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several quality improvements #127

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Sep 19, 2024
Merged

several quality improvements #127

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161 changes: 126 additions & 35 deletions cpp/zimt/fourier_bank.cc
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -73,44 +73,44 @@ float Loudness(float freq, float val) {
const float *valsNext = &pars[high_ix][0];
float vals1 = (1.0 - interp) * vals[1] + interp * valsNext[1];
float vals2 = (1.0 - interp) * vals[2] + interp * valsNext[2];
static const float constant1 = 46.249442992274332;
static const float constant2 = 80.768552802927118;
static const float kMul = 3.4173486834828384;
static const float constant1 = 46.37287;
static const float constant2 = 80.892916;
static const float kMul = 3.41562;
val *= (constant1 + vals1) * (1.0 / constant2);
val += kMul * vals2;
return val;
}

float SimpleDb(float energy) {
// ideally 78.3 db, but somehow this works better
static const float full_scale_sine_db = 75.868041059390563;
static const float full_scale_sine_db = 75.8495;
static const float exp_full_scale_sine_db = exp(full_scale_sine_db);
// epsilon, but the biggest one you saw (~4.95e23)
static const float epsilon = 1.0033294789821357e-09 * exp_full_scale_sine_db;
// kMul allows faster log instead of log10 below, incorporating multiplying by 10 for decibel.
static const float kMul0 = 7.7911366413917413;
static const float kMul0 = 7.7888;
static const float kMul = kMul0 / log(10);
return kMul * log(energy + epsilon);
}

void PrepareMasker(hwy::AlignedNDArray<float, 2>& freq,
float *masker,
size_t out_ix) {
static const double kMul = 0.92558468864724108;
static const double kMul = 0.925585;
// convolve in time and freq, 5 freq bins, 3 time bins
static const double c[12] = {
0.011551012731481482,
0.02009898726851852,
0.27419898726851855,
0.04009898726851849,
0.32702682291666668,
0.64009898726851855,
0.36397005208333333,
0.65050101273148142,
1.5422942263604758,
0.10333000000000001,
1.3735024915962184,
7.4513898383588755,
0.011792864242897921,
0.02141444616229312,
0.27204462940133883,
0.04081130408323199,
0.32503380520713393,
0.63960360145409523,
0.36547565427708706,
0.64646959791651382,
1.5271657112757793,
0.10296035397317034,
1.3755662770950172,
7.4439086735915927,
};
static const float div = 1.0 / (2*(c[0]+c[1]+c[2]+c[3]+c[4]+c[5]+c[6]+c[7]+c[8])+c[9]+c[10]+c[11]);
const size_t oi2 = std::max<size_t>(2, out_ix) - 2;
Expand All @@ -137,14 +137,78 @@ void PrepareMasker(hwy::AlignedNDArray<float, 2>& freq,
static const double octaves_in_20_to_20000 = log(20000/20.)/log(2);
static const double octaves_per_rot =
octaves_in_20_to_20000 / float(kNumRotators - 1);
static const double masker_step_per_octave_up_0 = 20.982514311296299;
static const double masker_step_per_octave_up_1 = 27.165698567146499;
static const double masker_step_per_octave_up_2 = -22.32086488660067;
static const double masker_step_per_rot_up_0 = octaves_per_rot * masker_step_per_octave_up_0;
static const double masker_step_per_rot_up_1 = octaves_per_rot * masker_step_per_octave_up_1;
static const double masker_step_per_rot_up_2 = octaves_per_rot * masker_step_per_octave_up_2;
static const double masker_step_per_octave_upZ[30] = {
20.98103630850407,
20.98103630850407,
20.98103630850407,
20.98103630850407,
20.98103630850407,
20.971036308504068,
20.98103630850407,
20.98103630850407,
20.98103630850407,
20.98103630850407,
27.164728846693212,
27.164728846693212,
27.164728846693212,
27.164728846693212,
27.164728846693212,
27.164728846693212,
27.164728846693212,
27.234728846693212,
27.164728846693212,
27.164728846693212,
-23.182165772713049,
-23.66616577271305,
-23.182165772713049,
-22.936865772713052,
-23.112165772713048,
-23.19216577271305,
-23.182165772713049,
-23.182165772713049,
-23.182165772713049,
-23.182165772713049,
};

