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 <algorithm>
   8
   9 #include "base/bind.h"
  10 #include "base/callback_helpers.h"
  11 #include "base/command_line.h"
  12 #include "base/logging.h"
  13 #include "base/memory/weak_ptr.h"
  14 #include "base/strings/stringprintf.h"
  15 #include "base/sys_info.h"
  16 #include "base/trace_event/trace_event.h"
  17 #include "chrome/common/chrome_switches.h"
  18 #include "chrome/renderer/media/cast_session.h"
  19 #include "chrome/renderer/media/cast_udp_transport.h"
  20 #include "content/public/renderer/media_stream_audio_sink.h"
  21 #include "content/public/renderer/media_stream_video_sink.h"
  22 #include "content/public/renderer/render_thread.h"
  23 #include "content/public/renderer/video_encode_accelerator.h"
  24 #include "media/audio/audio_parameters.h"
  25 #include "media/base/audio_bus.h"
  26 #include "media/base/audio_converter.h"
  27 #include "media/base/audio_fifo.h"
  28 #include "media/base/bind_to_current_loop.h"
  29 #include "media/base/video_frame.h"
  30 #include "media/cast/cast_config.h"
  31 #include "media/cast/cast_defines.h"
  32 #include "media/cast/cast_sender.h"
  33 #include "media/cast/net/cast_transport_config.h"
  34 #include "third_party/WebKit/public/platform/WebMediaStreamSource.h"
  35 #include "ui/gfx/geometry/size.h"
  36
  37 using media::cast::AudioSenderConfig;
  38 using media::cast::VideoSenderConfig;
  39
  40 namespace {
  41
  42 const char kCodecNameOpus[] = "OPUS";
  43 const char kCodecNameVp8[] = "VP8";
  44 const char kCodecNameH264[] = "H264";
  45
  46 // To convert from kilobits per second to bits to per second.
  47 const int kBitrateMultiplier = 1000;
  48
  49 CastRtpPayloadParams DefaultOpusPayload() {
  50   CastRtpPayloadParams payload;
  51   payload.payload_type = 127;
  52   payload.max_latency_ms = media::cast::kDefaultRtpMaxDelayMs;
  53   payload.ssrc = 1;
  54   payload.feedback_ssrc = 2;
  55   payload.clock_rate = media::cast::kDefaultAudioSamplingRate;
  56   // The value is 0 which means VBR.
  57   payload.min_bitrate = payload.max_bitrate =
  58       media::cast::kDefaultAudioEncoderBitrate;
  59   payload.channels = 2;
  60   payload.max_frame_rate = 100;  // 10 ms audio frames
  61   payload.codec_name = kCodecNameOpus;
  62   return payload;
  63 }
  64
  65 CastRtpPayloadParams DefaultVp8Payload() {
  66   CastRtpPayloadParams payload;
  67   payload.payload_type = 96;
  68   payload.max_latency_ms = media::cast::kDefaultRtpMaxDelayMs;
  69   payload.ssrc = 11;
  70   payload.feedback_ssrc = 12;
  71   payload.clock_rate = media::cast::kVideoFrequency;
  72   payload.max_bitrate = 2000;
  73   payload.min_bitrate = 50;
  74   payload.channels = 1;
  75   payload.max_frame_rate = media::cast::kDefaultMaxFrameRate;
  76   payload.codec_name = kCodecNameVp8;
  77   return payload;
  78 }
  79
  80 CastRtpPayloadParams DefaultH264Payload() {
  81   CastRtpPayloadParams payload;
  82   // TODO(hshi): set different ssrc/rtpPayloadType values for H264 and VP8
  83   // once b/13696137 is fixed.
  84   payload.payload_type = 96;
  85   payload.max_latency_ms = media::cast::kDefaultRtpMaxDelayMs;
  86   payload.ssrc = 11;
  87   payload.feedback_ssrc = 12;
  88   payload.clock_rate = media::cast::kVideoFrequency;
  89   payload.max_bitrate = 2000;
  90   payload.min_bitrate = 50;
  91   payload.channels = 1;
  92   payload.max_frame_rate = media::cast::kDefaultMaxFrameRate;
  93   payload.codec_name = kCodecNameH264;
  94   return payload;
  95 }
  96
  97 bool IsHardwareVP8EncodingSupported() {
  98   const base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
  99   if (cmd_line->HasSwitch(switches::kDisableCastStreamingHWEncoding)) {
 100     DVLOG(1) << "Disabled hardware VP8 support for Cast Streaming.";
 101     return false;
 102   }
 103
 104   // Query for hardware VP8 encoder support.
