webrtc_cng.h - mozsearch

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/*

 *  Copyright (c) 2012 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_CODING_CODECS_CNG_WEBRTC_CNG_H_

#define MODULES_AUDIO_CODING_CODECS_CNG_WEBRTC_CNG_H_

#include <stdint.h>

#include <cstddef>

#include "api/array_view.h"

#include "rtc_base/buffer.h"

#define WEBRTC_CNG_MAX_LPC_ORDER 12

namespace webrtc {

class ComfortNoiseDecoder {

 public:

  ComfortNoiseDecoder();

  ~ComfortNoiseDecoder() = default;

  ComfortNoiseDecoder(const ComfortNoiseDecoder&) = delete;

  ComfortNoiseDecoder& operator=(const ComfortNoiseDecoder&) = delete;

  void Reset();

  // Updates the CN state when a new SID packet arrives.

  // `sid` is a view of the SID packet without the headers.

  void UpdateSid(rtc::ArrayView<const uint8_t> sid);

  // Generates comfort noise.

  // `out_data` will be filled with samples - its size determines the number of

  // samples generated. When `new_period` is true, CNG history will be reset

  // before any audio is generated.  Returns `false` if outData is too large -

  // currently 640 bytes (equalling 10ms at 64kHz).

  // TODO(ossu): Specify better limits for the size of out_data. Either let it

  //             be unbounded or limit to 10ms in the current sample rate.

  bool Generate(rtc::ArrayView<int16_t> out_data, bool new_period);

 private:

  uint32_t dec_seed_;

  int32_t dec_target_energy_;

  int32_t dec_used_energy_;

  int16_t dec_target_reflCoefs_[WEBRTC_CNG_MAX_LPC_ORDER + 1];

  int16_t dec_used_reflCoefs_[WEBRTC_CNG_MAX_LPC_ORDER + 1];

  int16_t dec_filtstate_[WEBRTC_CNG_MAX_LPC_ORDER + 1];

  int16_t dec_filtstateLow_[WEBRTC_CNG_MAX_LPC_ORDER + 1];

  uint16_t dec_order_;

  int16_t dec_target_scale_factor_; /* Q29 */

  int16_t dec_used_scale_factor_;   /* Q29 */

};

class ComfortNoiseEncoder {

 public:

  // Creates a comfort noise encoder.

  // `fs` selects sample rate: 8000 for narrowband or 16000 for wideband.

  // `interval` sets the interval at which to generate SID data (in ms).

  // `quality` selects the number of refl. coeffs. Maximum allowed is 12.

  ComfortNoiseEncoder(int fs, int interval, int quality);

  ~ComfortNoiseEncoder() = default;

  ComfortNoiseEncoder(const ComfortNoiseEncoder&) = delete;

  ComfortNoiseEncoder& operator=(const ComfortNoiseEncoder&) = delete;

  // Resets the comfort noise encoder to its initial state.

  // Parameters are set as during construction.

  void Reset(int fs, int interval, int quality);

  // Analyzes background noise from `speech` and appends coefficients to

  // `output`.  Returns the number of coefficients generated.  If `force_sid` is

  // true, a SID frame is forced and the internal sid interval counter is reset.

  // Will fail if the input size is too large (> 640 samples, see

  // ComfortNoiseDecoder::Generate).

  size_t Encode(rtc::ArrayView<const int16_t> speech,

                bool force_sid,

                rtc::Buffer* output);

 private:

  size_t enc_nrOfCoefs_;

  int enc_sampfreq_;

  int16_t enc_interval_;

  int16_t enc_msSinceSid_;

  int32_t enc_Energy_;

  int16_t enc_reflCoefs_[WEBRTC_CNG_MAX_LPC_ORDER + 1];

  int32_t enc_corrVector_[WEBRTC_CNG_MAX_LPC_ORDER + 1];

  uint32_t enc_seed_;

};

}  // namespace webrtc

#endif  // MODULES_AUDIO_CODING_CODECS_CNG_WEBRTC_CNG_H_