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57 lines
2.1 KiB
C
57 lines
2.1 KiB
C
10 years ago
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/*
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* Copyright (c) 2011 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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// This file includes specific signal processing tools used in vad_core.c.
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#ifndef WEBRTC_COMMON_AUDIO_VAD_VAD_SP_H_
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#define WEBRTC_COMMON_AUDIO_VAD_VAD_SP_H_
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#include "webrtc/common_audio/vad/vad_core.h"
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#include "webrtc/typedefs.h"
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// Downsamples the signal by a factor 2, eg. 32->16 or 16->8.
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//
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// Inputs:
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// - signal_in : Input signal.
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// - in_length : Length of input signal in samples.
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//
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// Input & Output:
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// - filter_state : Current filter states of the two all-pass filters. The
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// |filter_state| is updated after all samples have been
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// processed.
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//
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// Output:
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// - signal_out : Downsampled signal (of length |in_length| / 2).
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void WebRtcVad_Downsampling(const int16_t* signal_in,
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int16_t* signal_out,
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int32_t* filter_state,
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int in_length);
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// Updates and returns the smoothed feature minimum. As minimum we use the
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// median of the five smallest feature values in a 100 frames long window.
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// As long as |handle->frame_counter| is zero, that is, we haven't received any
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// "valid" data, FindMinimum() outputs the default value of 1600.
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//
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// Inputs:
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// - feature_value : New feature value to update with.
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// - channel : Channel number.
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//
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// Input & Output:
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// - handle : State information of the VAD.
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//
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// Returns:
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// : Smoothed minimum value for a moving window.
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int16_t WebRtcVad_FindMinimum(VadInstT* handle,
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int16_t feature_value,
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int channel);
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#endif // WEBRTC_COMMON_AUDIO_VAD_VAD_SP_H_
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