chrome/renderer/media/cast_rtp_stream.cc

   1 // Copyright 2013 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 "chrome/renderer/media/cast_rtp_stream.h"
   6
   7 #include "base/bind.h"
   8 #include "base/command_line.h"
   9 #include "base/logging.h"
  10 #include "base/memory/weak_ptr.h"
  11 #include "base/strings/stringprintf.h"
  12 #include "base/sys_info.h"
  13 #include "base/trace_event/trace_event.h"
  14 #include "chrome/common/chrome_switches.h"
  15 #include "chrome/renderer/media/cast_session.h"
  16 #include "chrome/renderer/media/cast_udp_transport.h"
  17 #include "content/public/renderer/media_stream_audio_sink.h"
  18 #include "content/public/renderer/media_stream_video_sink.h"
  19 #include "content/public/renderer/render_thread.h"
  20 #include "content/public/renderer/video_encode_accelerator.h"
  21 #include "media/audio/audio_parameters.h"
  22 #include "media/base/audio_bus.h"
  23 #include "media/base/audio_converter.h"
  24 #include "media/base/audio_fifo.h"
  25 #include "media/base/bind_to_current_loop.h"
  26 #include "media/base/video_frame.h"
  27 #include "media/cast/cast_config.h"
  28 #include "media/cast/cast_defines.h"
  29 #include "media/cast/cast_sender.h"
  30 #include "media/cast/net/cast_transport_config.h"
  31 #include "third_party/WebKit/public/platform/WebMediaStreamSource.h"
  32 #include "ui/gfx/geometry/size.h"
  33
  34 using media::cast::AudioSenderConfig;
  35 using media::cast::VideoSenderConfig;
  36
  37 namespace {
  38
  39 const char kCodecNameOpus[] = "OPUS";
  40 const char kCodecNameVp8[] = "VP8";
  41 const char kCodecNameH264[] = "H264";
  42
  43 // To convert from kilobits per second to bits to per second.
  44 const int kBitrateMultiplier = 1000;
  45
  46 CastRtpPayloadParams DefaultOpusPayload() {
  47   CastRtpPayloadParams payload;
  48   payload.payload_type = 127;
  49   payload.max_latency_ms = media::cast::kDefaultRtpMaxDelayMs;
  50   payload.ssrc = 1;
  51   payload.feedback_ssrc = 2;
  52   payload.clock_rate = media::cast::kDefaultAudioSamplingRate;
  53   // The value is 0 which means VBR.
  54   payload.min_bitrate = payload.max_bitrate =
  55       media::cast::kDefaultAudioEncoderBitrate;
  56   payload.channels = 2;
  57   payload.max_frame_rate = 100;  // 10 ms audio frames
  58   payload.codec_name = kCodecNameOpus;
  59   return payload;
  60 }
  61
  62 CastRtpPayloadParams DefaultVp8Payload() {
  63   CastRtpPayloadParams payload;
  64   payload.payload_type = 96;
  65   payload.max_latency_ms = media::cast::kDefaultRtpMaxDelayMs;
  66   payload.ssrc = 11;
  67   payload.feedback_ssrc = 12;
  68   payload.clock_rate = media::cast::kVideoFrequency;
  69   payload.max_bitrate = 2000;
  70   payload.min_bitrate = 50;
  71   payload.channels = 1;
  72   payload.max_frame_rate = media::cast::kDefaultMaxFrameRate;
  73   payload.width = 1280;
  74   payload.height = 720;
  75   payload.codec_name = kCodecNameVp8;
  76   return payload;
  77 }
  78
  79 CastRtpPayloadParams DefaultH264Payload() {
  80   CastRtpPayloadParams payload;
  81   // TODO(hshi): set different ssrc/rtpPayloadType values for H264 and VP8
  82   // once b/13696137 is fixed.
  83   payload.payload_type = 96;
  84   payload.max_latency_ms = media::cast::kDefaultRtpMaxDelayMs;
  85   payload.ssrc = 11;
  86   payload.feedback_ssrc = 12;
  87   payload.clock_rate = media::cast::kVideoFrequency;
  88   payload.max_bitrate = 2000;
  89   payload.min_bitrate = 50;
  90   payload.channels = 1;
  91   payload.max_frame_rate = media::cast::kDefaultMaxFrameRate;
  92   payload.width = 1280;
  93   payload.height = 720;
  94   payload.codec_name = kCodecNameH264;
  95   return payload;
  96 }
  97
  98 bool IsHardwareVP8EncodingSupported() {
  99   const base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
 100   if (cmd_line->HasSwitch(switches::kDisableCastStreamingHWEncoding)) {
 101     DVLOG(1) << "Disabled hardware VP8 support for Cast Streaming.";
 102     return false;
 103   }
 104
 105   // Query for hardware VP8 encoder support.
