1 /* 2 * Copyright (c) 2012 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 /* 12 * This file includes feature calculating functionality used in vad_core.c. 13 */ 14 15 #ifndef COMMON_AUDIO_VAD_VAD_FILTERBANK_H_ 16 #define COMMON_AUDIO_VAD_VAD_FILTERBANK_H_ 17 18 #include "common_audio/vad/vad_core.h" 19 #include "typedefs.h" // NOLINT(build/include) 20 21 // Takes |data_length| samples of |data_in| and calculates the logarithm of the 22 // energy of each of the |kNumChannels| = 6 frequency bands used by the VAD: 23 // 80 Hz - 250 Hz 24 // 250 Hz - 500 Hz 25 // 500 Hz - 1000 Hz 26 // 1000 Hz - 2000 Hz 27 // 2000 Hz - 3000 Hz 28 // 3000 Hz - 4000 Hz 29 // 30 // The values are given in Q4 and written to |features|. Further, an approximate 31 // overall energy is returned. The return value is used in 32 // WebRtcVad_GmmProbability() as a signal indicator, hence it is arbitrary above 33 // the threshold |kMinEnergy|. 34 // 35 // - self [i/o] : State information of the VAD. 36 // - data_in [i] : Input audio data, for feature extraction. 37 // - data_length [i] : Audio data size, in number of samples. 38 // - features [o] : 10 * log10(energy in each frequency band), Q4. 39 // - returns : Total energy of the signal (NOTE! This value is not 40 // exact. It is only used in a comparison.) 41 int16_t WebRtcVad_CalculateFeatures(VadInstT* self, const int16_t* data_in, 42 size_t data_length, int16_t* features); 43 44 #endif // COMMON_AUDIO_VAD_VAD_FILTERBANK_H_ 45