content/renderer/media/webrtc_audio_capturer.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/renderer/media/webrtc_audio_capturer.h"
   6
   7 #include "base/bind.h"
   8 #include "base/logging.h"
   9 #include "base/metrics/histogram.h"
  10 #include "base/strings/string_util.h"
  11 #include "base/strings/stringprintf.h"
  12 #include "content/child/child_process.h"
  13 #include "content/renderer/media/audio_device_factory.h"
  14 #include "content/renderer/media/media_stream_audio_processor.h"
  15 #include "content/renderer/media/media_stream_audio_processor_options.h"
  16 #include "content/renderer/media/media_stream_audio_source.h"
  17 #include "content/renderer/media/media_stream_constraints_util.h"
  18 #include "content/renderer/media/webrtc_audio_device_impl.h"
  19 #include "content/renderer/media/webrtc_local_audio_track.h"
  20 #include "content/renderer/media/webrtc_logging.h"
  21 #include "media/audio/sample_rates.h"
  22
  23 namespace content {
  24
  25 namespace {
  26
  27 // Audio buffer sizes are specified in milliseconds.
  28 const char kAudioLatency[] = "latencyMs";
  29 const int kMinAudioLatencyMs = 0;
  30 const int kMaxAudioLatencyMs = 10000;
  31
  32 // Method to check if any of the data in |audio_source| has energy.
  33 bool HasDataEnergy(const media::AudioBus& audio_source) {
  34   for (int ch = 0; ch < audio_source.channels(); ++ch) {
  35     const float* channel_ptr = audio_source.channel(ch);
  36     for (int frame = 0; frame < audio_source.frames(); ++frame) {
  37       if (channel_ptr[frame] != 0)
  38         return true;
  39     }
  40   }
  41
  42   // All the data is zero.
  43   return false;
  44 }
  45
  46 }  // namespace
  47
  48 // Reference counted container of WebRtcLocalAudioTrack delegate.
  49 // TODO(xians): Switch to MediaStreamAudioSinkOwner.
  50 class WebRtcAudioCapturer::TrackOwner
  51     : public base::RefCountedThreadSafe<WebRtcAudioCapturer::TrackOwner> {
  52  public:
  53   explicit TrackOwner(WebRtcLocalAudioTrack* track)
  54       : delegate_(track) {}
  55
  56   void Capture(const media::AudioBus& audio_bus,
  57                base::TimeTicks estimated_capture_time,
  58                bool force_report_nonzero_energy) {
  59     base::AutoLock lock(lock_);
  60     if (delegate_) {
  61       delegate_->Capture(audio_bus,
  62                          estimated_capture_time,
  63                          force_report_nonzero_energy);
  64     }
  65   }
  66
  67   void OnSetFormat(const media::AudioParameters& params) {
  68     base::AutoLock lock(lock_);
  69     if (delegate_)
  70       delegate_->OnSetFormat(params);
  71   }
  72
  73   void SetAudioProcessor(
  74       const scoped_refptr<MediaStreamAudioProcessor>& processor) {
  75     base::AutoLock lock(lock_);
  76     if (delegate_)
  77       delegate_->SetAudioProcessor(processor);
  78   }
  79
  80   void Reset() {
  81     base::AutoLock lock(lock_);
  82     delegate_ = NULL;
  83   }
  84
  85   void Stop() {
  86     base::AutoLock lock(lock_);
  87     DCHECK(delegate_);
  88
  89     // This can be reentrant so reset |delegate_| before calling out.
  90     WebRtcLocalAudioTrack* temp = delegate_;
  91     delegate_ = NULL;
  92     temp->Stop();
  93   }
  94
  95   // Wrapper which allows to use std::find_if() when adding and removing
  96   // sinks to/from the list.
