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354 lines
12 KiB
C++
354 lines
12 KiB
C++
/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/modules/audio_coding/neteq/dsp_helper.h"
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#include <assert.h>
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#include <string.h> // Access to memset.
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#include <algorithm> // Access to min, max.
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#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
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namespace webrtc {
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// Table of constants used in method DspHelper::ParabolicFit().
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const int16_t DspHelper::kParabolaCoefficients[17][3] = {
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{ 120, 32, 64 },
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{ 140, 44, 75 },
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{ 150, 50, 80 },
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{ 160, 57, 85 },
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{ 180, 72, 96 },
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{ 200, 89, 107 },
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{ 210, 98, 112 },
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{ 220, 108, 117 },
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{ 240, 128, 128 },
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{ 260, 150, 139 },
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{ 270, 162, 144 },
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{ 280, 174, 149 },
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{ 300, 200, 160 },
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{ 320, 228, 171 },
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{ 330, 242, 176 },
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{ 340, 257, 181 },
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{ 360, 288, 192 } };
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// Filter coefficients used when downsampling from the indicated sample rates
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// (8, 16, 32, 48 kHz) to 4 kHz. Coefficients are in Q12. The corresponding Q0
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// values are provided in the comments before each array.
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// Q0 values: {0.3, 0.4, 0.3}.
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const int16_t DspHelper::kDownsample8kHzTbl[3] = { 1229, 1638, 1229 };
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// Q0 values: {0.15, 0.2, 0.3, 0.2, 0.15}.
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const int16_t DspHelper::kDownsample16kHzTbl[5] = { 614, 819, 1229, 819, 614 };
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// Q0 values: {0.1425, 0.1251, 0.1525, 0.1628, 0.1525, 0.1251, 0.1425}.
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const int16_t DspHelper::kDownsample32kHzTbl[7] = {
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584, 512, 625, 667, 625, 512, 584 };
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// Q0 values: {0.2487, 0.0952, 0.1042, 0.1074, 0.1042, 0.0952, 0.2487}.
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const int16_t DspHelper::kDownsample48kHzTbl[7] = {
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1019, 390, 427, 440, 427, 390, 1019 };
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int DspHelper::RampSignal(const int16_t* input,
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size_t length,
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int factor,
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int increment,
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int16_t* output) {
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int factor_q20 = (factor << 6) + 32;
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// TODO(hlundin): Add 32 to factor_q20 when converting back to Q14?
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for (size_t i = 0; i < length; ++i) {
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output[i] = (factor * input[i] + 8192) >> 14;
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factor_q20 += increment;
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factor_q20 = std::max(factor_q20, 0); // Never go negative.
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factor = std::min(factor_q20 >> 6, 16384);
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}
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return factor;
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}
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int DspHelper::RampSignal(int16_t* signal,
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size_t length,
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int factor,
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int increment) {
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return RampSignal(signal, length, factor, increment, signal);
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}
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int DspHelper::RampSignal(AudioMultiVector* signal,
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size_t start_index,
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size_t length,
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int factor,
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int increment) {
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assert(start_index + length <= signal->Size());
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if (start_index + length > signal->Size()) {
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// Wrong parameters. Do nothing and return the scale factor unaltered.
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return factor;
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}
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int end_factor = 0;
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// Loop over the channels, starting at the same |factor| each time.
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for (size_t channel = 0; channel < signal->Channels(); ++channel) {
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end_factor =
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RampSignal(&(*signal)[channel][start_index], length, factor, increment);
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}
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return end_factor;
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}
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void DspHelper::PeakDetection(int16_t* data, int data_length,
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int num_peaks, int fs_mult,
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int* peak_index, int16_t* peak_value) {
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int16_t min_index = 0;
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int16_t max_index = 0;
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for (int i = 0; i <= num_peaks - 1; i++) {
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if (num_peaks == 1) {
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// Single peak. The parabola fit assumes that an extra point is
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// available; worst case it gets a zero on the high end of the signal.
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// TODO(hlundin): This can potentially get much worse. It breaks the
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// API contract, that the length of |data| is |data_length|.
