelope[i] = maxf(Comp->Envelope[i], fabsf(OutBuffer[c][i]));
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}
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}
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/* Envelope detection/sensing can be done via:
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*
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* RMS - Rectangular windowed root mean square of linking stage.
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* Peak - Implicit output from linking stage.
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*/
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static void RmsDetection(Compressor *Comp, const ALsizei SamplesToDo)
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{
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ALuint sum = Comp->RmsSum;
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ALuint *window = Comp->RmsWindow;
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ALsizei index = Comp->RmsIndex;
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ALsizei i;
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for(i = 0;i < SamplesToDo;i++)
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{
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ALfloat sig = Comp->Envelope[i];
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sum -= window[index];
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window[index] = fastf2i(minf(sig * sig * 65536.0f, RMS_VALUE_MAX));
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sum += window[index];
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index = (index + 1) & RMS_WINDOW_MASK;
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Comp->Envelope[i] = sqrtf(sum / 65536.0f / RMS_WINDOW_SIZE);
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}
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Comp->RmsSum = sum;
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Comp->RmsIndex = index;
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}
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/* This isn't a very sophisticated envelope follower, but it gets the job
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* done. First, it operates at logarithmic scales to keep transitions
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* appropriate for human hearing. Second, it can apply adaptive (automated)
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* attack/release adjustments based on the signal.
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*/
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static void FollowEnvelope(Compressor *Comp, const ALsizei SamplesToDo)
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{
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ALfloat attackMin = Comp->AttackMin;
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ALfloat attackMax = Comp->AttackMax;
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ALfloat releaseMin = Comp->ReleaseMin;
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ALfloat releaseMax = Comp->ReleaseMax;
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ALfloat last = Comp->EnvLast;
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ALsizei i;
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for(i = 0;i < SamplesToDo;i++)
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{
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ALfloat env = maxf(-6.0f, log10f(Comp->Envelope[i]));
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ALfloat slope = minf(1.0f, fabsf(env - last) / 4.5f);
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if(env > last)
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last = minf(env, last + lerp(attackMin, attackMax, 1.0f - (slope * slope)));
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else
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last = maxf(env, last + lerp(releaseMin, releaseMax, 1.0f - (slope * slope)));
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Comp->Envelope[i] = last;
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}
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Comp->EnvLast = last;
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}
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/* The envelope is converted to control gain with an optional soft knee. */
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static void EnvelopeGain(Compressor *Comp, const ALsizei SamplesToDo, const ALfloat Slope)
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{
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const ALfloat threshold = Comp->Threshold;
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const ALfloat knee = Comp->Knee;
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ALsizei i;
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if(!(knee > 0.0f))
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{
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for(i = 0;i < SamplesToDo;i++)
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{
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ALfloat gain = Slope * (threshold - Comp->Envelope[i]);
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Comp->Envelope[i] = powf(10.0f, minf(0.0f, gain));
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}
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}
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else
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{
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const ALfloat lower = threshold - (0.5f * knee);
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const ALfloat upper = threshold + (0.5f * knee);
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const ALfloat m = 0.5f * Slope / knee;
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for(i = 0;i < SamplesToDo;i++)
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{
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ALfloat env = Comp->Envelope[i];
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ALfloat gain;
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if(env > lower && env < upper)
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gain = m * (env - lower) * (lower - env);
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else
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gain = Slope * (threshold - env);
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Comp->Envelope[i] = powf(10.0f, minf(0.0f, gain));
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}
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}
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}
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Compressor *CompressorInit(const ALfloat PreGainDb, const ALfloat PostGainDb,
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const ALboolean SummedLink, const ALboolean RmsSensing,
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const ALfloat AttackTimeMin, const ALfloat AttackTimeMax,
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const ALfloat ReleaseTimeMin, const ALfloat ReleaseTimeMax,
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const ALfloat Ratio, const ALfloat ThresholdDb,
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const ALfloat KneeDb, const ALuint SampleRate)
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{
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Compressor *Comp;
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size_t size;
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ALsizei i;
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size = sizeof(*Comp);
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if(RmsSensing)
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size += sizeof(Comp->RmsWindow[0]) * RMS_WINDOW_SIZE;
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Comp = al_calloc(16, size);
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Comp->PreGain = powf(10.0f, PreGainDb / 20.0f);
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Comp->PostGain = powf(10.0f, PostGainDb / 20.0f);
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Comp->SummedLink = SummedLink;
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Comp->AttackMin = 1.0f / maxf(0.000001f, AttackTimeMin * SampleRate * logf(10.0f));
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Comp->AttackMax = 1.0f / maxf(0.000001f, AttackTimeMax * SampleRate * logf(10.0f));
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Comp->ReleaseMin = -1.0f / maxf(0.000001f, ReleaseTimeMin * SampleRate * logf(10.0f));
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Comp->ReleaseMax = -1.0f / maxf(0.000001f, ReleaseTimeMax * SampleRate * logf(10.0f));
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Comp->Ratio = Ratio;
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Comp->Threshold = ThresholdDb / 20.0f;
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Comp->Knee = maxf(0.0f, KneeDb / 20.0f);
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Comp->SampleRate = SampleRate;
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Comp->RmsSum = 0;
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if(RmsSensing)
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Comp->RmsWindow = (ALuint*)(Comp+1);
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else
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Comp->RmsWindow = NULL;
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Comp->RmsIndex = 0;
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for(i = 0;i < BUFFERSIZE;i++)
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Comp->Envelope[i] = 0.0f;
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Comp->EnvLast = -6.0f;
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return Comp;
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}
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ALuint GetCompressorSampleRate(const Compressor *Comp)
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{
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return Comp->SampleRate;
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}
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void ApplyCompression(Compressor *Comp, const ALsizei NumChans, const ALsizei SamplesToDo,
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ALfloat (*restrict OutBuffer)[BUFFERSIZE])
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{
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ALsizei c, i;
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if(Comp->PreGain != 1.0f)
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{
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for(c = 0;c < NumChans;c++)
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{
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for(i = 0;i < SamplesToDo;i++)
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OutBuffer[c][i] *= Comp->PreGain;
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}
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}
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if(Comp->SummedLink)
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SumChannels(Comp, NumChans, SamplesToDo, OutBuffer);
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else
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MaxChannels(Comp, NumChans, SamplesToDo, OutBuffer);
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if(Comp->RmsWindow)
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RmsDetection(Comp, SamplesToDo);
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FollowEnvelope(Comp, SamplesToDo);
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if(Comp->Ratio > 0.0f)
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EnvelopeGain(Comp, SamplesToDo, 1.0f - (1.0f / Comp->Ratio));
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else
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EnvelopeGain(Comp, SamplesToDo, 1.0f);
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if(Comp->PostGain != 1.0f)
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{
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for(i = 0;i < SamplesToDo;i++)
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Comp->Envelope[i] *= Comp->PostGain;
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}
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for(c = 0;c < NumChans;c++)
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{
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for(i = 0;i < SamplesToDo;i++)
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OutBuffer[c][i] *= Comp->Envelope[i];
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}
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}
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