  97   struct TrackWrapper {
  98     explicit TrackWrapper(WebRtcLocalAudioTrack* track) : track_(track) {}
  99     bool operator()(
 100         const scoped_refptr<WebRtcAudioCapturer::TrackOwner>& owner) const {
 101       return owner->IsEqual(track_);
 102     }
 103     WebRtcLocalAudioTrack* track_;
 104   };
 105
 106  protected:
 107   virtual ~TrackOwner() {}
 108
 109  private:
 110   friend class base::RefCountedThreadSafe<WebRtcAudioCapturer::TrackOwner>;
 111
 112   bool IsEqual(const WebRtcLocalAudioTrack* other) const {
 113     base::AutoLock lock(lock_);
 114     return (other == delegate_);
 115   }
 116
 117   // Do NOT reference count the |delegate_| to avoid cyclic reference counting.
 118   WebRtcLocalAudioTrack* delegate_;
 119   mutable base::Lock lock_;
 120
 121   DISALLOW_COPY_AND_ASSIGN(TrackOwner);
 122 };
 123
 124 // static
 125 scoped_refptr<WebRtcAudioCapturer> WebRtcAudioCapturer::CreateCapturer(
 126     int render_frame_id,
 127     const StreamDeviceInfo& device_info,
 128     const blink::WebMediaConstraints& constraints,
 129     WebRtcAudioDeviceImpl* audio_device,
 130     MediaStreamAudioSource* audio_source) {
 131   scoped_refptr<WebRtcAudioCapturer> capturer = new WebRtcAudioCapturer(
 132       render_frame_id, device_info, constraints, audio_device, audio_source);
 133   if (capturer->Initialize())
 134     return capturer;
 135
 136   return NULL;
 137 }
 138
 139 bool WebRtcAudioCapturer::Initialize() {
 140   DCHECK(thread_checker_.CalledOnValidThread());
 141   DVLOG(1) << "WebRtcAudioCapturer::Initialize()";
 142   WebRtcLogMessage(base::StringPrintf(
 143       "WAC::Initialize. render_frame_id=%d"
 144       ", channel_layout=%d, sample_rate=%d, buffer_size=%d"
 145       ", session_id=%d, paired_output_sample_rate=%d"
 146       ", paired_output_frames_per_buffer=%d, effects=%d. ",
 147       render_frame_id_, device_info_.device.input.channel_layout,
 148       device_info_.device.input.sample_rate,
 149       device_info_.device.input.frames_per_buffer, device_info_.session_id,
 150       device_info_.device.matched_output.sample_rate,
 151       device_info_.device.matched_output.frames_per_buffer,
 152       device_info_.device.input.effects));
 153
 154   if (render_frame_id_ == -1) {
 155     // Return true here to allow injecting a new source via
 156     // SetCapturerSourceForTesting() at a later state.
 157     return true;
 158   }
 159
 160   MediaAudioConstraints audio_constraints(constraints_,
 161                                           device_info_.device.input.effects);
 162   if (!audio_constraints.IsValid())
 163     return false;
 164
 165   media::ChannelLayout channel_layout = static_cast<media::ChannelLayout>(
 166       device_info_.device.input.channel_layout);
 167
 168   // If KEYBOARD_MIC effect is set, change the layout to the corresponding
 169   // layout that includes the keyboard mic.
 170   if ((device_info_.device.input.effects &
 171           media::AudioParameters::KEYBOARD_MIC) &&
 172       audio_constraints.GetProperty(
 173           MediaAudioConstraints::kGoogExperimentalNoiseSuppression)) {
 174     if (channel_layout == media::CHANNEL_LAYOUT_STEREO) {
 175       channel_layout = media::CHANNEL_LAYOUT_STEREO_AND_KEYBOARD_MIC;
 176       DVLOG(1) << "Changed stereo layout to stereo + keyboard mic layout due "
 177                << "to KEYBOARD_MIC effect.";
 178     } else {
 179       DVLOG(1) << "KEYBOARD_MIC effect ignored, not compatible with layout "
 180                << channel_layout;
 181     }
 182   }
 183
 184   DVLOG(1) << "Audio input hardware channel layout: " << channel_layout;
 185   UMA_HISTOGRAM_ENUMERATION("WebRTC.AudioInputChannelLayout",
 186                             channel_layout, media::CHANNEL_LAYOUT_MAX + 1);
 187
 188   // Verify that the reported input channel configuration is supported.
