/**
* Ambisonic reverb engine for the OpenAL cross platform audio library
* Copyright (C) 2008-2017 by Chris Robinson and Christopher Fitzgerald.
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
* Or go to http://www.gnu.org/copyleft/lgpl.html
*/
#include "config.h"
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <array>
#include <numeric>
#include <algorithm>
#include <functional>
#include "alcmain.h"
#include "alcontext.h"
#include "alnumeric.h"
#include "bformatdec.h"
#include "core/filters/biquad.h"
#include "effectslot.h"
#include "vector.h"
#include "vecmat.h"
/* This is a user config option for modifying the overall output of the reverb
* effect.
*/
float ReverbBoost = 1.0f;
namespace {
#define MOD_FRACBITS 24
#define MOD_FRACONE (1<<MOD_FRACBITS)
#define MOD_FRACMASK (MOD_FRACONE-1)
using namespace std::placeholders;
/* Max samples per process iteration. Used to limit the size needed for
* temporary buffers. Must be a multiple of 4 for SIMD alignment.
*/
constexpr size_t MAX_UPDATE_SAMPLES{256};
/* The number of spatialized lines or channels to process. Four channels allows
* for a 3D A-Format response. NOTE: This can't be changed without taking care
* of the conversion matrices, and a few places where the length arrays are
* assumed to have 4 elements.
*/
constexpr size_t NUM_LINES{4u};
/* This coefficient is used to define the maximum frequency range controlled by
* the modulation depth. The current value of 0.05 will allow it to swing from
* 0.95x to 1.05x. This value must be below 1. At 1 it will cause the sampler
* to stall on the downswing, and above 1 it will cause it to sample backwards.
* The value 0.05 seems be nearest to Creative hardware behavior.
*/
constexpr float MODULATION_DEPTH_COEFF{0.05f};
/* The B-Format to A-Format conversion matrix. The arrangement of rows is
* deliberately chosen to align the resulting lines to their spatial opposites
* (0:above front left <-> 3:above back right, 1:below front right <-> 2:below
* back left). It's not quite opposite, since the A-Format results in a
* tetrahedron, but it's close enough. Should the model be extended to 8-lines
* in the future, true opposites can be used.
*/
alignas(16) constexpr float B2A[NUM_LINES][NUM_LINES]{
{ 0.288675134595f, 0.288675134595f, 0.288675134595f, 0.288675134595f },
{ 0.288675134595f, -0.288675134595f, -0.288675134595f, 0.288675134595f },
{ 0.288675134595f, 0.288675134595f, -0.288675134595f, -0.288675134595f },
{ 0.288675134595f, -0.288675134595f, 0.288675134595f, -0.288675134595f }
};
/* Converts A-Format to B-Format. */
alignas(16) constexpr float A2B[NUM_LINES][NUM_LINES]{
{ 0.866025403785f, 0.866025403785f, 0.866025403785f, 0.866025403785f },
{ 0.866025403785f, -0.866025403785f, 0.866025403785f, -0.866025403785f },
{ 0.866025403785f, -0.866025403785f, -0.866025403785f, 0.866025403785f },
{ 0.866025403785f, 0.866025403785f, -0.866025403785f, -0.866025403785f }
};
/* The all-pass and delay lines have a variable length dependent on the
* effect's density parameter, which helps alter the perceived environment
* size. The size-to-density conversion is a cubed scale:
*
* density = min(1.0, pow(size, 3.0) / DENSITY_SCALE);
*
* The line lengths scale linearly with room size, so the inverse density
* conversion is needed, taking the cube root of the re-scaled density to
* calculate the line length multiplier:
*
* length_mult = max(5.0, cbrt(density*DENSITY_SCALE));
*
* The density scale below will result in a max line multiplier of 50, for an
* effective size range of 5m to 50m.
*/
constexpr float DENSITY_SCALE{125000.0f};
/* All delay line lengths are specified in seconds.
*
* To approximate early reflections, we break them up into primary (those
* arriving from the same direction as the source) and secondary (those
* arriving from the opposite direction).
*
* The early taps decorrelate the 4-channel signal to approximate an average
* room response for the primary reflections after the initial early delay.
*
* Given an average room dimension (d_a) and the speed of sound (c) we can
* calculate the average reflection delay (r_a) regardless of listener and
* source positions as:
*
* r_a = d_a / c
* c = 343.3
*
* This can extended to finding the average difference (r_d) between the
* maximum (r_1) and minimum (r_0) reflection delays:
*
* r_0 = 2 / 3 r_a
* = r_a - r_d / 2
* = r_d
* r_1 = 4 / 3 r_a
* = r_a + r_d / 2
* = 2 r_d
* r_d = 2 / 3 r_a
* = r_1 - r_0
*
* As can be determined by integrating the 1D model with a source (s) and
* listener (l) positioned across the dimension of length (d_a):
*
* r_d = int_(l=0)^d_a (int_(s=0)^d_a |2 d_a - 2 (l + s)| ds) dl / c
*
* The initial taps (T_(i=0)^N) are then specified by taking a power series
* that ranges between r_0 and half of r_1 less r_0:
*
* R_i = 2^(i / (2 N - 1)) r_d
* = r_0 + (2^(i / (2 N - 1)) - 1) r_d
* = r_0 + T_i
* T_i = R_i - r_0
* = (2^(i / (2 N - 1)) - 1) r_d
*
* Assuming an average of 1m, we get the following taps:
*/
constexpr std::array<float,NUM_LINES> EARLY_TAP_LENGTHS{{
0.0000000e+0f, 2.0213520e-4f, 4.2531060e-4f, 6.7171600e-4f
}};
/* The early all-pass filter lengths are based on the early tap lengths:
*
* A_i = R_i / a
*
* Where a is the approximate maximum all-pass cycle limit (20).
*/
constexpr std::array<float,NUM_LINES> EARLY_ALLPASS_LENGTHS{{
9.7096800e-5f, 1.0720356e-4f, 1.1836234e-4f, 1.3068260e-4f
}};
/* The early delay lines are used to transform the primary reflections into
* the secondary reflections. The A-format is arranged in such a way that
* the channels/lines are spatially opposite:
*
* C_i is opposite C_(N-i-1)
*
* The delays of the two opposing reflections (R_i and O_i) from a source
* anywhere along a particular dimension always sum to twice its full delay:
*
* 2 r_a = R_i + O_i
*
* With that in mind we can determine the delay between the two reflections
* and thus specify our early line lengths (L_(i=0)^N) using:
*
* O_i = 2 r_a - R_(N-i-1)
* L_i = O_i - R_(N-i-1)
* = 2 (r_a - R_(N-i-1))
* = 2 (r_a - T_(N-i-1) - r_0)
* = 2 r_a (1 - (2 / 3) 2^((N - i - 1) / (2 N - 1)))
*
* Using an average dimension of 1m, we get:
*/
constexpr std::array<float,NUM_LINES> EARLY_LINE_LENGTHS{{
5.9850400e-4f, 1.0913150e-3f, 1.5376658e-3f, 1.9419362e-3f
}};
/* The late all-pass filter lengths are based on the late line lengths:
*
* A_i = (5 / 3) L_i / r_1
*/
constexpr std::array<float,NUM_LINES> LATE_ALLPASS_LENGTHS{{
1.6182800e-4f, 2.0389060e-4f, 2.8159360e-4f, 3.2365600e-4f
}};
/* The late lines are used to approximate the decaying cycle of recursive
* late reflections.
*
* Splitting the lines in half, we start with the shortest reflection paths
* (L_(i=0)^(N/2)):
*
* L_i = 2^(i / (N - 1)) r_d
*
* Then for the opposite (longest) reflection paths (L_(i=N/2)^N):
*
* L_i = 2 r_a - L_(i-N/2)
* = 2 r_a - 2^((i - N / 2) / (N - 1)) r_d
*
* For our 1m average room, we get:
*/
constexpr std::array<float,NUM_LINES> LATE_LINE_LENGTHS{{
1.9419362e-3f, 2.4466860e-3f, 3.3791220e-3f, 3.8838720e-3f
}};
using ReverbUpdateLine = std::array<float,MAX_UPDATE_SAMPLES>;
struct DelayLineI {
/* The delay lines use interleaved samples, with the lengths being powers
* of 2 to allow the use of bit-masking instead of a modulus for wrapping.
