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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
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.
*/
#ifndef RESONANCE_AUDIO_DSP_REVERB_ONSET_COMPENSATOR_H_
#define RESONANCE_AUDIO_DSP_REVERB_ONSET_COMPENSATOR_H_
#include <list>
#include <vector>
#include "base/audio_buffer.h"
#include "dsp/delay_filter.h"
#include "dsp/fft_manager.h"
#include "dsp/partitioned_fft_filter.h"
#include "dsp/reverb_onset_update_processor.h"
namespace vraudio {
// Implements a convolutional compensator for the spectral reverb onset curve.
class ReverbOnsetCompensator {
public:
// Constructs a |ReverbOnsetCompensator|.
//
// @param sampling_rate The sampling rate in Hz.
// @param frames_per_buffer The number of frames per buffer in the system.
// @param fft_manager Pointer to a FftManager to perform FFT transformations.
ReverbOnsetCompensator(int sampling_rate, size_t frames_per_buffer,
FftManager* fft_manager);
// Resets the reverb with a new set of reverberation times. The new tail is
// generated by replacing the current tail buffer by buffer.
//
// @param rt60_values |kNumReverbOctaveBands| values denoting the
// reverberation decay time to -60dB in octave bands starting at
// |kLowestOctaveBand|.
// @param gain Gain to be applied across all frequencies.
void Update(const float* rt60_values, float gain);
// Processes a mono |AudioBuffer| with a reverberant tail.
//
// @param input A mono |AudioBuffer| of input data.
// @param output Pointer to stereo output buffer.
void Process(const AudioBuffer& input, AudioBuffer* output);
private:
// Generates the constituent curves which are combined to make up the
// correction curve envelopes. These envelopes ensure the initial part of the
// specral reverb's impulse response, which exhibits 'growing' behaviour,
// follows the desired exponential decay.
void GenerateCorrectionCurves();
// Generates a pair of |kNumOctaveBands| band, octave filtered, noise buffers.
void GenerateNoiseVectors();
// Manager for all FFT related functionality (not owned).
FftManager* const fft_manager_;
// The system sampling rate.
const int sampling_rate_;
// The system number of frames per buffer.
const size_t frames_per_buffer_;
// Pre-generated band-passed noise to be used as a base for the reverb tail.
std::vector<AudioBuffer> bandpassed_noise_left_;
std::vector<AudioBuffer> bandpassed_noise_right_;
// The constituent curves used to generate the onset compensation envelopes.
AudioBuffer base_curves_;
AudioBuffer adder_curves_;
// Filter for processing the left reverberant channel.
PartitionedFftFilter left_filter_;
// Filter for processing the right reverberant channel.
PartitionedFftFilter right_filter_;
// Delay filter used to ensure the compensation curve starts at the same point
// as the spectral reverb.
DelayFilter delay_filter_;
// Number of active update processors.
size_t num_active_processors_;
// Active reverb update processors to replace the corresponding filter
// partitions of the reverb tail within each process call.
std::list<std::unique_ptr<ReverbOnsetUpdateProcessor>> update_processors_;
// Temporary buffer used to process filter kernel partitions.
AudioBuffer temp_kernel_buffer_;
// Temporary buffer to hold FFT frequency domain output.
PartitionedFftFilter::FreqDomainBuffer temp_freq_buffer_;
};
} // namespace vraudio
#endif // RESONANCE_AUDIO_DSP_REVERB_ONSET_COMPENSATOR_H_
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