 105   const std::vector<media::VideoEncodeAccelerator::SupportedProfile>
 106       vea_profiles = content::GetSupportedVideoEncodeAcceleratorProfiles();
 107   for (const auto& vea_profile : vea_profiles) {
 108     if (vea_profile.profile >= media::VP8PROFILE_MIN &&
 109         vea_profile.profile <= media::VP8PROFILE_MAX) {
 110       return true;
 111     }
 112   }
 113   return false;
 114 }
 115
 116 bool IsHardwareH264EncodingSupported() {
 117   const base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
 118   if (cmd_line->HasSwitch(switches::kDisableCastStreamingHWEncoding)) {
 119     DVLOG(1) << "Disabled hardware h264 support for Cast Streaming.";
 120     return false;
 121   }
 122
 123   // Query for hardware H.264 encoder support.
 124   const std::vector<media::VideoEncodeAccelerator::SupportedProfile>
 125       vea_profiles = content::GetSupportedVideoEncodeAcceleratorProfiles();
 126   for (const auto& vea_profile : vea_profiles) {
 127     if (vea_profile.profile >= media::H264PROFILE_MIN &&
 128         vea_profile.profile <= media::H264PROFILE_MAX) {
 129       return true;
 130     }
 131   }
 132   return false;
 133 }
 134
 135 int NumberOfEncodeThreads() {
 136   // Do not saturate CPU utilization just for encoding. On a lower-end system
 137   // with only 1 or 2 cores, use only one thread for encoding. On systems with
 138   // more cores, allow half of the cores to be used for encoding.
 139   return std::min(8, (base::SysInfo::NumberOfProcessors() + 1) / 2);
 140 }
 141
 142 std::vector<CastRtpParams> SupportedAudioParams() {
 143   // TODO(hclam): Fill in more codecs here.
 144   return std::vector<CastRtpParams>(1, CastRtpParams(DefaultOpusPayload()));
 145 }
 146
 147 std::vector<CastRtpParams> SupportedVideoParams() {
 148   std::vector<CastRtpParams> supported_params;
 149
 150   // Prefer VP8 over H.264 for hardware encoder.
 151   if (IsHardwareVP8EncodingSupported())
 152     supported_params.push_back(CastRtpParams(DefaultVp8Payload()));
 153   if (IsHardwareH264EncodingSupported())
 154     supported_params.push_back(CastRtpParams(DefaultH264Payload()));
 155
 156   // Propose the default software VP8 encoder, if no hardware encoders are
 157   // available.
 158   if (supported_params.empty())
 159     supported_params.push_back(CastRtpParams(DefaultVp8Payload()));
 160
 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       base::TimeTicks estimated_capture_time) {
 276     const base::TimeTicks timestamp = estimated_capture_time.is_null()
 277                                           ? base::TimeTicks::Now()
 278                                           : estimated_capture_time;
 279
 280     // Used by chrome/browser/extension/api/cast_streaming/performance_test.cc
 281     TRACE_EVENT_INSTANT2(
 282         "cast_perf_test", "MediaStreamVideoSink::OnVideoFrame",
 283         TRACE_EVENT_SCOPE_THREAD,
 284         "timestamp",  timestamp.ToInternalValue(),
 285         "time_delta", frame->timestamp().ToInternalValue());
 286     frame_input->InsertRawVideoFrame(frame, timestamp);
 287   }
 288
 289   // Attach this sink to a video track represented by |track_|.
 290   // Data received from the track will be submitted to |frame_input|.
