[Chromecast] Plumbs raw audio through CMA backend.

chromecast/media/audio/audio_output_stream.cc

+// Copyright 2015 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 "chromecast/media/audio/audio_output_stream.h"
+
+#include "base/bind.h"
+#include "base/thread_task_runner_handle.h"
+#include "chromecast/media/audio/audio_manager.h"
+#include "chromecast/media/cma/base/cast_decoder_buffer_impl.h"
+#include "chromecast/media/cma/base/decoder_buffer_adapter.h"
+#include "chromecast/media/cma/pipeline/frame_status_cb_impl.h"
+#include "chromecast/public/media/audio_pipeline_device.h"
+#include "chromecast/public/media/decoder_config.h"
+#include "chromecast/public/media/decrypt_context.h"
+#include "chromecast/public/media/media_clock_device.h"
+#include "chromecast/public/media/media_pipeline_backend.h"
+#include "media/audio/fake_audio_worker.h"
+#include "media/base/decoder_buffer.h"
+
+namespace chromecast {
+namespace media {
+
+namespace {
+bool InitClockDevice(MediaClockDevice* clock_device) {
+  DCHECK(clock_device);
+  DCHECK_EQ(clock_device->GetState(), MediaClockDevice::kStateUninitialized);
+
+  if (!clock_device->SetState(media::MediaClockDevice::kStateIdle))
+    return false;
+
+  if (!clock_device->ResetTimeline(0))
+    return false;
+
+  if (!clock_device->SetRate(1.0))
+    return false;
+
+  return true;
+}
+
+bool InitAudioDevice(const ::media::AudioParameters& audio_params,
+                     AudioPipelineDevice* audio_device) {
+  DCHECK(audio_device);
+  DCHECK_EQ(audio_device->GetState(), AudioPipelineDevice::kStateUninitialized);
+
+  AudioConfig audio_config;
+  audio_config.codec = kCodecPCM;
+  audio_config.sample_format = kSampleFormatPlanarS16;
+  audio_config.bytes_per_channel = audio_params.bits_per_sample() / 8;
+  audio_config.channel_number = audio_params.channels();
+  audio_config.samples_per_second = audio_params.sample_rate();
+  audio_config.extra_data = nullptr;
+  audio_config.extra_data_size = 0;
+  audio_config.is_encrypted = false;
+  if (!audio_device->SetConfig(audio_config))
+    return false;
+
+  if (!audio_device->SetState(AudioPipelineDevice::kStateIdle))
+    return false;
+
+  return true;
+}
+}  // namespace
+
+AudioOutputStream::AudioOutputStream(
+    const ::media::AudioParameters& audio_params,
+    AudioManager* audio_manager)
+    : audio_params_(audio_params),
+      audio_manager_(audio_manager),
+      volume_(1.0),
+      audio_device_busy_(false),
+      weak_factory_(this) {
+  LOG(INFO) << __FUNCTION__ << " : " << this;
+  LOG(INFO) << "Audio Parameters: " << audio_params_.AsHumanReadableString();

[halliwell, 2015/09/01 21:27:04]

nit: can we put these back on the same log line?