*/
size_t Mask{0u};
union {
uintptr_t LineOffset{0u};
std::array<float,NUM_LINES> *Line;
};
/* Given the allocated sample buffer, this function updates each delay line
* offset.
*/
void realizeLineOffset(std::array<float,NUM_LINES> *sampleBuffer) noexcept
{ Line = sampleBuffer + LineOffset; }
/* Calculate the length of a delay line and store its mask and offset. */
ALuint calcLineLength(const float length, const uintptr_t offset, const float frequency,
const ALuint extra)
{
/* All line lengths are powers of 2, calculated from their lengths in
* seconds, rounded up.
*/
ALuint samples{float2uint(std::ceil(length*frequency))};
samples = NextPowerOf2(samples + extra);
/* All lines share a single sample buffer. */
Mask = samples - 1;
LineOffset = offset;
/* Return the sample count for accumulation. */
return samples;
}
void write(size_t offset, const size_t c, const float *RESTRICT in, const size_t count) const noexcept
{
ASSUME(count > 0);
for(size_t i{0u};i < count;)
{
offset &= Mask;
size_t td{minz(Mask+1 - offset, count - i)};
do {
Line[offset++][c] = in[i++];
} while(--td);
}
}
};
struct VecAllpass {
DelayLineI Delay;
float Coeff{0.0f};
size_t Offset[NUM_LINES][2]{};
void processFaded(const al::span<ReverbUpdateLine,NUM_LINES> samples, size_t offset,
const float xCoeff, const float yCoeff, float fadeCount, const float fadeStep,
const size_t todo);
void processUnfaded(const al::span<ReverbUpdateLine,NUM_LINES> samples, size_t offset,
const float xCoeff, const float yCoeff, const size_t todo);
};
struct T60Filter {
/* Two filters are used to adjust the signal. One to control the low
* frequencies, and one to control the high frequencies.
*/
float MidGain[2]{0.0f, 0.0f};
BiquadFilter HFFilter, LFFilter;
void calcCoeffs(const float length, const float lfDecayTime, const float mfDecayTime,
const float hfDecayTime, const float lf0norm, const float hf0norm);
/* Applies the two T60 damping filter sections. */
void process(const al::span<float> samples)
{ DualBiquad{HFFilter, LFFilter}.process(samples, samples.data()); }
};
struct EarlyReflections {
/* A Gerzon vector all-pass filter is used to simulate initial diffusion.
* The spread from this filter also helps smooth out the reverb tail.
*/
VecAllpass VecAp;
/* An echo line is used to complete the second half of the early
* reflections.
*/
DelayLineI Delay;
size_t Offset[NUM_LINES][2]{};
float Coeff[NUM_LINES][2]{};
/* The gain for each output channel based on 3D panning. */
float CurrentGain[NUM_LINES][MAX_OUTPUT_CHANNELS]{};
float PanGain[NUM_LINES][MAX_OUTPUT_CHANNELS]{};
void updateLines(const float density_mult, const float diffusion, const float decayTime,
const float frequency);
};
struct Modulation {
/* The vibrato time is tracked with an index over a (MOD_FRACONE)
* normalized range.
*/
ALuint Index, Step;
/* The depth of frequency change, in samples. */
float Depth[2];
float ModDelays[MAX_UPDATE_SAMPLES];
void updateModulator(float modTime, float modDepth, float frequency);
void calcDelays(size_t todo);
void calcFadedDelays(size_t todo, float fadeCount, float fadeStep);
};
struct LateReverb {
/* A recursive delay line is used fill in the reverb tail. */
DelayLineI Delay;
size_t Offset[NUM_LINES][2]{};
/* Attenuation to compensate for the modal density and decay rate of the
* late lines.
*/
float DensityGain[2]{0.0f, 0.0f};
/* T60 decay filters are used to simulate absorption. */
T60Filter T60[NUM_LINES];
Modulation Mod;
/* A Gerzon vector all-pass filter is used to simulate diffusion. */
VecAllpass VecAp;
/* The gain for each output channel based on 3D panning. */
float CurrentGain[NUM_LINES][MAX_OUTPUT_CHANNELS]{};
float PanGain[NUM_LINES][MAX_OUTPUT_CHANNELS]{};
void updateLines(const float density_mult, const float diffusion, const float lfDecayTime,
const float mfDecayTime, const float hfDecayTime, const float lf0norm,
const float hf0norm, const float frequency);
};
struct ReverbState final : public EffectState {
/* All delay lines are allocated as a single buffer to reduce memory
* fragmentation and management code.
*/
al::vector<std::array<float,NUM_LINES>,16> mSampleBuffer;
struct {
/* Calculated parameters which indicate if cross-fading is needed after
* an update.
*/
float Density{AL_EAXREVERB_DEFAULT_DENSITY};
float Diffusion{AL_EAXREVERB_DEFAULT_DIFFUSION};
float DecayTime{AL_EAXREVERB_DEFAULT_DECAY_TIME};
float HFDecayTime{AL_EAXREVERB_DEFAULT_DECAY_HFRATIO * AL_EAXREVERB_DEFAULT_DECAY_TIME};
float LFDecayTime{AL_EAXREVERB_DEFAULT_DECAY_LFRATIO * AL_EAXREVERB_DEFAULT_DECAY_TIME};
float ModulationTime{AL_EAXREVERB_DEFAULT_MODULATION_TIME};
float ModulationDepth{AL_EAXREVERB_DEFAULT_MODULATION_DEPTH};
float HFReference{AL_EAXREVERB_DEFAULT_HFREFERENCE};
float LFReference{AL_EAXREVERB_DEFAULT_LFREFERENCE};
} mParams;
/* Master effect filters */
struct {
BiquadFilter Lp;
BiquadFilter Hp;
} mFilter[NUM_LINES];
/* Core delay line (early reflections and late reverb tap from this). */
DelayLineI mDelay;
/* Tap points for early reflection delay. */
size_t mEarlyDelayTap[NUM_LINES][2]{};
float mEarlyDelayCoeff[NUM_LINES][2]{};
/* Tap points for late reverb feed and delay. */
size_t mLateFeedTap{};
size_t mLateDelayTap[NUM_LINES][2]{};
/* Coefficients for the all-pass and line scattering matrices. */
float mMixX{0.0f};
float mMixY{0.0f};
EarlyReflections mEarly;
LateReverb mLate;
bool mDoFading{};
/* Maximum number of samples to process at once. */
size_t mMaxUpdate[2]{MAX_UPDATE_SAMPLES, MAX_UPDATE_SAMPLES};
/* The current write offset for all delay lines. */
size_t mOffset{};
/* Temporary storage used when processing. */
union {
alignas(16) FloatBufferLine mTempLine{};
alignas(16) std::array<ReverbUpdateLine,NUM_LINES> mTempSamples;
};
alignas(16) std::array<ReverbUpdateLine,NUM_LINES> mEarlySamples{};
alignas(16) std::array<ReverbUpdateLine,NUM_LINES> mLateSamples{};
using MixOutT = void (ReverbState::*)(const al::span<FloatBufferLine> samplesOut,
const size_t counter, const size_t offset, const size_t todo);
MixOutT mMixOut{&ReverbState::MixOutPlain};
std::array<float,MaxAmbiOrder+1> mOrderScales{};
std::array<std::array<BandSplitter,NUM_LINES>,2> mAmbiSplitter;
static void DoMixRow(const al::span<float> OutBuffer, const al::span<const float> Gains,
const float *InSamples, const size_t InStride)
{
std::fill(OutBuffer.begin(), OutBuffer.end(), 0.0f);
for(const float gain : Gains)
{
const float *RESTRICT input{al::assume_aligned<16>(InSamples)};
InSamples += InStride;
if(!(std::fabs(gain) > GainSilenceThreshold))
continue;
for(float &sample : OutBuffer)
{
sample += *input * gain;
++input;
}
}
}
void MixOutPlain(const al::span<FloatBufferLine> samplesOut, const size_t counter,
const size_t offset, const size_t todo)
{
ASSUME(todo > 0);
/* Convert back to B-Format, and mix the results to output. */
const al::span<float> tmpspan{al::assume_aligned<16>(mTempLine.data()), todo};
for(size_t c{0u};c < NUM_LINES;c++)
{
DoMixRow(tmpspan, A2B[c], mEarlySamples[0].data(), mEarlySamples[0].size());
MixSamples(tmpspan, samplesOut, mEarly.CurrentGain[c], mEarly.PanGain[c], counter,
offset);
}
for(size_t c{0u};c < NUM_LINES;c++)
{
DoMixRow(tmpspan, A2B[c], mLateSamples[0].data(), mLateSamples[0].size());
MixSamples(tmpspan, samplesOut, mLate.CurrentGain[c], mLate.PanGain[c], counter,
offset);
}
}
void MixOutAmbiUp(const al::span<FloatBufferLine> samplesOut, const size_t counter,
const size_t offset, const size_t todo)
{
ASSUME(todo > 0);
const al::span<float> tmpspan{al::assume_aligned<16>(mTempLine.data()), todo};
for(size_t c{0u};c < NUM_LINES;c++)
{
DoMixRow(tmpspan, A2B[c], mEarlySamples[0].data(), mEarlySamples[0].size());
/* Apply scaling to the B-Format's HF response to "upsample" it to
* higher-order output.
