ambisonic_binaural_decoder_node.h

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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_GRAPH_AMBISONIC_BINAURAL_DECODER_NODE_H_

#define RESONANCE_AUDIO_GRAPH_AMBISONIC_BINAURAL_DECODER_NODE_H_

#include <memory>

#include <string>

#include "ambisonics/ambisonic_binaural_decoder.h"

#include "base/audio_buffer.h"

#include "dsp/fft_manager.h"

#include "dsp/resampler.h"

#include "graph/system_settings.h"

#include "node/processing_node.h"

#include "utils/buffer_crossfader.h"

namespace vraudio {

// Node that takes an ambisonic soundfield as input and renders a binaural

// stereo buffer as output.

class AmbisonicBinauralDecoderNode : public ProcessingNode {

 public:

  // Initializes AmbisonicBinauralDecoderNode class.

//

  // @param system_settings Global system configuration.

  // @param ambisonic_order Ambisonic order.

  // @param sh_hrir_filename Filename to load the HRIR data from.

  // @param fft_manager Pointer to a manager to perform FFT transformations.

  // @resampler Pointer to a resampler used to convert HRIRs to the system rate.

  AmbisonicBinauralDecoderNode(const SystemSettings& system_settings,

                               int ambisonic_order,

                               const std::string& sh_hrir_filename,

                               FftManager* fft_manager, Resampler* resampler);

  ~AmbisonicBinauralDecoderNode() override;

 protected:

  // Implements ProcessingNode.

  const AudioBuffer* AudioProcess(const NodeInput& input) override;

 private:

  const SystemSettings& system_settings_;

  // Number of Ambisonic channels.

  const size_t num_ambisonic_channels_;

  // Denotes if the stereo speaker mode is enabled.

  bool is_stereo_speaker_mode_;

  // Ambisonic decoder used to render binaural output.

  std::unique_ptr<AmbisonicBinauralDecoder> ambisonic_binaural_decoder_;

  size_t num_frames_processed_on_empty_input_;

  // Stereo output buffer.

  AudioBuffer stereo_output_buffer_;

  // Silence mono buffer to render reverb tails.

  AudioBuffer silence_input_buffer_;

  // Buffer crossfader to apply linear crossfade when the stereo speaker mode is

  // changed.

  BufferCrossfader crossfader_;

  // Stereo output buffer to store the crossfaded decode output when necessary.

  AudioBuffer crossfaded_output_buffer_;

  // Temporary crossfade buffer to store the intermediate stereo output.

  AudioBuffer temp_crossfade_buffer_;

};

}  // namespace vraudio

#endif  // RESONANCE_AUDIO_GRAPH_AMBISONIC_BINAURAL_DECODER_NODE_H_