46 lines
1.8 KiB
C
46 lines
1.8 KiB
C
/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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/*
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* This file includes feature calculating functionality used in vad_core.c.
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*/
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#ifndef COMMON_AUDIO_VAD_VAD_FILTERBANK_H_
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#define COMMON_AUDIO_VAD_VAD_FILTERBANK_H_
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#include "common_audio/vad/vad_core.h"
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// Takes |data_length| samples of |data_in| and calculates the logarithm of the
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// energy of each of the |kNumChannels| = 6 frequency bands used by the VAD:
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// 80 Hz - 250 Hz
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// 250 Hz - 500 Hz
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// 500 Hz - 1000 Hz
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// 1000 Hz - 2000 Hz
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// 2000 Hz - 3000 Hz
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// 3000 Hz - 4000 Hz
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//
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// The values are given in Q4 and written to |features|. Further, an approximate
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// overall energy is returned. The return value is used in
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// WebRtcVad_GmmProbability() as a signal indicator, hence it is arbitrary above
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// the threshold |kMinEnergy|.
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//
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// - self [i/o] : State information of the VAD.
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// - data_in [i] : Input audio data, for feature extraction.
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// - data_length [i] : Audio data size, in number of samples.
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// - features [o] : 10 * log10(energy in each frequency band), Q4.
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// - returns : Total energy of the signal (NOTE! This value is not
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// exact. It is only used in a comparison.)
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int16_t WebRtcVad_CalculateFeatures(VadInstT* self,
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const int16_t* data_in,
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size_t data_length,
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int16_t* features);
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#endif // COMMON_AUDIO_VAD_VAD_FILTERBANK_H_
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