 106   std::vector<media::VideoEncodeAccelerator::SupportedProfile> vea_profiles =
 107       content::GetSupportedVideoEncodeAcceleratorProfiles();
 108   for (size_t i = 0; i < vea_profiles.size(); ++i) {
 109     if (vea_profiles[i].profile >= media::VP8PROFILE_MIN &&
 110         vea_profiles[i].profile <= media::VP8PROFILE_MAX) {
 111       return true;
 112     }
 113   }
 114   return false;
 115 }
 116
 117 bool IsHardwareH264EncodingSupported() {
 118   const base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
 119   if (cmd_line->HasSwitch(switches::kDisableCastStreamingHWEncoding)) {
 120     DVLOG(1) << "Disabled hardware h264 support for Cast Streaming.";
 121     return false;
 122   }
 123
 124   // Query for hardware H.264 encoder support.
 125   std::vector<media::VideoEncodeAccelerator::SupportedProfile> vea_profiles =
 126       content::GetSupportedVideoEncodeAcceleratorProfiles();
 127   for (size_t i = 0; i < vea_profiles.size(); ++i) {
 128     if (vea_profiles[i].profile >= media::H264PROFILE_MIN &&
 129         vea_profiles[i].profile <= media::H264PROFILE_MAX) {
 130       return true;
 131     }
 132   }
 133   return false;
 134 }
 135
 136 int NumberOfEncodeThreads() {
 137   // We want to give CPU cycles for capturing and not to saturate the system
 138   // just for encoding. So on a lower end system with only 1 or 2 cores we
 139   // use only one thread for encoding.
 140   if (base::SysInfo::NumberOfProcessors() <= 2)
 141     return 1;
 142
 143   // On higher end we want to use 2 threads for encoding to reduce latency.
 144   // In theory a physical CPU core has maximum 2 hyperthreads. Having 3 or
 145   // more logical processors means the system has at least 2 physical cores.
 146   return 2;
 147 }
 148
 149 std::vector<CastRtpParams> SupportedAudioParams() {
 150   // TODO(hclam): Fill in more codecs here.
 151   std::vector<CastRtpParams> supported_params;
 152   supported_params.push_back(CastRtpParams(DefaultOpusPayload()));
 153   return supported_params;
 154 }
 155
 156 std::vector<CastRtpParams> SupportedVideoParams() {
 157   std::vector<CastRtpParams> supported_params;
 158   if (IsHardwareH264EncodingSupported())
 159     supported_params.push_back(CastRtpParams(DefaultH264Payload()));
 160   supported_params.push_back(CastRtpParams(DefaultVp8Payload()));
 161   return supported_params;
 162 }
 163
 164 bool ToAudioSenderConfig(const CastRtpParams& params,
 165                          AudioSenderConfig* config) {
 166   config->ssrc = params.payload.ssrc;
 167   config->receiver_ssrc = params.payload.feedback_ssrc;
 168   if (config->ssrc == config->receiver_ssrc)
 169     return false;
 170   config->min_playout_delay =
 171       base::TimeDelta::FromMilliseconds(
 172           params.payload.min_latency_ms ?
 173           params.payload.min_latency_ms :
 174           params.payload.max_latency_ms);
 175   config->max_playout_delay =
 176       base::TimeDelta::FromMilliseconds(params.payload.max_latency_ms);
 177   if (config->min_playout_delay <= base::TimeDelta())
 178     return false;
 179   if (config->min_playout_delay > config->max_playout_delay)
 180     return false;
 181   config->rtp_payload_type = params.payload.payload_type;
 182   config->use_external_encoder = false;
 183   config->frequency = params.payload.clock_rate;
 184   if (config->frequency < 8000)
 185     return false;
 186   config->channels = params.payload.channels;
 187   if (config->channels < 1)
 188     return false;
 189   config->bitrate = params.payload.max_bitrate * kBitrateMultiplier;
 190   if (params.payload.codec_name == kCodecNameOpus)
 191     config->codec = media::cast::CODEC_AUDIO_OPUS;
 192   else
 193     return false;
 194   config->aes_key = params.payload.aes_key;
 195   config->aes_iv_mask = params.payload.aes_iv_mask;
 196   return true;
 197 }
 198
 199 bool ToVideoSenderConfig(const CastRtpParams& params,
 200                          VideoSenderConfig* config) {
 201   config->ssrc = params.payload.ssrc;
 202   config->receiver_ssrc = params.payload.feedback_ssrc;
 203   if (config->ssrc == config->receiver_ssrc)
 204     return false;
 205   config->min_playout_delay =
 206       base::TimeDelta::FromMilliseconds(
 207           params.payload.min_latency_ms ?