+}
+
+AudioOutputStream::~AudioOutputStream() {}
+
+bool AudioOutputStream::Open() {
+  ::media::AudioParameters::Format format = audio_params_.format();
+  if ((format != ::media::AudioParameters::AUDIO_PCM_LINEAR) &&
+      (format != ::media::AudioParameters::AUDIO_PCM_LOW_LATENCY)) {
+    LOG(WARNING) << "Unsupported audio format: " << format;
+    return false;
+  }
+
+  ::media::ChannelLayout channel_layout = audio_params_.channel_layout();
+  if ((channel_layout != ::media::CHANNEL_LAYOUT_MONO) &&
+      (channel_layout != ::media::CHANNEL_LAYOUT_STEREO)) {
+    LOG(WARNING) << "Unsupported channel layout: " << channel_layout;
+    return false;
+  }
+  DCHECK_GE(audio_params_.channels(), 1);
+  DCHECK_LE(audio_params_.channels(), 2);
+
+  media_pipeline_backend_ = audio_manager_->CreateMediaPipelineBackend();
+  if (!media_pipeline_backend_) {
+    LOG(WARNING) << "Failed to create media pipeline backend.";
+    return false;
+  }
+
+  if (!InitClockDevice(media_pipeline_backend_->GetClock())) {
+    LOG(WARNING) << "Failed to initialize clock device.";
+    return false;
+  }
+
+  if (!InitAudioDevice(audio_params_, media_pipeline_backend_->GetAudio())) {
+    LOG(WARNING) << "Failed to initialize audio device.";
+    return false;
+  }
+
+  audio_bus_ = ::media::AudioBus::Create(audio_params_);
+  audio_worker_.reset(new ::media::FakeAudioWorker(
+      base::ThreadTaskRunnerHandle::Get(), audio_params_));
+
+  LOG(INFO) << __FUNCTION__ << " : " << this;
+  return true;
+}
+
+void AudioOutputStream::Close() {
+  LOG(INFO) << __FUNCTION__ << " : " << this;
+
+  if (media_pipeline_backend_) {
+    media_pipeline_backend_->GetClock()->SetState(MediaClockDevice::kStateIdle);
+    media_pipeline_backend_->GetAudio()->SetState(
+        AudioPipelineDevice::kStateIdle);
+  }
+
+  audio_worker_.reset();
+  audio_bus_.reset();
+  media_pipeline_backend_.reset();
+
+  // Signal to the manager that we're closed and can be removed.
+  // This should be the last call in the function as it deletes "this".
+  audio_manager_->ReleaseOutputStream(this);
+}
+
+void AudioOutputStream::Start(AudioSourceCallback* source_callback) {
+  MediaClockDevice* clock_device = media_pipeline_backend_->GetClock();
+  DCHECK(clock_device);
+  if (!clock_device->SetState(MediaClockDevice::kStateRunning)) {
+    LOG(WARNING) << "Failed to run clock device.";
+    return;
+  }
+  clock_device->SetRate(1.0f);
+
+  AudioPipelineDevice* audio_device = media_pipeline_backend_->GetAudio();
+  DCHECK(audio_device);
+  if (!audio_device->SetState(AudioPipelineDevice::kStateRunning)) {
+    LOG(WARNING) << "Failed to run audio device.";
+    return;
+  }
+
+  LOG(INFO) << __FUNCTION__ << " : " << this;
+  audio_worker_->Start(base::Bind(&AudioOutputStream::PushFrame,
+                                  weak_factory_.GetWeakPtr(), source_callback));
+}
+
+void AudioOutputStream::Stop() {
+  LOG(INFO) << __FUNCTION__ << " : " << this;
+
+  MediaClockDevice* clock_device = media_pipeline_backend_->GetClock();
+  DCHECK(clock_device);
+  clock_device->SetState(MediaClockDevice::kStateIdle);
+  clock_device->SetRate(0.0f);
+
+  AudioPipelineDevice* audio_device = media_pipeline_backend_->GetAudio();
+  DCHECK(audio_device);
+  audio_device->SetState(AudioPipelineDevice::kStatePaused);
+  audio_worker_->Stop();
+  audio_device_busy_ = false;
+}
+
+void AudioOutputStream::SetVolume(double volume) {
+  AudioPipelineDevice* audio_device = media_pipeline_backend_->GetAudio();
+  DCHECK(audio_device);
+  audio_device->SetStreamVolumeMultiplier(volume);
+  volume_ = volume;
+}
+
+void AudioOutputStream::GetVolume(double* volume) {
+  *volume = volume_;
+}
+
+void AudioOutputStream::PushFrame(AudioSourceCallback* source_callback) {
+  DCHECK(source_callback);
+  if (audio_device_busy_) {
+    // Skip pulling data if audio device is still busy.
+    LOG(WARNING) << __FUNCTION__ << " : " << this
+                 << " skipped because audio device is busy.";

[halliwell, 2015/09/01 21:27:03]

hmmm ... isn't this log going to happen all the time?

I don't know how the feeding of audio data happens with AudioOutputStream, but
with media pipelines, we essentially always hit this condition where the
hardware buffer is full and have to wait to push more frames.  We wouldn't want
to log for every frame in that case.

[alokp, 2015/09/01 23:26:12]

No it should not fire all the time. AudioWorker calls PushFrame at playback
rate, so the device being busy is an error condition.

+    return;
+  }
+
+  int frame_count = source_callback->OnMoreData(audio_bus_.get(), 0);
+  DCHECK_EQ(frame_count, audio_bus_->frames());
+  int buffer_size = frame_count * audio_params_.GetBytesPerFrame();
+  scoped_refptr<::media::DecoderBuffer> decoder_buffer(
+      new ::media::DecoderBuffer(buffer_size));
+  audio_bus_->ToInterleaved(frame_count, audio_params_.bits_per_sample() / 8,
+                            decoder_buffer->writable_data());
+
+  AudioPipelineDevice* audio_device = media_pipeline_backend_->GetAudio();
+  DCHECK(audio_device);
+  MediaComponentDevice::FrameStatus status = audio_device->PushFrame(
+      nullptr,  // decrypt_context
+      new CastDecoderBufferImpl(new DecoderBufferAdapter(decoder_buffer)),
+      new media::FrameStatusCBImpl(
+          base::Bind(&AudioOutputStream::OnPushFrameStatus,
+                     weak_factory_.GetWeakPtr(), source_callback)));
+
+  if (status == MediaComponentDevice::kFrameFailed) {
+    // Note: We cannot call OnPushFrameError directly because it will lead to
+    // a recursive lock, which is not supported by base::Lock.
+    // This callback is called with a lock held inside FakeAudioWorker.
+    // Calling FakeAudioWorker::Stop will try to acquire the lock again.
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&AudioOutputStream::OnPushFrameError,
+                              weak_factory_.GetWeakPtr(), source_callback));
+  } else if (status == MediaComponentDevice::kFramePending) {
+    audio_device_busy_ = true;
+  }
+}
+
+void AudioOutputStream::OnPushFrameStatus(
+    AudioSourceCallback* source_callback,
+    MediaComponentDevice::FrameStatus status) {
+  DCHECK(audio_device_busy_);
+  audio_device_busy_ = false;
+
+  DCHECK_NE(status, MediaComponentDevice::kFramePending);
+  if (status == MediaComponentDevice::kFrameFailed)
+    OnPushFrameError(source_callback);
+}
+
+void AudioOutputStream::OnPushFrameError(AudioSourceCallback* source_callback) {
+  LOG(WARNING) << __FUNCTION__ << " : " << this;
+  // Inform audio source about the error and stop pulling data.
+  audio_worker_->Stop();
+  source_callback->OnError(this);
+}
+
+}  // namespace media
+}  // namespace chromecast