Rename neteq4 folder to neteq

Keep the old neteq4/audio_decoder_unittests.isolate while waiting for
a hard-coded reference to change.

This CL effectively reverts r6257 "Rename neteq4 folder to neteq".

BUG=2996
TBR=tina.legrand@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/21629004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6367 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_coding/neteq/background_noise.cc

@@ -0,0 +1,260 @@
+/*
+ *  Copyright (c) 2012 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 "webrtc/modules/audio_coding/neteq/background_noise.h"
+
+#include <assert.h>
+#include <string.h>  // memcpy
+
+#include <algorithm>  // min, max
+
+#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
+#include "webrtc/modules/audio_coding/neteq/audio_multi_vector.h"
+#include "webrtc/modules/audio_coding/neteq/post_decode_vad.h"
+
+namespace webrtc {
+
+BackgroundNoise::BackgroundNoise(size_t num_channels)
+    : num_channels_(num_channels),
+      channel_parameters_(new ChannelParameters[num_channels_]),
+      mode_(kBgnOn) {
+  Reset();
+}
+
+BackgroundNoise::~BackgroundNoise() {}
+
+void BackgroundNoise::Reset() {
+  initialized_ = false;
+  for (size_t channel = 0; channel < num_channels_; ++channel) {
+    channel_parameters_[channel].Reset();
+  }
+  // Keep _bgnMode as it is.
+}
+
+void BackgroundNoise::Update(const AudioMultiVector& input,
+                             const PostDecodeVad& vad) {
+  if (vad.running() && vad.active_speech()) {
+    // Do not update the background noise parameters if we know that the signal
+    // is active speech.
+    return;
+  }
+
+  int32_t auto_correlation[kMaxLpcOrder + 1];
+  int16_t fiter_output[kMaxLpcOrder + kResidualLength];
+  int16_t reflection_coefficients[kMaxLpcOrder];
+  int16_t lpc_coefficients[kMaxLpcOrder + 1];
+
+  for (size_t channel_ix = 0; channel_ix < num_channels_; ++channel_ix) {
+    ChannelParameters& parameters = channel_parameters_[channel_ix];
+    int16_t temp_signal_array[kVecLen + kMaxLpcOrder] = {0};
+    int16_t* temp_signal = &temp_signal_array[kMaxLpcOrder];
+    memcpy(temp_signal,
+           &input[channel_ix][input.Size() - kVecLen],
+           sizeof(int16_t) * kVecLen);
+
+    int32_t sample_energy = CalculateAutoCorrelation(temp_signal, kVecLen,
+                                                     auto_correlation);
+
+    if ((!vad.running() &&
+        sample_energy < parameters.energy_update_threshold) ||
+        (vad.running() && !vad.active_speech())) {
+      // Generate LPC coefficients.
+      if (auto_correlation[0] > 0) {
+        // Regardless of whether the filter is actually updated or not,
+        // update energy threshold levels, since we have in fact observed
+        // a low energy signal.
+        if (sample_energy < parameters.energy_update_threshold) {
+          // Never go under 1.0 in average sample energy.
+          parameters.energy_update_threshold = std::max(sample_energy, 1);
+          parameters.low_energy_update_threshold = 0;
+        }
+
+        // Only update BGN if filter is stable, i.e., if return value from
+        // Levinson-Durbin function is 1.
+        if (WebRtcSpl_LevinsonDurbin(auto_correlation, lpc_coefficients,
+                                     reflection_coefficients,
+                                     kMaxLpcOrder) != 1) {
+          return;
+        }
+      } else {
+        // Center value in auto-correlation is not positive. Do not update.
+        return;
+      }
+
+      // Generate the CNG gain factor by looking at the energy of the residual.
+      WebRtcSpl_FilterMAFastQ12(temp_signal + kVecLen - kResidualLength,
+                                fiter_output, lpc_coefficients,
+                                kMaxLpcOrder + 1, kResidualLength);
+      int32_t residual_energy = WebRtcSpl_DotProductWithScale(fiter_output,
+                                                              fiter_output,
+                                                              kResidualLength,
+                                                              0);
+
+      // Check spectral flatness.
+      // Comparing the residual variance with the input signal variance tells
+      // if the spectrum is flat or not.
+      // If 20 * residual_energy >= sample_energy << 6, the spectrum is flat
+      // enough.  Also ensure that the energy is non-zero.
+      if ((residual_energy * 20 >= (sample_energy << 6)) &&
+          (sample_energy > 0)) {
+        // Spectrum is flat enough; save filter parameters.
+        // |temp_signal| + |kVecLen| - |kMaxLpcOrder| points at the first of the
+        // |kMaxLpcOrder| samples in the residual signal, which will form the
+        // filter state for the next noise generation.
+        SaveParameters(channel_ix, lpc_coefficients,
+                       temp_signal + kVecLen - kMaxLpcOrder, sample_energy,
+                       residual_energy);
+      }
+    } else {
+      // Will only happen if post-decode VAD is disabled and |sample_energy| is
+      // not low enough. Increase the threshold for update so that it increases
+      // by a factor 4 in 4 seconds.
+      IncrementEnergyThreshold(channel_ix, sample_energy);
+    }
+  }
+  return;
+}
+
+int32_t BackgroundNoise::Energy(size_t channel) const {
+  assert(channel < num_channels_);
+  return channel_parameters_[channel].energy;
+}
+
+void BackgroundNoise::SetMuteFactor(size_t channel, int16_t value) {
