media/audio/simple_sources.cc

   1 // Copyright (c) 2012 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 // MSVC++ requires this to be set before any other includes to get M_PI.
   5 #define _USE_MATH_DEFINES
   6 #include <cmath>
   7
   8 #include "media/audio/simple_sources.h"
   9
  10 #include <algorithm>
  11
  12 #include "base/files/file.h"
  13 #include "base/lazy_instance.h"
  14 #include "base/logging.h"
  15 #include "media/audio/sounds/wav_audio_handler.h"
  16 #include "media/base/audio_bus.h"
  17
  18 namespace media {
  19
  20 // Opens |wav_filename|, reads it and loads it as a wav file. This function will
  21 // bluntly trigger CHECKs if we can't read the file or if it's malformed. The
  22 // caller takes ownership of the returned data. The size of the data is stored
  23 // in |read_length|.
  24 static scoped_ptr<uint8[]> ReadWavFile(const base::FilePath& wav_filename,
  25                                        size_t* file_length) {
  26   base::File wav_file(
  27       wav_filename, base::File::FLAG_OPEN | base::File::FLAG_READ);
  28   CHECK(wav_file.IsValid())
  29       << "Failed to read " << wav_filename.value()
  30       << " as input to the fake device.";
  31
  32   size_t wav_file_length = wav_file.GetLength();
  33   CHECK_GT(wav_file_length, 0u)
  34       << "Input file to fake device is empty: " << wav_filename.value();
  35
  36   uint8* wav_file_data = new uint8[wav_file_length];
  37   size_t read_bytes = wav_file.Read(0, reinterpret_cast<char*>(wav_file_data),
  38                                     wav_file_length);
  39   CHECK_EQ(read_bytes, wav_file_length)
  40       << "Failed to read all bytes of " << wav_filename.value();
  41   *file_length = wav_file_length;
  42   return scoped_ptr<uint8[]>(wav_file_data);
  43 }
  44
  45 // Opens |wav_filename|, reads it and loads it as a wav file. This function will
  46 // bluntly trigger CHECKs if we can't read the file or if it's malformed.
  47 static scoped_ptr<WavAudioHandler> CreateWavAudioHandler(
  48     const base::FilePath& wav_filename, const uint8* wav_file_data,
  49     size_t wav_file_length, const AudioParameters& expected_params) {
  50   base::StringPiece wav_data(reinterpret_cast<const char*>(wav_file_data),
  51                              wav_file_length);
  52   scoped_ptr<WavAudioHandler> wav_audio_handler(new WavAudioHandler(wav_data));
  53   return wav_audio_handler.Pass();
  54 }
  55
  56 // These values are based on experiments for local-to-local
  57 // PeerConnection to demonstrate audio/video synchronization.
  58 static const int kBeepDurationMilliseconds = 20;
  59 static const int kBeepFrequency = 400;
  60
  61 // Intervals between two automatic beeps.
  62 static const int kAutomaticBeepIntervalInMs = 500;
  63
  64 // Automatic beep will be triggered every |kAutomaticBeepIntervalInMs| unless
  65 // users explicitly call BeepOnce(), which will disable the automatic beep.
  66 class BeepContext {
  67  public:
  68   BeepContext() : beep_once_(false), automatic_beep_(true) {}
  69
  70   void SetBeepOnce(bool enable) {
  71     base::AutoLock auto_lock(lock_);
  72     beep_once_ = enable;
  73
  74     // Disable the automatic beep if users explicit set |beep_once_| to true.
  75     if (enable)
  76       automatic_beep_ = false;
  77   }
  78
  79   bool beep_once() const {
  80     base::AutoLock auto_lock(lock_);
  81     return beep_once_;
  82   }
  83
  84   bool automatic_beep() const {
  85     base::AutoLock auto_lock(lock_);
  86     return automatic_beep_;
  87   }
  88
  89  private:
  90   mutable base::Lock lock_;
  91   bool beep_once_;
  92   bool automatic_beep_;
  93 };
  94
  95 static base::LazyInstance<BeepContext>::Leaky g_beep_context =
  96     LAZY_INSTANCE_INITIALIZER;
  97
  98 //////////////////////////////////////////////////////////////////////////////
  99 // SineWaveAudioSource implementation.
