Avoid reporting 0 as input level when AudioProcessing zero out the audio data

content/renderer/media/webrtc_audio_capturer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/webrtc_audio_capturer.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "content/child/child_process.h"
 #include "content/renderer/media/audio_device_factory.h"
 #include "content/renderer/media/media_stream_audio_processor.h"
 #include "content/renderer/media/media_stream_audio_processor_options.h"
 #include "content/renderer/media/media_stream_audio_source.h"
 #include "content/renderer/media/webrtc_audio_device_impl.h"
 #include "content/renderer/media/webrtc_local_audio_track.h"
 #include "content/renderer/media/webrtc_logging.h"
 #include "media/audio/sample_rates.h"
 
 namespace content {
 
+namespace {
+
+// Method to check if any of the data in |audio_source| has energy.
+bool HasDataEnergy(const media::AudioBus& audio_source) {
+  for (int ch = 0; ch < audio_source.channels(); ++ch) {
+    const float* channel_ptr = audio_source.channel(ch);
+    for (int frame = 0; frame < audio_source.frames(); ++frame) {
+      if (channel_ptr[frame] != 0)
+        return true;
+    }
+  }
+
+  // All the data is zero.
+  return false;
+}
+
+}  // namespace
+
 // Reference counted container of WebRtcLocalAudioTrack delegate.
 // TODO(xians): Switch to MediaStreamAudioSinkOwner.
 class WebRtcAudioCapturer::TrackOwner
     : public base::RefCountedThreadSafe<WebRtcAudioCapturer::TrackOwner> {
  public:
   explicit TrackOwner(WebRtcLocalAudioTrack* track)
       : delegate_(track) {}
 
   void Capture(const int16* audio_data,
                base::TimeDelta delay,
                double volume,
                bool key_pressed,
-               bool need_audio_processing) {
+               bool need_audio_processing,
+               bool force_report_nonzero_energy) {
     base::AutoLock lock(lock_);
     if (delegate_) {
       delegate_->Capture(audio_data,
                          delay,
                          volume,
                          key_pressed,
-                         need_audio_processing);
+                         need_audio_processing,
+                         force_report_nonzero_energy);
     }
   }
 
   void OnSetFormat(const media::AudioParameters& params) {
     base::AutoLock lock(lock_);
     if (delegate_)
       delegate_->OnSetFormat(params);
   }
 
   void SetAudioProcessor(
@@ skipping 426 matching lines @@
 
   // Notify the tracks on when the format changes. This will do nothing if
   // |tracks_to_notify_format| is empty.
   media::AudioParameters output_params = audio_processor_->OutputFormat();
   for (TrackList::ItemList::const_iterator it = tracks_to_notify_format.begin();
        it != tracks_to_notify_format.end(); ++it) {
     (*it)->OnSetFormat(output_params);
     (*it)->SetAudioProcessor(audio_processor_);
   }
 
+  // Figure out if the pre-processed data has any energy or not, the
+  // information will be passed to the track to force the calculator
+  // to report energy in case the post-processed data is zeroed by the audio
+  // processing.
+  const bool force_report_nonzero_energy = HasDataEnergy(*audio_source);
+
   // Push the data to the processor for processing.
   audio_processor_->PushCaptureData(audio_source);
 
   // Process and consume the data in the processor until there is not enough
   // data in the processor.
   int16* output = NULL;
   int new_volume = 0;
   while (audio_processor_->ProcessAndConsumeData(
       audio_delay, current_volume, key_pressed, &new_volume, &output)) {
     // Feed the post-processed data to the tracks.
     for (TrackList::ItemList::const_iterator it = tracks.begin();
          it != tracks.end(); ++it) {
       (*it)->Capture(output, audio_delay, current_volume, key_pressed,
-                     need_audio_processing);
+                     need_audio_processing, force_report_nonzero_energy);
     }
 
     if (new_volume) {
       SetVolume(new_volume);
 
       // Update the |current_volume| to avoid passing the old volume to AGC.
       current_volume = new_volume;
     }
   }
 }
@@ skipping 59 matching lines @@
 
 void WebRtcAudioCapturer::SetCapturerSourceForTesting(
     const scoped_refptr<media::AudioCapturerSource>& source,
     media::AudioParameters params) {
   // Create a new audio stream as source which uses the new source.
   SetCapturerSource(source, params.channel_layout(),
                     static_cast<float>(params.sample_rate()));
 }
 
 }  // namespace content