text: /*
   *  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.
   */
  
  
  /*
   * This header file includes the VAD API calls. Specific function calls are given below.
   */
  
  #ifndef COMMON_AUDIO_VAD_INCLUDE_WEBRTC_VAD_H_  // NOLINT
  #define COMMON_AUDIO_VAD_INCLUDE_WEBRTC_VAD_H_
  
  #include <stddef.h>
  
  #include "typedefs.h"  // NOLINT(build/include)
  
  typedef struct WebRtcVadInst VadInst;
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  // Creates an instance to the VAD structure.
  VadInst* WebRtcVad_Create(void);
  
  // Frees the dynamic memory of a specified VAD instance.
  //
  // - handle [i] : Pointer to VAD instance that should be freed.
  void WebRtcVad_Free(VadInst* handle);
  
  // Initializes a VAD instance.
  //
  // - handle [i/o] : Instance that should be initialized.
  //
  // returns        : 0 - (OK),
  //                 -1 - (null pointer or Default mode could not be set).
  int WebRtcVad_Init(VadInst* handle);
  
  // Sets the VAD operating mode. A more aggressive (higher mode) VAD is more
  // restrictive in reporting speech. Put in other words the probability of being
  // speech when the VAD returns 1 is increased with increasing mode. As a
  // consequence also the missed detection rate goes up.
  //
  // - handle [i/o] : VAD instance.
  // - mode   [i]   : Aggressiveness mode (0, 1, 2, or 3).
  //
  // returns        : 0 - (OK),
  //                 -1 - (null pointer, mode could not be set or the VAD instance
  //                       has not been initialized).
  int WebRtcVad_set_mode(VadInst* handle, int mode);
  
  // Calculates a VAD decision for the |audio_frame|. For valid sampling rates
  // frame lengths, see the description of WebRtcVad_ValidRatesAndFrameLengths().
  //
  // - handle       [i/o] : VAD Instance. Needs to be initialized by
  //                        WebRtcVad_Init() before call.
  // - fs           [i]   : Sampling frequency (Hz): 8000, 16000, or 32000
  // - audio_frame  [i]   : Audio frame buffer.
  // - frame_length [i]   : Length of audio frame buffer in number of samples.
  //
  // returns              : 1 - (Active Voice),
  //                        0 - (Non-active Voice),
  //                       -1 - (Error)
  int WebRtcVad_Process(VadInst* handle, int fs, const int16_t* audio_frame,
                        size_t frame_length);
  
  // Checks for valid combinations of |rate| and |frame_length|. We support 10,
  // 20 and 30 ms frames and the rates 8000, 16000 and 32000 Hz.
  //
  // - rate         [i] : Sampling frequency (Hz).
  // - frame_length [i] : Speech frame buffer length in number of samples.
  //
  // returns            : 0 - (valid combination), -1 - (invalid combination)
  int WebRtcVad_ValidRateAndFrameLength(int rate, size_t frame_length);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif  // COMMON_AUDIO_VAD_INCLUDE_WEBRTC_VAD_H_  // NOLINT
  