 100
 101 SineWaveAudioSource::SineWaveAudioSource(int channels,
 102                                          double freq, double sample_freq)
 103     : channels_(channels),
 104       f_(freq / sample_freq),
 105       time_state_(0),
 106       cap_(0),
 107       callbacks_(0),
 108       errors_(0) {
 109 }
 110
 111 SineWaveAudioSource::~SineWaveAudioSource() {
 112 }
 113
 114 // The implementation could be more efficient if a lookup table is constructed
 115 // but it is efficient enough for our simple needs.
 116 int SineWaveAudioSource::OnMoreData(AudioBus* audio_bus,
 117                                     uint32 total_bytes_delay) {
 118   base::AutoLock auto_lock(time_lock_);
 119   callbacks_++;
 120
 121   // The table is filled with s(t) = kint16max*sin(Theta*t),
 122   // where Theta = 2*PI*fs.
 123   // We store the discrete time value |t| in a member to ensure that the
 124   // next pass starts at a correct state.
 125   int max_frames = cap_ > 0 ?
 126       std::min(audio_bus->frames(), cap_ - time_state_) : audio_bus->frames();
 127   for (int i = 0; i < max_frames; ++i)
 128     audio_bus->channel(0)[i] = sin(2.0 * M_PI * f_ * time_state_++);
 129   for (int i = 1; i < audio_bus->channels(); ++i) {
 130     memcpy(audio_bus->channel(i), audio_bus->channel(0),
 131            max_frames * sizeof(*audio_bus->channel(i)));
 132   }
 133   return max_frames;
 134 }
 135
 136 void SineWaveAudioSource::OnError(AudioOutputStream* stream) {
 137   errors_++;
 138 }
 139
 140 void SineWaveAudioSource::CapSamples(int cap) {
 141   base::AutoLock auto_lock(time_lock_);
 142   DCHECK_GT(cap, 0);
 143   cap_ = cap;
 144 }
 145
 146 void SineWaveAudioSource::Reset() {
 147   base::AutoLock auto_lock(time_lock_);
 148   time_state_ = 0;
 149 }
 150
 151 FileSource::FileSource(const AudioParameters& params,
 152                        const base::FilePath& path_to_wav_file)
 153     : params_(params),
 154       path_to_wav_file_(path_to_wav_file),
 155       wav_file_read_pos_(0) {
 156 }
 157
 158 FileSource::~FileSource() {
 159 }
 160
 161 void FileSource::LoadWavFile(const base::FilePath& path_to_wav_file) {
 162   // Read the file, and put its data in a scoped_ptr so it gets deleted later.
 163   size_t file_length = 0;
 164   wav_file_data_ = ReadWavFile(path_to_wav_file, &file_length);
 165   wav_audio_handler_ = CreateWavAudioHandler(
 166       path_to_wav_file, wav_file_data_.get(), file_length, params_);
 167
 168   // Hook us up so we pull in data from the file into the converter. We need to
 169   // modify the wav file's audio parameters since we'll be reading small slices
 170   // of it at a time and not the whole thing (like 10 ms at a time).
 171   AudioParameters file_audio_slice(
 172       wav_audio_handler_->params().format(),
 173       wav_audio_handler_->params().channel_layout(),
 174       wav_audio_handler_->params().sample_rate(),
 175       wav_audio_handler_->params().bits_per_sample(),
 176       params_.frames_per_buffer());
 177
 178   file_audio_converter_.reset(
 179       new AudioConverter(file_audio_slice, params_, false));
 180   file_audio_converter_->AddInput(this);
 181 }
 182
 183 int FileSource::OnMoreData(AudioBus* audio_bus, uint32 total_bytes_delay) {
 184   // Load the file if we haven't already. This load needs to happen on the
 185   // audio thread, otherwise we'll run on the UI thread on Mac for instance.
 186   // This will massively delay the first OnMoreData, but we'll catch up.