 291   void AddToTrack(
 292       const scoped_refptr<media::cast::VideoFrameInput>& frame_input) {
 293     DCHECK(!sink_added_);
 294     sink_added_ = true;
 295     AddToVideoTrack(
 296         this,
 297         base::Bind(
 298             &CastVideoSink::OnVideoFrame,
 299             error_callback_,
 300             frame_input),
 301         track_);
 302   }
 303
 304  private:
 305   blink::WebMediaStreamTrack track_;
 306   bool sink_added_;
 307   CastRtpStream::ErrorCallback error_callback_;
 308
 309   DISALLOW_COPY_AND_ASSIGN(CastVideoSink);
 310 };
 311
 312 // Receives audio data from a MediaStreamTrack. Data is submitted to
 313 // media::cast::FrameInput.
 314 //
 315 // Threading: Audio frames are received on the real-time audio thread.
 316 // Note that RemoveFromAudioTrack() is synchronous and we have
 317 // gurantee that there will be no more audio data after calling it.
 318 class CastAudioSink : public base::SupportsWeakPtr<CastAudioSink>,
 319                       public content::MediaStreamAudioSink,
 320                       public media::AudioConverter::InputCallback {
 321  public:
 322   // |track| provides data for this sink.
 323   CastAudioSink(const blink::WebMediaStreamTrack& track,
 324                 int output_channels,
 325                 int output_sample_rate)
 326       : track_(track),
 327         output_channels_(output_channels),
 328         output_sample_rate_(output_sample_rate),
 329         current_input_bus_(nullptr),
 330         sample_frames_in_(0),
 331         sample_frames_out_(0) {}
 332
 333   ~CastAudioSink() override {
 334     if (frame_input_.get())
 335       RemoveFromAudioTrack(this, track_);
 336   }
 337
 338   // Add this sink to the track. Data received from the track will be
 339   // submitted to |frame_input|.
 340   void AddToTrack(
 341       const scoped_refptr<media::cast::AudioFrameInput>& frame_input) {
 342     DCHECK(frame_input.get());
 343     DCHECK(!frame_input_.get());
 344     // This member is written here and then accessed on the IO thread
 345     // We will not get data until AddToAudioTrack is called so it is
 346     // safe to access this member now.
 347     frame_input_ = frame_input;
 348     AddToAudioTrack(this, track_);
 349   }
 350
 351  protected:
 352   // Called on real-time audio thread.
 353   void OnData(const media::AudioBus& input_bus,
 354               base::TimeTicks estimated_capture_time) override {
 355     DCHECK(input_params_.IsValid());
 356     DCHECK_EQ(input_bus.channels(), input_params_.channels());
 357     DCHECK_EQ(input_bus.frames(), input_params_.frames_per_buffer());
 358     DCHECK(!estimated_capture_time.is_null());
 359     DCHECK(converter_.get());
 360
 361     // Determine the duration of the audio signal enqueued within |converter_|.
 362     const base::TimeDelta signal_duration_already_buffered =
 363         (sample_frames_in_ * base::TimeDelta::FromSeconds(1) /
 364              input_params_.sample_rate()) -
 365         (sample_frames_out_ * base::TimeDelta::FromSeconds(1) /
 366              output_sample_rate_);
 367     DVLOG(2) << "Audio reference time adjustment: -("
 368              << signal_duration_already_buffered.InMicroseconds() << " us)";
 369     const base::TimeTicks capture_time_of_first_converted_sample =
 370         estimated_capture_time - signal_duration_already_buffered;
 371
 372     // Convert the entire input signal.  AudioConverter is efficient in that no
 373     // additional copying or conversion will occur if the input signal is in the
 374     // same format as the output.  Note that, while the number of sample frames
 375     // provided as input is always the same, the chunk size (and the size of the
 376     // |audio_bus| here) can be variable.  This is not an issue since
 377     // media::cast::AudioFrameInput can handle variable-sized AudioBuses.
 378     scoped_ptr<media::AudioBus> audio_bus =
 379         media::AudioBus::Create(output_channels_, converter_->ChunkSize());
 380     // AudioConverter will call ProvideInput() to fetch from |current_data_|.
 381     current_input_bus_ = &input_bus;
 382     converter_->Convert(audio_bus.get());
 383     DCHECK(!current_input_bus_);  // ProvideInput() called exactly once?
 384
 385     sample_frames_in_ += input_params_.frames_per_buffer();
 386     sample_frames_out_ += audio_bus->frames();
 387
 388     frame_input_->InsertAudio(audio_bus.Pass(),
 389                               capture_time_of_first_converted_sample);
 390   }
 391
 392   // Called on real-time audio thread.