 208           params.payload.min_latency_ms :
 209           params.payload.max_latency_ms);
 210   config->max_playout_delay =
 211       base::TimeDelta::FromMilliseconds(params.payload.max_latency_ms);
 212   if (config->min_playout_delay <= base::TimeDelta())
 213     return false;
 214   if (config->min_playout_delay > config->max_playout_delay)
 215     return false;
 216   config->rtp_payload_type = params.payload.payload_type;
 217   config->min_bitrate = config->start_bitrate =
 218       params.payload.min_bitrate * kBitrateMultiplier;
 219   config->max_bitrate = params.payload.max_bitrate * kBitrateMultiplier;
 220   if (config->min_bitrate > config->max_bitrate)
 221     return false;
 222   config->start_bitrate = config->min_bitrate;
 223   config->max_frame_rate = static_cast<int>(
 224       std::max(1.0, params.payload.max_frame_rate) + 0.5);
 225   if (config->max_frame_rate > 120)
 226     return false;
 227   if (params.payload.codec_name == kCodecNameVp8) {
 228     config->use_external_encoder = IsHardwareVP8EncodingSupported();
 229     config->codec = media::cast::CODEC_VIDEO_VP8;
 230   } else if (params.payload.codec_name == kCodecNameH264) {
 231     config->use_external_encoder = IsHardwareH264EncodingSupported();
 232     config->codec = media::cast::CODEC_VIDEO_H264;
 233   } else {
 234     return false;
 235   }
 236   if (!config->use_external_encoder) {
 237     config->number_of_encode_threads = NumberOfEncodeThreads();
 238   }
 239   config->aes_key = params.payload.aes_key;
 240   config->aes_iv_mask = params.payload.aes_iv_mask;
 241   return true;
 242 }
 243
 244 }  // namespace
 245
 246 // This class receives MediaStreamTrack events and video frames from a
 247 // MediaStreamTrack.
 248 //
 249 // Threading: Video frames are received on the IO thread and then
 250 // forwarded to media::cast::VideoFrameInput through a static method.
 251 // Member variables of this class are only accessed on the render thread.
 252 class CastVideoSink : public base::SupportsWeakPtr<CastVideoSink>,
 253                       public content::MediaStreamVideoSink {
 254  public:
 255   // |track| provides data for this sink.
 256   // |error_callback| is called if video formats don't match.
 257   CastVideoSink(const blink::WebMediaStreamTrack& track,
 258                 const CastRtpStream::ErrorCallback& error_callback)
 259       : track_(track),
 260         sink_added_(false),
 261         error_callback_(error_callback) {}
 262
 263   ~CastVideoSink() override {
 264     if (sink_added_)
 265       RemoveFromVideoTrack(this, track_);
 266   }
 267
 268   // This static method is used to forward video frames to |frame_input|.
 269   static void OnVideoFrame(
 270       // These parameters are already bound when callback is created.
 271       const CastRtpStream::ErrorCallback& error_callback,
 272       const scoped_refptr<media::cast::VideoFrameInput> frame_input,
 273       // These parameters are passed for each frame.
 274       const scoped_refptr<media::VideoFrame>& frame,
 275       const media::VideoCaptureFormat& format,
 276       const base::TimeTicks& estimated_capture_time) {
 277     base::TimeTicks timestamp;
 278     if (estimated_capture_time.is_null())
 279       timestamp = base::TimeTicks::Now();
 280     else
 281       timestamp = estimated_capture_time;
 282
 283     // Used by chrome/browser/extension/api/cast_streaming/performance_test.cc
 284     TRACE_EVENT_INSTANT2(
 285         "cast_perf_test", "MediaStreamVideoSink::OnVideoFrame",
 286         TRACE_EVENT_SCOPE_THREAD,
 287         "timestamp",  timestamp.ToInternalValue(),
 288         "time_delta", frame->timestamp().ToInternalValue());
 289     frame_input->InsertRawVideoFrame(frame, timestamp);
 290   }
 291
 292   // Attach this sink to a video track represented by |track_|.
