1 files changed, 172 insertions, 0 deletions
diff --git a/src/modules/audio_processing/level_estimator_impl.cc b/src/modules/audio_processing/level_estimator_impl.cc
new file mode 100644
index 0000000000..f127d4abde
--- /dev/null
+++ b/src/modules/audio_processing/level_estimator_impl.cc
@@ -0,0 +1,172 @@
+/*
+ *  Copyright (c) 2011 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 "level_estimator_impl.h"
+
+#include <assert.h>
+#include <math.h>
+#include <string.h>
+
+#include "audio_processing_impl.h"
+#include "audio_buffer.h"
+#include "critical_section_wrapper.h"
+
+namespace webrtc {
+namespace {
+
+const double kMaxSquaredLevel = 32768.0 * 32768.0;
+
+class Level {
+ public:
+  static const int kMinLevel = 127;
+
+  Level()
+    : sum_square_(0.0),
+      sample_count_(0) {}
+  ~Level() {}
+
+  void Init() {
+    sum_square_ = 0.0;
+    sample_count_ = 0;
+  }
+
+  void Process(int16_t* data, int length) {
+    assert(data != NULL);
+    assert(length > 0);
+    sum_square_ += SumSquare(data, length);
+    sample_count_ += length;
+  }
+
+  void ProcessMuted(int length) {
+    assert(length > 0);
+    sample_count_ += length;
+  }
+
+  int RMS() {
+    if (sample_count_ == 0 || sum_square_ == 0.0) {
+      Init();
+      return kMinLevel;
+    }
+
+    // Normalize by the max level.
+    double rms = sum_square_ / (sample_count_ * kMaxSquaredLevel);
+    // 20log_10(x^0.5) = 10log_10(x)
+    rms = 10 * log10(rms);
+    if (rms > 0)
+      rms = 0;
+    else if (rms < -kMinLevel)
+      rms = -kMinLevel;
+
+    rms = -rms;
+    Init();
+    return static_cast<int>(rms + 0.5);
+  }
+
+ private:
+  static double SumSquare(int16_t* data, int length) {
+    double sum_square = 0.0;
+    for (int i = 0; i < length; ++i) {
+      double data_d = static_cast<double>(data[i]);
+      sum_square += data_d * data_d;
+    }
+    return sum_square;
+  }
+
+  double sum_square_;
+  int sample_count_;
+};
+}  // namespace
+
+LevelEstimatorImpl::LevelEstimatorImpl(const AudioProcessingImpl* apm)
+  : ProcessingComponent(apm),
+    apm_(apm) {}
+
+LevelEstimatorImpl::~LevelEstimatorImpl() {}
+
+int LevelEstimatorImpl::ProcessStream(AudioBuffer* audio) {
+  if (!is_component_enabled()) {
+    return apm_->kNoError;
+  }
+
+  Level* level = static_cast<Level*>(handle(0));
+  if (audio->is_muted()) {
+    level->ProcessMuted(audio->samples_per_channel());
+    return apm_->kNoError;
+  }
+
+  int16_t* mixed_data = audio->data(0);
+  if (audio->num_channels() > 1) {
+    audio->CopyAndMix(1);
+    mixed_data = audio->mixed_data(0);
+  }
+
+  level->Process(mixed_data, audio->samples_per_channel());
+
+  return apm_->kNoError;
+}
+
+int LevelEstimatorImpl::Enable(bool enable) {
+  CriticalSectionScoped crit_scoped(*apm_->crit());
+  return EnableComponent(enable);
+}
+
+bool LevelEstimatorImpl::is_enabled() const {
+  return is_component_enabled();
+}
+
+int LevelEstimatorImpl::RMS() {
+  if (!is_component_enabled()) {
+    return apm_->kNotEnabledError;
+  }
+
+  Level* level = static_cast<Level*>(handle(0));
+  return level->RMS();
+}
+
+int LevelEstimatorImpl::get_version(char* version,
+                                    int version_len_bytes) const {
+  // An empty string is used to indicate no version information.
+  memset(version, 0, version_len_bytes);
+  return apm_->kNoError;
+}
+
+void* LevelEstimatorImpl::CreateHandle() const {
+  return new Level;
+}
+
+int LevelEstimatorImpl::DestroyHandle(void* handle) const {
+  assert(handle != NULL);
+  Level* level = static_cast<Level*>(handle);
+  delete level;
+  return apm_->kNoError;
+}
+
+int LevelEstimatorImpl::InitializeHandle(void* handle) const {
+  assert(handle != NULL);
+  Level* level = static_cast<Level*>(handle);
+  level->Init();
+
+  return apm_->kNoError;
+}
+
+int LevelEstimatorImpl::ConfigureHandle(void* /*handle*/) const {
+  return apm_->kNoError;
+}
+
+int LevelEstimatorImpl::num_handles_required() const {
+  return 1;
+}
+
+int LevelEstimatorImpl::GetHandleError(void* handle) const {
+  // The component has no detailed errors.
+  assert(handle != NULL);
+  return apm_->kUnspecifiedError;
+}
+}  // namespace webrtc