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/*
* Copyright (c) 2011 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 description of the internal VAD call
* WebRtcVad_GaussianProbability.
*/
#ifndef WEBRTC_VAD_FILTERBANK_H_
#define WEBRTC_VAD_FILTERBANK_H_
#include "vad_core.h"
/****************************************************************************
* WebRtcVad_HpOutput(...)
*
* This function removes DC from the lowest frequency band
*
* Input:
* - in_vector : Samples in the frequency interval 0 - 250 Hz
* - in_vector_length : Length of input and output vector
* - filter_state : Current state of the filter
*
* Output:
* - out_vector : Samples in the frequency interval 80 - 250 Hz
* - filter_state : Updated state of the filter
*
*/
void WebRtcVad_HpOutput(WebRtc_Word16* in_vector,
WebRtc_Word16 in_vector_length,
WebRtc_Word16* out_vector,
WebRtc_Word16* filter_state);
/****************************************************************************
* WebRtcVad_Allpass(...)
*
* This function is used when before splitting a speech file into
* different frequency bands
*
* Note! Do NOT let the arrays in_vector and out_vector correspond to the same address.
*
* Input:
* - in_vector : (Q0)
* - filter_coefficients : (Q15)
* - vector_length : Length of input and output vector
* - filter_state : Current state of the filter (Q(-1))
*
* Output:
* - out_vector : Output speech signal (Q(-1))
* - filter_state : Updated state of the filter (Q(-1))
*
*/
void WebRtcVad_Allpass(WebRtc_Word16* in_vector,
WebRtc_Word16* outw16,
WebRtc_Word16 filter_coefficients,
int vector_length,
WebRtc_Word16* filter_state);
/****************************************************************************
* WebRtcVad_SplitFilter(...)
*
* This function is used when before splitting a speech file into
* different frequency bands
*
* Input:
* - in_vector : Input signal to be split into two frequency bands.
* - upper_state : Current state of the upper filter
* - lower_state : Current state of the lower filter
* - in_vector_length : Length of input vector
*
* Output:
* - out_vector_hp : Upper half of the spectrum
* - out_vector_lp : Lower half of the spectrum
* - upper_state : Updated state of the upper filter
* - lower_state : Updated state of the lower filter
*
*/
void WebRtcVad_SplitFilter(WebRtc_Word16* in_vector,
WebRtc_Word16* out_vector_hp,
WebRtc_Word16* out_vector_lp,
WebRtc_Word16* upper_state,
WebRtc_Word16* lower_state,
int in_vector_length);
/****************************************************************************
* WebRtcVad_get_features(...)
*
* This function is used to get the logarithm of the power of each of the
* 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
*
* Input:
* - inst : Pointer to VAD instance
* - in_vector : Input speech signal
* - frame_size : Frame size, in number of samples
*
* Output:
* - out_vector : 10*log10(power in each freq. band), Q4
*
* Return: total power in the signal (NOTE! This value is not exact since it
* is only used in a comparison.
*/
WebRtc_Word16 WebRtcVad_get_features(VadInstT* inst,
WebRtc_Word16* in_vector,
int frame_size,
WebRtc_Word16* out_vector);
/****************************************************************************
* WebRtcVad_LogOfEnergy(...)
*
* This function is used to get the logarithm of the power of one frequency band.
*
* Input:
* - vector : Input speech samples for one frequency band
* - offset : Offset value for the current frequency band
* - vector_length : Length of input vector
*
* Output:
* - enerlogval : 10*log10(energy);
* - power : Update total power in speech frame. NOTE! This value
* is not exact since it is only used in a comparison.
*
*/
void WebRtcVad_LogOfEnergy(WebRtc_Word16* vector,
WebRtc_Word16* enerlogval,
WebRtc_Word16* power,
WebRtc_Word16 offset,
int vector_length);
#endif // WEBRTC_VAD_FILTERBANK_H_
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