components/copresence/mediums/audio/audio_recorder.cc

// Copyright 2014 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 "components/copresence/mediums/audio/audio_recorder.h"

#include <algorithm>
#include <vector>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/logging.h"
#include "base/run_loop.h"
#include "base/synchronization/waitable_event.h"
#include "components/copresence/public/copresence_constants.h"
#include "content/public/browser/browser_thread.h"
#include "media/audio/audio_manager.h"
#include "media/audio/audio_manager_base.h"
#include "media/base/audio_bus.h"

namespace copresence {

namespace {

const float kProcessIntervalMs = 500.0f;  // milliseconds.

void AudioBusToString(scoped_ptr<media::AudioBus> source, std::string* buffer) {
  buffer->resize(source->frames() * source->channels() * sizeof(float));
  float* buffer_view = reinterpret_cast<float*>(string_as_array(buffer));

  const int channels = source->channels();
  for (int ch = 0; ch < channels; ++ch) {
    for (int si = 0, di = ch; si < source->frames(); ++si, di += channels)
      buffer_view[di] = source->channel(ch)[si];
  }
}

// Called every kProcessIntervalMs to process the recorded audio. This
// converts our samples to the required sample rate, interleaves the samples
// and sends them to the whispernet decoder to process.
void ProcessSamples(scoped_ptr<media::AudioBus> bus,
                    const AudioRecorder::DecodeSamplesCallback& callback) {
  std::string samples;
  AudioBusToString(bus.Pass(), &samples);
  content::BrowserThread::PostTask(
      content::BrowserThread::UI, FROM_HERE, base::Bind(callback, samples));
}

}  // namespace

// Public methods.

AudioRecorder::AudioRecorder(const DecodeSamplesCallback& decode_callback)
    : is_recording_(false),
      stream_(NULL),
      decode_callback_(decode_callback),
      total_buffer_frames_(0),
      buffer_frame_index_(0) {
}

void AudioRecorder::Initialize() {
  media::AudioManager::Get()->GetTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&AudioRecorder::InitializeOnAudioThread,
                 base::Unretained(this)));
}

AudioRecorder::~AudioRecorder() {
}

void AudioRecorder::Record() {
  media::AudioManager::Get()->GetTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&AudioRecorder::RecordOnAudioThread, base::Unretained(this)));
}

void AudioRecorder::Stop() {
  media::AudioManager::Get()->GetTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&AudioRecorder::StopOnAudioThread, base::Unretained(this)));
}

bool AudioRecorder::IsRecording() {
  return is_recording_;
}

void AudioRecorder::Finalize() {
  media::AudioManager::Get()->GetTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&AudioRecorder::FinalizeOnAudioThread,
                 base::Unretained(this)));
}

// Private methods.

void AudioRecorder::InitializeOnAudioThread() {
  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());

  media::AudioParameters params =
      params_for_testing_
          ? *params_for_testing_
          : media::AudioManager::Get()->GetInputStreamParameters(
                media::AudioManagerBase::kDefaultDeviceId);

  const media::AudioParameters dest_params(params.format(),
                                           kDefaultChannelLayout,
                                           kDefaultSampleRate,
                                           kDefaultBitsPerSample,
                                           params.frames_per_buffer(),
                                           media::AudioParameters::NO_EFFECTS);

  converter_.reset(new media::AudioConverter(
      params, dest_params, params.sample_rate() == dest_params.sample_rate()));
  converter_->AddInput(this);

  total_buffer_frames_ = kProcessIntervalMs * dest_params.sample_rate() / 1000;
  buffer_ =
      media::AudioBus::Create(dest_params.channels(), total_buffer_frames_);
  buffer_frame_index_ = 0;

  stream_ = input_stream_for_testing_
                ? input_stream_for_testing_.get()
                : media::AudioManager::Get()->MakeAudioInputStream(
                      params, media::AudioManagerBase::kDefaultDeviceId);

  if (!stream_ || !stream_->Open()) {
    LOG(ERROR) << "Failed to open an input stream.";
    if (stream_) {
      stream_->Close();
      stream_ = NULL;
    }
    return;
  }
  stream_->SetVolume(stream_->GetMaxVolume());
}

void AudioRecorder::RecordOnAudioThread() {
  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
  if (!stream_ || is_recording_)
    return;

  converter_->Reset();
  stream_->Start(this);
  is_recording_ = true;
}

void AudioRecorder::StopOnAudioThread() {
  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
  if (!stream_ || !is_recording_)
    return;

  stream_->Stop();
  is_recording_ = false;
}

void AudioRecorder::StopAndCloseOnAudioThread() {
  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
  if (!stream_)
    return;

