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Diffstat (limited to 'third_party/libwebrtc/modules/audio_processing/agc2/rnn_vad/spectral_features_internal.cc')
| -rw-r--r-- | third_party/libwebrtc/modules/audio_processing/agc2/rnn_vad/spectral_features_internal.cc | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/audio_processing/agc2/rnn_vad/spectral_features_internal.cc b/third_party/libwebrtc/modules/audio_processing/agc2/rnn_vad/spectral_features_internal.cc new file mode 100644 index 0000000000..a10b0f7ec9 --- /dev/null +++ b/third_party/libwebrtc/modules/audio_processing/agc2/rnn_vad/spectral_features_internal.cc @@ -0,0 +1,188 @@ +/* + * Copyright (c) 2018 The WebRTC project authors. All Rights Reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + +#include "modules/audio_processing/agc2/rnn_vad/spectral_features_internal.h" + +#include <algorithm> +#include <cmath> +#include <cstddef> + +#include "rtc_base/checks.h" +#include "rtc_base/numerics/safe_compare.h" + +namespace webrtc { +namespace rnn_vad { +namespace { + +// Weights for each FFT coefficient for each Opus band (Nyquist frequency +// excluded). The size of each band is specified in +// `kOpusScaleNumBins24kHz20ms`. +constexpr std::array<float, kFrameSize20ms24kHz / 2> kOpusBandWeights24kHz20ms = + {{ + 0.f, 0.25f, 0.5f, 0.75f, // Band 0 + 0.f, 0.25f, 0.5f, 0.75f, // Band 1 + 0.f, 0.25f, 0.5f, 0.75f, // Band 2 + 0.f, 0.25f, 0.5f, 0.75f, // Band 3 + 0.f, 0.25f, 0.5f, 0.75f, // Band 4 + 0.f, 0.25f, 0.5f, 0.75f, // Band 5 + 0.f, 0.25f, 0.5f, 0.75f, // Band 6 + 0.f, 0.25f, 0.5f, 0.75f, // Band 7 + 0.f, 0.125f, 0.25f, 0.375f, 0.5f, + 0.625f, 0.75f, 0.875f, // Band 8 + 0.f, 0.125f, 0.25f, 0.375f, 0.5f, + 0.625f, 0.75f, 0.875f, // Band 9 + 0.f, 0.125f, 0.25f, 0.375f, 0.5f, + 0.625f, 0.75f, 0.875f, // Band 10 + 0.f, 0.125f, 0.25f, 0.375f, 0.5f, + 0.625f, 0.75f, 0.875f, // Band 11 + 0.f, 0.0625f, 0.125f, 0.1875f, 0.25f, + 0.3125f, 0.375f, 0.4375f, 0.5f, 0.5625f, + 0.625f, 0.6875f, 0.75f, 0.8125f, 0.875f, + 0.9375f, // Band 12 + 0.f, 0.0625f, 0.125f, 0.1875f, 0.25f, + 0.3125f, 0.375f, 0.4375f, 0.5f, 0.5625f, + 0.625f, 0.6875f, 0.75f, 0.8125f, 0.875f, + 0.9375f, // Band 13 + 0.f, 0.0625f, 0.125f, 0.1875f, 0.25f, + 0.3125f, 0.375f, 0.4375f, 0.5f, 0.5625f, + 0.625f, 0.6875f, 0.75f, 0.8125f, 0.875f, + 0.9375f, // Band 14 + 0.f, 0.0416667f, 0.0833333f, 0.125f, 0.166667f, + 0.208333f, 0.25f, 0.291667f, 0.333333f, 0.375f, + 0.416667f, 0.458333f, 0.5f, 0.541667f, 0.583333f, + 0.625f, 0.666667f, 0.708333f, 0.75f, 0.791667f, + 0.833333f, 0.875f, 0.916667f, 0.958333f, // Band 15 + 0.f, 0.0416667f, 0.0833333f, 0.125f, 0.166667f, + 0.208333f, 0.25f, 0.291667f, 0.333333f, 0.375f, + 0.416667f, 0.458333f, 0.5f, 0.541667f, 0.583333f, + 0.625f, 0.666667f, 0.708333f, 0.75f, 0.791667f, + 0.833333f, 0.875f, 0.916667f, 0.958333f, // Band 16 + 0.f, 0.03125f, 0.0625f, 0.09375f, 0.125f, + 0.15625f, 0.1875f, 0.21875f, 0.25f, 0.28125f, + 0.3125f, 0.34375f, 0.375f, 0.40625f, 0.4375f, + 0.46875f, 0.5f, 0.53125f, 0.5625f, 0.59375f, + 0.625f, 0.65625f, 0.6875f, 0.71875f, 0.75f, + 0.78125f, 0.8125f, 0.84375f, 0.875f, 0.90625f, + 0.9375f, 0.96875f, // Band 17 + 0.f, 0.0208333f, 0.0416667f, 0.0625f, 0.0833333f, + 0.104167f, 0.125f, 0.145833f, 0.166667f, 0.1875f, + 0.208333f, 0.229167f, 0.25f, 0.270833f, 0.291667f, + 0.3125f, 0.333333f, 0.354167f, 0.375f, 0.395833f, + 0.416667f, 0.4375f, 0.458333f, 0.479167f, 0.5f, + 0.520833f, 0.541667f, 0.5625f, 0.583333f, 0.604167f, + 0.625f, 0.645833f, 0.666667f, 0.6875f, 0.708333f, + 0.729167f, 0.75f, 0.770833f, 0.791667f, 0.8125f, + 0.833333f, 0.854167f, 0.875f, 0.895833f, 0.916667f, + 0.9375f, 0.958333f, 0.979167f // Band 18 + }}; + +} // namespace + +SpectralCorrelator::SpectralCorrelator() + : weights_(kOpusBandWeights24kHz20ms.begin(), + kOpusBandWeights24kHz20ms.end()) {} + +SpectralCorrelator::~SpectralCorrelator() = default; + +void SpectralCorrelator::ComputeAutoCorrelation( + rtc::ArrayView<const float> x, + rtc::ArrayView<float, kOpusBands24kHz> auto_corr) const { + ComputeCrossCorrelation(x, x, auto_corr); +} + +void SpectralCorrelator::ComputeCrossCorrelation( + rtc::ArrayView<const float> x, + rtc::ArrayView<const float> y, + rtc::ArrayView<float, kOpusBands24kHz> cross_corr) const { + RTC_DCHECK_EQ(x.size(), kFrameSize20ms24kHz); + RTC_DCHECK_EQ(x.size(), y.size()); + RTC_DCHECK_EQ(x[1], 0.f) << "The Nyquist coefficient must be zeroed."; + RTC_DCHECK_EQ(y[1], 0.f) << "The Nyquist coefficient must be zeroed."; + constexpr auto kOpusScaleNumBins24kHz20ms = GetOpusScaleNumBins24kHz20ms(); + int k = 0; // Next Fourier coefficient index. + cross_corr[0] = 0.f; + for (int i = 0; i < kOpusBands24kHz - 1; ++i) { + cross_corr[i + 1] = 0.f; + for (int j = 0; j < kOpusScaleNumBins24kHz20ms[i]; ++j) { // Band size. + const float v = x[2 * k] * y[2 * k] + x[2 * k + 1] * y[2 * k + 1]; + const float tmp = weights_[k] * v; + cross_corr[i] += v - tmp; + cross_corr[i + 1] += tmp; + k++; + } + } + cross_corr[0] *= 2.f; // The first band only gets half contribution. + RTC_DCHECK_EQ(k, kFrameSize20ms24kHz / 2); // Nyquist coefficient never used. +} + +void ComputeSmoothedLogMagnitudeSpectrum( + rtc::ArrayView<const float> bands_energy, + rtc::ArrayView<float, kNumBands> log_bands_energy) { + RTC_DCHECK_LE(bands_energy.size(), kNumBands); + constexpr float kOneByHundred = 1e-2f; + constexpr float kLogOneByHundred = -2.f; + // Init. + float log_max = kLogOneByHundred; + float follow = kLogOneByHundred; + const auto smooth = [&log_max, &follow](float x) { + x = std::max(log_max - 7.f, std::max(follow - 1.5f, x)); + log_max = std::max(log_max, x); + follow = std::max(follow - 1.5f, x); + return x; + }; + // Smoothing over the bands for which the band energy is defined. + for (int i = 0; rtc::SafeLt(i, bands_energy.size()); ++i) { + log_bands_energy[i] = smooth(std::log10(kOneByHundred + bands_energy[i])); + } + // Smoothing over the remaining bands (zero energy). + for (int i = bands_energy.size(); i < kNumBands; ++i) { + log_bands_energy[i] = smooth(kLogOneByHundred); + } +} + +std::array<float, kNumBands * kNumBands> ComputeDctTable() { + std::array<float, kNumBands * kNumBands> dct_table; + const double k = std::sqrt(0.5); + for (int i = 0; i < kNumBands; ++i) { + for (int j = 0; j < kNumBands; ++j) + dct_table[i * kNumBands + j] = std::cos((i + 0.5) * j * kPi / kNumBands); + dct_table[i * kNumBands] *= k; + } + return dct_table; +} + +void ComputeDct(rtc::ArrayView<const float> in, + rtc::ArrayView<const float, kNumBands * kNumBands> dct_table, + rtc::ArrayView<float> out) { + // DCT scaling factor - i.e., sqrt(2 / kNumBands). + constexpr float kDctScalingFactor = 0.301511345f; + constexpr float kDctScalingFactorError = + kDctScalingFactor * kDctScalingFactor - + 2.f / static_cast<float>(kNumBands); + static_assert( + (kDctScalingFactorError >= 0.f && kDctScalingFactorError < 1e-1f) || + (kDctScalingFactorError < 0.f && kDctScalingFactorError > -1e-1f), + "kNumBands changed and kDctScalingFactor has not been updated."); + RTC_DCHECK_NE(in.data(), out.data()) << "In-place DCT is not supported."; + RTC_DCHECK_LE(in.size(), kNumBands); + RTC_DCHECK_LE(1, out.size()); + RTC_DCHECK_LE(out.size(), in.size()); + for (int i = 0; rtc::SafeLt(i, out.size()); ++i) { + out[i] = 0.f; + for (int j = 0; rtc::SafeLt(j, in.size()); ++j) { + out[i] += in[j] * dct_table[j * kNumBands + i]; + } + // TODO(bugs.webrtc.org/10480): Scaling factor in the DCT table. + out[i] *= kDctScalingFactor; + } +} + +} // namespace rnn_vad +} // namespace webrtc |