 293   // Data received from the track will be submitted to |frame_input|.
 294   void AddToTrack(
 295       const scoped_refptr<media::cast::VideoFrameInput>& frame_input) {
 296     DCHECK(!sink_added_);
 297     sink_added_ = true;
 298     AddToVideoTrack(
 299         this,
 300         base::Bind(
 301             &CastVideoSink::OnVideoFrame,
 302             error_callback_,
 303             frame_input),
 304         track_);
 305   }
 306
 307  private:
 308   blink::WebMediaStreamTrack track_;
 309   bool sink_added_;
 310   CastRtpStream::ErrorCallback error_callback_;
 311
 312   DISALLOW_COPY_AND_ASSIGN(CastVideoSink);
 313 };
 314
 315 // Receives audio data from a MediaStreamTrack. Data is submitted to
 316 // media::cast::FrameInput.
 317 //
 318 // Threading: Audio frames are received on the real-time audio thread.
 319 // Note that RemoveFromAudioTrack() is synchronous and we have
 320 // gurantee that there will be no more audio data after calling it.
 321 class CastAudioSink : public base::SupportsWeakPtr<CastAudioSink>,
 322                       public content::MediaStreamAudioSink,
 323                       public media::AudioConverter::InputCallback {
 324  public:
 325   // |track| provides data for this sink.
 326   CastAudioSink(const blink::WebMediaStreamTrack& track,
 327                 int output_channels,
 328                 int output_sample_rate)
 329       : track_(track),
 330         output_channels_(output_channels),
 331         output_sample_rate_(output_sample_rate),
 332         current_input_bus_(nullptr),
 333         sample_frames_in_(0),
 334         sample_frames_out_(0) {}
 335
 336   ~CastAudioSink() override {
 337     if (frame_input_.get())
 338       RemoveFromAudioTrack(this, track_);
 339   }
 340
 341   // Add this sink to the track. Data received from the track will be
 342   // submitted to |frame_input|.
 343   void AddToTrack(
 344       const scoped_refptr<media::cast::AudioFrameInput>& frame_input) {
 345     DCHECK(frame_input.get());
 346     DCHECK(!frame_input_.get());
 347     // This member is written here and then accessed on the IO thread
 348     // We will not get data until AddToAudioTrack is called so it is
 349     // safe to access this member now.
 350     frame_input_ = frame_input;
 351     AddToAudioTrack(this, track_);
 352   }
 353
 354  protected:
 355   // Called on real-time audio thread.
 356   void OnData(const media::AudioBus& input_bus,
 357               base::TimeTicks estimated_capture_time) override {
 358     DCHECK(input_params_.IsValid());
 359     DCHECK_EQ(input_bus.channels(), input_params_.channels());
 360     DCHECK_EQ(input_bus.frames(), input_params_.frames_per_buffer());
 361     DCHECK(!estimated_capture_time.is_null());
 362     DCHECK(converter_.get());
 363
 364     // Determine the duration of the audio signal enqueued within |converter_|.
 365     const base::TimeDelta signal_duration_already_buffered =
 366         (sample_frames_in_ * base::TimeDelta::FromSeconds(1) /
 367              input_params_.sample_rate()) -
 368         (sample_frames_out_ * base::TimeDelta::FromSeconds(1) /
 369              output_sample_rate_);
 370     DVLOG(2) << "Audio reference time adjustment: -("
 371              << signal_duration_already_buffered.InMicroseconds() << " us)";
 372     const base::TimeTicks capture_time_of_first_converted_sample =
 373         estimated_capture_time - signal_duration_already_buffered;
 374
 375     // Convert the entire input signal.  AudioConverter is efficient in that no
 376     // additional copying or conversion will occur if the input signal is in the
 377     // same format as the output.  Note that, while the number of sample frames
 378     // provided as input is always the same, the chunk size (and the size of the
 379     // |audio_bus| here) can be variable.  This is not an issue since
 380     // media::cast::AudioFrameInput can handle variable-sized AudioBuses.
