src/cobalt/audio/audio_buffer.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.h"

#include "cobalt/audio/audio_helpers.h"
#include "cobalt/dom/dom_exception.h"

namespace cobalt {
namespace audio {

AudioBuffer::AudioBuffer(script::EnvironmentSettings* settings,
                         float sample_rate, int32 number_of_frames,
                         int32 number_of_channels,
                         scoped_array<uint8> channels_data,
                         SampleType sample_type)
    : sample_rate_(sample_rate),
      length_(number_of_frames),
      sample_type_(sample_type) {
  DCHECK_GT(sample_rate_, 0);
  DCHECK_GT(length_, 0);
  DCHECK_GT(number_of_channels, 0);

  // Create an ArrayBuffer stores sample data from all channels.
  const uint32 length =
      number_of_frames * number_of_channels *
      (sample_type == kSampleTypeFloat32 ? sizeof(float) : sizeof(int16));
  scoped_refptr<dom::ArrayBuffer> array_buffer(new dom::ArrayBuffer(
      settings, dom::ArrayBuffer::kFromHeap, channels_data.Pass(), length));

  // Each channel should have |number_of_frames * size_of_sample_type| bytes.
  // We create |number_of_channels| of {Float32,Int16}Array as views into the
  // above ArrayBuffer.  This does not need any extra allocation.
  if (sample_type == kSampleTypeFloat32) {
    channels_data_.resize(static_cast<size_t>(number_of_channels));
    uint32 start_offset_in_bytes = 0;
    for (int32 i = 0; i < number_of_channels; ++i) {
      channels_data_[static_cast<size_t>(i)] =
          new dom::Float32Array(settings, array_buffer, start_offset_in_bytes,
                                static_cast<uint32>(number_of_frames), NULL);
      start_offset_in_bytes += number_of_frames * sizeof(float);
    }
  } else if (sample_type == kSampleTypeInt16) {
    channels_int16_data_.resize(static_cast<size_t>(number_of_channels));
    uint32 start_offset_in_bytes = 0;
    for (int32 i = 0; i < number_of_channels; ++i) {
      channels_int16_data_[static_cast<size_t>(i)] =
          new dom::Int16Array(settings, array_buffer, start_offset_in_bytes,
                              static_cast<uint32>(number_of_frames), NULL);
      start_offset_in_bytes += number_of_frames * sizeof(int16);
    }
  } else {
    NOTREACHED();
  }
}

scoped_refptr<dom::Float32Array> AudioBuffer::GetChannelData(
    uint32 channel_index, script::ExceptionState* exception_state) const {
  DCHECK_EQ(sample_type_, kSampleTypeFloat32);
  // The index value MUST be less than number_of_channels() or an INDEX_SIZE_ERR
  // exception MUST be thrown.
  if (channel_index >= channels_data_.size()) {
    dom::DOMException::Raise(dom::DOMException::kIndexSizeErr, exception_state);
    return NULL;
  }

  return channels_data_[channel_index];
}

scoped_refptr<dom::Int16Array> AudioBuffer::GetChannelDataInt16(
    uint32 channel_index, script::ExceptionState* exception_state) const {
  DCHECK_EQ(sample_type_, kSampleTypeInt16);
  // The index value MUST be less than number_of_channels() or an INDEX_SIZE_ERR
  // exception MUST be thrown.
  if (channel_index >= channels_int16_data_.size()) {
    dom::DOMException::Raise(dom::DOMException::kIndexSizeErr, exception_state);
    return NULL;
  }

  return channels_int16_data_[channel_index];
}

}  // namespace audio
}  // namespace cobalt