*/
const float hfscale{(c==0) ? mOrderScales[0] : mOrderScales[1]};
mAmbiSplitter[0][c].processHfScale(tmpspan, hfscale);
MixSamples(tmpspan, samplesOut, mEarly.CurrentGain[c], mEarly.PanGain[c], counter,
offset);
}
for(size_t c{0u};c < NUM_LINES;c++)
{
DoMixRow(tmpspan, A2B[c], mLateSamples[0].data(), mLateSamples[0].size());
const float hfscale{(c==0) ? mOrderScales[0] : mOrderScales[1]};
mAmbiSplitter[1][c].processHfScale(tmpspan, hfscale);
MixSamples(tmpspan, samplesOut, mLate.CurrentGain[c], mLate.PanGain[c], counter,
offset);
}
}
void allocLines(const float frequency);
void updateDelayLine(const float earlyDelay, const float lateDelay, const float density_mult,
const float decayTime, const float frequency);
void update3DPanning(const float *ReflectionsPan, const float *LateReverbPan,
const float earlyGain, const float lateGain, const EffectTarget &target);
void earlyUnfaded(const size_t offset, const size_t todo);
void earlyFaded(const size_t offset, const size_t todo, const float fade,
const float fadeStep);
void lateUnfaded(const size_t offset, const size_t todo);
void lateFaded(const size_t offset, const size_t todo, const float fade,
const float fadeStep);
void deviceUpdate(const ALCdevice *device) override;
void update(const ALCcontext *context, const EffectSlot *slot, const EffectProps *props,
const EffectTarget target) override;
void process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn,
const al::span<FloatBufferLine> samplesOut) override;
DEF_NEWDEL(ReverbState)
};
/**************************************
* Device Update *
**************************************/
inline float CalcDelayLengthMult(float density)
{ return maxf(5.0f, std::cbrt(density*DENSITY_SCALE)); }
/* Calculates the delay line metrics and allocates the shared sample buffer
* for all lines given the sample rate (frequency).
*/
void ReverbState::allocLines(const float frequency)
{
/* All delay line lengths are calculated to accomodate the full range of
* lengths given their respective paramters.
*/
size_t totalSamples{0u};
/* Multiplier for the maximum density value, i.e. density=1, which is
* actually the least density...
*/
const float multiplier{CalcDelayLengthMult(AL_EAXREVERB_MAX_DENSITY)};
/* The main delay length includes the maximum early reflection delay, the
* largest early tap width, the maximum late reverb delay, and the
* largest late tap width. Finally, it must also be extended by the
* update size (BufferLineSize) for block processing.
*/
float length{AL_EAXREVERB_MAX_REFLECTIONS_DELAY + EARLY_TAP_LENGTHS.back()*multiplier +
AL_EAXREVERB_MAX_LATE_REVERB_DELAY +
(LATE_LINE_LENGTHS.back() - LATE_LINE_LENGTHS.front())/float{NUM_LINES}*multiplier};
totalSamples += mDelay.calcLineLength(length, totalSamples, frequency, BufferLineSize);
/* The early vector all-pass line. */
length = EARLY_ALLPASS_LENGTHS.back() * multiplier;
totalSamples += mEarly.VecAp.Delay.calcLineLength(length, totalSamples, frequency, 0);
/* The early reflection line. */
length = EARLY_LINE_LENGTHS.back() * multiplier;
totalSamples += mEarly.Delay.calcLineLength(length, totalSamples, frequency, 0);
/* The late vector all-pass line. */
length = LATE_ALLPASS_LENGTHS.back() * multiplier;
totalSamples += mLate.VecAp.Delay.calcLineLength(length, totalSamples, frequency, 0);
/* The modulator's line length is calculated from the maximum modulation
* time and depth coefficient, and halfed for the low-to-high frequency
* swing.
*/
constexpr float max_mod_delay{AL_EAXREVERB_MAX_MODULATION_TIME*MODULATION_DEPTH_COEFF / 2.0f};
/* The late delay lines are calculated from the largest maximum density
* line length, and the maximum modulation delay. An additional sample is
* added to keep it stable when there is no modulation.
*/
length = LATE_LINE_LENGTHS.back()*multiplier + max_mod_delay;
totalSamples += mLate.Delay.calcLineLength(length, totalSamples, frequency, 1);
if(totalSamples != mSampleBuffer.size())
decltype(mSampleBuffer)(totalSamples).swap(mSampleBuffer);
/* Clear the sample buffer. */
std::fill(mSampleBuffer.begin(), mSampleBuffer.end(), decltype(mSampleBuffer)::value_type{});
/* Update all delays to reflect the new sample buffer. */
mDelay.realizeLineOffset(mSampleBuffer.data());
mEarly.VecAp.Delay.realizeLineOffset(mSampleBuffer.data());
mEarly.Delay.realizeLineOffset(mSampleBuffer.data());
mLate.VecAp.Delay.realizeLineOffset(mSampleBuffer.data());
mLate.Delay.realizeLineOffset(mSampleBuffer.data());
}
void ReverbState::deviceUpdate(const ALCdevice *device)
{
const auto frequency = static_cast<float>(device->Frequency);
/* Allocate the delay lines. */
allocLines(frequency);
const float multiplier{CalcDelayLengthMult(AL_EAXREVERB_MAX_DENSITY)};
/* The late feed taps are set a fixed position past the latest delay tap. */
mLateFeedTap = float2uint(
(AL_EAXREVERB_MAX_REFLECTIONS_DELAY + EARLY_TAP_LENGTHS.back()*multiplier) * frequency);
/* Clear filters and gain coefficients since the delay lines were all just
* cleared (if not reallocated).
*/
for(auto &filter : mFilter)
{
filter.Lp.clear();
filter.Hp.clear();
}
for(auto &coeff : mEarlyDelayCoeff)
std::fill(std::begin(coeff), std::end(coeff), 0.0f);
for(auto &coeff : mEarly.Coeff)
std::fill(std::begin(coeff), std::end(coeff), 0.0f);
mLate.DensityGain[0] = 0.0f;
mLate.DensityGain[1] = 0.0f;
for(auto &t60 : mLate.T60)
{
t60.MidGain[0] = 0.0f;
t60.MidGain[1] = 0.0f;
t60.HFFilter.clear();
t60.LFFilter.clear();
}
mLate.Mod.Index = 0;
mLate.Mod.Step = 1;
std::fill(std::begin(mLate.Mod.Depth), std::end(mLate.Mod.Depth), 0.0f);
for(auto &gains : mEarly.CurrentGain)
std::fill(std::begin(gains), std::end(gains), 0.0f);
for(auto &gains : mEarly.PanGain)
std::fill(std::begin(gains), std::end(gains), 0.0f);
for(auto &gains : mLate.CurrentGain)
std::fill(std::begin(gains), std::end(gains), 0.0f);
for(auto &gains : mLate.PanGain)
std::fill(std::begin(gains), std::end(gains), 0.0f);
/* Reset fading and offset base. */
mDoFading = true;
std::fill(std::begin(mMaxUpdate), std::end(mMaxUpdate), MAX_UPDATE_SAMPLES);
mOffset = 0;
if(device->mAmbiOrder > 1)
{
mMixOut = &ReverbState::MixOutAmbiUp;
mOrderScales = BFormatDec::GetHFOrderScales(1, device->mAmbiOrder);
}
else
{
mMixOut = &ReverbState::MixOutPlain;
mOrderScales.fill(1.0f);
}
mAmbiSplitter[0][0].init(400.0f / frequency);
std::fill(mAmbiSplitter[0].begin()+1, mAmbiSplitter[0].end(), mAmbiSplitter[0][0]);
std::fill(mAmbiSplitter[1].begin(), mAmbiSplitter[1].end(), mAmbiSplitter[0][0]);
}
/**************************************
* Effect Update *
**************************************/
/* Calculate a decay coefficient given the length of each cycle and the time
* until the decay reaches -60 dB.