 187   if (!wav_audio_handler_)
 188     LoadWavFile(path_to_wav_file_);
 189
 190   DCHECK(wav_audio_handler_.get());
 191
 192   // Stop playing if we've played out the whole file.
 193   if (wav_audio_handler_->AtEnd(wav_file_read_pos_))
 194     return 0;
 195
 196   // This pulls data from ProvideInput.
 197   file_audio_converter_->Convert(audio_bus);
 198   return audio_bus->frames();
 199 }
 200
 201 double FileSource::ProvideInput(AudioBus* audio_bus_into_converter,
 202                                 base::TimeDelta buffer_delay) {
 203   // Unfilled frames will be zeroed by CopyTo.
 204   size_t bytes_written;
 205   wav_audio_handler_->CopyTo(audio_bus_into_converter, wav_file_read_pos_,
 206                              &bytes_written);
 207   wav_file_read_pos_ += bytes_written;
 208   return 1.0;
 209 };
 210
 211 void FileSource::OnError(AudioOutputStream* stream) {
 212 }
 213
 214 BeepingSource::BeepingSource(const AudioParameters& params)
 215     : buffer_size_(params.GetBytesPerBuffer()),
 216       buffer_(new uint8[buffer_size_]),
 217       params_(params),
 218       last_callback_time_(base::TimeTicks::Now()),
 219       beep_duration_in_buffers_(kBeepDurationMilliseconds *
 220                                 params.sample_rate() /
 221                                 params.frames_per_buffer() /
 222                                 1000),
 223       beep_generated_in_buffers_(0),
 224       beep_period_in_frames_(params.sample_rate() / kBeepFrequency) {
 225 }
 226
 227 BeepingSource::~BeepingSource() {
 228 }
 229
 230 int BeepingSource::OnMoreData(AudioBus* audio_bus, uint32 total_bytes_delay) {
 231   // Accumulate the time from the last beep.
 232   interval_from_last_beep_ += base::TimeTicks::Now() - last_callback_time_;
 233
 234   memset(buffer_.get(), 0, buffer_size_);
 235   bool should_beep = false;
 236   BeepContext* beep_context = g_beep_context.Pointer();
 237   if (beep_context->automatic_beep()) {
 238     base::TimeDelta delta = interval_from_last_beep_ -
 239         base::TimeDelta::FromMilliseconds(kAutomaticBeepIntervalInMs);
 240     if (delta > base::TimeDelta()) {
 241       should_beep = true;
 242       interval_from_last_beep_ = delta;
 243     }
 244   } else {
 245     should_beep = beep_context->beep_once();
 246     beep_context->SetBeepOnce(false);
 247   }
 248
 249   // If this object was instructed to generate a beep or has started to
 250   // generate a beep sound.
 251   if (should_beep || beep_generated_in_buffers_) {
 252     // Compute the number of frames to output high value. Then compute the
 253     // number of bytes based on channels and bits per channel.
 254     int high_frames = beep_period_in_frames_ / 2;
 255     int high_bytes = high_frames * params_.bits_per_sample() *
 256         params_.channels() / 8;
 257
 258     // Separate high and low with the same number of bytes to generate a
 259     // square wave.
 260     int position = 0;
 261     while (position + high_bytes <= buffer_size_) {
 262       // Write high values first.
 263       memset(buffer_.get() + position, 128, high_bytes);
 264       // Then leave low values in the buffer with |high_bytes|.
 265       position += high_bytes * 2;
 266     }
 267
 268     ++beep_generated_in_buffers_;
 269     if (beep_generated_in_buffers_ >= beep_duration_in_buffers_)
 270       beep_generated_in_buffers_ = 0;
 271   }
 272
 273   last_callback_time_ = base::TimeTicks::Now();
 274   audio_bus->FromInterleaved(
 275       buffer_.get(), audio_bus->frames(), params_.bits_per_sample() / 8);
 276   return audio_bus->frames();
 277 }
 278
 279 void BeepingSource::OnError(AudioOutputStream* stream) {
 280 }
 281
 282 void BeepingSource::BeepOnce() {
 283   g_beep_context.Pointer()->SetBeepOnce(true);
 284 }
 285
 286 }  // namespace media