 381     scoped_ptr<media::AudioBus> audio_bus =
 382         media::AudioBus::Create(output_channels_, converter_->ChunkSize());
 383     // AudioConverter will call ProvideInput() to fetch from |current_data_|.
 384     current_input_bus_ = &input_bus;
 385     converter_->Convert(audio_bus.get());
 386     DCHECK(!current_input_bus_);  // ProvideInput() called exactly once?
 387
 388     sample_frames_in_ += input_params_.frames_per_buffer();
 389     sample_frames_out_ += audio_bus->frames();
 390
 391     frame_input_->InsertAudio(audio_bus.Pass(),
 392                               capture_time_of_first_converted_sample);
 393   }
 394
 395   // Called on real-time audio thread.
 396   void OnSetFormat(const media::AudioParameters& params) override {
 397     if (input_params_.Equals(params))
 398       return;
 399     input_params_ = params;
 400
 401     DVLOG(1) << "Setting up audio resampling: {"
 402              << input_params_.channels() << " channels, "
 403              << input_params_.sample_rate() << " Hz} --> {"
 404              << output_channels_ << " channels, "
 405              << output_sample_rate_ << " Hz}";
 406     const media::AudioParameters output_params(
 407         media::AudioParameters::AUDIO_PCM_LOW_LATENCY,
 408         media::GuessChannelLayout(output_channels_),
 409         output_sample_rate_, 32,
 410         output_sample_rate_ * input_params_.frames_per_buffer() /
 411             input_params_.sample_rate());
 412     converter_.reset(
 413         new media::AudioConverter(input_params_, output_params, false));
 414     converter_->AddInput(this);
 415     sample_frames_in_ = 0;
 416     sample_frames_out_ = 0;
 417   }
 418
 419   // Called on real-time audio thread.
 420   double ProvideInput(media::AudioBus* audio_bus,
 421                       base::TimeDelta buffer_delay) override {
 422     DCHECK(current_input_bus_);
 423     current_input_bus_->CopyTo(audio_bus);
 424     current_input_bus_ = nullptr;
 425     return 1.0;
 426   }
 427
 428  private:
 429   const blink::WebMediaStreamTrack track_;
 430   const int output_channels_;
 431   const int output_sample_rate_;
 432
 433   // This must be set before the real-time audio thread starts calling OnData(),
 434   // and remain unchanged until after the thread will stop calling OnData().
 435   scoped_refptr<media::cast::AudioFrameInput> frame_input_;
 436
 437   // These members are accessed on the real-time audio time only.
 438   media::AudioParameters input_params_;
 439   scoped_ptr<media::AudioConverter> converter_;
 440   const media::AudioBus* current_input_bus_;
 441   int64 sample_frames_in_;
 442   int64 sample_frames_out_;
 443
 444   DISALLOW_COPY_AND_ASSIGN(CastAudioSink);
 445 };
 446
 447 CastRtpParams::CastRtpParams(const CastRtpPayloadParams& payload_params)
 448     : payload(payload_params) {}
 449
 450 CastCodecSpecificParams::CastCodecSpecificParams() {}
 451
 452 CastCodecSpecificParams::~CastCodecSpecificParams() {}
 453
 454 CastRtpPayloadParams::CastRtpPayloadParams()
 455     : payload_type(0),
 456       max_latency_ms(0),
 457       min_latency_ms(0),
 458       ssrc(0),
 459       feedback_ssrc(0),
 460       clock_rate(0),
 461       max_bitrate(0),
 462       min_bitrate(0),
 463       channels(0),
 464       max_frame_rate(0.0),
 465       width(0),
 466       height(0) {}
 467
 468 CastRtpPayloadParams::~CastRtpPayloadParams() {}
 469
 470 CastRtpParams::CastRtpParams() {}
 471
 472 CastRtpParams::~CastRtpParams() {}
 473
 474 CastRtpStream::CastRtpStream(const blink::WebMediaStreamTrack& track,
 475                              const scoped_refptr<CastSession>& session)
 476     : track_(track), cast_session_(session), weak_factory_(this) {}
 477
 478 CastRtpStream::~CastRtpStream() {}
 479
 480 std::vector<CastRtpParams> CastRtpStream::GetSupportedParams() {
 481   if (IsAudio())
 482     return SupportedAudioParams();
 483   else
 484     return SupportedVideoParams();
 485 }
 486
 487 CastRtpParams CastRtpStream::GetParams() { return params_; }
 488
 489 void CastRtpStream::Start(const CastRtpParams& params,
 490                           const base::Closure& start_callback,
 491                           const base::Closure& stop_callback,
 492                           const ErrorCallback& error_callback) {
 493   DVLOG(1) << "CastRtpStream::Start = " << (IsAudio() ? "audio" : "video");
 494   stop_callback_ = stop_callback;
 495   error_callback_ = error_callback;
 496
 497   if (IsAudio()) {
 498     AudioSenderConfig config;
 499     if (!ToAudioSenderConfig(params, &config)) {
 500       DidEncounterError("Invalid parameters for audio.");
 501       return;
 502     }
 503
 504     // In case of error we have to go through DidEncounterError() to stop
 505     // the streaming after reporting the error.