*/
inline float CalcDecayCoeff(const float length, const float decayTime)
{ return std::pow(ReverbDecayGain, length/decayTime); }
/* Calculate a decay length from a coefficient and the time until the decay
* reaches -60 dB.
*/
inline float CalcDecayLength(const float coeff, const float decayTime)
{
constexpr float log10_decaygain{-3.0f/*std::log10(ReverbDecayGain)*/};
return std::log10(coeff) * decayTime / log10_decaygain;
}
/* Calculate an attenuation to be applied to the input of any echo models to
* compensate for modal density and decay time.
*/
inline float CalcDensityGain(const float a)
{
/* The energy of a signal can be obtained by finding the area under the
* squared signal. This takes the form of Sum(x_n^2), where x is the
* amplitude for the sample n.
*
* Decaying feedback matches exponential decay of the form Sum(a^n),
* where a is the attenuation coefficient, and n is the sample. The area
* under this decay curve can be calculated as: 1 / (1 - a).
*
* Modifying the above equation to find the area under the squared curve
* (for energy) yields: 1 / (1 - a^2). Input attenuation can then be
* calculated by inverting the square root of this approximation,
* yielding: 1 / sqrt(1 / (1 - a^2)), simplified to: sqrt(1 - a^2).
*/
return std::sqrt(1.0f - a*a);
}
/* Calculate the scattering matrix coefficients given a diffusion factor. */
inline void CalcMatrixCoeffs(const float diffusion, float *x, float *y)
{
/* The matrix is of order 4, so n is sqrt(4 - 1). */
constexpr float n{1.73205080756887719318f/*std::sqrt(3.0f)*/};
const float t{diffusion * std::atan(n)};
/* Calculate the first mixing matrix coefficient. */
*x = std::cos(t);
/* Calculate the second mixing matrix coefficient. */
*y = std::sin(t) / n;
}
/* Calculate the limited HF ratio for use with the late reverb low-pass
* filters.
*/
float CalcLimitedHfRatio(const float hfRatio, const float airAbsorptionGainHF,
const float decayTime)
{
/* Find the attenuation due to air absorption in dB (converting delay
* time to meters using the speed of sound). Then reversing the decay
* equation, solve for HF ratio. The delay length is cancelled out of
* the equation, so it can be calculated once for all lines.
*/
float limitRatio{1.0f / SpeedOfSoundMetersPerSec /
CalcDecayLength(airAbsorptionGainHF, decayTime)};
/* Using the limit calculated above, apply the upper bound to the HF ratio. */
return minf(limitRatio, hfRatio);
}
/* Calculates the 3-band T60 damping coefficients for a particular delay line
* of specified length, using a combination of two shelf filter sections given
* decay times for each band split at two reference frequencies.
*/
void T60Filter::calcCoeffs(const float length, const float lfDecayTime,
const float mfDecayTime, const float hfDecayTime, const float lf0norm,
const float hf0norm)
{
const float mfGain{CalcDecayCoeff(length, mfDecayTime)};
const float lfGain{CalcDecayCoeff(length, lfDecayTime) / mfGain};
const float hfGain{CalcDecayCoeff(length, hfDecayTime) / mfGain};
MidGain[1] = mfGain;
LFFilter.setParamsFromSlope(BiquadType::LowShelf, lf0norm, lfGain, 1.0f);
HFFilter.setParamsFromSlope(BiquadType::HighShelf, hf0norm, hfGain, 1.0f);
}
/* Update the early reflection line lengths and gain coefficients. */
void EarlyReflections::updateLines(const float density_mult, const float diffusion,
const float decayTime, const float frequency)
{
constexpr float sqrt1_2{0.70710678118654752440f/*1.0f/std::sqrt(2.0f)*/};
/* Calculate the all-pass feed-back/forward coefficient. */
VecAp.Coeff = diffusion*diffusion * sqrt1_2;
for(size_t i{0u};i < NUM_LINES;i++)
{
/* Calculate the delay length of each all-pass line. */
float length{EARLY_ALLPASS_LENGTHS[i] * density_mult};
VecAp.Offset[i][1] = float2uint(length * frequency);
/* Calculate the delay length of each delay line. */
length = EARLY_LINE_LENGTHS[i] * density_mult;
Offset[i][1] = float2uint(length * frequency);
/* Calculate the gain (coefficient) for each line. */
Coeff[i][1] = CalcDecayCoeff(length, decayTime);
}
}
/* Update the EAX modulation step and depth. Keep in mind that this kind of
* vibrato is additive and not multiplicative as one may expect. The downswing
* will sound stronger than the upswing.
*/
void Modulation::updateModulator(float modTime, float modDepth, float frequency)
{
/* Modulation is calculated in two parts.
*
* The modulation time effects the sinus rate, altering the speed of
* frequency changes. An index is incremented for each sample with an
* appropriate step size to generate an LFO, which will vary the feedback
* delay over time.
*/
Step = maxu(fastf2u(MOD_FRACONE / (frequency * modTime)), 1);
/* The modulation depth effects the amount of frequency change over the
* range of the sinus. It needs to be scaled by the modulation time so that
* a given depth produces a consistent change in frequency over all ranges
* of time. Since the depth is applied to a sinus value, it needs to be
* halved once for the sinus range and again for the sinus swing in time
* (half of it is spent decreasing the frequency, half is spent increasing
* it).
*/
if(modTime >= AL_EAXREVERB_DEFAULT_MODULATION_TIME)
{
/* To cancel the effects of a long period modulation on the late
* reverberation, the amount of pitch should be varied (decreased)
* according to the modulation time. The natural form is varying
* inversely, in fact resulting in an invariant.
*/
Depth[1] = MODULATION_DEPTH_COEFF / 4.0f * AL_EAXREVERB_DEFAULT_MODULATION_TIME *
modDepth * frequency;
}
else
Depth[1] = MODULATION_DEPTH_COEFF / 4.0f * modTime * modDepth * frequency;
}
/* Update the late reverb line lengths and T60 coefficients. */
void LateReverb::updateLines(const float density_mult, const float diffusion,
const float lfDecayTime, const float mfDecayTime, const float hfDecayTime,
const float lf0norm, const float hf0norm, const float frequency)
{
/* Scaling factor to convert the normalized reference frequencies from
* representing 0...freq to 0...max_reference.
*/
const float norm_weight_factor{frequency / AL_EAXREVERB_MAX_HFREFERENCE};
const float late_allpass_avg{
std::accumulate(LATE_ALLPASS_LENGTHS.begin(), LATE_ALLPASS_LENGTHS.end(), 0.0f) /
float{NUM_LINES}};
/* To compensate for changes in modal density and decay time of the late
* reverb signal, the input is attenuated based on the maximal energy of
* the outgoing signal. This approximation is used to keep the apparent
* energy of the signal equal for all ranges of density and decay time.
*
* The average length of the delay lines is used to calculate the
* attenuation coefficient.
*/
float length{std::accumulate(LATE_LINE_LENGTHS.begin(), LATE_LINE_LENGTHS.end(), 0.0f) /
float{NUM_LINES} + late_allpass_avg};
length *= density_mult;
/* The density gain calculation uses an average decay time weighted by
* approximate bandwidth. This attempts to compensate for losses of energy
* that reduce decay time due to scattering into highly attenuated bands.
