| /* |
| * 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_ |