 189   if (channel_layout != media::CHANNEL_LAYOUT_MONO &&
 190       channel_layout != media::CHANNEL_LAYOUT_STEREO &&
 191       channel_layout != media::CHANNEL_LAYOUT_STEREO_AND_KEYBOARD_MIC) {
 192     DLOG(ERROR) << channel_layout
 193                 << " is not a supported input channel configuration.";
 194     return false;
 195   }
 196
 197   DVLOG(1) << "Audio input hardware sample rate: "
 198            << device_info_.device.input.sample_rate;
 199   media::AudioSampleRate asr;
 200   if (media::ToAudioSampleRate(device_info_.device.input.sample_rate, &asr)) {
 201     UMA_HISTOGRAM_ENUMERATION(
 202         "WebRTC.AudioInputSampleRate", asr, media::kAudioSampleRateMax + 1);
 203   } else {
 204     UMA_HISTOGRAM_COUNTS("WebRTC.AudioInputSampleRateUnexpected",
 205                          device_info_.device.input.sample_rate);
 206   }
 207
 208   // Initialize the buffer size to zero, which means it wasn't specified.
 209   // If it is out of range, we return it to zero.
 210   int buffer_size_ms = 0;
 211   int buffer_size_samples = 0;
 212   GetConstraintValueAsInteger(constraints_, kAudioLatency, &buffer_size_ms);
 213   if (buffer_size_ms < kMinAudioLatencyMs ||
 214       buffer_size_ms > kMaxAudioLatencyMs) {
 215     DVLOG(1) << "Ignoring out of range buffer size " << buffer_size_ms;
 216   } else {
 217     buffer_size_samples =
 218         device_info_.device.input.sample_rate * buffer_size_ms / 1000;
 219   }
 220   DVLOG_IF(1, buffer_size_samples > 0)
 221       << "Custom audio buffer size: " << buffer_size_samples << " samples";
 222
 223   // Create and configure the default audio capturing source.
 224   SetCapturerSourceInternal(
 225       AudioDeviceFactory::NewInputDevice(render_frame_id_),
 226       channel_layout,
 227       device_info_.device.input.sample_rate,
 228       buffer_size_samples);
 229
 230   // Add the capturer to the WebRtcAudioDeviceImpl since it needs some hardware
 231   // information from the capturer.
 232   if (audio_device_)
 233     audio_device_->AddAudioCapturer(this);
 234
 235   return true;
 236 }
 237
 238 WebRtcAudioCapturer::WebRtcAudioCapturer(
 239     int render_frame_id,
 240     const StreamDeviceInfo& device_info,
 241     const blink::WebMediaConstraints& constraints,
 242     WebRtcAudioDeviceImpl* audio_device,
 243     MediaStreamAudioSource* audio_source)
 244     : constraints_(constraints),
 245       audio_processor_(new rtc::RefCountedObject<MediaStreamAudioProcessor>(
 246           constraints,
 247           device_info.device.input.effects,
 248           audio_device)),
 249       running_(false),
 250       render_frame_id_(render_frame_id),
 251       device_info_(device_info),
 252       volume_(0),
 253       peer_connection_mode_(false),
 254       audio_device_(audio_device),
 255       audio_source_(audio_source) {
 256   DVLOG(1) << "WebRtcAudioCapturer::WebRtcAudioCapturer()";
 257 }
 258
 259 WebRtcAudioCapturer::~WebRtcAudioCapturer() {
 260   DCHECK(thread_checker_.CalledOnValidThread());
 261   DCHECK(tracks_.IsEmpty());
 262   DVLOG(1) << "WebRtcAudioCapturer::~WebRtcAudioCapturer()";
 263   Stop();
 264 }
 265
 266 void WebRtcAudioCapturer::AddTrack(WebRtcLocalAudioTrack* track) {
 267   DCHECK(track);
 268   DVLOG(1) << "WebRtcAudioCapturer::AddTrack()";
 269
 270   {
 271     base::AutoLock auto_lock(lock_);
 272     // Verify that |track| is not already added to the list.