*/
const float decayTimeWeighted{
lf0norm*norm_weight_factor*lfDecayTime +
(hf0norm - lf0norm)*norm_weight_factor*mfDecayTime +
(1.0f - hf0norm*norm_weight_factor)*hfDecayTime};
DensityGain[1] = CalcDensityGain(CalcDecayCoeff(length, decayTimeWeighted));
/* Calculate the all-pass feed-back/forward coefficient. */
constexpr float sqrt1_2{0.70710678118654752440f/*1.0f/std::sqrt(2.0f)*/};
VecAp.Coeff = diffusion*diffusion * sqrt1_2;
for(size_t i{0u};i < NUM_LINES;i++)
{
/* Calculate the delay length of each all-pass line. */
length = LATE_ALLPASS_LENGTHS[i] * density_mult;
VecAp.Offset[i][1] = float2uint(length * frequency);
/* Calculate the delay length of each feedback delay line. */
length = LATE_LINE_LENGTHS[i] * density_mult;
Offset[i][1] = float2uint(length*frequency + 0.5f);
/* Approximate the absorption that the vector all-pass would exhibit
* given the current diffusion so we don't have to process a full T60
* filter for each of its four lines. Also include the average
* modulation delay (depth is half the max delay in samples).
*/
length += lerp(LATE_ALLPASS_LENGTHS[i], late_allpass_avg, diffusion)*density_mult +
Mod.Depth[1]/frequency;
/* Calculate the T60 damping coefficients for each line. */
T60[i].calcCoeffs(length, lfDecayTime, mfDecayTime, hfDecayTime, lf0norm, hf0norm);
}
}
/* Update the offsets for the main effect delay line. */
void ReverbState::updateDelayLine(const float earlyDelay, const float lateDelay,
const float density_mult, const float decayTime, const float frequency)
{
/* Early reflection taps are decorrelated by means of an average room
* reflection approximation described above the definition of the taps.
* This approximation is linear and so the above density multiplier can
* be applied to adjust the width of the taps. A single-band decay
* coefficient is applied to simulate initial attenuation and absorption.
*
* Late reverb taps are based on the late line lengths to allow a zero-
* delay path and offsets that would continue the propagation naturally
* into the late lines.
*/
for(size_t i{0u};i < NUM_LINES;i++)
{
float length{EARLY_TAP_LENGTHS[i]*density_mult};
mEarlyDelayTap[i][1] = float2uint((earlyDelay+length) * frequency);
mEarlyDelayCoeff[i][1] = CalcDecayCoeff(length, decayTime);
length = (LATE_LINE_LENGTHS[i] - LATE_LINE_LENGTHS.front())/float{NUM_LINES}*density_mult +
lateDelay;
mLateDelayTap[i][1] = mLateFeedTap + float2uint(length * frequency);
}
}
/* Creates a transform matrix given a reverb vector. The vector pans the reverb
* reflections toward the given direction, using its magnitude (up to 1) as a
* focal strength. This function results in a B-Format transformation matrix
* that spatially focuses the signal in the desired direction.
*/
alu::Matrix GetTransformFromVector(const float *vec)
{
constexpr float sqrt3{1.73205080756887719318f};
/* Normalize the panning vector according to the N3D scale, which has an
* extra sqrt(3) term on the directional components. Converting from OpenAL
* to B-Format also requires negating X (ACN 1) and Z (ACN 3). Note however
* that the reverb panning vectors use left-handed coordinates, unlike the
* rest of OpenAL which use right-handed. This is fixed by negating Z,
* which cancels out with the B-Format Z negation.
*/
float norm[3];
float mag{std::sqrt(vec[0]*vec[0] + vec[1]*vec[1] + vec[2]*vec[2])};
if(mag > 1.0f)
{
norm[0] = vec[0] / mag * -sqrt3;
norm[1] = vec[1] / mag * sqrt3;
norm[2] = vec[2] / mag * sqrt3;
mag = 1.0f;
}
else
{
/* If the magnitude is less than or equal to 1, just apply the sqrt(3)
* term. There's no need to renormalize the magnitude since it would
* just be reapplied in the matrix.
*/
norm[0] = vec[0] * -sqrt3;
norm[1] = vec[1] * sqrt3;
norm[2] = vec[2] * sqrt3;
}
return alu::Matrix{
1.0f, 0.0f, 0.0f, 0.0f,
norm[0], 1.0f-mag, 0.0f, 0.0f,
norm[1], 0.0f, 1.0f-mag, 0.0f,
norm[2], 0.0f, 0.0f, 1.0f-mag
};
}
/* Update the early and late 3D panning gains. */
void ReverbState::update3DPanning(const float *ReflectionsPan, const float *LateReverbPan,
const float earlyGain, const float lateGain, const EffectTarget &target)
{
/* Create matrices that transform a B-Format signal according to the
* panning vectors.
*/
const alu::Matrix earlymat{GetTransformFromVector(ReflectionsPan)};
const alu::Matrix latemat{GetTransformFromVector(LateReverbPan)};
mOutTarget = target.Main->Buffer;
for(size_t i{0u};i < NUM_LINES;i++)
{
const float coeffs[MaxAmbiChannels]{earlymat[0][i], earlymat[1][i], earlymat[2][i],
earlymat[3][i]};
ComputePanGains(target.Main, coeffs, earlyGain, mEarly.PanGain[i]);
}
for(size_t i{0u};i < NUM_LINES;i++)
{
const float coeffs[MaxAmbiChannels]{latemat[0][i], latemat[1][i], latemat[2][i],
latemat[3][i]};
ComputePanGains(target.Main, coeffs, lateGain, mLate.PanGain[i]);
}
}
void ReverbState::update(const ALCcontext *Context, const EffectSlot *Slot,
const EffectProps *props, const EffectTarget target)
{
const ALCdevice *Device{Context->mDevice.get()};
const auto frequency = static_cast<float>(Device->Frequency);
/* Calculate the master filters */
float hf0norm{minf(props->Reverb.HFReference/frequency, 0.49f)};
mFilter[0].Lp.setParamsFromSlope(BiquadType::HighShelf, hf0norm, props->Reverb.GainHF, 1.0f);
float lf0norm{minf(props->Reverb.LFReference/frequency, 0.49f)};
mFilter[0].Hp.setParamsFromSlope(BiquadType::LowShelf, lf0norm, props->Reverb.GainLF, 1.0f);
for(size_t i{1u};i < NUM_LINES;i++)
{
mFilter[i].Lp.copyParamsFrom(mFilter[0].Lp);
mFilter[i].Hp.copyParamsFrom(mFilter[0].Hp);
}
/* The density-based room size (delay length) multiplier. */
const float density_mult{CalcDelayLengthMult(props->Reverb.Density)};
/* Update the main effect delay and associated taps. */
updateDelayLine(props->Reverb.ReflectionsDelay, props->Reverb.LateReverbDelay,
density_mult, props->Reverb.DecayTime, frequency);
/* Update the early lines. */
mEarly.updateLines(density_mult, props->Reverb.Diffusion, props->Reverb.DecayTime, frequency);
/* Get the mixing matrix coefficients. */
CalcMatrixCoeffs(props->Reverb.Diffusion, &mMixX, &mMixY);
/* If the HF limit parameter is flagged, calculate an appropriate limit
* based on the air absorption parameter.
*/
float hfRatio{props->Reverb.DecayHFRatio};
if(props->Reverb.DecayHFLimit && props->Reverb.AirAbsorptionGainHF < 1.0f)
hfRatio = CalcLimitedHfRatio(hfRatio, props->Reverb.AirAbsorptionGainHF,
props->Reverb.DecayTime);
/* Calculate the LF/HF decay times. */
const float lfDecayTime{clampf(props->Reverb.DecayTime * props->Reverb.DecayLFRatio,
AL_EAXREVERB_MIN_DECAY_TIME, AL_EAXREVERB_MAX_DECAY_TIME)};
const float hfDecayTime{clampf(props->Reverb.DecayTime * hfRatio,
AL_EAXREVERB_MIN_DECAY_TIME, AL_EAXREVERB_MAX_DECAY_TIME)};
/* Update the modulator rate and depth. */
mLate.Mod.updateModulator(props->Reverb.ModulationTime, props->Reverb.ModulationDepth,
frequency);
/* Update the late lines. */
mLate.updateLines(density_mult, props->Reverb.Diffusion, lfDecayTime,
props->Reverb.DecayTime, hfDecayTime, lf0norm, hf0norm, frequency);
/* Update early and late 3D panning. */
const float gain{props->Reverb.Gain * Slot->Gain * ReverbBoost};
update3DPanning(props->Reverb.ReflectionsPan, props->Reverb.LateReverbPan,
props->Reverb.ReflectionsGain*gain, props->Reverb.LateReverbGain*gain, target);
/* Calculate the max update size from the smallest relevant delay. */
mMaxUpdate[1] = minz(MAX_UPDATE_SAMPLES, minz(mEarly.Offset[0][1], mLate.Offset[0][1]));
/* Determine if delay-line cross-fading is required. Density is essentially
* a master control for the feedback delays, so changes the offsets of many
* delay lines.