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data_length++;
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}
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peak_index[i] = WebRtcSpl_MaxIndexW16(data, data_length - 1);
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if (i != num_peaks - 1) {
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min_index = std::max(0, peak_index[i] - 2);
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max_index = std::min(data_length - 1, peak_index[i] + 2);
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}
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if ((peak_index[i] != 0) && (peak_index[i] != (data_length - 2))) {
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ParabolicFit(&data[peak_index[i] - 1], fs_mult, &peak_index[i],
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&peak_value[i]);
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} else {
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if (peak_index[i] == data_length - 2) {
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if (data[peak_index[i]] > data[peak_index[i] + 1]) {
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ParabolicFit(&data[peak_index[i] - 1], fs_mult, &peak_index[i],
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&peak_value[i]);
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} else if (data[peak_index[i]] <= data[peak_index[i] + 1]) {
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// Linear approximation.
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peak_value[i] = (data[peak_index[i]] + data[peak_index[i] + 1]) >> 1;
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peak_index[i] = (peak_index[i] * 2 + 1) * fs_mult;
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}
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} else {
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peak_value[i] = data[peak_index[i]];
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peak_index[i] = peak_index[i] * 2 * fs_mult;
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}
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}
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if (i != num_peaks - 1) {
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memset(&data[min_index], 0,
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sizeof(data[0]) * (max_index - min_index + 1));
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}
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}
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}
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void DspHelper::ParabolicFit(int16_t* signal_points, int fs_mult,
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int* peak_index, int16_t* peak_value) {
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uint16_t fit_index[13];
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if (fs_mult == 1) {
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fit_index[0] = 0;
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fit_index[1] = 8;
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fit_index[2] = 16;
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} else if (fs_mult == 2) {
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fit_index[0] = 0;
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fit_index[1] = 4;
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fit_index[2] = 8;
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fit_index[3] = 12;
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fit_index[4] = 16;
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} else if (fs_mult == 4) {
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fit_index[0] = 0;
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fit_index[1] = 2;
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fit_index[2] = 4;
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fit_index[3] = 6;
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fit_index[4] = 8;
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fit_index[5] = 10;
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fit_index[6] = 12;
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fit_index[7] = 14;
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fit_index[8] = 16;
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} else {
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fit_index[0] = 0;
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fit_index[1] = 1;
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fit_index[2] = 3;
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fit_index[3] = 4;
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fit_index[4] = 5;
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fit_index[5] = 7;
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fit_index[6] = 8;
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fit_index[7] = 9;
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fit_index[8] = 11;
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fit_index[9] = 12;
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fit_index[10] = 13;
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fit_index[11] = 15;
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fit_index[12] = 16;
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}
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// num = -3 * signal_points[0] + 4 * signal_points[1] - signal_points[2];
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// den = signal_points[0] - 2 * signal_points[1] + signal_points[2];
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int32_t num = (signal_points[0] * -3) + (signal_points[1] * 4)
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- signal_points[2];
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int32_t den = signal_points[0] + (signal_points[1] * -2) + signal_points[2];
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int32_t temp = num * 120;
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int flag = 1;
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int16_t stp = kParabolaCoefficients[fit_index[fs_mult]][0]
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- kParabolaCoefficients[fit_index[fs_mult - 1]][0];
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int16_t strt = (kParabolaCoefficients[fit_index[fs_mult]][0]
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+ kParabolaCoefficients[fit_index[fs_mult - 1]][0]) / 2;
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int16_t lmt;
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if (temp < -den * strt) {
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lmt = strt - stp;
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while (flag) {
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if ((flag == fs_mult) || (temp > -den * lmt)) {
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*peak_value = (den * kParabolaCoefficients[fit_index[fs_mult - flag]][1]
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+ num * kParabolaCoefficients[fit_index[fs_mult - flag]][2]
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+ signal_points[0] * 256) / 256;
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*peak_index = *peak_index * 2 * fs_mult - flag;
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flag = 0;
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} else {
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flag++;
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lmt -= stp;
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}
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}
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} else if (temp > -den * (strt + stp)) {
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lmt = strt + 2 * stp;
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while (flag) {
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if ((flag == fs_mult) || (temp < -den * lmt)) {
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int32_t temp_term_1 =
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den * kParabolaCoefficients[fit_index[fs_mult+flag]][1];
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int32_t temp_term_2 =
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num * kParabolaCoefficients[fit_index[fs_mult+flag]][2];
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int32_t temp_term_3 = signal_points[0] * 256;
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*peak_value = (temp_term_1 + temp_term_2 + temp_term_3) / 256;
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*peak_index = *peak_index * 2 * fs_mult + flag;
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flag = 0;
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} else {
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flag++;
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lmt += stp;
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}
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}
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} else {
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*peak_value = signal_points[1];
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*peak_index = *peak_index * 2 * fs_mult;
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}
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}
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int DspHelper::MinDistortion(const int16_t* signal, int min_lag,
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int max_lag, int length,
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int32_t* distortion_value) {
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int best_index = -1;
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int32_t min_distortion = WEBRTC_SPL_WORD32_MAX;
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for (int i = min_lag; i <= max_lag; i++) {
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int32_t sum_diff = 0;
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const int16_t* data1 = signal;
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const int16_t* data2 = signal - i;
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for (int j = 0; j < length; j++) {
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sum_diff += WEBRTC_SPL_ABS_W32(data1[j] - data2[j]);
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}
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// Compare with previous minimum.
