diff options
Diffstat (limited to 'third_party/libwebrtc/common_audio/vad/vad_sp.c')
| -rw-r--r-- | third_party/libwebrtc/common_audio/vad/vad_sp.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/third_party/libwebrtc/common_audio/vad/vad_sp.c b/third_party/libwebrtc/common_audio/vad/vad_sp.c new file mode 100644 index 0000000000..3d24cf64b3 --- /dev/null +++ b/third_party/libwebrtc/common_audio/vad/vad_sp.c @@ -0,0 +1,176 @@ +/* + * 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. + */ + +#include "common_audio/vad/vad_sp.h" + +#include "rtc_base/checks.h" +#include "common_audio/signal_processing/include/signal_processing_library.h" +#include "common_audio/vad/vad_core.h" + +// Allpass filter coefficients, upper and lower, in Q13. +// Upper: 0.64, Lower: 0.17. +static const int16_t kAllPassCoefsQ13[2] = { 5243, 1392 }; // Q13. +static const int16_t kSmoothingDown = 6553; // 0.2 in Q15. +static const int16_t kSmoothingUp = 32439; // 0.99 in Q15. + +// TODO(bjornv): Move this function to vad_filterbank.c. +// Downsampling filter based on splitting filter and allpass functions. +void WebRtcVad_Downsampling(const int16_t* signal_in, + int16_t* signal_out, + int32_t* filter_state, + size_t in_length) { + int16_t tmp16_1 = 0, tmp16_2 = 0; + int32_t tmp32_1 = filter_state[0]; + int32_t tmp32_2 = filter_state[1]; + size_t n = 0; + // Downsampling by 2 gives half length. + size_t half_length = (in_length >> 1); + + // Filter coefficients in Q13, filter state in Q0. + for (n = 0; n < half_length; n++) { + // All-pass filtering upper branch. + tmp16_1 = (int16_t) ((tmp32_1 >> 1) + + ((kAllPassCoefsQ13[0] * *signal_in) >> 14)); + *signal_out = tmp16_1; + tmp32_1 = (int32_t)(*signal_in++) - ((kAllPassCoefsQ13[0] * tmp16_1) >> 12); + + // All-pass filtering lower branch. + tmp16_2 = (int16_t) ((tmp32_2 >> 1) + + ((kAllPassCoefsQ13[1] * *signal_in) >> 14)); + *signal_out++ += tmp16_2; + tmp32_2 = (int32_t)(*signal_in++) - ((kAllPassCoefsQ13[1] * tmp16_2) >> 12); + } + // Store the filter states. + filter_state[0] = tmp32_1; + filter_state[1] = tmp32_2; +} + +// Inserts `feature_value` into `low_value_vector`, if it is one of the 16 +// smallest values the last 100 frames. Then calculates and returns the median +// of the five smallest values. +int16_t WebRtcVad_FindMinimum(VadInstT* self, + int16_t feature_value, + int channel) { + int i = 0, j = 0; + int position = -1; + // Offset to beginning of the 16 minimum values in memory. + const int offset = (channel << 4); + int16_t current_median = 1600; + int16_t alpha = 0; + int32_t tmp32 = 0; + // Pointer to memory for the 16 minimum values and the age of each value of + // the `channel`. + int16_t* age = &self->index_vector[offset]; + int16_t* smallest_values = &self->low_value_vector[offset]; + + RTC_DCHECK_LT(channel, kNumChannels); + + // Each value in `smallest_values` is getting 1 loop older. Update `age`, and + // remove old values. + for (i = 0; i < 16; i++) { + if (age[i] != 100) { + age[i]++; + } else { + // Too old value. Remove from memory and shift larger values downwards. + for (j = i; j < 15; j++) { + smallest_values[j] = smallest_values[j + 1]; + age[j] = age[j + 1]; + } + age[15] = 101; + smallest_values[15] = 10000; + } + } + + // Check if `feature_value` is smaller than any of the values in + // `smallest_values`. If so, find the `position` where to insert the new value + // (`feature_value`). + if (feature_value < smallest_values[7]) { + if (feature_value < smallest_values[3]) { + if (feature_value < smallest_values[1]) { + if (feature_value < smallest_values[0]) { + position = 0; + } else { + position = 1; + } + } else if (feature_value < smallest_values[2]) { + position = 2; + } else { + position = 3; + } + } else if (feature_value < smallest_values[5]) { + if (feature_value < smallest_values[4]) { + position = 4; + } else { + position = 5; + } + } else if (feature_value < smallest_values[6]) { + position = 6; + } else { + position = 7; + } + } else if (feature_value < smallest_values[15]) { + if (feature_value < smallest_values[11]) { + if (feature_value < smallest_values[9]) { + if (feature_value < smallest_values[8]) { + position = 8; + } else { + position = 9; + } + } else if (feature_value < smallest_values[10]) { + position = 10; + } else { + position = 11; + } + } else if (feature_value < smallest_values[13]) { + if (feature_value < smallest_values[12]) { + position = 12; + } else { + position = 13; + } + } else if (feature_value < smallest_values[14]) { + position = 14; + } else { + position = 15; + } + } + + // If we have detected a new small value, insert it at the correct position + // and shift larger values up. + if (position > -1) { + for (i = 15; i > position; i--) { + smallest_values[i] = smallest_values[i - 1]; + age[i] = age[i - 1]; + } + smallest_values[position] = feature_value; + age[position] = 1; + } + + // Get `current_median`. + if (self->frame_counter > 2) { + current_median = smallest_values[2]; + } else if (self->frame_counter > 0) { + current_median = smallest_values[0]; + } + + // Smooth the median value. + if (self->frame_counter > 0) { + if (current_median < self->mean_value[channel]) { + alpha = kSmoothingDown; // 0.2 in Q15. + } else { + alpha = kSmoothingUp; // 0.99 in Q15. + } + } + tmp32 = (alpha + 1) * self->mean_value[channel]; + tmp32 += (WEBRTC_SPL_WORD16_MAX - alpha) * current_median; + tmp32 += 16384; + self->mean_value[channel] = (int16_t) (tmp32 >> 15); + + return self->mean_value[channel]; +} |