Adding audio support to the new webmediaplyer

content/renderer/media/webrtc_audio_renderer.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_renderer.h"
+
+#include "base/logging.h"
+#include "base/metrics/histogram.h"
+#include "base/string_util.h"
+#include "content/renderer/media/audio_device_factory.h"
+#include "content/renderer/media/audio_hardware.h"
+#include "content/renderer/media/webrtc_audio_device_impl.h"
+#include "media/audio/audio_util.h"
+#include "media/audio/sample_rates.h"
+
+namespace content {
+
+namespace {
+
+// Supported hardware sample rates for output sides.
+#if defined(OS_WIN) || defined(OS_MACOSX)
+// media::GetAudioOutputHardwareSampleRate() asks the audio layer
+// for its current sample rate (set by the user) on Windows and Mac OS X.
+// The listed rates below adds restrictions and Initialize()
+// will fail if the user selects any rate outside these ranges.
+int kValidOutputRates[] = {96000, 48000, 44100};
+#elif defined(OS_LINUX) || defined(OS_OPENBSD)
+int kValidOutputRates[] = {48000, 44100};
+#endif
+
+
+// TODO(xians): Merge the following code to WebRtcAudioCapturer, or remove.
+enum AudioFramesPerBuffer {
+  k160,
+  k320,
+  k440,  // WebRTC works internally with 440 audio frames at 44.1kHz.
+  k480,
+  k640,
+  k880,
+  k960,
+  k1440,
+  k1920,
+  kUnexpectedAudioBufferSize  // Must always be last!
+};
+
+// Helper method to convert integral values to their respective enum values
+// above, or kUnexpectedAudioBufferSize if no match exists.
+AudioFramesPerBuffer AsAudioFramesPerBuffer(int frames_per_buffer) {
+  switch (frames_per_buffer) {
+    case 160: return k160;
+    case 320: return k320;
+    case 440: return k440;
+    case 480: return k480;
+    case 640: return k640;
+    case 880: return k880;
+    case 960: return k960;
+    case 1440: return k1440;
+    case 1920: return k1920;
+  }
+  return kUnexpectedAudioBufferSize;
+}
+
+void AddHistogramFramesPerBuffer(int param) {
+  AudioFramesPerBuffer afpb = AsAudioFramesPerBuffer(param);
+  if (afpb != kUnexpectedAudioBufferSize) {
+    UMA_HISTOGRAM_ENUMERATION("WebRTC.AudioOutputFramesPerBuffer",
+                              afpb, kUnexpectedAudioBufferSize);
+  } else {
+    // Report unexpected sample rates using a unique histogram name.
+    UMA_HISTOGRAM_COUNTS("WebRTC.AudioOutputFramesPerBufferUnexpected", param);
+  }
+}
+
+}  // namespace
+
+WebRtcAudioRenderer::WebRtcAudioRenderer()
+    : state_(UNINITIALIZED),
+      source_(NULL) {
+}
+
+WebRtcAudioRenderer::~WebRtcAudioRenderer() {
+  DCHECK_EQ(state_, UNINITIALIZED);
+  buffer_.reset();
+}
+
+bool WebRtcAudioRenderer::Initialize(WebRtcAudioRendererSource* source) {
+  base::AutoLock auto_lock(lock_);
+  DCHECK_EQ(state_, UNINITIALIZED);
+  DCHECK(source);
+  DCHECK(!sink_);
+  DCHECK(!source_);
+
+  sink_ = AudioDeviceFactory::NewOutputDevice();
+  DCHECK(sink_);
+
+  // Ask the browser for the default audio output hardware sample-rate.
+  // This request is based on a synchronous IPC message.
+  int sample_rate = GetAudioOutputSampleRate();
+  DVLOG(1) << "Audio output hardware sample rate: " << sample_rate;
+  UMA_HISTOGRAM_ENUMERATION("WebRTC.AudioOutputSampleRate",
+                            sample_rate, media::kUnexpectedAudioSampleRate);
+
+  // Verify that the reported output hardware sample rate is supported
+  // on the current platform.
+  if (std::find(&kValidOutputRates[0],
+                &kValidOutputRates[0] + arraysize(kValidOutputRates),
+                sample_rate) ==
+                    &kValidOutputRates[arraysize(kValidOutputRates)]) {
+    DLOG(ERROR) << sample_rate << " is not a supported output rate.";
+    return false;
+  }
+
+  media::ChannelLayout channel_layout = media::CHANNEL_LAYOUT_STEREO;
+
+  int buffer_size = 0;
+
+  // Windows
+#if defined(OS_WIN)
+  // Always use stereo rendering on Windows.
+  channel_layout = media::CHANNEL_LAYOUT_STEREO;
+
+  // Render side: AUDIO_PCM_LOW_LATENCY is based on the Core Audio (WASAPI)
+  // API which was introduced in Windows Vista. For lower Windows versions,
+  // a callback-driven Wave implementation is used instead. An output buffer
+  // size of 10ms works well for WASAPI but 30ms is needed for Wave.
+
+  // Use different buffer sizes depending on the current hardware sample rate.