*/
mDoFading |= (mParams.Density != props->Reverb.Density ||
/* Diffusion and decay times influences the decay rate (gain) of the
* late reverb T60 filter.
*/
mParams.Diffusion != props->Reverb.Diffusion ||
mParams.DecayTime != props->Reverb.DecayTime ||
mParams.HFDecayTime != hfDecayTime ||
mParams.LFDecayTime != lfDecayTime ||
/* Modulation time and depth both require fading the modulation delay. */
mParams.ModulationTime != props->Reverb.ModulationTime ||
mParams.ModulationDepth != props->Reverb.ModulationDepth ||
/* HF/LF References control the weighting used to calculate the density
* gain.
*/
mParams.HFReference != props->Reverb.HFReference ||
mParams.LFReference != props->Reverb.LFReference);
if(mDoFading)
{
mParams.Density = props->Reverb.Density;
mParams.Diffusion = props->Reverb.Diffusion;
mParams.DecayTime = props->Reverb.DecayTime;
mParams.HFDecayTime = hfDecayTime;
mParams.LFDecayTime = lfDecayTime;
mParams.ModulationTime = props->Reverb.ModulationTime;
mParams.ModulationDepth = props->Reverb.ModulationDepth;
mParams.HFReference = props->Reverb.HFReference;
mParams.LFReference = props->Reverb.LFReference;
}
}
/**************************************
* Effect Processing *
**************************************/
/* Applies a scattering matrix to the 4-line (vector) input. This is used
* for both the below vector all-pass model and to perform modal feed-back
* delay network (FDN) mixing.
*
* The matrix is derived from a skew-symmetric matrix to form a 4D rotation
* matrix with a single unitary rotational parameter:
*
* [ d, a, b, c ] 1 = a^2 + b^2 + c^2 + d^2
* [ -a, d, c, -b ]
* [ -b, -c, d, a ]
* [ -c, b, -a, d ]
*
* The rotation is constructed from the effect's diffusion parameter,
* yielding:
*
* 1 = x^2 + 3 y^2
*
* Where a, b, and c are the coefficient y with differing signs, and d is the
* coefficient x. The final matrix is thus:
*
* [ x, y, -y, y ] n = sqrt(matrix_order - 1)
* [ -y, x, y, y ] t = diffusion_parameter * atan(n)
* [ y, -y, x, y ] x = cos(t)
* [ -y, -y, -y, x ] y = sin(t) / n
*
* Any square orthogonal matrix with an order that is a power of two will
* work (where ^T is transpose, ^-1 is inverse):
*
* M^T = M^-1
*
* Using that knowledge, finding an appropriate matrix can be accomplished
* naively by searching all combinations of:
*
* M = D + S - S^T
*
* Where D is a diagonal matrix (of x), and S is a triangular matrix (of y)
* whose combination of signs are being iterated.
*/
inline auto VectorPartialScatter(const std::array<float,NUM_LINES> &RESTRICT in,
const float xCoeff, const float yCoeff) -> std::array<float,NUM_LINES>
{
return std::array<float,NUM_LINES>{{
xCoeff*in[0] + yCoeff*( in[1] + -in[2] + in[3]),
xCoeff*in[1] + yCoeff*(-in[0] + in[2] + in[3]),
xCoeff*in[2] + yCoeff*( in[0] + -in[1] + in[3]),
xCoeff*in[3] + yCoeff*(-in[0] + -in[1] + -in[2] )
}};
}
/* Utilizes the above, but reverses the input channels. */
void VectorScatterRevDelayIn(const DelayLineI delay, size_t offset, const float xCoeff,
const float yCoeff, const al::span<const ReverbUpdateLine,NUM_LINES> in, const size_t count)
{
ASSUME(count > 0);
for(size_t i{0u};i < count;)
{
offset &= delay.Mask;
size_t td{minz(delay.Mask+1 - offset, count-i)};
do {
std::array<float,NUM_LINES> f;
for(size_t j{0u};j < NUM_LINES;j++)
f[NUM_LINES-1-j] = in[j][i];
++i;
delay.Line[offset++] = VectorPartialScatter(f, xCoeff, yCoeff);
} while(--td);
}
}
/* This applies a Gerzon multiple-in/multiple-out (MIMO) vector all-pass
* filter to the 4-line input.
*
* It works by vectorizing a regular all-pass filter and replacing the delay
* element with a scattering matrix (like the one above) and a diagonal
* matrix of delay elements.
*
* Two static specializations are used for transitional (cross-faded) delay
* line processing and non-transitional processing.
*/
void VecAllpass::processUnfaded(const al::span<ReverbUpdateLine,NUM_LINES> samples, size_t offset,
const float xCoeff, const float yCoeff, const size_t todo)
{
const DelayLineI delay{Delay};
const float feedCoeff{Coeff};
ASSUME(todo > 0);
size_t vap_offset[NUM_LINES];
for(size_t j{0u};j < NUM_LINES;j++)
vap_offset[j] = offset - Offset[j][0];
for(size_t i{0u};i < todo;)
{
for(size_t j{0u};j < NUM_LINES;j++)
vap_offset[j] &= delay.Mask;
offset &= delay.Mask;
size_t maxoff{offset};
for(size_t j{0u};j < NUM_LINES;j++)
maxoff = maxz(maxoff, vap_offset[j]);
size_t td{minz(delay.Mask+1 - maxoff, todo - i)};
do {
std::array<float,NUM_LINES> f;
for(size_t j{0u};j < NUM_LINES;j++)
{
const float input{samples[j][i]};
const float out{delay.Line[vap_offset[j]++][j] - feedCoeff*input};
f[j] = input + feedCoeff*out;
samples[j][i] = out;
}
++i;
delay.Line[offset++] = VectorPartialScatter(f, xCoeff, yCoeff);
} while(--td);
}
}
void VecAllpass::processFaded(const al::span<ReverbUpdateLine,NUM_LINES> samples, size_t offset,
const float xCoeff, const float yCoeff, float fadeCount, const float fadeStep,
const size_t todo)
{
const DelayLineI delay{Delay};
const float feedCoeff{Coeff};
ASSUME(todo > 0);
size_t vap_offset[NUM_LINES][2];
for(size_t j{0u};j < NUM_LINES;j++)
{
vap_offset[j][0] = offset - Offset[j][0];
vap_offset[j][1] = offset - Offset[j][1];
}
for(size_t i{0u};i < todo;)
{
for(size_t j{0u};j < NUM_LINES;j++)
{
vap_offset[j][0] &= delay.Mask;
vap_offset[j][1] &= delay.Mask;
}
offset &= delay.Mask;
size_t maxoff{offset};
for(size_t j{0u};j < NUM_LINES;j++)
maxoff = maxz(maxoff, maxz(vap_offset[j][0], vap_offset[j][1]));
size_t td{minz(delay.Mask+1 - maxoff, todo - i)};
do {
fadeCount += 1.0f;
const float fade{fadeCount * fadeStep};
std::array<float,NUM_LINES> f;
for(size_t j{0u};j < NUM_LINES;j++)
f[j] = delay.Line[vap_offset[j][0]++][j]*(1.0f-fade) +
delay.Line[vap_offset[j][1]++][j]*fade;
for(size_t j{0u};j < NUM_LINES;j++)
{
const float input{samples[j][i]};
const float out{f[j] - feedCoeff*input};
f[j] = input + feedCoeff*out;
samples[j][i] = out;
}
++i;
delay.Line[offset++] = VectorPartialScatter(f, xCoeff, yCoeff);
} while(--td);
}
}
/* This generates early reflections.
*
* This is done by obtaining the primary reflections (those arriving from the
* same direction as the source) from the main delay line. These are
* attenuated and all-pass filtered (based on the diffusion parameter).
*
* The early lines are then fed in reverse (according to the approximately
* opposite spatial location of the A-Format lines) to create the secondary
* reflections (those arriving from the opposite direction as the source).
*
* The early response is then completed by combining the primary reflections
* with the delayed and attenuated output from the early lines.
*
* Finally, the early response is reversed, scattered (based on diffusion),
* and fed into the late reverb section of the main delay line.
*
* Two static specializations are used for transitional (cross-faded) delay
* line processing and non-transitional processing.