 273     DCHECK(!tracks_.Contains(TrackOwner::TrackWrapper(track)));
 274
 275     // Add with a tag, so we remember to call OnSetFormat() on the new
 276     // track.
 277     scoped_refptr<TrackOwner> track_owner(new TrackOwner(track));
 278     tracks_.AddAndTag(track_owner.get());
 279   }
 280 }
 281
 282 void WebRtcAudioCapturer::RemoveTrack(WebRtcLocalAudioTrack* track) {
 283   DCHECK(thread_checker_.CalledOnValidThread());
 284   DVLOG(1) << "WebRtcAudioCapturer::RemoveTrack()";
 285   bool stop_source = false;
 286   {
 287     base::AutoLock auto_lock(lock_);
 288
 289     scoped_refptr<TrackOwner> removed_item =
 290         tracks_.Remove(TrackOwner::TrackWrapper(track));
 291
 292     // Clear the delegate to ensure that no more capture callbacks will
 293     // be sent to this sink. Also avoids a possible crash which can happen
 294     // if this method is called while capturing is active.
 295     if (removed_item.get()) {
 296       removed_item->Reset();
 297       stop_source = tracks_.IsEmpty();
 298     }
 299   }
 300   if (stop_source) {
 301     // Since WebRtcAudioCapturer does not inherit MediaStreamAudioSource,
 302     // and instead MediaStreamAudioSource is composed of a WebRtcAudioCapturer,
 303     // we have to call StopSource on the MediaStreamSource. This will call
 304     // MediaStreamAudioSource::DoStopSource which in turn call
 305     // WebRtcAudioCapturerer::Stop();
 306     audio_source_->StopSource();
 307   }
 308 }
 309
 310 void WebRtcAudioCapturer::SetCapturerSourceInternal(
 311     const scoped_refptr<media::AudioCapturerSource>& source,
 312     media::ChannelLayout channel_layout,
 313     int sample_rate,
 314     int buffer_size) {
 315   DCHECK(thread_checker_.CalledOnValidThread());
 316   DVLOG(1) << "SetCapturerSource(channel_layout=" << channel_layout << ","
 317            << "sample_rate=" << sample_rate << ")";
 318   scoped_refptr<media::AudioCapturerSource> old_source;
 319   {
 320     base::AutoLock auto_lock(lock_);
 321     if (source_.get() == source.get())
 322       return;
 323
 324     source_.swap(old_source);
 325     source_ = source;
 326
 327     // Reset the flag to allow starting the new source.
 328     running_ = false;
 329   }
 330
 331   DVLOG(1) << "Switching to a new capture source.";
 332   if (old_source.get())
 333     old_source->Stop();
 334
 335   // If the buffer size is zero, it has not been specified.
 336   // We either default to 10ms, or use the hardware buffer size.
 337   if (buffer_size == 0)
 338     buffer_size = GetBufferSize(sample_rate);
 339
 340   // Dispatch the new parameters both to the sink(s) and to the new source,
 341   // also apply the new |constraints|.
 342   // The idea is to get rid of any dependency of the microphone parameters
 343   // which would normally be used by default.
 344   // bits_per_sample is always 16 for now.
 345   media::AudioParameters params(media::AudioParameters::AUDIO_PCM_LOW_LATENCY,
 346                                 channel_layout,
 347                                 sample_rate,
 348                                 16,
 349                                 buffer_size,
 350                                 device_info_.device.input.effects);
 351
 352   {
 353     base::AutoLock auto_lock(lock_);
 354     // Notify the |audio_processor_| of the new format.
