Moved the fake input stream's processing onto the audio worker thread.

media/audio/simple_sources.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.
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 #include <cmath>
 
 #include "media/audio/simple_sources.h"
 
 #include <algorithm>
 
+#include "base/files/file.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
+#include "media/audio/sounds/wav_audio_handler.h"
+#include "media/base/audio_bus.h"
 
 namespace media {
 
+// Opens |wav_filename|, reads it and loads it as a wav file. This function will
+// bluntly trigger CHECKs if we can't read the file or if it's malformed. The
+// caller takes ownership of the returned data. The size of the data is stored
+// in |read_length|.
+static scoped_ptr<uint8[]> ReadWavFile(const base::FilePath& wav_filename,
+                                       size_t* file_length) {
+  base::File wav_file(
+      wav_filename, base::File::FLAG_OPEN | base::File::FLAG_READ);
+  CHECK(wav_file.IsValid())
+      << "Failed to read " << wav_filename.value()
+      << " as input to the fake device.";
+
+  size_t wav_file_length = wav_file.GetLength();
+  CHECK_GT(wav_file_length, 0u)
+      << "Input file to fake device is empty: " << wav_filename.value();
+
+  uint8* wav_file_data = new uint8[wav_file_length];
+  size_t read_bytes = wav_file.Read(0, reinterpret_cast<char*>(wav_file_data),
+                                    wav_file_length);
+  CHECK_EQ(read_bytes, wav_file_length)
+      << "Failed to read all bytes of " << wav_filename.value();
+  *file_length = wav_file_length;
+  return scoped_ptr<uint8[]>(wav_file_data);
+}
+
+// Opens |wav_filename|, reads it and loads it as a wav file. This function will
+// bluntly trigger CHECKs if we can't read the file or if it's malformed.
+static scoped_ptr<WavAudioHandler> CreateWavAudioHandler(
+    const base::FilePath& wav_filename, const uint8* wav_file_data,
+    size_t wav_file_length, const AudioParameters& expected_params) {
+  base::StringPiece wav_data(reinterpret_cast<const char*>(wav_file_data),
+                             wav_file_length);
+  scoped_ptr<WavAudioHandler> wav_audio_handler(new WavAudioHandler(wav_data));
+  return wav_audio_handler.Pass();
+}
+
+// These values are based on experiments for local-to-local
+// PeerConnection to demonstrate audio/video synchronization.
+static const int kBeepDurationMilliseconds = 20;
+static const int kBeepFrequency = 400;
+
+// Intervals between two automatic beeps.
+static const int kAutomaticBeepIntervalInMs = 500;
+
+// Automatic beep will be triggered every |kAutomaticBeepIntervalInMs| unless
+// users explicitly call BeepOnce(), which will disable the automatic beep.
+class BeepContext {
+ public:
+  BeepContext() : beep_once_(false), automatic_beep_(true) {}
+
+  void SetBeepOnce(bool enable) {
+    base::AutoLock auto_lock(lock_);
+    beep_once_ = enable;
+
+    // Disable the automatic beep if users explicit set |beep_once_| to true.
+    if (enable)
+      automatic_beep_ = false;
+  }
+
+  bool beep_once() const {
+    base::AutoLock auto_lock(lock_);
+    return beep_once_;
+  }
+
+  bool automatic_beep() const {
+    base::AutoLock auto_lock(lock_);
+    return automatic_beep_;
+  }
+
+ private:
+  mutable base::Lock lock_;
+  bool beep_once_;
+  bool automatic_beep_;
+};
+
+static base::LazyInstance<BeepContext>::Leaky g_beep_context =
+    LAZY_INSTANCE_INITIALIZER;
+
 //////////////////////////////////////////////////////////////////////////////
 // SineWaveAudioSource implementation.
 
 SineWaveAudioSource::SineWaveAudioSource(int channels,
                                          double freq, double sample_freq)
     : channels_(channels),
       f_(freq / sample_freq),
       time_state_(0),
       cap_(0),
       callbacks_(0),
       errors_(0) {
 }
 
+SineWaveAudioSource::~SineWaveAudioSource() {
+}
+
 // The implementation could be more efficient if a lookup table is constructed
 // but it is efficient enough for our simple needs.
 int SineWaveAudioSource::OnMoreData(AudioBus* audio_bus,
                                     uint32 total_bytes_delay) {
   base::AutoLock auto_lock(time_lock_);
   callbacks_++;
 
   // The table is filled with s(t) = kint16max*sin(Theta*t),
   // where Theta = 2*PI*fs.
   // We store the discrete time value |t| in a member to ensure that the
@@ skipping 17 matching lines @@
   base::AutoLock auto_lock(time_lock_);
   DCHECK_GT(cap, 0);
   cap_ = cap;
 }
 
 void SineWaveAudioSource::Reset() {
   base::AutoLock auto_lock(time_lock_);
   time_state_ = 0;
 }
 
