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1 /* | 1 /* |
2 * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved. | 2 * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved. |
3 * | 3 * |
4 * Use of this source code is governed by a BSD-style license | 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 | 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 | 6 * tree. An additional intellectual property rights grant can be found |
7 * in the file PATENTS. All contributing project authors may | 7 * in the file PATENTS. All contributing project authors may |
8 * be found in the AUTHORS file in the root of the source tree. | 8 * be found in the AUTHORS file in the root of the source tree. |
9 */ | 9 */ |
10 | 10 |
11 #include "webrtc/modules/audio_processing/vad/pitch_internal.h" | 11 #include "webrtc/modules/audio_processing/agc/pitch_internal.h" |
12 | 12 |
13 #include <cmath> | 13 #include <cmath> |
14 | 14 |
15 // A 4-to-3 linear interpolation. | 15 // A 4-to-3 linear interpolation. |
16 // The interpolation constants are derived as following: | 16 // The interpolation constants are derived as following: |
17 // Input pitch parameters are updated every 7.5 ms. Within a 30-ms interval | 17 // Input pitch parameters are updated every 7.5 ms. Within a 30-ms interval |
18 // we are interested in pitch parameters of 0-5 ms, 10-15ms and 20-25ms. This is | 18 // we are interested in pitch parameters of 0-5 ms, 10-15ms and 20-25ms. This is |
19 // like interpolating 4-to-6 and keep the odd samples. | 19 // like interpolating 4-to-6 and keep the odd samples. |
20 // The reason behind this is that LPC coefficients are computed for the first | 20 // The reason behind this is that LPC coefficients are computed for the first |
21 // half of each 10ms interval. | 21 // half of each 10ms interval. |
22 static void PitchInterpolation(double old_val, const double* in, double* out) { | 22 static void PitchInterpolation(double old_val, const double* in, double* out) { |
23 out[0] = 1. / 6. * old_val + 5. / 6. * in[0]; | 23 out[0] = 1. / 6. * old_val + 5. / 6. * in[0]; |
24 out[1] = 5. / 6. * in[1] + 1. / 6. * in[2]; | 24 out[1] = 5. / 6. * in[1] + 1. / 6. * in[2]; |
25 out[2] = 0.5 * in[2] + 0.5 * in[3]; | 25 out[2] = 0.5 * in[2] + 0.5 * in[3]; |
26 } | 26 } |
27 | 27 |
| 28 |
28 void GetSubframesPitchParameters(int sampling_rate_hz, | 29 void GetSubframesPitchParameters(int sampling_rate_hz, |
29 double* gains, | 30 double* gains, |
30 double* lags, | 31 double* lags, |
31 int num_in_frames, | 32 int num_in_frames, |
32 int num_out_frames, | 33 int num_out_frames, |
33 double* log_old_gain, | 34 double* log_old_gain, |
34 double* old_lag, | 35 double* old_lag, |
35 double* log_pitch_gain, | 36 double* log_pitch_gain, |
36 double* pitch_lag_hz) { | 37 double* pitch_lag_hz) { |
37 // Gain interpolation is in log-domain, also returned in log-domain. | 38 // Gain interpolation is in log-domain, also returned in log-domain. |
38 for (int n = 0; n < num_in_frames; n++) | 39 for (int n = 0; n < num_in_frames; n++) |
39 gains[n] = log(gains[n] + 1e-12); | 40 gains[n] = log(gains[n] + 1e-12); |
40 | 41 |
41 // Interpolate lags and gains. | 42 // Interpolate lags and gains. |
42 PitchInterpolation(*log_old_gain, gains, log_pitch_gain); | 43 PitchInterpolation(*log_old_gain, gains, log_pitch_gain); |
43 *log_old_gain = gains[num_in_frames - 1]; | 44 *log_old_gain = gains[num_in_frames - 1]; |
44 PitchInterpolation(*old_lag, lags, pitch_lag_hz); | 45 PitchInterpolation(*old_lag, lags, pitch_lag_hz); |
45 *old_lag = lags[num_in_frames - 1]; | 46 *old_lag = lags[num_in_frames - 1]; |
46 | 47 |
47 // Convert pitch-lags to Hertz. | 48 // Convert pitch-lags to Hertz. |
48 for (int n = 0; n < num_out_frames; n++) { | 49 for (int n = 0; n < num_out_frames; n++) { |
49 pitch_lag_hz[n] = (sampling_rate_hz) / (pitch_lag_hz[n]); | 50 pitch_lag_hz[n] = (sampling_rate_hz) / (pitch_lag_hz[n]); |
50 } | 51 } |
51 } | 52 } |
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