 355     audio_processor_->OnCaptureFormatChanged(params);
 356
 357     // Notify all tracks about the new format.
 358     tracks_.TagAll();
 359   }
 360
 361   if (source.get())
 362     source->Initialize(params, this, session_id());
 363
 364   Start();
 365 }
 366
 367 void WebRtcAudioCapturer::EnablePeerConnectionMode() {
 368   DCHECK(thread_checker_.CalledOnValidThread());
 369   DVLOG(1) << "EnablePeerConnectionMode";
 370   // Do nothing if the peer connection mode has been enabled.
 371   if (peer_connection_mode_)
 372     return;
 373
 374   peer_connection_mode_ = true;
 375   int render_frame_id = -1;
 376   media::AudioParameters input_params;
 377   {
 378     base::AutoLock auto_lock(lock_);
 379     // Simply return if there is no existing source or the |render_frame_id_| is
 380     // not valid.
 381     if (!source_.get() || render_frame_id_ == -1)
 382       return;
 383
 384     render_frame_id = render_frame_id_;
 385     input_params = audio_processor_->InputFormat();
 386   }
 387
 388   // Do nothing if the current buffer size is the WebRtc native buffer size.
 389   if (GetBufferSize(input_params.sample_rate()) ==
 390           input_params.frames_per_buffer()) {
 391     return;
 392   }
 393
 394   // Create a new audio stream as source which will open the hardware using
 395   // WebRtc native buffer size.
 396   SetCapturerSourceInternal(AudioDeviceFactory::NewInputDevice(render_frame_id),
 397                             input_params.channel_layout(),
 398                             input_params.sample_rate(),
 399                             0);
 400 }
 401
 402 void WebRtcAudioCapturer::Start() {
 403   DCHECK(thread_checker_.CalledOnValidThread());
 404   DVLOG(1) << "WebRtcAudioCapturer::Start()";
 405   base::AutoLock auto_lock(lock_);
 406   if (running_ || !source_.get())
 407     return;
 408
 409   // Start the data source, i.e., start capturing data from the current source.
 410   // We need to set the AGC control before starting the stream.
 411   source_->SetAutomaticGainControl(true);
 412   source_->Start();
 413   running_ = true;
 414 }
 415
 416 void WebRtcAudioCapturer::Stop() {
 417   DCHECK(thread_checker_.CalledOnValidThread());
 418   DVLOG(1) << "WebRtcAudioCapturer::Stop()";
 419   scoped_refptr<media::AudioCapturerSource> source;
 420   TrackList::ItemList tracks;
 421   {
 422     base::AutoLock auto_lock(lock_);
 423     if (!running_)
 424       return;
 425
 426     source = source_;
 427     tracks = tracks_.Items();
 428     tracks_.Clear();
 429     running_ = false;
 430   }
 431
 432   // Remove the capturer object from the WebRtcAudioDeviceImpl.
 433   if (audio_device_)
 434     audio_device_->RemoveAudioCapturer(this);
 435
 436   for (TrackList::ItemList::const_iterator it = tracks.begin();
 437        it != tracks.end();
 438        ++it) {
 439     (*it)->Stop();
 440   }
 441
 442   if (source.get())
 443     source->Stop();
 444
 445   // Stop the audio processor to avoid feeding render data into the processor.