 393   void OnSetFormat(const media::AudioParameters& params) override {
 394     if (input_params_.Equals(params))
 395       return;
 396     input_params_ = params;
 397
 398     DVLOG(1) << "Setting up audio resampling: {"
 399              << input_params_.channels() << " channels, "
 400              << input_params_.sample_rate() << " Hz} --> {"
 401              << output_channels_ << " channels, "
 402              << output_sample_rate_ << " Hz}";
 403     const media::AudioParameters output_params(
 404         media::AudioParameters::AUDIO_PCM_LOW_LATENCY,
 405         media::GuessChannelLayout(output_channels_),
 406         output_sample_rate_, 32,
 407         output_sample_rate_ * input_params_.frames_per_buffer() /
 408             input_params_.sample_rate());
 409     converter_.reset(
 410         new media::AudioConverter(input_params_, output_params, false));
 411     converter_->AddInput(this);
 412     sample_frames_in_ = 0;
 413     sample_frames_out_ = 0;
 414   }
 415
 416   // Called on real-time audio thread.
 417   double ProvideInput(media::AudioBus* audio_bus,
 418                       base::TimeDelta buffer_delay) override {
 419     DCHECK(current_input_bus_);
 420     current_input_bus_->CopyTo(audio_bus);
 421     current_input_bus_ = nullptr;
 422     return 1.0;
 423   }
 424
 425  private:
 426   const blink::WebMediaStreamTrack track_;
 427   const int output_channels_;
 428   const int output_sample_rate_;
 429
 430   // This must be set before the real-time audio thread starts calling OnData(),
 431   // and remain unchanged until after the thread will stop calling OnData().
 432   scoped_refptr<media::cast::AudioFrameInput> frame_input_;
 433
 434   // These members are accessed on the real-time audio time only.
 435   media::AudioParameters input_params_;
 436   scoped_ptr<media::AudioConverter> converter_;
 437   const media::AudioBus* current_input_bus_;
 438   int64 sample_frames_in_;
 439   int64 sample_frames_out_;
 440
 441   DISALLOW_COPY_AND_ASSIGN(CastAudioSink);
 442 };
 443
 444 CastRtpParams::CastRtpParams(const CastRtpPayloadParams& payload_params)
 445     : payload(payload_params) {}
 446
 447 CastCodecSpecificParams::CastCodecSpecificParams() {}
 448
 449 CastCodecSpecificParams::~CastCodecSpecificParams() {}
 450
 451 CastRtpPayloadParams::CastRtpPayloadParams()
 452     : payload_type(0),
 453       max_latency_ms(0),
 454       min_latency_ms(0),
 455       ssrc(0),
 456       feedback_ssrc(0),
 457       clock_rate(0),
 458       max_bitrate(0),
 459       min_bitrate(0),
 460       channels(0),
 461       max_frame_rate(0.0) {
 462 }
 463
 464 CastRtpPayloadParams::~CastRtpPayloadParams() {}
 465
 466 CastRtpParams::CastRtpParams() {}
 467
 468 CastRtpParams::~CastRtpParams() {}
 469
 470 CastRtpStream::CastRtpStream(const blink::WebMediaStreamTrack& track,
 471                              const scoped_refptr<CastSession>& session)
 472     : track_(track), cast_session_(session), weak_factory_(this) {}
 473
 474 CastRtpStream::~CastRtpStream() {
 475   Stop();
 476 }
 477
 478 std::vector<CastRtpParams> CastRtpStream::GetSupportedParams() {
 479   if (IsAudio())
 480     return SupportedAudioParams();
 481   else
 482     return SupportedVideoParams();
 483 }
 484
 485 CastRtpParams CastRtpStream::GetParams() { return params_; }
 486
 487 void CastRtpStream::Start(const CastRtpParams& params,
 488                           const base::Closure& start_callback,
 489                           const base::Closure& stop_callback,
 490                           const ErrorCallback& error_callback) {
 491   DCHECK(!start_callback.is_null());
 492   DCHECK(!stop_callback.is_null());
 493   DCHECK(!error_callback.is_null());
 494
 495   DVLOG(1) << "CastRtpStream::Start = " << (IsAudio() ? "audio" : "video");
 496   stop_callback_ = stop_callback;
 497   error_callback_ = error_callback;
 498
 499   if (IsAudio()) {
 500     AudioSenderConfig config;
 501     if (!ToAudioSenderConfig(params, &config)) {
 502       DidEncounterError("Invalid parameters for audio.");
 503       return;
 504     }
 505
 506     // In case of error we have to go through DidEncounterError() to stop
 507     // the streaming after reporting the error.
