| /* | |
| * 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 file includes specific signal processing tools used in vad_core.c. | |
| // Downsamples the signal by a factor 2, eg. 32->16 or 16->8. | |
| // | |
| // Inputs: | |
| // - signal_in : Input signal. | |
| // - in_length : Length of input signal in samples. | |
| // | |
| // Input & Output: | |
| // - filter_state : Current filter states of the two all-pass filters. The | |
| // `filter_state` is updated after all samples have been | |
| // processed. | |
| // | |
| // Output: | |
| // - signal_out : Downsampled signal (of length `in_length` / 2). | |
| void WebRtcVad_Downsampling(const int16_t* signal_in, | |
| int16_t* signal_out, | |
| int32_t* filter_state, | |
| size_t in_length); | |
| // Updates and returns the smoothed feature minimum. As minimum we use the | |
| // median of the five smallest feature values in a 100 frames long window. | |
| // As long as `handle->frame_counter` is zero, that is, we haven't received any | |
| // "valid" data, FindMinimum() outputs the default value of 1600. | |
| // | |
| // Inputs: | |
| // - feature_value : New feature value to update with. | |
| // - channel : Channel number. | |
| // | |
| // Input & Output: | |
| // - handle : State information of the VAD. | |
| // | |
| // Returns: | |
| // : Smoothed minimum value for a moving window. | |
| int16_t WebRtcVad_FindMinimum(VadInstT* handle, | |
| int16_t feature_value, | |
| int channel); | |