modules/audio_processing/transient/transient_suppressor.h

/*
 *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef MODULES_AUDIO_PROCESSING_TRANSIENT_TRANSIENT_SUPPRESSOR_H_
#define MODULES_AUDIO_PROCESSING_TRANSIENT_TRANSIENT_SUPPRESSOR_H_

#include <stddef.h>
#include <stdint.h>
#include <memory>

namespace webrtc {

// Detects transients in an audio stream and suppress them using a simple
// restoration algorithm that attenuates unexpected spikes in the spectrum.
class TransientSuppressor {
 public:
  virtual ~TransientSuppressor() {}

  virtual int Initialize(int sample_rate_hz,
                         int detector_rate_hz,
                         int num_channels) = 0;

  // Processes a |data| chunk, and returns it with keystrokes suppressed from
  // it. The float format is assumed to be int16 ranged. If there are more than
  // one channel, the chunks are concatenated one after the other in |data|.
  // |data_length| must be equal to |data_length_|.
  // |num_channels| must be equal to |num_channels_|.
  // A sub-band, ideally the higher, can be used as |detection_data|. If it is
  // NULL, |data| is used for the detection too. The |detection_data| is always
  // assumed mono.
  // If a reference signal (e.g. keyboard microphone) is available, it can be
  // passed in as |reference_data|. It is assumed mono and must have the same
  // length as |data|. NULL is accepted if unavailable.
  // This suppressor performs better if voice information is available.
  // |voice_probability| is the probability of voice being present in this chunk
  // of audio. If voice information is not available, |voice_probability| must
  // always be set to 1.
  // |key_pressed| determines if a key was pressed on this audio chunk.
  // Returns 0 on success and -1 otherwise.
  virtual int Suppress(float* data,
                       size_t data_length,
                       int num_channels,
                       const float* detection_data,
                       size_t detection_length,
                       const float* reference_data,
                       size_t reference_length,
                       float voice_probability,
                       bool key_pressed) = 0;
};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_TRANSIENT_TRANSIENT_SUPPRESSOR_H_