1 /* 2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 // This file includes specific signal processing tools used in vad_core.c. 12 13 #ifndef COMMON_AUDIO_VAD_VAD_SP_H_ 14 #define COMMON_AUDIO_VAD_VAD_SP_H_ 15 16 #include "common_audio/vad/vad_core.h" 17 18 // Downsamples the signal by a factor 2, eg. 32->16 or 16->8. 19 // 20 // Inputs: 21 // - signal_in : Input signal. 22 // - in_length : Length of input signal in samples. 23 // 24 // Input & Output: 25 // - filter_state : Current filter states of the two all-pass filters. The 26 // |filter_state| is updated after all samples have been 27 // processed. 28 // 29 // Output: 30 // - signal_out : Downsampled signal (of length |in_length| / 2). 31 void WebRtcVad_Downsampling(const int16_t* signal_in, 32 int16_t* signal_out, 33 int32_t* filter_state, 34 size_t in_length); 35 36 // Updates and returns the smoothed feature minimum. As minimum we use the 37 // median of the five smallest feature values in a 100 frames long window. 38 // As long as |handle->frame_counter| is zero, that is, we haven't received any 39 // "valid" data, FindMinimum() outputs the default value of 1600. 40 // 41 // Inputs: 42 // - feature_value : New feature value to update with. 43 // - channel : Channel number. 44 // 45 // Input & Output: 46 // - handle : State information of the VAD. 47 // 48 // Returns: 49 // : Smoothed minimum value for a moving window. 50 int16_t WebRtcVad_FindMinimum(VadInstT* handle, 51 int16_t feature_value, 52 int channel); 53 54 #endif // COMMON_AUDIO_VAD_VAD_SP_H_ 55