*/
void ReverbState::earlyUnfaded(const size_t offset, const size_t todo)
{
const DelayLineI early_delay{mEarly.Delay};
const DelayLineI main_delay{mDelay};
const float mixX{mMixX};
const float mixY{mMixY};
ASSUME(todo > 0);
/* First, load decorrelated samples from the main delay line as the primary
* reflections.
*/
for(size_t j{0u};j < NUM_LINES;j++)
{
size_t early_delay_tap{offset - mEarlyDelayTap[j][0]};
const float coeff{mEarlyDelayCoeff[j][0]};
for(size_t i{0u};i < todo;)
{
early_delay_tap &= main_delay.Mask;
size_t td{minz(main_delay.Mask+1 - early_delay_tap, todo - i)};
do {
mTempSamples[j][i++] = main_delay.Line[early_delay_tap++][j] * coeff;
} while(--td);
}
}
/* Apply a vector all-pass, to help color the initial reflections based on
* the diffusion strength.
*/
mEarly.VecAp.processUnfaded(mTempSamples, offset, mixX, mixY, todo);
/* Apply a delay and bounce to generate secondary reflections, combine with
* the primary reflections and write out the result for mixing.
*/
for(size_t j{0u};j < NUM_LINES;j++)
{
size_t feedb_tap{offset - mEarly.Offset[j][0]};
const float feedb_coeff{mEarly.Coeff[j][0]};
float *out{mEarlySamples[j].data()};
for(size_t i{0u};i < todo;)
{
feedb_tap &= early_delay.Mask;
size_t td{minz(early_delay.Mask+1 - feedb_tap, todo - i)};
do {
out[i] = mTempSamples[j][i] + early_delay.Line[feedb_tap++][j]*feedb_coeff;
++i;
} while(--td);
}
}
for(size_t j{0u};j < NUM_LINES;j++)
early_delay.write(offset, NUM_LINES-1-j, mTempSamples[j].data(), todo);
/* Also write the result back to the main delay line for the late reverb
* stage to pick up at the appropriate time, appplying a scatter and
* bounce to improve the initial diffusion in the late reverb.
*/
const size_t late_feed_tap{offset - mLateFeedTap};
VectorScatterRevDelayIn(main_delay, late_feed_tap, mixX, mixY, mEarlySamples, todo);
}
void ReverbState::earlyFaded(const size_t offset, const size_t todo, const float fade,
const float fadeStep)
{
const DelayLineI early_delay{mEarly.Delay};
const DelayLineI main_delay{mDelay};
const float mixX{mMixX};
const float mixY{mMixY};
ASSUME(todo > 0);
for(size_t j{0u};j < NUM_LINES;j++)
{
size_t early_delay_tap0{offset - mEarlyDelayTap[j][0]};
size_t early_delay_tap1{offset - mEarlyDelayTap[j][1]};
const float oldCoeff{mEarlyDelayCoeff[j][0]};
const float oldCoeffStep{-oldCoeff * fadeStep};
const float newCoeffStep{mEarlyDelayCoeff[j][1] * fadeStep};
float fadeCount{fade};
for(size_t i{0u};i < todo;)
{
early_delay_tap0 &= main_delay.Mask;
early_delay_tap1 &= main_delay.Mask;
size_t td{minz(main_delay.Mask+1 - maxz(early_delay_tap0, early_delay_tap1), todo-i)};
do {
fadeCount += 1.0f;
const float fade0{oldCoeff + oldCoeffStep*fadeCount};
const float fade1{newCoeffStep*fadeCount};
mTempSamples[j][i++] =
main_delay.Line[early_delay_tap0++][j]*fade0 +
main_delay.Line[early_delay_tap1++][j]*fade1;
} while(--td);
}
}
mEarly.VecAp.processFaded(mTempSamples, offset, mixX, mixY, fade, fadeStep, todo);
for(size_t j{0u};j < NUM_LINES;j++)
{
size_t feedb_tap0{offset - mEarly.Offset[j][0]};
size_t feedb_tap1{offset - mEarly.Offset[j][1]};
const float feedb_oldCoeff{mEarly.Coeff[j][0]};
const float feedb_oldCoeffStep{-feedb_oldCoeff * fadeStep};
const float feedb_newCoeffStep{mEarly.Coeff[j][1] * fadeStep};
float *out{mEarlySamples[j].data()};
float fadeCount{fade};
for(size_t i{0u};i < todo;)
{
feedb_tap0 &= early_delay.Mask;
feedb_tap1 &= early_delay.Mask;
size_t td{minz(early_delay.Mask+1 - maxz(feedb_tap0, feedb_tap1), todo - i)};
do {
fadeCount += 1.0f;
const float fade0{feedb_oldCoeff + feedb_oldCoeffStep*fadeCount};
const float fade1{feedb_newCoeffStep*fadeCount};
out[i] = mTempSamples[j][i] +
early_delay.Line[feedb_tap0++][j]*fade0 +
early_delay.Line[feedb_tap1++][j]*fade1;
++i;
} while(--td);
}
}
for(size_t j{0u};j < NUM_LINES;j++)
early_delay.write(offset, NUM_LINES-1-j, mTempSamples[j].data(), todo);
const size_t late_feed_tap{offset - mLateFeedTap};
VectorScatterRevDelayIn(main_delay, late_feed_tap, mixX, mixY, mEarlySamples, todo);
}
void Modulation::calcDelays(size_t todo)
{
constexpr float inv_scale{MOD_FRACONE / al::MathDefs<float>::Tau()};
ALuint idx{Index};
const ALuint step{Step};
const float depth{Depth[0]};
for(size_t i{0};i < todo;++i)
{
idx += step;
const float lfo{std::sin(static_cast<float>(idx&MOD_FRACMASK) / inv_scale)};
ModDelays[i] = (lfo+1.0f) * depth;
}
Index = idx;
}
void Modulation::calcFadedDelays(size_t todo, float fadeCount, float fadeStep)
{
constexpr float inv_scale{MOD_FRACONE / al::MathDefs<float>::Tau()};
ALuint idx{Index};
const ALuint step{Step};
const float depth{Depth[0]};
const float depthStep{(Depth[1]-depth) * fadeStep};
for(size_t i{0};i < todo;++i)
{
fadeCount += 1.0f;
idx += step;
const float lfo{std::sin(static_cast<float>(idx&MOD_FRACMASK) / inv_scale)};
ModDelays[i] = (lfo+1.0f) * (depth + depthStep*fadeCount);
}
Index = idx;
}
/* This generates the reverb tail using a modified feed-back delay network
* (FDN).
*
* Results from the early reflections are mixed with the output from the
* modulated late delay lines.
*
* The late response is then completed by T60 and all-pass filtering the mix.
*
* Finally, the lines are reversed (so they feed their opposite directions)
* and scattered with the FDN matrix before re-feeding the delay lines.
*
* Two variations are made, one for for transitional (cross-faded) delay line
* processing and one for non-transitional processing.
*/
void ReverbState::lateUnfaded(const size_t offset, const size_t todo)
{
const DelayLineI late_delay{mLate.Delay};
const DelayLineI main_delay{mDelay};
const float mixX{mMixX};
const float mixY{mMixY};
ASSUME(todo > 0);
/* First, calculate the modulated delays for the late feedback. */
mLate.Mod.calcDelays(todo);
/* Next, load decorrelated samples from the main and feedback delay lines.
* Filter the signal to apply its frequency-dependent decay.
*/
for(size_t j{0u};j < NUM_LINES;j++)
{
size_t late_delay_tap{offset - mLateDelayTap[j][0]};
size_t late_feedb_tap{offset - mLate.Offset[j][0]};
const float midGain{mLate.T60[j].MidGain[0]};
const float densityGain{mLate.DensityGain[0] * midGain};
for(size_t i{0u};i < todo;)
{
late_delay_tap &= main_delay.Mask;
size_t td{minz(todo - i, main_delay.Mask+1 - late_delay_tap)};
do {
/* Calculate the read offset and fraction between it and the
* next sample.
*/
const float fdelay{mLate.Mod.ModDelays[i]};
const size_t delay{float2uint(fdelay)};
const float frac{fdelay - static_cast<float>(delay)};
/* Feed the delay line with the late feedback sample, and get
* the two samples crossed by the delayed offset.