 508     audio_sink_.reset(new CastAudioSink(
 509         track_,
 510         params.payload.channels,
 511         params.payload.clock_rate));
 512     cast_session_->StartAudio(
 513         config,
 514         base::Bind(&CastAudioSink::AddToTrack, audio_sink_->AsWeakPtr()),
 515         base::Bind(&CastRtpStream::DidEncounterError,
 516                    weak_factory_.GetWeakPtr()));
 517     start_callback.Run();
 518   } else {
 519     VideoSenderConfig config;
 520     if (!ToVideoSenderConfig(params, &config)) {
 521       DidEncounterError("Invalid parameters for video.");
 522       return;
 523     }
 524     // See the code for audio above for explanation of callbacks.
 525     video_sink_.reset(new CastVideoSink(
 526         track_,
 527         media::BindToCurrentLoop(base::Bind(&CastRtpStream::DidEncounterError,
 528                                             weak_factory_.GetWeakPtr()))));
 529     cast_session_->StartVideo(
 530         config,
 531         base::Bind(&CastVideoSink::AddToTrack, video_sink_->AsWeakPtr()),
 532         base::Bind(&CastRtpStream::DidEncounterError,
 533                    weak_factory_.GetWeakPtr()));
 534     start_callback.Run();
 535   }
 536 }
 537
 538 void CastRtpStream::Stop() {
 539   DVLOG(1) << "CastRtpStream::Stop = " << (IsAudio() ? "audio" : "video");
 540   if (stop_callback_.is_null())
 541     return;  // Already stopped.
 542   weak_factory_.InvalidateWeakPtrs();
 543   error_callback_.Reset();
 544   audio_sink_.reset();
 545   video_sink_.reset();
 546   base::ResetAndReturn(&stop_callback_).Run();
 547 }
 548
 549 void CastRtpStream::ToggleLogging(bool enable) {
 550   DVLOG(1) << "CastRtpStream::ToggleLogging(" << enable << ") = "
 551            << (IsAudio() ? "audio" : "video");
 552   cast_session_->ToggleLogging(IsAudio(), enable);
 553 }
 554
 555 void CastRtpStream::GetRawEvents(
 556     const base::Callback<void(scoped_ptr<base::BinaryValue>)>& callback,
 557     const std::string& extra_data) {
 558   DVLOG(1) << "CastRtpStream::GetRawEvents = "
 559            << (IsAudio() ? "audio" : "video");
 560   cast_session_->GetEventLogsAndReset(IsAudio(), extra_data, callback);
 561 }
 562
 563 void CastRtpStream::GetStats(
 564     const base::Callback<void(scoped_ptr<base::DictionaryValue>)>& callback) {
 565   DVLOG(1) << "CastRtpStream::GetStats = "
 566            << (IsAudio() ? "audio" : "video");
 567   cast_session_->GetStatsAndReset(IsAudio(), callback);
 568 }
 569
 570 bool CastRtpStream::IsAudio() const {
 571   return track_.source().type() == blink::WebMediaStreamSource::TypeAudio;
 572 }
 573
 574 void CastRtpStream::DidEncounterError(const std::string& message) {
 575   DCHECK(content::RenderThread::Get());
 576   DVLOG(1) << "CastRtpStream::DidEncounterError(" << message << ") = "
 577            << (IsAudio() ? "audio" : "video");
 578   // Save the WeakPtr first because the error callback might delete this object.
 579   base::WeakPtr<CastRtpStream> ptr = weak_factory_.GetWeakPtr();
 580   error_callback_.Run(message);
 581   base::ThreadTaskRunnerHandle::Get()->PostTask(
 582       FROM_HERE,
 583       base::Bind(&CastRtpStream::Stop, ptr));
 584 }