 446   audio_processor_->Stop();
 447 }
 448
 449 void WebRtcAudioCapturer::SetVolume(int volume) {
 450   DVLOG(1) << "WebRtcAudioCapturer::SetVolume()";
 451   DCHECK_LE(volume, MaxVolume());
 452   double normalized_volume = static_cast<double>(volume) / MaxVolume();
 453   base::AutoLock auto_lock(lock_);
 454   if (source_.get())
 455     source_->SetVolume(normalized_volume);
 456 }
 457
 458 int WebRtcAudioCapturer::Volume() const {
 459   base::AutoLock auto_lock(lock_);
 460   return volume_;
 461 }
 462
 463 int WebRtcAudioCapturer::MaxVolume() const {
 464   return WebRtcAudioDeviceImpl::kMaxVolumeLevel;
 465 }
 466
 467 media::AudioParameters WebRtcAudioCapturer::GetOutputFormat() const {
 468   DCHECK(thread_checker_.CalledOnValidThread());
 469   return audio_processor_->OutputFormat();
 470 }
 471
 472 void WebRtcAudioCapturer::Capture(const media::AudioBus* audio_source,
 473                                   int audio_delay_milliseconds,
 474                                   double volume,
 475                                   bool key_pressed) {
 476 // This callback is driven by AudioInputDevice::AudioThreadCallback if
 477 // |source_| is AudioInputDevice, otherwise it is driven by client's
 478 // CaptureCallback.
 479 #if defined(OS_WIN) || defined(OS_MACOSX)
 480   DCHECK_LE(volume, 1.0);
 481 #elif (defined(OS_LINUX) && !defined(OS_CHROMEOS)) || defined(OS_OPENBSD)
 482   // We have a special situation on Linux where the microphone volume can be
 483   // "higher than maximum". The input volume slider in the sound preference
 484   // allows the user to set a scaling that is higher than 100%. It means that
 485   // even if the reported maximum levels is N, the actual microphone level can
 486   // go up to 1.5x*N and that corresponds to a normalized |volume| of 1.5x.
 487   DCHECK_LE(volume, 1.6);
 488 #endif
 489
 490   // TODO(miu): Plumbing is needed to determine the actual capture timestamp
 491   // of the audio, instead of just snapshotting TimeTicks::Now(), for proper
 492   // audio/video sync.  http://crbug.com/335335
 493   const base::TimeTicks reference_clock_snapshot = base::TimeTicks::Now();
 494
 495   TrackList::ItemList tracks;
 496   TrackList::ItemList tracks_to_notify_format;
 497   int current_volume = 0;
 498   {
 499     base::AutoLock auto_lock(lock_);
 500     if (!running_)
 501       return;
 502
 503     // Map internal volume range of [0.0, 1.0] into [0, 255] used by AGC.
 504     // The volume can be higher than 255 on Linux, and it will be cropped to
 505     // 255 since AGC does not allow values out of range.
 506     volume_ = static_cast<int>((volume * MaxVolume()) + 0.5);
 507     current_volume = volume_ > MaxVolume() ? MaxVolume() : volume_;
 508     tracks = tracks_.Items();
 509     tracks_.RetrieveAndClearTags(&tracks_to_notify_format);
 510   }
 511
 512   DCHECK(audio_processor_->InputFormat().IsValid());
 513   DCHECK_EQ(audio_source->channels(),
 514             audio_processor_->InputFormat().channels());
 515   DCHECK_EQ(audio_source->frames(),
 516             audio_processor_->InputFormat().frames_per_buffer());
 517
 518   // Notify the tracks on when the format changes. This will do nothing if
 519   // |tracks_to_notify_format| is empty.
 520   const media::AudioParameters& output_params =
 521       audio_processor_->OutputFormat();
 522   for (const auto& track : tracks_to_notify_format) {
 523     track->OnSetFormat(output_params);
 524     track->SetAudioProcessor(audio_processor_);
 525   }
 526
 527   // Figure out if the pre-processed data has any energy or not, the
 528   // information will be passed to the track to force the calculator
 529   // to report energy in case the post-processed data is zeroed by the audio
 530   // processing.
 531   const bool force_report_nonzero_energy = HasDataEnergy(*audio_source);
 532
 533   // Push the data to the processor for processing.