+FileSource::FileSource(const AudioParameters& params,
+                       const base::FilePath& path_to_wav_file)
+    : params_(params),
+      path_to_wav_file_(path_to_wav_file),
+      wav_file_read_pos_(0) {
+}
+
+FileSource::~FileSource() {
+}
+
+void FileSource::LoadWavFile(const base::FilePath& path_to_wav_file) {
+  // Read the file, and put its data in a scoped_ptr so it gets deleted later.
+  size_t file_length = 0;
+  wav_file_data_ = ReadWavFile(path_to_wav_file, &file_length);
+  wav_audio_handler_ = CreateWavAudioHandler(
+      path_to_wav_file, wav_file_data_.get(), file_length, params_);
+
+  // Hook us up so we pull in data from the file into the converter. We need to
+  // modify the wav file's audio parameters since we'll be reading small slices
+  // of it at a time and not the whole thing (like 10 ms at a time).
+  AudioParameters file_audio_slice(
+      wav_audio_handler_->params().format(),
+      wav_audio_handler_->params().channel_layout(),
+      wav_audio_handler_->params().sample_rate(),
+      wav_audio_handler_->params().bits_per_sample(),
+      params_.frames_per_buffer());
+
+  file_audio_converter_.reset(
+      new AudioConverter(file_audio_slice, params_, false));
+  file_audio_converter_->AddInput(this);
+}
+
+int FileSource::OnMoreData(AudioBus* audio_bus, uint32 total_bytes_delay) {
+  // Load the file if we haven't already. This load needs to happen on the
+  // audio thread, otherwise we'll run on the UI thread on Mac for instance.
+  // This will massively delay the first OnMoreData, but we'll catch up.
+  if (!wav_audio_handler_)
+    LoadWavFile(path_to_wav_file_);
+
+  DCHECK(wav_audio_handler_.get());
+
+  // Stop playing if we've played out the whole file.
+  if (wav_audio_handler_->AtEnd(wav_file_read_pos_))
+    return 0;
+
+  // This pulls data from ProvideInput.
+  file_audio_converter_->Convert(audio_bus);
+  return audio_bus->frames();
+}
+
+double FileSource::ProvideInput(AudioBus* audio_bus_into_converter,
+                                base::TimeDelta buffer_delay) {
+  // Unfilled frames will be zeroed by CopyTo.
+  size_t bytes_written;
+  wav_audio_handler_->CopyTo(audio_bus_into_converter, wav_file_read_pos_,
+                             &bytes_written);
+  wav_file_read_pos_ += bytes_written;
+  return 1.0;
+};
+
+void FileSource::OnError(AudioOutputStream* stream) {
+}
+
+BeepingSource::BeepingSource(const AudioParameters& params)
+    : buffer_size_(params.GetBytesPerBuffer()),
+      buffer_(new uint8[buffer_size_]),
+      params_(params),
+      last_callback_time_(base::TimeTicks::Now()),
+      beep_duration_in_buffers_(kBeepDurationMilliseconds *
+                                params.sample_rate() /
+                                params.frames_per_buffer() /
+                                1000),
+      beep_generated_in_buffers_(0),
+      beep_period_in_frames_(params.sample_rate() / kBeepFrequency) {
+}
+
+BeepingSource::~BeepingSource() {
+}
+
+int BeepingSource::OnMoreData(AudioBus* audio_bus, uint32 total_bytes_delay) {
+  // Accumulate the time from the last beep.
+  interval_from_last_beep_ += base::TimeTicks::Now() - last_callback_time_;
+
+  memset(buffer_.get(), 0, buffer_size_);
+  bool should_beep = false;
+  BeepContext* beep_context = g_beep_context.Pointer();
+  if (beep_context->automatic_beep()) {
+    base::TimeDelta delta = interval_from_last_beep_ -
+        base::TimeDelta::FromMilliseconds(kAutomaticBeepIntervalInMs);
+    if (delta > base::TimeDelta()) {
+      should_beep = true;
+      interval_from_last_beep_ = delta;
+    }
+  } else {
+    should_beep = beep_context->beep_once();
+    beep_context->SetBeepOnce(false);
+  }
+
+  // If this object was instructed to generate a beep or has started to
+  // generate a beep sound.
+  if (should_beep || beep_generated_in_buffers_) {
+    // Compute the number of frames to output high value. Then compute the
+    // number of bytes based on channels and bits per channel.
+    int high_frames = beep_period_in_frames_ / 2;
+    int high_bytes = high_frames * params_.bits_per_sample() *
+        params_.channels() / 8;
+
+    // Separate high and low with the same number of bytes to generate a
+    // square wave.
+    int position = 0;
+    while (position + high_bytes <= buffer_size_) {
+      // Write high values first.
+      memset(buffer_.get() + position, 128, high_bytes);
+      // Then leave low values in the buffer with |high_bytes|.
+      position += high_bytes * 2;
+    }
+
+    ++beep_generated_in_buffers_;
+    if (beep_generated_in_buffers_ >= beep_duration_in_buffers_)
+      beep_generated_in_buffers_ = 0;
+  }
+
+  last_callback_time_ = base::TimeTicks::Now();
+  audio_bus->FromInterleaved(
+      buffer_.get(), audio_bus->frames(), params_.bits_per_sample() / 8);
+  return audio_bus->frames();
+}
+
+void BeepingSource::OnError(AudioOutputStream* stream) {
+}
+
+void BeepingSource::BeepOnce() {
+  g_beep_context.Pointer()->SetBeepOnce(true);
+}
+
 }  // namespace media