  StopOnAudioThread();
  stream_->Close();
  stream_ = NULL;
}

void AudioRecorder::FinalizeOnAudioThread() {
  DCHECK(media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
  StopAndCloseOnAudioThread();
  delete this;
}

void AudioRecorder::OnData(media::AudioInputStream* stream,
                           const media::AudioBus* source,
                           uint32 /* hardware_delay_bytes */,
                           double /* volume */) {
  temp_conversion_buffer_ = source;
  while (temp_conversion_buffer_) {
    // source->frames() == source_params.frames_per_buffer(), so we only have
    // one chunk of data in the source; correspondingly set the destination
    // size to one chunk.
    // TODO(rkc): Optimize this to directly write into buffer_ so we can avoid
    // the copy into this buffer and then the copy back into buffer_.
    scoped_ptr<media::AudioBus> converted_source =
        media::AudioBus::Create(kDefaultChannels, converter_->ChunkSize());

    // Convert accumulated samples into converted_source. Note: One call may not
    // be enough to consume the samples from |source|.  The converter may have
    // accumulated samples over time due to a fractional input:output sample
    // rate ratio.  Since |source| is ephemeral, Convert() must be called until
    // |source| is at least buffered into the converter.  Once |source| is
    // consumed during ProvideInput(), |temp_conversion_buffer_| will be set to
    // NULL, which will break the conversion loop.
    converter_->Convert(converted_source.get());

    int remaining_buffer_frames = buffer_->frames() - buffer_frame_index_;
    int frames_to_copy =
        std::min(remaining_buffer_frames, converted_source->frames());
    converted_source->CopyPartialFramesTo(
        0, frames_to_copy, buffer_frame_index_, buffer_.get());
    buffer_frame_index_ += frames_to_copy;

    // Buffer full, send it for processing.
    if (buffer_->frames() == buffer_frame_index_) {
      ProcessSamples(buffer_.Pass(), decode_callback_);
      buffer_ = media::AudioBus::Create(kDefaultChannels, total_buffer_frames_);
      buffer_frame_index_ = 0;

      // Copy any remaining frames in the source to our buffer.
      int remaining_source_frames = converted_source->frames() - frames_to_copy;
      converted_source->CopyPartialFramesTo(frames_to_copy,
                                            remaining_source_frames,
                                            buffer_frame_index_,
                                            buffer_.get());
      buffer_frame_index_ += remaining_source_frames;
    }
  }
}

void AudioRecorder::OnError(media::AudioInputStream* /* stream */) {
  LOG(ERROR) << "Error during sound recording.";
  media::AudioManager::Get()->GetTaskRunner()->PostTask(
      FROM_HERE,
      base::Bind(&AudioRecorder::StopAndCloseOnAudioThread,
                 base::Unretained(this)));
}

double AudioRecorder::ProvideInput(media::AudioBus* dest,
                                   base::TimeDelta /* buffer_delay */) {
  DCHECK(temp_conversion_buffer_);
  DCHECK_LE(temp_conversion_buffer_->frames(), dest->frames());
  temp_conversion_buffer_->CopyTo(dest);
  temp_conversion_buffer_ = NULL;
  return 1.0;
}

void AudioRecorder::FlushAudioLoopForTesting() {
  if (media::AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread())
    return;

  // Queue task on the audio thread, when it is executed, that means we've
  // successfully executed all the tasks before us.
  base::RunLoop rl;
  media::AudioManager::Get()->GetTaskRunner()->PostTaskAndReply(
      FROM_HERE,
      base::Bind(base::IgnoreResult(&AudioRecorder::FlushAudioLoopForTesting),
                 base::Unretained(this)),
      rl.QuitClosure());
  rl.Run();
}

}  // namespace copresence