src/cobalt/audio/audio_buffer_source_node.cc

/*
 * Copyright 2015 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "cobalt/audio/audio_buffer_source_node.h"

#include <algorithm>

#include "cobalt/audio/audio_context.h"
#include "cobalt/audio/audio_node_output.h"

namespace cobalt {
namespace audio {

typedef ::media::ShellAudioBus ShellAudioBus;

// numberOfInputs  : 0
// numberOfOutputs : 1
AudioBufferSourceNode::AudioBufferSourceNode(AudioContext* context)
    : AudioNode(context), state_(kNone), read_index_(0) {
  AudioLock::AutoLock lock(audio_lock());

  AddOutput(new AudioNodeOutput(this));
}

AudioBufferSourceNode::~AudioBufferSourceNode() {
  AudioLock::AutoLock lock(audio_lock());

  DCHECK_EQ(number_of_inputs(), 0u);
  RemoveAllOutputs();
}

void AudioBufferSourceNode::set_buffer(
    const scoped_refptr<AudioBuffer>& buffer) {
  AudioLock::AutoLock lock(audio_lock());

  buffer_ = buffer;
}

void AudioBufferSourceNode::Start(double when, double offset,
                                  script::ExceptionState* exception_state) {
  Start(when, offset, 0, exception_state);
}

// TODO: Fully implement start and stop method. The starting time is
// based on the current time of AudioContext. We only support start at 0
// currently.
void AudioBufferSourceNode::Start(double when, double offset, double duration,
                                  script::ExceptionState* exception_state) {
  AudioLock::AutoLock lock(audio_lock());

  DCHECK_EQ(when, 0);
  DCHECK_EQ(offset, 0);
  DCHECK_EQ(duration, 0);

  if (state_ != kNone) {
    dom::DOMException::Raise(dom::DOMException::kInvalidStateErr,
                             exception_state);
    return;
  }
  state_ = kStarted;
}

void AudioBufferSourceNode::Stop(double when,
                                 script::ExceptionState* exception_state) {
  AudioLock::AutoLock lock(audio_lock());

  DCHECK_EQ(when, 0);

  if (state_ != kStarted) {
    dom::DOMException::Raise(dom::DOMException::kInvalidStateErr,
                             exception_state);
    return;
  }
  state_ = kStoped;
}

scoped_ptr<ShellAudioBus> AudioBufferSourceNode::PassAudioBusFromSource(
    int32 number_of_frames) {
  // This is called by Audio thread.
  audio_lock()->AssertLocked();

  if (state_ != kStarted || !buffer_ || buffer_->length() == read_index_) {
    return scoped_ptr<ShellAudioBus>();
  }

  DCHECK_GT(number_of_frames, 0);
  int32 frames_to_end = buffer_->length() - read_index_;
  number_of_frames = std::min(number_of_frames, frames_to_end);

  size_t channels = static_cast<size_t>(buffer_->number_of_channels());

  std::vector<float*> audio_buffer;
  for (size_t i = 0; i < channels; ++i) {
    scoped_refptr<dom::Float32Array> buffer_data =
        buffer_->GetChannelData(static_cast<uint32>(i), NULL);
    scoped_refptr<dom::Float32Array> sub_array = buffer_data->Subarray(
        NULL, read_index_, read_index_ + number_of_frames);
    audio_buffer.push_back(sub_array->data());
  }

  read_index_ += number_of_frames;

  scoped_ptr<ShellAudioBus> audio_bus(
      new ShellAudioBus(static_cast<size_t>(number_of_frames), audio_buffer));

  return audio_bus.Pass();
}

}  // namespace audio
}  // namespace cobalt