comparison data/fileio/AudioFileSizeEstimator.cpp @ 1527:710e6250a401 zoom

Merge from default branch
author Chris Cannam
date Mon, 17 Sep 2018 13:51:14 +0100
parents aadfb395e933
children 70e172e6cc59 f8e3dcbafb4d
comparison
equal deleted inserted replaced
1324:d4a28d1479a8 1527:710e6250a401
16 16
17 #include "WavFileReader.h" 17 #include "WavFileReader.h"
18 18
19 #include <QFile> 19 #include <QFile>
20 20
21 //#define DEBUG_AUDIO_FILE_SIZE_ESTIMATOR 1 21 #include "base/Debug.h"
22 22
23 sv_frame_t 23 sv_frame_t
24 AudioFileSizeEstimator::estimate(FileSource source, 24 AudioFileSizeEstimator::estimate(FileSource source,
25 sv_samplerate_t targetRate) 25 sv_samplerate_t targetRate)
26 { 26 {
27 sv_frame_t estimate = 0; 27 sv_frame_t estimate = 0;
28 28
29 SVDEBUG << "AudioFileSizeEstimator: Sample count estimate requested for file \""
30 << source.getLocalFilename() << "\"" << endl;
31
29 // Most of our file readers don't know the sample count until 32 // Most of our file readers don't know the sample count until
30 // after they've finished decoding. This is an exception: 33 // after they've finished decoding. This is an exception:
31 34
32 WavFileReader *reader = new WavFileReader(source); 35 WavFileReader *reader = new WavFileReader(source);
33 if (reader->isOK() && 36 if (reader->isOK() &&
34 reader->getChannelCount() > 0 && 37 reader->getChannelCount() > 0 &&
35 reader->getFrameCount() > 0) { 38 reader->getFrameCount() > 0) {
36 sv_frame_t samples = 39 sv_frame_t samples =
37 reader->getFrameCount() * reader->getChannelCount(); 40 reader->getFrameCount() * reader->getChannelCount();
38 sv_samplerate_t rate = reader->getSampleRate(); 41 sv_samplerate_t rate = reader->getSampleRate();
39 if (targetRate != 0.0 && targetRate != rate) { 42 if (targetRate != 0.0 && targetRate != rate) {
40 samples = sv_frame_t(double(samples) * targetRate / rate); 43 samples = sv_frame_t(double(samples) * targetRate / rate);
41 } 44 }
42 delete reader; 45 SVDEBUG << "AudioFileSizeEstimator: WAV file reader accepts this file, reports "
43 estimate = samples; 46 << samples << " samples" << endl;
47 estimate = samples;
48 } else {
49 SVDEBUG << "AudioFileSizeEstimator: WAV file reader doesn't like this file, "
50 << "estimating from file size and extension instead" << endl;
44 } 51 }
52
53 delete reader;
54 reader = 0;
45 55
46 if (estimate == 0) { 56 if (estimate == 0) {
47 57
48 // The remainder just makes an estimate based on the file size 58 // The remainder just makes an estimate based on the file size
49 // and extension. We don't even know its sample rate at this 59 // and extension. We don't even know its sample rate at this
50 // point, so the following is a wild guess. 60 // point, so the following is a wild guess.
51 61
52 double rateRatio = 1.0; 62 double rateRatio = 1.0;
53 if (targetRate != 0.0) { 63 if (targetRate != 0.0) {
54 rateRatio = targetRate / 44100.0; 64 rateRatio = targetRate / 44100.0;
55 } 65 }
56 66
57 QString extension = source.getExtension(); 67 QString extension = source.getExtension();
58 68
59 source.waitForData(); 69 source.waitForData();
60 if (!source.isOK()) return 0; 70 if (!source.isOK()) return 0;
61 71
62 sv_frame_t sz = 0; 72 sv_frame_t sz = 0;
63 {
64 QFile f(source.getLocalFilename());
65 if (f.open(QFile::ReadOnly)) {
66 #ifdef DEBUG_AUDIO_FILE_SIZE_ESTIMATOR
67 cerr << "opened file, size is " << f.size() << endl;
68 #endif
69 sz = f.size();
70 f.close();
71 }
72 }
73 73
74 if (extension == "ogg" || extension == "oga" || 74 {
75 extension == "m4a" || extension == "mp3" || 75 QFile f(source.getLocalFilename());
76 extension == "wma") { 76 if (f.open(QFile::ReadOnly)) {
77 SVDEBUG << "AudioFileSizeEstimator: opened file, size is "
78 << f.size() << endl;
79 sz = f.size();
80 f.close();
81 }
82 }
77 83
78 // Usually a lossy file. Compression ratios can vary 84 if (extension == "ogg" || extension == "oga" ||
79 // dramatically, but don't usually exceed about 20x compared 85 extension == "m4a" || extension == "mp3" ||
80 // to 16-bit PCM (e.g. a 128kbps mp3 has 11x ratio over WAV at 86 extension == "wma") {
81 // 44.1kHz). We can estimate the number of samples to be file
82 // size x 20, divided by 2 as we're comparing with 16-bit PCM.
83 87
84 estimate = sv_frame_t(double(sz) * 10 * rateRatio); 88 // Usually a lossy file. Compression ratios can vary
85 } 89 // dramatically, but don't usually exceed about 20x compared
90 // to 16-bit PCM (e.g. a 128kbps mp3 has 11x ratio over WAV at
91 // 44.1kHz). We can estimate the number of samples to be file
92 // size x 20, divided by 2 as we're comparing with 16-bit PCM.
86 93
87 if (extension == "flac") { 94 estimate = sv_frame_t(double(sz) * 10 * rateRatio);
88 95 }
89 // FLAC usually takes up a bit more than half the space of
90 // 16-bit PCM. So the number of 16-bit samples is roughly the
91 // same as the file size in bytes. As above, let's be
92 // conservative.
93 96
94 estimate = sv_frame_t(double(sz) * 1.2 * rateRatio); 97 if (extension == "flac") {
95 } 98
99 // FLAC usually takes up a bit more than half the space of
100 // 16-bit PCM. So the number of 16-bit samples is roughly the
101 // same as the file size in bytes. As above, let's be
102 // conservative.
96 103
97 #ifdef DEBUG_AUDIO_FILE_SIZE_ESTIMATOR 104 estimate = sv_frame_t(double(sz) * 1.2 * rateRatio);
98 cerr << "AudioFileSizeEstimator: for extension " << extension << ", estimate = " << estimate << endl; 105 }
99 #endif 106
107 SVDEBUG << "AudioFileSizeEstimator: for extension \""
108 << extension << "\", estimate = " << estimate << " samples" << endl;
100 } 109 }
101
102 #ifdef DEBUG_AUDIO_FILE_SIZE_ESTIMATOR
103 cerr << "estimate = " << estimate << endl;
104 #endif
105 110
106 return estimate; 111 return estimate;
107 } 112 }
108 113