*/
const float out0{late_delay.Line[(late_feedb_tap-delay) & late_delay.Mask][j]};
const float out1{late_delay.Line[(late_feedb_tap-delay-1) & late_delay.Mask][j]};
++late_feedb_tap;
/* The output is obtained by linearly interpolating the two
* samples that were acquired above, and combined with the main
* delay tap.
*/
mTempSamples[j][i] = lerp(out0, out1, frac)*midGain +
main_delay.Line[late_delay_tap++][j]*densityGain;
++i;
} while(--td);
}
mLate.T60[j].process({mTempSamples[j].data(), todo});
}
/* Apply a vector all-pass to improve micro-surface diffusion, and write
* out the results for mixing.
*/
mLate.VecAp.processUnfaded(mTempSamples, offset, mixX, mixY, todo);
for(size_t j{0u};j < NUM_LINES;j++)
std::copy_n(mTempSamples[j].begin(), todo, mLateSamples[j].begin());
/* Finally, scatter and bounce the results to refeed the feedback buffer. */
VectorScatterRevDelayIn(late_delay, offset, mixX, mixY, mTempSamples, todo);
}
void ReverbState::lateFaded(const size_t offset, const size_t todo, const float fade,
const float fadeStep)
{
const DelayLineI late_delay{mLate.Delay};
const DelayLineI main_delay{mDelay};
const float mixX{mMixX};
const float mixY{mMixY};
ASSUME(todo > 0);
mLate.Mod.calcFadedDelays(todo, fade, fadeStep);
for(size_t j{0u};j < NUM_LINES;j++)
{
const float oldMidGain{mLate.T60[j].MidGain[0]};
const float midGain{mLate.T60[j].MidGain[1]};
const float oldMidStep{-oldMidGain * fadeStep};
const float midStep{midGain * fadeStep};
const float oldDensityGain{mLate.DensityGain[0] * oldMidGain};
const float densityGain{mLate.DensityGain[1] * midGain};
const float oldDensityStep{-oldDensityGain * fadeStep};
const float densityStep{densityGain * fadeStep};
size_t late_delay_tap0{offset - mLateDelayTap[j][0]};
size_t late_delay_tap1{offset - mLateDelayTap[j][1]};
size_t late_feedb_tap0{offset - mLate.Offset[j][0]};
size_t late_feedb_tap1{offset - mLate.Offset[j][1]};
float fadeCount{fade};
for(size_t i{0u};i < todo;)
{
late_delay_tap0 &= main_delay.Mask;
late_delay_tap1 &= main_delay.Mask;
size_t td{minz(todo - i, main_delay.Mask+1 - maxz(late_delay_tap0, late_delay_tap1))};
do {
fadeCount += 1.0f;
const float fdelay{mLate.Mod.ModDelays[i]};
const size_t delay{float2uint(fdelay)};
const float frac{fdelay - static_cast<float>(delay)};
const float out00{late_delay.Line[(late_feedb_tap0-delay) & late_delay.Mask][j]};
const float out01{late_delay.Line[(late_feedb_tap0-delay-1) & late_delay.Mask][j]};
++late_feedb_tap0;
const float out10{late_delay.Line[(late_feedb_tap1-delay) & late_delay.Mask][j]};
const float out11{late_delay.Line[(late_feedb_tap1-delay-1) & late_delay.Mask][j]};
++late_feedb_tap1;
const float fade0{oldDensityGain + oldDensityStep*fadeCount};
const float fade1{densityStep*fadeCount};
const float gfade0{oldMidGain + oldMidStep*fadeCount};
const float gfade1{midStep*fadeCount};
mTempSamples[j][i] = lerp(out00, out01, frac)*gfade0 +
lerp(out10, out11, frac)*gfade1 +
main_delay.Line[late_delay_tap0++][j]*fade0 +
main_delay.Line[late_delay_tap1++][j]*fade1;
++i;
} while(--td);
}
mLate.T60[j].process({mTempSamples[j].data(), todo});
}
mLate.VecAp.processFaded(mTempSamples, offset, mixX, mixY, fade, fadeStep, todo);
for(size_t j{0u};j < NUM_LINES;j++)
std::copy_n(mTempSamples[j].begin(), todo, mLateSamples[j].begin());
VectorScatterRevDelayIn(late_delay, offset, mixX, mixY, mTempSamples, todo);
}
void ReverbState::process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn, const al::span<FloatBufferLine> samplesOut)
{
size_t offset{mOffset};
ASSUME(samplesToDo > 0);
/* Convert B-Format to A-Format for processing. */
const size_t numInput{minz(samplesIn.size(), NUM_LINES)};
const al::span<float> tmpspan{al::assume_aligned<16>(mTempLine.data()), samplesToDo};
for(size_t c{0u};c < NUM_LINES;c++)
{
std::fill(tmpspan.begin(), tmpspan.end(), 0.0f);
for(size_t i{0};i < numInput;++i)
{
const float gain{B2A[c][i]};
const float *RESTRICT input{al::assume_aligned<16>(samplesIn[i].data())};
for(float &sample : tmpspan)
{
sample += *input * gain;
++input;
}
}
/* Band-pass the incoming samples and feed the initial delay line. */
DualBiquad{mFilter[c].Lp, mFilter[c].Hp}.process(tmpspan, tmpspan.data());
mDelay.write(offset, c, tmpspan.cbegin(), samplesToDo);
}
/* Process reverb for these samples. */
if LIKELY(!mDoFading)
{
for(size_t base{0};base < samplesToDo;)
{
/* Calculate the number of samples we can do this iteration. */
size_t todo{minz(samplesToDo - base, mMaxUpdate[0])};
/* Some mixers require maintaining a 4-sample alignment, so ensure
* that if it's not the last iteration.
*/
if(base+todo < samplesToDo) todo &= ~size_t{3};
ASSUME(todo > 0);
/* Generate non-faded early reflections and late reverb. */
earlyUnfaded(offset, todo);
lateUnfaded(offset, todo);
/* Finally, mix early reflections and late reverb. */
(this->*mMixOut)(samplesOut, samplesToDo-base, base, todo);
offset += todo;
base += todo;
}
}
else
{
const float fadeStep{1.0f / static_cast<float>(samplesToDo)};
for(size_t base{0};base < samplesToDo;)
{
size_t todo{minz(samplesToDo - base, minz(mMaxUpdate[0], mMaxUpdate[1]))};
if(base+todo < samplesToDo) todo &= ~size_t{3};
ASSUME(todo > 0);
/* Generate cross-faded early reflections and late reverb. */
auto fadeCount = static_cast<float>(base);
earlyFaded(offset, todo, fadeCount, fadeStep);
lateFaded(offset, todo, fadeCount, fadeStep);
(this->*mMixOut)(samplesOut, samplesToDo-base, base, todo);
offset += todo;
base += todo;
}
/* Update the cross-fading delay line taps. */
for(size_t c{0u};c < NUM_LINES;c++)
{
mEarlyDelayTap[c][0] = mEarlyDelayTap[c][1];
mEarlyDelayCoeff[c][0] = mEarlyDelayCoeff[c][1];
mLateDelayTap[c][0] = mLateDelayTap[c][1];
mEarly.VecAp.Offset[c][0] = mEarly.VecAp.Offset[c][1];
mEarly.Offset[c][0] = mEarly.Offset[c][1];
mEarly.Coeff[c][0] = mEarly.Coeff[c][1];
mLate.Offset[c][0] = mLate.Offset[c][1];
mLate.T60[c].MidGain[0] = mLate.T60[c].MidGain[1];
mLate.VecAp.Offset[c][0] = mLate.VecAp.Offset[c][1];
}
mLate.DensityGain[0] = mLate.DensityGain[1];
mLate.Mod.Depth[0] = mLate.Mod.Depth[1];
mMaxUpdate[0] = mMaxUpdate[1];
mDoFading = false;
}
mOffset = offset;
}
struct ReverbStateFactory final : public EffectStateFactory {
EffectState *create() override { return new ReverbState{}; }
};
struct StdReverbStateFactory final : public EffectStateFactory {
EffectState *create() override { return new ReverbState{}; }
};
} // namespace
EffectStateFactory *ReverbStateFactory_getFactory()
{
static ReverbStateFactory ReverbFactory{};
return &ReverbFactory;
}
EffectStateFactory *StdReverbStateFactory_getFactory()
{
static StdReverbStateFactory ReverbFactory{};
return &ReverbFactory;
}