1 /* 2 * Copyright (c) 2011 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 #include "vad_sp.h" 12 13 #include <assert.h> 14 15 #include "signal_processing_library.h" 16 #include "typedefs.h" 17 #include "vad_defines.h" 18 19 // Allpass filter coefficients, upper and lower, in Q13. 20 // Upper: 0.64, Lower: 0.17. 21 static const int16_t kAllPassCoefsQ13[2] = { 5243, 1392 }; // Q13 22 23 // TODO(bjornv): Move this function to vad_filterbank.c. 24 // Downsampling filter based on splitting filter and allpass functions. 25 void WebRtcVad_Downsampling(int16_t* signal_in, 26 int16_t* signal_out, 27 int32_t* filter_state, 28 int in_length) { 29 int16_t tmp16_1 = 0, tmp16_2 = 0; 30 int32_t tmp32_1 = filter_state[0]; 31 int32_t tmp32_2 = filter_state[1]; 32 int n = 0; 33 int half_length = (in_length >> 1); // Downsampling by 2 gives half length. 34 35 // Filter coefficients in Q13, filter state in Q0. 36 for (n = 0; n < half_length; n++) { 37 // All-pass filtering upper branch. 38 tmp16_1 = (int16_t) ((tmp32_1 >> 1) + 39 WEBRTC_SPL_MUL_16_16_RSFT(kAllPassCoefsQ13[0], *signal_in, 14)); 40 *signal_out = tmp16_1; 41 tmp32_1 = (int32_t) (*signal_in++) - 42 WEBRTC_SPL_MUL_16_16_RSFT(kAllPassCoefsQ13[0], tmp16_1, 12); 43 44 // All-pass filtering lower branch. 45 tmp16_2 = (int16_t) ((tmp32_2 >> 1) + 46 WEBRTC_SPL_MUL_16_16_RSFT(kAllPassCoefsQ13[1], *signal_in, 14)); 47 *signal_out++ += tmp16_2; 48 tmp32_2 = (int32_t) (*signal_in++) - 49 WEBRTC_SPL_MUL_16_16_RSFT(kAllPassCoefsQ13[1], tmp16_2, 12); 50 } 51 // Store the filter states. 52 filter_state[0] = tmp32_1; 53 filter_state[1] = tmp32_2; 54 } 55 56 // Inserts |feature_value| into |low_value_vector|, if it is one of the 16 57 // smallest values the last 100 frames. Then calculates and returns the median 58 // of the five smallest values. 59 int16_t WebRtcVad_FindMinimum(VadInstT* self, 60 int16_t feature_value, 61 int channel) { 62 int i = 0, j = 0; 63 int position = -1; 64 // Offset to beginning of the 16 minimum values in memory. 65 int offset = (channel << 4); 66 int16_t current_median = 1600; 67 int16_t alpha = 0; 68 int32_t tmp32 = 0; 69 // Pointer to memory for the 16 minimum values and the age of each value of 70 // the |channel|. 71 int16_t* age_ptr = &self->index_vector[offset]; 72 int16_t* value_ptr = &self->low_value_vector[offset]; 73 int16_t *p1, *p2, *p3; 74 75 assert(channel < NUM_CHANNELS); 76 77 // Each value in |low_value_vector| is getting 1 loop older. 78 // Update age of each value in |age_ptr|, and remove old values. 79 for (i = 0; i < 16; i++) { 80 p3 = age_ptr + i; 81 if (*p3 != 100) { 82 *p3 += 1; 83 } else { 84 p1 = value_ptr + i + 1; 85 p2 = p3 + 1; 86 for (j = i; j < 16; j++) { 87 *(value_ptr + j) = *p1++; 88 *(age_ptr + j) = *p2++; 89 } 90 *(age_ptr + 15) = 101; 91 *(value_ptr + 15) = 10000; 92 } 93 } 94 95 // Check if |feature_value| is smaller than any of the values in 96 // |low_value_vector|. If so, find the |position| where to insert the new 97 // value. 98 if (feature_value < *(value_ptr + 7)) { 99 if (feature_value < *(value_ptr + 3)) { 100 if (feature_value < *(value_ptr + 1)) { 101 if (feature_value < *value_ptr) { 102 position = 0; 103 } else { 104 position = 1; 105 } 106 } else if (feature_value < *(value_ptr + 2)) { 107 position = 2; 108 } else { 109 position = 3; 110 } 111 } else if (feature_value < *(value_ptr + 5)) { 112 if (feature_value < *(value_ptr + 4)) { 113 position = 4; 114 } else { 115 position = 5; 116 } 117 } else if (feature_value < *(value_ptr + 6)) { 118 position = 6; 119 } else { 120 position = 7; 121 } 122 } else if (feature_value < *(value_ptr + 15)) { 123 if (feature_value < *(value_ptr + 11)) { 124 if (feature_value < *(value_ptr + 9)) { 125 if (feature_value < *(value_ptr + 8)) { 126 position = 8; 127 } else { 128 position = 9; 129 } 130 } else if (feature_value < *(value_ptr + 10)) { 131 position = 10; 132 } else { 133 position = 11; 134 } 135 } else if (feature_value < *(value_ptr + 13)) { 136 if (feature_value < *(value_ptr + 12)) { 137 position = 12; 138 } else { 139 position = 13; 140 } 141 } else if (feature_value < *(value_ptr + 14)) { 142 position = 14; 143 } else { 144 position = 15; 145 } 146 } 147 148 // If we have a new small value, put it in the correct position and shift 149 // larger values up. 150 if (position > -1) { 151 for (i = 15; i > position; i--) { 152 j = i - 1; 153 *(value_ptr + i) = *(value_ptr + j); 154 *(age_ptr + i) = *(age_ptr + j); 155 } 156 *(value_ptr + position) = feature_value; 157 *(age_ptr + position) = 1; 158 } 159 160 // Get |current_median|. 161 if (self->frame_counter > 2) { 162 current_median = *(value_ptr + 2); 163 } else if (self->frame_counter > 0) { 164 current_median = *value_ptr; 165 } 166 167 // Smooth the median value. 168 if (self->frame_counter > 0) { 169 if (current_median < self->mean_value[channel]) { 170 alpha = (int16_t) ALPHA1; // 0.2 in Q15. 171 } else { 172 alpha = (int16_t) ALPHA2; // 0.99 in Q15. 173 } 174 } 175 tmp32 = WEBRTC_SPL_MUL_16_16(alpha + 1, self->mean_value[channel]); 176 tmp32 += WEBRTC_SPL_MUL_16_16(WEBRTC_SPL_WORD16_MAX - alpha, current_median); 177 tmp32 += 16384; 178 self->mean_value[channel] = (int16_t) (tmp32 >> 15); 179 180 return self->mean_value[channel]; 181 } 182