+  assert(channel < num_channels_);
+  channel_parameters_[channel].mute_factor = value;
+}
+
+int16_t BackgroundNoise::MuteFactor(size_t channel) const {
+  assert(channel < num_channels_);
+  return channel_parameters_[channel].mute_factor;
+}
+
+const int16_t* BackgroundNoise::Filter(size_t channel) const {
+  assert(channel < num_channels_);
+  return channel_parameters_[channel].filter;
+}
+
+const int16_t* BackgroundNoise::FilterState(size_t channel) const {
+  assert(channel < num_channels_);
+  return channel_parameters_[channel].filter_state;
+}
+
+void BackgroundNoise::SetFilterState(size_t channel, const int16_t* input,
+                                     size_t length) {
+  assert(channel < num_channels_);
+  length = std::min(length, static_cast<size_t>(kMaxLpcOrder));
+  memcpy(channel_parameters_[channel].filter_state, input,
+         length * sizeof(int16_t));
+}
+
+int16_t BackgroundNoise::Scale(size_t channel) const {
+  assert(channel < num_channels_);
+  return channel_parameters_[channel].scale;
+}
+int16_t BackgroundNoise::ScaleShift(size_t channel) const {
+  assert(channel < num_channels_);
+  return channel_parameters_[channel].scale_shift;
+}
+
+int32_t BackgroundNoise::CalculateAutoCorrelation(
+    const int16_t* signal, int length, int32_t* auto_correlation) const {
+  int16_t signal_max = WebRtcSpl_MaxAbsValueW16(signal, length);
+  int correlation_scale = kLogVecLen -
+      WebRtcSpl_NormW32(signal_max * signal_max);
+  correlation_scale = std::max(0, correlation_scale);
+
+  static const int kCorrelationStep = -1;
+  WebRtcSpl_CrossCorrelation(auto_correlation, signal, signal, length,
+                             kMaxLpcOrder + 1, correlation_scale,
+                             kCorrelationStep);
+
+  // Number of shifts to normalize energy to energy/sample.
+  int energy_sample_shift = kLogVecLen - correlation_scale;
+  return auto_correlation[0] >> energy_sample_shift;
+}
+
+void BackgroundNoise::IncrementEnergyThreshold(size_t channel,
+                                               int32_t sample_energy) {
+  // TODO(hlundin): Simplify the below threshold update. What this code
+  // does is simply "threshold += (increment * threshold) >> 16", but due
+  // to the limited-width operations, it is not exactly the same. The
+  // difference should be inaudible, but bit-exactness would not be
+  // maintained.
+  assert(channel < num_channels_);
+  ChannelParameters& parameters = channel_parameters_[channel];
+  int32_t temp_energy =
+      WEBRTC_SPL_MUL_16_16_RSFT(kThresholdIncrement,
+                                parameters.low_energy_update_threshold, 16);
+  temp_energy += kThresholdIncrement *
+      (parameters.energy_update_threshold & 0xFF);
+  temp_energy += (kThresholdIncrement *
+      ((parameters.energy_update_threshold>>8) & 0xFF)) << 8;
+  parameters.low_energy_update_threshold += temp_energy;
+
+  parameters.energy_update_threshold += kThresholdIncrement *
+      (parameters.energy_update_threshold>>16);
+  parameters.energy_update_threshold +=
+      parameters.low_energy_update_threshold >> 16;
+  parameters.low_energy_update_threshold =
+      parameters.low_energy_update_threshold & 0x0FFFF;
+
+  // Update maximum energy.
+  // Decrease by a factor 1/1024 each time.
+  parameters.max_energy = parameters.max_energy -
+      (parameters.max_energy >> 10);
+  if (sample_energy > parameters.max_energy) {
+    parameters.max_energy = sample_energy;
+  }
+
+  // Set |energy_update_threshold| to no less than 60 dB lower than
+  // |max_energy_|. Adding 524288 assures proper rounding.
+  int32_t energy_update_threshold = (parameters.max_energy + 524288) >> 20;
+  if (energy_update_threshold > parameters.energy_update_threshold) {
+    parameters.energy_update_threshold = energy_update_threshold;
+  }
+}
+
+void BackgroundNoise::SaveParameters(size_t channel,
+                                     const int16_t* lpc_coefficients,
+                                     const int16_t* filter_state,
+                                     int32_t sample_energy,
+                                     int32_t residual_energy) {
+  assert(channel < num_channels_);
+  ChannelParameters& parameters = channel_parameters_[channel];
+  memcpy(parameters.filter, lpc_coefficients,
+         (kMaxLpcOrder+1) * sizeof(int16_t));
+  memcpy(parameters.filter_state, filter_state,
+         kMaxLpcOrder * sizeof(int16_t));
+  // Save energy level and update energy threshold levels.
+  // Never get under 1.0 in average sample energy.
+  parameters.energy = std::max(sample_energy, 1);
+  parameters.energy_update_threshold = parameters.energy;
+  parameters.low_energy_update_threshold = 0;
+
+  // Normalize residual_energy to 29 or 30 bits before sqrt.
+  int norm_shift = WebRtcSpl_NormW32(residual_energy) - 1;
+  if (norm_shift & 0x1) {
+    norm_shift -= 1;  // Even number of shifts required.
+  }
+  assert(norm_shift >= 0);  // Should always be positive.
+  residual_energy = residual_energy << norm_shift;
+
+  // Calculate scale and shift factor.
+  parameters.scale = WebRtcSpl_SqrtFloor(residual_energy);
+  // Add 13 to the |scale_shift_|, since the random numbers table is in
+  // Q13.
+  // TODO(hlundin): Move the "13" to where the |scale_shift_| is used?
+  parameters.scale_shift = 13 + ((kLogResidualLength + norm_shift) / 2);
+
+  initialized_ = true;
+}
+
+}  // namespace webrtc