| andrew@webrtc.org | a7b57da | 2012-10-22 18:19:23 +0000 | [diff] [blame] | 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 WEBRTC_COMMON_AUDIO_VAD_VAD_FILTERBANK_H_ |
| 16 | #define WEBRTC_COMMON_AUDIO_VAD_VAD_FILTERBANK_H_ |
| 17 | |
| pbos@webrtc.org | abf0cd8 | 2013-05-27 09:49:58 +0000 | [diff] [blame] | 18 | #include "webrtc/common_audio/vad/vad_core.h" |
| 19 | #include "webrtc/typedefs.h" |
| andrew@webrtc.org | a7b57da | 2012-10-22 18:19:23 +0000 | [diff] [blame] | 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 | int data_length, int16_t* features); |
| 43 | |
| 44 | #endif // WEBRTC_COMMON_AUDIO_VAD_VAD_FILTERBANK_H_ |