+  if (sample_rate == 96000 || sample_rate == 48000) {
+    buffer_size = (sample_rate / 100);
+  } else {
+    // We do run at 44.1kHz at the actual audio layer, but ask for frames
+    // at 44.0kHz to ensure that we can feed them to the webrtc::VoiceEngine.
+    // TODO(henrika): figure out why we seem to need 20ms here for glitch-
+    // free audio.
+    buffer_size = 2 * 440;
+  }
+
+  // Windows XP and lower can't cope with 10 ms output buffer size.
+  // It must be extended to 30 ms (60 ms will be used internally by WaveOut).
+  if (!media::IsWASAPISupported()) {
+    buffer_size = 3 * buffer_size;
+    DLOG(WARNING) << "Extending the output buffer size by a factor of three "
+                  << "since Windows XP has been detected.";
+  }
+#elif defined(OS_MACOSX)
+  channel_layout = media::CHANNEL_LAYOUT_MONO;
+
+  // Render side: AUDIO_PCM_LOW_LATENCY on Mac OS X is based on a callback-
+  // driven Core Audio implementation. Tests have shown that 10ms is a suitable
+  // frame size to use, both for 48kHz and 44.1kHz.
+
+  // Use different buffer sizes depending on the current hardware sample rate.
+  if (sample_rate == 48000) {
+    buffer_size = 480;
+  } else {
+    // We do run at 44.1kHz at the actual audio layer, but ask for frames
+    // at 44.0kHz to ensure that we can feed them to the webrtc::VoiceEngine.
+    buffer_size = 440;
+  }
+#elif defined(OS_LINUX) || defined(OS_OPENBSD)
+  channel_layout = media::CHANNEL_LAYOUT_MONO;
+
+  // Based on tests using the current ALSA implementation in Chrome, we have
+  // found that 10ms buffer size on the output side works fine.
+  buffer_size = 480;
+#else
+  DLOG(ERROR) << "Unsupported platform";
+  return false;
+#endif
+
+  // Store utilized parameters to ensure that we can check them
+  // after a successful initialization.
+  params_.Reset(media::AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout,
+                sample_rate, 16, buffer_size);
+
+  // Allocate local audio buffers based on the parameters above.
+  // It is assumed that each audio sample contains 16 bits and each
+  // audio frame contains one or two audio samples depending on the
+  // number of channels.
+  buffer_.reset(new int16[params_.frames_per_buffer() * params_.channels()]);
+
+  source_ = source;
+  source->SetRenderFormat(params_);
+
+  // Configure the audio rendering client and start the rendering.
+  sink_->Initialize(params_, this);
+
+  sink_->Start();
+
+  state_ = PAUSED;
+
+  UMA_HISTOGRAM_ENUMERATION("WebRTC.AudioOutputChannelLayout",
+                            channel_layout, media::CHANNEL_LAYOUT_MAX);
+  UMA_HISTOGRAM_ENUMERATION("WebRTC.AudioOutputFramesPerBuffer",
+                            buffer_size, kUnexpectedAudioBufferSize);
+  AddHistogramFramesPerBuffer(buffer_size);
+
+  return true;
+}
+
+void WebRtcAudioRenderer::Play() {
+  base::AutoLock auto_lock(lock_);
+  if (state_ == UNINITIALIZED)
+    return;
+
+  state_ = PLAYING;
+}
+
+void WebRtcAudioRenderer::Pause() {
+  base::AutoLock auto_lock(lock_);
+  if (state_ == UNINITIALIZED)
+    return;
+
+  state_ = PAUSED;
+}
+
+void WebRtcAudioRenderer::Stop() {
+  base::AutoLock auto_lock(lock_);
+  if (state_ == UNINITIALIZED)
+    return;
+
+  state_ = UNINITIALIZED;
+  source_ = NULL;
+  sink_->Stop();
+}
+
+void WebRtcAudioRenderer::SetVolume(float volume) {
+  base::AutoLock auto_lock(lock_);
+  if (state_ == UNINITIALIZED)
+    return;
+
+  sink_->SetVolume(volume);
+}
+
+int WebRtcAudioRenderer::Render(media::AudioBus* audio_bus,
+                                int audio_delay_milliseconds) {
+  {
+    base::AutoLock auto_lock(lock_);
+    // Return 0 frames to play out zero if it is not in PLAYING state.
+    if (state_ != PLAYING)
+      return 0;
+
+    // We need to keep render data for the |source_| reglardless of |state_|,
+    // otherwise the data will be buffered up inside |source_|.
+    source_->RenderData(reinterpret_cast<uint8*>(buffer_.get()),
+                        audio_bus->channels(), audio_bus->frames(),
+                        audio_delay_milliseconds);
+  }
+
+  // Deinterleave each channel and convert to 32-bit floating-point
+  // with nominal range -1.0 -> +1.0 to match the callback format.
+  audio_bus->FromInterleaved(buffer_.get(), audio_bus->frames(),
+                             params_.bits_per_sample() / 8);
+  return audio_bus->frames();
+}
+
+void WebRtcAudioRenderer::OnRenderError() {
+  NOTIMPLEMENTED();
+  LOG(ERROR) << "OnRenderError()";
+}
+
+}  // namespace content