1 files changed, 114 insertions, 0 deletions
diff --git a/webrtc/modules/audio_processing/agc2/vad_with_level.cc b/webrtc/modules/audio_processing/agc2/vad_with_level.cc
new file mode 100644
index 0000000..3dbb557
--- /dev/null
+++ b/webrtc/modules/audio_processing/agc2/vad_with_level.cc
@@ -0,0 +1,114 @@
+/*
+ *  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/vad_with_level.h"
+
+#include <algorithm>
+#include <array>
+#include <cmath>
+
+#include "api/array_view.h"
+#include "common_audio/include/audio_util.h"
+#include "common_audio/resampler/include/push_resampler.h"
+#include "modules/audio_processing/agc2/agc2_common.h"
+#include "modules/audio_processing/agc2/rnn_vad/common.h"
+#include "modules/audio_processing/agc2/rnn_vad/features_extraction.h"
+#include "modules/audio_processing/agc2/rnn_vad/rnn.h"
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+namespace {
+
+using VoiceActivityDetector = VadLevelAnalyzer::VoiceActivityDetector;
+
+// Default VAD that combines a resampler and the RNN VAD.
+// Computes the speech probability on the first channel.
+class Vad : public VoiceActivityDetector {
+ public:
+  Vad() = default;
+  Vad(const Vad&) = delete;
+  Vad& operator=(const Vad&) = delete;
+  ~Vad() = default;
+
+  float ComputeProbability(AudioFrameView<const float> frame) override {
+    // The source number of channels is 1, because we always use the 1st
+    // channel.
+    resampler_.InitializeIfNeeded(
+        /*sample_rate_hz=*/static_cast<int>(frame.samples_per_channel() * 100),
+        rnn_vad::kSampleRate24kHz,
+        /*num_channels=*/1);
+
+    std::array<float, rnn_vad::kFrameSize10ms24kHz> work_frame;
+    // Feed the 1st channel to the resampler.
+    resampler_.Resample(frame.channel(0).data(), frame.samples_per_channel(),
+                        work_frame.data(), rnn_vad::kFrameSize10ms24kHz);
+
+    std::array<float, rnn_vad::kFeatureVectorSize> feature_vector;
+    const bool is_silence = features_extractor_.CheckSilenceComputeFeatures(
+        work_frame, feature_vector);
+    return rnn_vad_.ComputeVadProbability(feature_vector, is_silence);
+  }
+
+ private:
+  PushResampler<float> resampler_;
+  rnn_vad::FeaturesExtractor features_extractor_;
+  rnn_vad::RnnBasedVad rnn_vad_;
+};
+
+// Returns an updated version of `p_old` by using instant decay and the given
+// `attack` on a new VAD probability value `p_new`.
+float SmoothedVadProbability(float p_old, float p_new, float attack) {
+  RTC_DCHECK_GT(attack, 0.f);
+  RTC_DCHECK_LE(attack, 1.f);
+  if (p_new < p_old || attack == 1.f) {
+    // Instant decay (or no smoothing).
+    return p_new;
+  } else {
+    // Attack phase.
+    return attack * p_new + (1.f - attack) * p_old;
+  }
+}
+
+}  // namespace
+
+VadLevelAnalyzer::VadLevelAnalyzer()
+    : VadLevelAnalyzer(kDefaultSmoothedVadProbabilityAttack,
+                       std::make_unique<Vad>()) {}
+
+VadLevelAnalyzer::VadLevelAnalyzer(float vad_probability_attack)
+    : VadLevelAnalyzer(vad_probability_attack, std::make_unique<Vad>()) {}
+
+VadLevelAnalyzer::VadLevelAnalyzer(float vad_probability_attack,
+                                   std::unique_ptr<VoiceActivityDetector> vad)
+    : vad_(std::move(vad)), vad_probability_attack_(vad_probability_attack) {
+  RTC_DCHECK(vad_);
+}
+
+VadLevelAnalyzer::~VadLevelAnalyzer() = default;
+
+VadLevelAnalyzer::Result VadLevelAnalyzer::AnalyzeFrame(
+    AudioFrameView<const float> frame) {
+  // Compute levels.
+  float peak = 0.f;
+  float rms = 0.f;
+  for (const auto& x : frame.channel(0)) {
+    peak = std::max(std::fabs(x), peak);
+    rms += x * x;
+  }
+  // Compute smoothed speech probability.
+  vad_probability_ = SmoothedVadProbability(
+      /*p_old=*/vad_probability_, /*p_new=*/vad_->ComputeProbability(frame),
+      vad_probability_attack_);
+  return {vad_probability_,
+          FloatS16ToDbfs(std::sqrt(rms / frame.samples_per_channel())),
+          FloatS16ToDbfs(peak)};
+}
+
+}  // namespace webrtc