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comparison data/model/WaveformOversampler.cpp @ 1536:eb10ed56d5a4 zoom

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Add custom waveform oversampler method
author Chris Cannam
date Wed, 26 Sep 2018 13:03:46 +0100
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children fa67fbbff8fc
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1535:22fe34dd7f26 1536:eb10ed56d5a4
1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
2
3 /*
4 Sonic Visualiser
5 An audio file viewer and annotation editor.
6 Centre for Digital Music, Queen Mary, University of London.
7
8 This program is free software; you can redistribute it and/or
9 modify it under the terms of the GNU General Public License as
10 published by the Free Software Foundation; either version 2 of the
11 License, or (at your option) any later version. See the file
12 COPYING included with this distribution for more information.
13 */
14
15 #include "WaveformOversampler.h"
16
17 #include "data/model/DenseTimeValueModel.h"
18
19 floatvec_t
20 WaveformOversampler::getOversampledData(const DenseTimeValueModel *source,
21 int channel,
22 sv_frame_t sourceStartFrame,
23 sv_frame_t sourceFrameCount,
24 int oversampleBy)
25 {
26 // Oversampled at a fixed ratio of m_filterRatio
27 floatvec_t fixedRatio = getFixedRatioData(source, channel,
28 sourceStartFrame,
29 sourceFrameCount);
30 sv_frame_t fixedCount = fixedRatio.size();
31 sv_frame_t targetCount = (fixedCount / m_filterRatio) * oversampleBy;
32
33 // And apply linear interpolation to the desired factor
34
35 floatvec_t result(targetCount, 0.f);
36
37 for (int i = 0; i < targetCount; ++i) {
38 double pos = (double(i) / oversampleBy) * m_filterRatio;
39 double diff = pos - floor(pos);
40 int ix = int(floor(pos));
41 float interpolated = (1.0 - diff) * fixedRatio[ix];
42 if (in_range_for(fixedRatio, ix + 1)) {
43 interpolated += diff * fixedRatio[ix + 1];
44 }
45 result[i] = interpolated;
46 }
47
48 return result;
49 }
50
51 floatvec_t
52 WaveformOversampler::getFixedRatioData(const DenseTimeValueModel *source,
53 int channel,
54 sv_frame_t sourceStartFrame,
55 sv_frame_t sourceFrameCount)
56 {
57 sv_frame_t sourceLength = source->getEndFrame();
58
59 if (sourceStartFrame + sourceFrameCount > sourceLength) {
60 sourceFrameCount = sourceLength - sourceStartFrame;
61 if (sourceFrameCount <= 0) return {};
62 }
63
64 sv_frame_t targetFrameCount = sourceFrameCount * m_filterRatio;
65
66 sv_frame_t filterLength = m_filter.size(); // NB this is known to be odd
67 sv_frame_t filterTailOut = (filterLength - 1) / 2;
68 sv_frame_t filterTailIn = filterTailIn / m_filterRatio;
69
70 floatvec_t oversampled(targetFrameCount, 0.f);
71
72 sv_frame_t i0 = sourceStartFrame - filterTailIn;
73 if (i0 < 0) {
74 i0 = 0;
75 }
76 sv_frame_t i1 = sourceStartFrame + sourceFrameCount + filterTailIn;
77 if (i1 > sourceLength) {
78 i1 = sourceLength;
79 }
80
81 floatvec_t sourceData = source->getData(channel, i0, i1 - i0);
82
83 for (sv_frame_t i = i0; i < i1; ++i) {
84 float v = sourceData[i - i0];
85 sv_frame_t outOffset =
86 (i - sourceStartFrame) * m_filterRatio - filterTailOut;
87 for (sv_frame_t j = 0; j < filterLength; ++j) {
88 sv_frame_t outIndex = outOffset + j;
89 if (outIndex < 0 || outIndex >= targetFrameCount) {
90 continue;
91 }
92 oversampled[outIndex] += v * m_filter[j];
93 }
94 }
95
96 return oversampled;
97 }
98
99 int
100 WaveformOversampler::m_filterRatio = 8;
101
102 /// Precalculated windowed sinc FIR filter for oversampling ratio of 8
103 floatvec_t
104 WaveformOversampler::m_filter {