 534   audio_processor_->PushCaptureData(
 535       *audio_source,
 536       base::TimeDelta::FromMilliseconds(audio_delay_milliseconds));
 537
 538   // Process and consume the data in the processor until there is not enough
 539   // data in the processor.
 540   media::AudioBus* processed_data = nullptr;
 541   base::TimeDelta processed_data_audio_delay;
 542   int new_volume = 0;
 543   while (audio_processor_->ProcessAndConsumeData(
 544              current_volume, key_pressed,
 545              &processed_data, &processed_data_audio_delay, &new_volume)) {
 546     DCHECK(processed_data);
 547     const base::TimeTicks processed_data_capture_time =
 548         reference_clock_snapshot - processed_data_audio_delay;
 549     for (const auto& track : tracks) {
 550       track->Capture(*processed_data,
 551                      processed_data_capture_time,
 552                      force_report_nonzero_energy);
 553     }
 554
 555     if (new_volume) {
 556       SetVolume(new_volume);
 557
 558       // Update the |current_volume| to avoid passing the old volume to AGC.
 559       current_volume = new_volume;
 560     }
 561   }
 562 }
 563
 564 void WebRtcAudioCapturer::OnCaptureError() {
 565   NOTIMPLEMENTED();
 566 }
 567
 568 media::AudioParameters WebRtcAudioCapturer::source_audio_parameters() const {
 569   base::AutoLock auto_lock(lock_);
 570   return audio_processor_.get() ? audio_processor_->InputFormat()
 571                                 : media::AudioParameters();
 572 }
 573
 574 bool WebRtcAudioCapturer::GetPairedOutputParameters(
 575     int* session_id,
 576     int* output_sample_rate,
 577     int* output_frames_per_buffer) const {
 578   // Don't set output parameters unless all of them are valid.
 579   if (device_info_.session_id <= 0 ||
 580       !device_info_.device.matched_output.sample_rate ||
 581       !device_info_.device.matched_output.frames_per_buffer)
 582     return false;
 583
 584   *session_id = device_info_.session_id;
 585   *output_sample_rate = device_info_.device.matched_output.sample_rate;
 586   *output_frames_per_buffer =
 587       device_info_.device.matched_output.frames_per_buffer;
 588
 589   return true;
 590 }
 591
 592 int WebRtcAudioCapturer::GetBufferSize(int sample_rate) const {
 593   DCHECK(thread_checker_.CalledOnValidThread());
 594 #if defined(OS_ANDROID)
 595   // TODO(henrika): Tune and adjust buffer size on Android.
 596   return (2 * sample_rate / 100);
 597 #endif
 598
 599   // PeerConnection is running at a buffer size of 10ms data. A multiple of
 600   // 10ms as the buffer size can give the best performance to PeerConnection.
 601   int peer_connection_buffer_size = sample_rate / 100;
 602
 603   // Use the native hardware buffer size in non peer connection mode when the
 604   // platform is using a native buffer size smaller than the PeerConnection
 605   // buffer size and audio processing is off.
 606   int hardware_buffer_size = device_info_.device.input.frames_per_buffer;
 607   if (!peer_connection_mode_ && hardware_buffer_size &&
 608       hardware_buffer_size <= peer_connection_buffer_size &&
 609       !audio_processor_->has_audio_processing()) {
 610     DVLOG(1) << "WebRtcAudioCapturer is using hardware buffer size "
 611              << hardware_buffer_size;
 612     return hardware_buffer_size;
 613   }
 614
 615   return (sample_rate / 100);
 616 }
 617
 618 void WebRtcAudioCapturer::SetCapturerSource(
 619     const scoped_refptr<media::AudioCapturerSource>& source,
 620     media::AudioParameters params) {
 621   // Create a new audio stream as source which uses the new source.
 622   SetCapturerSourceInternal(source,
 623                             params.channel_layout(),
 624                             params.sample_rate(),
 625                             0);
 626 }
 627
 628 }  // namespace content