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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.
*/
/*
* This file includes feature calculating functionality used in vad_core.c.
*/
#ifndef COMMON_AUDIO_VAD_VAD_FILTERBANK_H_
#define COMMON_AUDIO_VAD_VAD_FILTERBANK_H_
#include "common_audio/vad/vad_core.h"
// Takes `data_length` samples of `data_in` and calculates the logarithm of the
// energy of each of the `kNumChannels` = 6 frequency bands used by the VAD:
// 80 Hz - 250 Hz
// 250 Hz - 500 Hz
// 500 Hz - 1000 Hz
// 1000 Hz - 2000 Hz
// 2000 Hz - 3000 Hz
// 3000 Hz - 4000 Hz
//
// The values are given in Q4 and written to `features`. Further, an approximate
// overall energy is returned. The return value is used in
// WebRtcVad_GmmProbability() as a signal indicator, hence it is arbitrary above
// the threshold `kMinEnergy`.
//
// - self [i/o] : State information of the VAD.
// - data_in [i] : Input audio data, for feature extraction.
// - data_length [i] : Audio data size, in number of samples.
// - features [o] : 10 * log10(energy in each frequency band), Q4.
// - returns : Total energy of the signal (NOTE! This value is not
// exact. It is only used in a comparison.)
int16_t WebRtcVad_CalculateFeatures(VadInstT* self,
const int16_t* data_in,
size_t data_length,
int16_t* features);
#endif // COMMON_AUDIO_VAD_VAD_FILTERBANK_H_
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