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/*
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_DSP_MIXER_H_
#define RESONANCE_AUDIO_DSP_MIXER_H_
#include <memory>
#include "base/audio_buffer.h"
namespace vraudio {
// Accepts multiple input buffers and outputs a downmix to a single output
// buffer. All input buffers must have the same number of frames per buffer, the
// output will have the target number of channels regardless of the input number
// of channels.
class Mixer {
public:
// Constructor.
//
// @param target_num_channels Target number of channels in accumulator buffer.
// @param frames_per_buffer Number of frames in accumulator buffer.
Mixer(size_t target_num_channels, size_t frames_per_buffer);
// Adds an input buffer to the mixer, updates the output buffer accordingly.
//
// @param input Input buffer to be added.
void AddInput(const AudioBuffer& input);
// Returns a pointer to the accumulator.
//
// @return Pointer to the processed (mixed) output buffer, or nullptr if no
// input has been added to the accumulator.
const AudioBuffer* GetOutput() const;
// Resets the state of the accumulator.
void Reset();
private:
// Output buffer (accumulator).
AudioBuffer output_;
// Denotes whether the accumulator has processed any inputs or not.
bool is_empty_;
};
} // namespace vraudio
#endif // RESONANCE_AUDIO_DSP_MIXER_H_