ILIAS  release_4-3 Revision
 All Data Structures Namespaces Files Functions Variables Groups Pages
module.audio.lpac.php
Go to the documentation of this file.
1 <?php
4 // available at http://getid3.sourceforge.net //
5 // or http://www.getid3.org //
7 // See readme.txt for more details //
9 // //
10 // module.audio.lpac.php //
11 // module for analyzing LPAC Audio files //
12 // dependencies: module.audio-video.riff.php //
13 // ///
15 
16 getid3_lib::IncludeDependency(GETID3_INCLUDEPATH.'module.audio-video.riff.php', __FILE__, true);
17 
18 class getid3_lpac
19 {
20 
21  function getid3_lpac(&$fd, &$ThisFileInfo) {
22 
23  fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);
24  $LPACheader = fread($fd, 14);
25  if (substr($LPACheader, 0, 4) != 'LPAC') {
26  $ThisFileInfo['error'][] = 'Expected "LPAC" at offset '.$ThisFileInfo['avdataoffset'].', found "'.$StreamMarker.'"';
27  return false;
28  }
29  $ThisFileInfo['avdataoffset'] += 14;
30 
31  $ThisFileInfo['fileformat'] = 'lpac';
32  $ThisFileInfo['audio']['dataformat'] = 'lpac';
33  $ThisFileInfo['audio']['lossless'] = true;
34  $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
35 
36  $ThisFileInfo['lpac']['file_version'] = getid3_lib::BigEndian2Int(substr($LPACheader, 4, 1));
37  $flags['audio_type'] = getid3_lib::BigEndian2Int(substr($LPACheader, 5, 1));
38  $ThisFileInfo['lpac']['total_samples']= getid3_lib::BigEndian2Int(substr($LPACheader, 6, 4));
39  $flags['parameters'] = getid3_lib::BigEndian2Int(substr($LPACheader, 10, 4));
40 
41  $ThisFileInfo['lpac']['flags']['is_wave'] = (bool) ($flags['audio_type'] & 0x40);
42  $ThisFileInfo['lpac']['flags']['stereo'] = (bool) ($flags['audio_type'] & 0x04);
43  $ThisFileInfo['lpac']['flags']['24_bit'] = (bool) ($flags['audio_type'] & 0x02);
44  $ThisFileInfo['lpac']['flags']['16_bit'] = (bool) ($flags['audio_type'] & 0x01);
45 
46  if ($ThisFileInfo['lpac']['flags']['24_bit'] && $ThisFileInfo['lpac']['flags']['16_bit']) {
47  $ThisFileInfo['warning'][] = '24-bit and 16-bit flags cannot both be set';
48  }
49 
50  $ThisFileInfo['lpac']['flags']['fast_compress'] = (bool) ($flags['parameters'] & 0x40000000);
51  $ThisFileInfo['lpac']['flags']['random_access'] = (bool) ($flags['parameters'] & 0x08000000);
52  $ThisFileInfo['lpac']['block_length'] = pow(2, (($flags['parameters'] & 0x07000000) >> 24)) * 256;
53  $ThisFileInfo['lpac']['flags']['adaptive_prediction_order'] = (bool) ($flags['parameters'] & 0x00800000);
54  $ThisFileInfo['lpac']['flags']['adaptive_quantization'] = (bool) ($flags['parameters'] & 0x00400000);
55  $ThisFileInfo['lpac']['flags']['joint_stereo'] = (bool) ($flags['parameters'] & 0x00040000);
56  $ThisFileInfo['lpac']['quantization'] = ($flags['parameters'] & 0x00001F00) >> 8;
57  $ThisFileInfo['lpac']['max_prediction_order'] = ($flags['parameters'] & 0x0000003F);
58 
59  if ($ThisFileInfo['lpac']['flags']['fast_compress'] && ($ThisFileInfo['lpac']['max_prediction_order'] != 3)) {
60  $ThisFileInfo['warning'][] = 'max_prediction_order expected to be "3" if fast_compress is true, actual value is "'.$ThisFileInfo['lpac']['max_prediction_order'].'"';
61  }
62  switch ($ThisFileInfo['lpac']['file_version']) {
63  case 6:
64  if ($ThisFileInfo['lpac']['flags']['adaptive_quantization']) {
65  $ThisFileInfo['warning'][] = 'adaptive_quantization expected to be false in LPAC file stucture v6, actually true';
66  }
67  if ($ThisFileInfo['lpac']['quantization'] != 20) {
68  $ThisFileInfo['warning'][] = 'Quantization expected to be 20 in LPAC file stucture v6, actually '.$ThisFileInfo['lpac']['flags']['Q'];
69  }
70  break;
71 
72  default:
73  //$ThisFileInfo['warning'][] = 'This version of getID3() only supports LPAC file format version 6, this file is version '.$ThisFileInfo['lpac']['file_version'].' - please report to info@getid3.org';
74  break;
75  }
76 
77  $dummy = $ThisFileInfo;
78  $riff = new getid3_riff($fd, $dummy);
79  $ThisFileInfo['avdataoffset'] = $dummy['avdataoffset'];
80  $ThisFileInfo['riff'] = $dummy['riff'];
81  $ThisFileInfo['error'] = $dummy['error'];
82  $ThisFileInfo['warning'] = $dummy['warning'];
83  $ThisFileInfo['lpac']['comments']['comment'] = $dummy['comments'];
84  $ThisFileInfo['audio']['sample_rate'] = $dummy['audio']['sample_rate'];
85 
86  $ThisFileInfo['audio']['channels'] = ($ThisFileInfo['lpac']['flags']['stereo'] ? 2 : 1);
87 
88  if ($ThisFileInfo['lpac']['flags']['24_bit']) {
89  $ThisFileInfo['audio']['bits_per_sample'] = $ThisFileInfo['riff']['audio'][0]['bits_per_sample'];
90  } elseif ($ThisFileInfo['lpac']['flags']['16_bit']) {
91  $ThisFileInfo['audio']['bits_per_sample'] = 16;
92  } else {
93  $ThisFileInfo['audio']['bits_per_sample'] = 8;
94  }
95 
96  if ($ThisFileInfo['lpac']['flags']['fast_compress']) {
97  // fast
98  $ThisFileInfo['audio']['encoder_options'] = '-1';
99  } else {
100  switch ($ThisFileInfo['lpac']['max_prediction_order']) {
101  case 20: // simple
102  $ThisFileInfo['audio']['encoder_options'] = '-2';
103  break;
104  case 30: // medium
105  $ThisFileInfo['audio']['encoder_options'] = '-3';
106  break;
107  case 40: // high
108  $ThisFileInfo['audio']['encoder_options'] = '-4';
109  break;
110  case 60: // extrahigh
111  $ThisFileInfo['audio']['encoder_options'] = '-5';
112  break;
113  }
114  }
115 
116  $ThisFileInfo['playtime_seconds'] = $ThisFileInfo['lpac']['total_samples'] / $ThisFileInfo['audio']['sample_rate'];
117  $ThisFileInfo['audio']['bitrate'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / $ThisFileInfo['playtime_seconds'];
118 
119  return true;
120  }
121 
122 }
123 
124 
125 ?>