annotate data/fileio/AudioFileSizeEstimator.cpp @ 1104:393134235fa0 simple-fft-model

Two-channel test
author Chris Cannam
date Tue, 16 Jun 2015 20:32:44 +0100
parents 329ddaf7415d
children 513e4d67d8df
rev   line source
Chris@1098 1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
Chris@1098 2
Chris@1098 3 /*
Chris@1098 4 Sonic Visualiser
Chris@1098 5 An audio file viewer and annotation editor.
Chris@1098 6 Centre for Digital Music, Queen Mary, University of London.
Chris@1098 7
Chris@1098 8 This program is free software; you can redistribute it and/or
Chris@1098 9 modify it under the terms of the GNU General Public License as
Chris@1098 10 published by the Free Software Foundation; either version 2 of the
Chris@1098 11 License, or (at your option) any later version. See the file
Chris@1098 12 COPYING included with this distribution for more information.
Chris@1098 13 */
Chris@1098 14
Chris@1098 15 #include "AudioFileSizeEstimator.h"
Chris@1098 16
Chris@1098 17 #include "WavFileReader.h"
Chris@1098 18
Chris@1098 19 #include <QFile>
Chris@1098 20
Chris@1104 21 //#define DEBUG_AUDIO_FILE_SIZE_ESTIMATOR 1
Chris@1104 22
Chris@1098 23 sv_frame_t
Chris@1098 24 AudioFileSizeEstimator::estimate(FileSource source,
Chris@1098 25 sv_samplerate_t targetRate)
Chris@1098 26 {
Chris@1098 27 sv_frame_t estimate = 0;
Chris@1098 28
Chris@1098 29 // Most of our file readers don't know the sample count until
Chris@1098 30 // after they've finished decoding. This is an exception:
Chris@1098 31
Chris@1098 32 WavFileReader *reader = new WavFileReader(source);
Chris@1098 33 if (reader->isOK() &&
Chris@1098 34 reader->getChannelCount() > 0 &&
Chris@1098 35 reader->getFrameCount() > 0) {
Chris@1098 36 sv_frame_t samples =
Chris@1098 37 reader->getFrameCount() * reader->getChannelCount();
Chris@1098 38 sv_samplerate_t rate = reader->getSampleRate();
Chris@1098 39 if (targetRate != 0.0 && targetRate != rate) {
Chris@1098 40 samples = sv_frame_t(double(samples) * targetRate / rate);
Chris@1098 41 }
Chris@1098 42 delete reader;
Chris@1098 43 estimate = samples;
Chris@1098 44 }
Chris@1098 45
Chris@1098 46 if (estimate == 0) {
Chris@1098 47
Chris@1098 48 // The remainder just makes an estimate based on the file size
Chris@1098 49 // and extension. We don't even know its sample rate at this
Chris@1098 50 // point, so the following is a wild guess.
Chris@1098 51
Chris@1098 52 double rateRatio = 1.0;
Chris@1098 53 if (targetRate != 0.0) {
Chris@1098 54 rateRatio = targetRate / 44100.0;
Chris@1098 55 }
Chris@1098 56
Chris@1098 57 QString extension = source.getExtension();
Chris@1098 58
Chris@1098 59 source.waitForData();
Chris@1098 60 if (!source.isOK()) return 0;
Chris@1098 61
Chris@1098 62 sv_frame_t sz = 0;
Chris@1098 63 {
Chris@1098 64 QFile f(source.getLocalFilename());
Chris@1098 65 if (f.open(QFile::ReadOnly)) {
Chris@1104 66 #ifdef DEBUG_AUDIO_FILE_SIZE_ESTIMATOR
Chris@1098 67 cerr << "opened file, size is " << f.size() << endl;
Chris@1104 68 #endif
Chris@1098 69 sz = f.size();
Chris@1098 70 f.close();
Chris@1098 71 }
Chris@1098 72 }
Chris@1098 73
Chris@1098 74 if (extension == "ogg" || extension == "oga" ||
Chris@1098 75 extension == "m4a" || extension == "mp3" ||
Chris@1098 76 extension == "wma") {
Chris@1098 77
Chris@1098 78 // Usually a lossy file. Compression ratios can vary
Chris@1098 79 // dramatically, but don't usually exceed about 20x compared
Chris@1098 80 // to 16-bit PCM (e.g. a 128kbps mp3 has 11x ratio over WAV at
Chris@1098 81 // 44.1kHz). We can estimate the number of samples to be file
Chris@1098 82 // size x 20, divided by 2 as we're comparing with 16-bit PCM.
Chris@1098 83
Chris@1098 84 estimate = sv_frame_t(double(sz) * 10 * rateRatio);
Chris@1098 85 }
Chris@1098 86
Chris@1098 87 if (extension == "flac") {
Chris@1098 88
Chris@1098 89 // FLAC usually takes up a bit more than half the space of
Chris@1098 90 // 16-bit PCM. So the number of 16-bit samples is roughly the
Chris@1098 91 // same as the file size in bytes. As above, let's be
Chris@1098 92 // conservative.
Chris@1098 93
Chris@1098 94 estimate = sv_frame_t(double(sz) * 1.2 * rateRatio);
Chris@1098 95 }
Chris@1098 96
Chris@1104 97 #ifdef DEBUG_AUDIO_FILE_SIZE_ESTIMATOR
Chris@1098 98 cerr << "AudioFileSizeEstimator: for extension " << extension << ", estimate = " << estimate << endl;
Chris@1104 99 #endif
Chris@1098 100 }
Chris@1098 101
Chris@1104 102 #ifdef DEBUG_AUDIO_FILE_SIZE_ESTIMATOR
Chris@1098 103 cerr << "estimate = " << estimate << endl;
Chris@1104 104 #endif
Chris@1098 105
Chris@1098 106 return estimate;
Chris@1098 107 }
Chris@1098 108