// Strange masking (flip from usual positive to negative mask damping per
// octave in the higher freqs) -- this could be related to middle ear
// mechanisms having sprung mass, distributing lower and mid frequencies
// into higher frequencies more directly and causing masking.
// Could be a fluke.
static const double masker_step_per_octave_up[30] = {
20.98103630850407,
17.593036308504068,
23.781036308504071,
20.98103630850407,
20.98103630850407,
20.971036308504068,
20.98103630850407,
21.98103630850407,
22.98103630850407,
23.98103630850407,
24.164728846693212,
25.164728846693212,
26.164728846693212,
27.164728846693212,
27.164728846693212,
27.164728846693212,
27.164728846693212,
20.234728846693212,
17.432728846693212,
5.1647288466932118,
-5.1821657727130486,
-10.66616577271305,
-15.182165772713049,
-15.33686577271305,
-23.112165772713048,
-23.19216577271305,
-23.182165772713049,
-23.182165772713049,
-17.022165772713048,
-23.182165772713049,
};

static const double masker_step_per_octave_down = 22.395986972317345;
static const double masker_step_per_octave_down = 22.2;
static const double masker_step_per_rot_down = octaves_per_rot * masker_step_per_octave_down;
// propagate masker up
float mask = 0;
Expand All @@ -154,13 +218,7 @@ void PrepareMasker(hwy::AlignedNDArray<float, 2>& freq,
mask = v;
}
masker[k] = std::max<float>(masker[k], mask);
if (3 * k < kNumRotators) {
mask -= masker_step_per_rot_up_0;
} else if (3 * k < 2 * kNumRotators) {
mask -= masker_step_per_rot_up_1;
} else {
mask -= masker_step_per_rot_up_2;
}
mask -= octaves_per_rot * masker_step_per_octave_up[30 * k / kNumRotators];
}
// propagate masker down
mask = 0;
Expand All @@ -185,13 +243,44 @@ void FinalizeDb(std::vector<float> rotator_frequency,
PrepareMasker(channels, &masker[0], out_ix);


static const double masker_gap = 20.831477534908842;
static const float maskingStrength = 0.40206083915840007;
static const double masker_gap = 20.832650866565942;
static const double maskingStrengthLut[8] = {
0.40243735146213372,
0.53929582802463372,
0.2330768290011962,
0.45162153347411349,
0.40441574013400872,
0.3624992033380407,
0.40282874306369626,
0.58086335243869625,
};
static const double mulLut[8] = {
1.0676829999999999,
0.89912999999999998,
0.90283000000000002,
1.0,
0.92053000000000007,
1.0,
1.0008999999999999,
0.93271699999999991,
};
static const double addLut[8] = {
0,
0.079470000000000013,
0.14000000000000001,
0,
0.0070000000000000001,
0.009470000000000001,
0,
0,
};
static const float min_limit = 0;

// Scan frequencies from bottom to top, let lower frequencies to mask higher frequencies.
// 'masker' maintains the masking envelope from one bin to next.
for (int k = 0; k < kNumRotators; ++k) {
int ix = 8 * k / kNumRotators;
float maskingStrength = maskingStrengthLut[ix];
float v = channels[{out_ix}][k];
double mask = masker[k] - masker_gap;
if (v < min_limit) {
Expand All @@ -201,6 +290,8 @@ void FinalizeDb(std::vector<float> rotator_frequency,
v = maskingStrength * mask + (1.0 - maskingStrength) * v;
}
channels[{out_ix}][k] = v;
channels[{out_ix}][k] *= mulLut[ix];
channels[{out_ix}][k] += addLut[ix];
}
}

Expand Down Expand Up @@ -269,7 +360,7 @@ Rotators::Rotators(int num_channels, std::vector<float> frequency,
window[i] = std::pow(kWindow, bw * kBandwidthMagic);
float windowM1 = 1.0f - window[i];
float f = frequency[i] * 2.0f * M_PI / sample_rate;
static const float full_scale_sine_db = exp(76.63936108268561);
static const float full_scale_sine_db = exp(76.639635259053421);
const float gainer = sqrt(full_scale_sine_db);
gain[i] = gainer * filter_gains[i] * pow(windowM1, 3.0);
rot[0][i] = float(std::cos(f));
Expand Down
6 changes: 3 additions & 3 deletions cpp/zimt/nsim.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -199,9 +199,9 @@ float HwyNSIM(const hwy::AlignedNDArray<float, 2>& a,
return Mul(delta_a, delta_b);
});
const Vec two = Set(d, 2.0);
const Vec C1 = Set(d, 131.86067981547336);
const Vec C3 = Set(d, 68.649258792691157);
const Vec C4 = Set(d, 27.590645775908353e-7);
const Vec C1 = Set(d, 130.53981769200561);
const Vec C3 = Set(d, 68.621068848124807);
const Vec C4 = Set(d, 1.9205364350341391e-05);
float nsim_sum = 0.0;
const Vec num_channels_vec = Set(d, num_channels);
const Vec zero = Zero(d);
Expand Down
4 changes: 2 additions & 2 deletions cpp/zimt/zimtohrli.h
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Original file line number Diff line number Diff line change
Expand Up @@ -285,10 +285,10 @@ struct Zimtohrli {
std::optional<CamFilterbank> cam_filterbank;

// The window in perceptual_sample_rate time steps when compting the NSIM.
size_t nsim_step_window = 8;
size_t nsim_step_window = 6;

// The window in channels when computing the NSIM.
size_t nsim_channel_window = 7;
size_t nsim_channel_window = 6; // TODO(jyrki): reduce further

// The window of the dynamic time warp that matches audio signals.
//
Expand Down
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