105 2.0171043153063023E-4, 2.887198196326776E-4,
106 3.410439309101285E-4, 3.4267123819805857E-4,
107 2.843462511901066E-4, 1.6636986363946504E-4,
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152 7.520535431851951E-17, 0.006032144534828161,
153 0.011445734103106982, 0.015355551390625357,
154 0.017065088242935025, 0.016186450815185452,
155 0.012718051439340603, 0.0070655888687995785,
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160 2.5712475624993567E-17, 0.009161748270723635,
161 0.0173729814451255, 0.023294901939595228,
162 0.02587678878709242, 0.02453592568963366,
163 0.01927365323131565, 0.010706050935569809,
164 -2.8133472199037193E-17, -0.011280308241551094,
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168 3.042099156841831E-17, 0.013951594368737923,
169 0.0264884258371512, 0.03556693609945249,
170 0.03957036852169639, 0.0375845888664677,
171 0.029579845398822833, 0.016465167405787955,
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173 -0.03315356952091943, -0.04460179422099746,
174 -0.0497244634100025, -0.04733366619358394,
175 -0.037341081614037944, -0.020838316594689998,
176 3.439626695384943E-17, 0.022185914535618936,
177 0.04232958202159685, 0.05713801867687856,
178 0.06393033000280622, 0.06109191933191721,
179 0.04839482380906132, 0.027127167584840003,
180 -3.5992766927138734E-17, -0.029168755716052385,
181 -0.055960213335110184, -0.07598693477350407,
182 -0.08556575102599769, -0.08233350786406181,
183 -0.06571046000158454, -0.03713224848702707,
184 3.727625511036616E-17, 0.04066438975848791,
185 0.07882920057770397, 0.10826166115536123,
186 0.12343378955977465, 0.12040455825217859,
187 0.09755344650130694, 0.056053367635801106,
188 -3.8215953158245473E-17, -0.0638435745677513,
189 -0.12667849902789644, -0.17861887575594584,
190 -0.20985333136704623, -0.21188193950868073,
191 -0.17867464086818077, -0.10760048593620072,
192 3.8789099095340224E-17, 0.13868670259490817,
193 0.29927055936918734, 0.46961864377510765,
194 0.6358321371992203, 0.7836674214332147,
195 0.9000377382311825, 0.9744199685311685,
196 1.0000000000000004, 0.9744199685311685,
197 0.9000377382311825, 0.7836674214332147,
198 0.6358321371992203, 0.46961864377510765,
199 0.29927055936918734, 0.13868670259490817,
200 3.8789099095340224E-17, -0.10760048593620072,
201 -0.17867464086818077, -0.21188193950868073,
202 -0.20985333136704623, -0.17861887575594584,
203 -0.12667849902789644, -0.0638435745677513,
204 -3.8215953158245473E-17, 0.056053367635801106,
205 0.09755344650130694, 0.12040455825217859,
206 0.12343378955977465, 0.10826166115536123,
207 0.07882920057770397, 0.04066438975848791,
208 3.727625511036616E-17, -0.03713224848702707,
209 -0.06571046000158454, -0.08233350786406181,
210 -0.08556575102599769, -0.07598693477350407,
211 -0.055960213335110184, -0.029168755716052385,
212 -3.5992766927138734E-17, 0.027127167584840003,
213 0.04839482380906132, 0.06109191933191721,
214 0.06393033000280622, 0.05713801867687856,
215 0.04232958202159685, 0.022185914535618936,
216 3.439626695384943E-17, -0.020838316594689998,
217 -0.037341081614037944, -0.04733366619358394,
218 -0.0497244634100025, -0.04460179422099746,
219 -0.03315356952091943, -0.017431115375410273,
220 -3.2524514488155654E-17, 0.016465167405787955,
221 0.029579845398822833, 0.0375845888664677,
222 0.03957036852169639, 0.03556693609945249,
223 0.0264884258371512, 0.013951594368737923,
224 3.042099156841831E-17, -0.013220449772289724,
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254 0.00689578873526276, 0.006174912111845945,
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287 2.0171043153063023E-4
288 };
289