Source code
Revision control
Copy as Markdown
/*
Copyright 2018 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
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.
*/
#ifndef RESONANCE_AUDIO_BASE_AUDIO_BUFFER_H_
#define RESONANCE_AUDIO_BASE_AUDIO_BUFFER_H_
#include <algorithm>
#include <memory>
#include "base/integral_types.h"
#include "base/aligned_allocator.h"
#include "base/channel_view.h"
#include "base/constants_and_types.h"
#include "base/logging.h"
#include "base/simd_utils.h"
namespace vraudio {
// Audio buffer that manages multi-channel audio data in a planar data format.
// All channels are sequentially stored within a single consecutive chunk of
// memory. To access individual channel data, the array subscript operator can
// be used to obtain a |AudioBuffer::Channel|. Note that the user must guarantee
// that the AudioBuffer instance lives as long as its channel data is accessed
// via |AudioBuffer::Channel|s. Note that allocated buffers may *not* be
// initialized to zero.
//
// Examples:
//
// // Range-based for-loop over all channels and all samples.
// AudioBuffer audio_buffer(...)
// for (AudioBuffer::Channel& channel : audio_buffer) {
// for (float& sample : channel) {
// sample *= gain;
// }
// }
//
// // Range-based for-loop over all channels and array subscripts-based for-loop
// // to access samples.
// AudioBuffer audio_buffer(...)
// for (AudioBuffer::Channel& channel : audio_buffer) {
// for (size_t i = 0; i < channel.num_frames(); ++i) {
// channel[i] *= gain;
// }
// }
//
// // Array subscript-based for-loops over all channels samples.
// // AudioBuffer audio_buffer(...)
// for (size_t c=0; c < audio_buffer.num_channels(); ++c) {
// // First obtain a reference to AudioBuffer::Channel.
// AudioBuffer::Channel& channel = audio_buffer[c];
// for (size_t i = 0; i < channel.num_frames(); ++i) {
// channel[i] *= gain;
// }
// }
//
// Note do *NOT* use double array subscripts to iterate over multiple samples
// since it performs a channel iterator lookup for every sample:
// for (size_t c=0; c < audio_buffer.num_channels(); ++c) {
// for (size_t i = 0; i < channel.size(); ++i) {
// audio_buffer[c][i] *= gain; // *BAD*
// }
// }
//
class AudioBuffer {
public:
// View on separate audio channel.
typedef ChannelView Channel;
// Allocator class to allocate aligned floats.
typedef AlignedAllocator<float, kMemoryAlignmentBytes> FloatAllocator;
// Allocator class to allocate aligned int16s.
typedef AlignedAllocator<int16, kMemoryAlignmentBytes> Int16Allocator;
// AlignedFloatBuffer for storing audio data.
typedef std::vector<float, FloatAllocator> AlignedFloatVector;
// AlignedInt16Buffer for storing audio data.
typedef std::vector<int16, Int16Allocator> AlignedInt16Vector;
// Default constructor initializes an empty |AudioBuffer|.
AudioBuffer();
// Constructor.
//
// @param num_channels Number of channels.
// @param num_frames Number of frames.
AudioBuffer(size_t num_channels, size_t num_frames);
// Move constructor.
AudioBuffer(AudioBuffer&& other);
// Copy constructor is explicitly deleted to prevent accidental copies.
// Use copy assignment operator instead.
AudioBuffer(const AudioBuffer& other) = delete;
// Copy assignment from AudioBuffer.
AudioBuffer& operator=(const AudioBuffer& other);
// Returns the number of audio channels.
size_t num_channels() const { return channel_views_.size(); }
// Returns the number of frames per buffer.
size_t num_frames() const { return num_frames_; }
// Returns this buffer's source id.
SourceId source_id() const { return source_id_; }
// Returns a reference to the selected ChannelView.
Channel& operator[](size_t channel) {
DCHECK_LT(channel, channel_views_.size());
return channel_views_[channel];
}
// Returns a const reference to the selected ChannelView.
const Channel& operator[](size_t channel) const {
DCHECK_LT(channel, channel_views_.size());
return channel_views_[channel];
}
// Copy assignment from std::vector<std::vector<float>>.
AudioBuffer& operator=(const std::vector<std::vector<float>>& other) {
DCHECK_EQ(other.size(), channel_views_.size());
for (size_t channel = 0; channel < channel_views_.size(); ++channel) {
channel_views_[channel] = other[channel];
}
return *this;
}
// += operator
AudioBuffer& operator+=(const AudioBuffer& other) {
DCHECK_EQ(other.num_channels(), num_channels());
DCHECK_EQ(other.num_frames(), num_frames());
for (size_t i = 0; i < channel_views_.size(); ++i)
channel_views_[i] += other[i];
return *this;
}
// -= operator
AudioBuffer& operator-=(const AudioBuffer& other) {
DCHECK_EQ(other.num_channels(), num_channels());
DCHECK_EQ(other.num_frames(), num_frames());
for (size_t i = 0; i < channel_views_.size(); ++i)
channel_views_[i] -= other[i];
return *this;
}
// Returns an iterator to the ChannelView of the first channel.
std::vector<Channel>::iterator begin() { return channel_views_.begin(); }
// Returns an iterator to the end of the ChannelView vector.
std::vector<Channel>::iterator end() { return channel_views_.end(); }
// Returns a const_iterator to the ChannelView of the first channel.
std::vector<Channel>::const_iterator begin() const {
return channel_views_.begin();
}
// Returns an const_iterator to the end of the ChannelView vector.
std::vector<Channel>::const_iterator end() const {
return channel_views_.end();
}
// Fills all channels with zeros and reenables |Channel|s.
void Clear() {
for (Channel& channel : channel_views_) {
channel.SetEnabled(true);
channel.Clear();
}
}
// Returns the number of allocated frames per |Channel|. Note this may
// differ from the actual size of the |Channel| to ensure alignment of all
// |Channel|s.
size_t GetChannelStride() const {
return FindNextAlignedArrayIndex(num_frames_, sizeof(float),
kMemoryAlignmentBytes);
}
// Sets the source id of which the buffer belongs to.
void set_source_id(SourceId source_id) { source_id_ = source_id; }
private:
// Allocates memory and initializes vector of |ChannelView|s.
void InitChannelViews(size_t num_channels);
// Number of frames per buffer.
size_t num_frames_;
// Audio buffer that sequentially stores multiple audio channels in a planar
// format.
AlignedFloatVector data_;
// Size of audio buffer.
size_t data_size_;
// Vector of |AudioBuffer::Channel|s.
std::vector<Channel> channel_views_;
// Id of a source that this buffer belongs to.
SourceId source_id_;
};
} // namespace vraudio
#endif // RESONANCE_AUDIO_BASE_AUDIO_BUFFER_H_