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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_REFLECTIONS_PROCESSOR_H_
#define RESONANCE_AUDIO_DSP_REFLECTIONS_PROCESSOR_H_
#include <utility>
#include <vector>
#include "api/resonance_audio_api.h"
#include "base/audio_buffer.h"
#include "base/misc_math.h"
#include "dsp/delay_filter.h"
#include "dsp/gain_processor.h"
#include "dsp/mono_pole_filter.h"
#include "dsp/reflection.h"
#include "utils/buffer_crossfader.h"
namespace vraudio {
// Class that accepts single mono buffer as input and outputs a first order
// ambisonic buffer of the mix of all the rooms early reflections computed for
// the buffer.
//
// The input consists of a mono mix of all the sound objects in the system. The
// reflections are assumed to be aligned with the aabb axes and thus the first
// order ambisonic axes.
class ReflectionsProcessor {
public:
// Constructs a |ReflectionsProcessor|.
//
// @param sample_rate System sampling rate.
// @param frames_per_buffer System frames per buffer.
ReflectionsProcessor(int sample_rate, size_t frames_per_buffer);
// Updates reflections according to the new |ReflectionProperties|.
//
// @param reflection_properties New reflection properties.
// @param listener_position New listener position.
void Update(const ReflectionProperties& reflection_properties,
const WorldPosition& listener_position);
// Processes a mono |AudioBuffer| into an ambisonic |AudioBuffer|.
//
// @param input Mono input buffer.
// @param output Ambisonic output buffer.
void Process(const AudioBuffer& input, AudioBuffer* output);
// Returns the number of frames required to keep processing on empty input
// signal. This value can be used to avoid any potential artifacts on the
// final output signal when the input signal stream is empty.
size_t num_frames_to_process_on_empty_input() const {
return num_frames_to_process_on_empty_input_;
}
private:
// Updates |gains_| and |delays_| vectors of the |ReflectionsProcessor|.
void UpdateGainsAndDelays();
// Applies |target_reflections_| and fast-encodes them into first order
// ambisonics.
//
// @param output Ambisonic output buffer.
void ApplyReflections(AudioBuffer* output);
// System sampling rate.
const int sample_rate_;
// System number of frames per buffer.
const size_t frames_per_buffer_;
// Maximum allowed delay time for a reflection (in samples).
const size_t max_delay_samples_;
// Low pass filter to be applied to input signal.
MonoPoleFilter low_pass_filter_;
// Audio buffer to store mono low pass filtered buffers during processing.
AudioBuffer temp_mono_buffer_;
// Audio buffers to store FOA reflections buffers during crossfading.
AudioBuffer current_reflection_buffer_;
AudioBuffer target_reflection_buffer_;
// Target reflections filled with new data when |Update| is called.
std::vector<Reflection> target_reflections_;
// Indicates whether relfections have been updated and a crossfade is needed.
bool crossfade_;
// Buffer crossfader to apply linear crossfade during reflections update.
BufferCrossfader crossfader_;
// Number of frames needed to keep processing on empty input signal.
size_t num_frames_to_process_on_empty_input_;
// Number of samples of delay to be applied for each reflection.
std::vector<size_t> delays_;
// Delay filter to delay the incoming buffer.
DelayFilter delay_filter_;
// Delay buffer used to store delayed reflections before scaling and encoding.
AudioBuffer delay_buffer_;
// Gains to be applied for each reflection.
std::vector<float> gains_;
// |GainProcessor|s to apply |gains_|.
std::vector<GainProcessor> gain_processors_;
};
} // namespace vraudio
#endif // RESONANCE_AUDIO_DSP_REFLECTIONS_PROCESSOR_H_
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