 506     audio_sink_.reset(new CastAudioSink(
 507         track_,
 508         params.payload.channels,
 509         params.payload.clock_rate));
 510     cast_session_->StartAudio(
 511         config,
 512         base::Bind(&CastAudioSink::AddToTrack, audio_sink_->AsWeakPtr()),
 513         base::Bind(&CastRtpStream::DidEncounterError,
 514                    weak_factory_.GetWeakPtr()));
 515     start_callback.Run();
 516   } else {
 517     VideoSenderConfig config;
 518     if (!ToVideoSenderConfig(params, &config)) {
 519       DidEncounterError("Invalid parameters for video.");
 520       return;
 521     }
 522     // See the code for audio above for explanation of callbacks.
 523     video_sink_.reset(new CastVideoSink(
 524         track_,
 525         media::BindToCurrentLoop(base::Bind(&CastRtpStream::DidEncounterError,
 526                                             weak_factory_.GetWeakPtr()))));
 527     cast_session_->StartVideo(
 528         config,
 529         base::Bind(&CastVideoSink::AddToTrack, video_sink_->AsWeakPtr()),
 530         base::Bind(&CastRtpStream::DidEncounterError,
 531                    weak_factory_.GetWeakPtr()));
 532     start_callback.Run();
 533   }
 534 }
 535
 536 void CastRtpStream::Stop() {
 537   DVLOG(1) << "CastRtpStream::Stop = " << (IsAudio() ? "audio" : "video");
 538   audio_sink_.reset();
 539   video_sink_.reset();
 540   if (!stop_callback_.is_null())
 541     stop_callback_.Run();
 542 }
 543
 544 void CastRtpStream::ToggleLogging(bool enable) {
 545   DVLOG(1) << "CastRtpStream::ToggleLogging(" << enable << ") = "
 546            << (IsAudio() ? "audio" : "video");
 547   cast_session_->ToggleLogging(IsAudio(), enable);
 548 }
 549
 550 void CastRtpStream::GetRawEvents(
 551     const base::Callback<void(scoped_ptr<base::BinaryValue>)>& callback,
 552     const std::string& extra_data) {
 553   DVLOG(1) << "CastRtpStream::GetRawEvents = "
 554            << (IsAudio() ? "audio" : "video");
 555   cast_session_->GetEventLogsAndReset(IsAudio(), extra_data, callback);
 556 }
 557
 558 void CastRtpStream::GetStats(
 559     const base::Callback<void(scoped_ptr<base::DictionaryValue>)>& callback) {
 560   DVLOG(1) << "CastRtpStream::GetStats = "
 561            << (IsAudio() ? "audio" : "video");
 562   cast_session_->GetStatsAndReset(IsAudio(), callback);
 563 }
 564
 565 bool CastRtpStream::IsAudio() const {
 566   return track_.source().type() == blink::WebMediaStreamSource::TypeAudio;
 567 }
 568
 569 void CastRtpStream::DidEncounterError(const std::string& message) {
 570   DVLOG(1) << "CastRtpStream::DidEncounterError(" << message << ") = "
 571            << (IsAudio() ? "audio" : "video");
 572   // Save the WeakPtr first because the error callback might delete this object.
 573   base::WeakPtr<CastRtpStream> ptr = weak_factory_.GetWeakPtr();
 574   error_callback_.Run(message);
 575   content::RenderThread::Get()->GetTaskRunner()->PostTask(
 576       FROM_HERE,
 577       base::Bind(&CastRtpStream::Stop, ptr));
 578 }