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if (sum_diff < min_distortion) {
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min_distortion = sum_diff;
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best_index = i;
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}
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}
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*distortion_value = min_distortion;
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return best_index;
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}
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void DspHelper::CrossFade(const int16_t* input1, const int16_t* input2,
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size_t length, int16_t* mix_factor,
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int16_t factor_decrement, int16_t* output) {
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int16_t factor = *mix_factor;
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int16_t complement_factor = 16384 - factor;
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for (size_t i = 0; i < length; i++) {
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output[i] =
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(factor * input1[i] + complement_factor * input2[i] + 8192) >> 14;
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factor -= factor_decrement;
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complement_factor += factor_decrement;
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}
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*mix_factor = factor;
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}
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void DspHelper::UnmuteSignal(const int16_t* input, size_t length,
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int16_t* factor, int16_t increment,
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int16_t* output) {
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uint16_t factor_16b = *factor;
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int32_t factor_32b = (static_cast<int32_t>(factor_16b) << 6) + 32;
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for (size_t i = 0; i < length; i++) {
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output[i] = (factor_16b * input[i] + 8192) >> 14;
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factor_32b = std::max(factor_32b + increment, 0);
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factor_16b = std::min(16384, factor_32b >> 6);
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}
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*factor = factor_16b;
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}
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void DspHelper::MuteSignal(int16_t* signal, int16_t mute_slope, size_t length) {
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int32_t factor = (16384 << 6) + 32;
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for (size_t i = 0; i < length; i++) {
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signal[i] = ((factor >> 6) * signal[i] + 8192) >> 14;
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factor -= mute_slope;
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}
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}
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int DspHelper::DownsampleTo4kHz(const int16_t* input, size_t input_length,
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int output_length, int input_rate_hz,
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bool compensate_delay, int16_t* output) {
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// Set filter parameters depending on input frequency.
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// NOTE: The phase delay values are wrong compared to the true phase delay
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// of the filters. However, the error is preserved (through the +1 term) for
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// consistency.
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const int16_t* filter_coefficients; // Filter coefficients.
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int16_t filter_length; // Number of coefficients.
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int16_t filter_delay; // Phase delay in samples.
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int16_t factor; // Conversion rate (inFsHz / 8000).
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switch (input_rate_hz) {
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case 8000: {
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filter_length = 3;
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factor = 2;
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filter_coefficients = kDownsample8kHzTbl;
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filter_delay = 1 + 1;
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break;
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}
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case 16000: {
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filter_length = 5;
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factor = 4;
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filter_coefficients = kDownsample16kHzTbl;
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filter_delay = 2 + 1;
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break;
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}
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case 32000: {
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filter_length = 7;
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factor = 8;
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filter_coefficients = kDownsample32kHzTbl;
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filter_delay = 3 + 1;
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break;
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}
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case 48000: {
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filter_length = 7;
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factor = 12;
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filter_coefficients = kDownsample48kHzTbl;
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filter_delay = 3 + 1;
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break;
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}
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default: {
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assert(false);
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return -1;
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}
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}
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if (!compensate_delay) {
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// Disregard delay compensation.
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filter_delay = 0;
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}
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// Returns -1 if input signal is too short; 0 otherwise.
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return WebRtcSpl_DownsampleFast(
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&input[filter_length - 1], static_cast<int>(input_length) -
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(filter_length - 1), output, output_length, filter_coefficients,
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filter_length, factor, filter_delay);
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}
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} // namespace webrtc
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