ILIAS  eassessment Revision 61809
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module.audio.voc.php
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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.voc.php //
11 // module for analyzing Creative VOC Audio files //
12 // dependencies: NONE //
13 // ///
15 
16 
17 class getid3_voc
18 {
19 
20  function getid3_voc(&$fd, &$ThisFileInfo) {
21 
22  $OriginalAVdataOffset = $ThisFileInfo['avdataoffset'];
23  fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);
24  $VOCheader = fread($fd, 26);
25 
26  if (substr($VOCheader, 0, 19) != 'Creative Voice File') {
27  $ThisFileInfo['error'][] = 'Expecting "Creative Voice File" at offset '.$ThisFileInfo['avdataoffset'].', found "'.substr($VOCheader, 0, 19).'"';
28  return false;
29  }
30 
31  // shortcuts
32  $thisfile_audio = &$ThisFileInfo['audio'];
33  $ThisFileInfo['voc'] = array();
34  $thisfile_voc = &$ThisFileInfo['voc'];
35 
36  $ThisFileInfo['fileformat'] = 'voc';
37  $thisfile_audio['dataformat'] = 'voc';
38  $thisfile_audio['bitrate_mode'] = 'cbr';
39  $thisfile_audio['lossless'] = true;
40  $thisfile_audio['channels'] = 1; // might be overriden below
41  $thisfile_audio['bits_per_sample'] = 8; // might be overriden below
42 
43  // byte # Description
44  // ------ ------------------------------------------
45  // 00-12 'Creative Voice File'
46  // 13 1A (eof to abort printing of file)
47  // 14-15 Offset of first datablock in .voc file (std 1A 00 in Intel Notation)
48  // 16-17 Version number (minor,major) (VOC-HDR puts 0A 01)
49  // 18-19 2's Comp of Ver. # + 1234h (VOC-HDR puts 29 11)
50 
51  $thisfile_voc['header']['datablock_offset'] = getid3_lib::LittleEndian2Int(substr($VOCheader, 20, 2));
52  $thisfile_voc['header']['minor_version'] = getid3_lib::LittleEndian2Int(substr($VOCheader, 22, 1));
53  $thisfile_voc['header']['major_version'] = getid3_lib::LittleEndian2Int(substr($VOCheader, 23, 1));
54 
55  do {
56 
57  $BlockOffset = ftell($fd);
58  $BlockData = fread($fd, 4);
59  $BlockType = ord($BlockData{0});
60  $BlockSize = getid3_lib::LittleEndian2Int(substr($BlockData, 1, 3));
61  $ThisBlock = array();
62 
63  @$thisfile_voc['blocktypes'][$BlockType]++;
64  switch ($BlockType) {
65  case 0: // Terminator
66  // do nothing, we'll break out of the loop down below
67  break;
68 
69  case 1: // Sound data
70  $BlockData .= fread($fd, 2);
71  if ($ThisFileInfo['avdataoffset'] <= $OriginalAVdataOffset) {
72  $ThisFileInfo['avdataoffset'] = ftell($fd);
73  }
74  fseek($fd, $BlockSize - 2, SEEK_CUR);
75 
76  $ThisBlock['sample_rate_id'] = getid3_lib::LittleEndian2Int(substr($BlockData, 4, 1));
77  $ThisBlock['compression_type'] = getid3_lib::LittleEndian2Int(substr($BlockData, 5, 1));
78 
79  $ThisBlock['compression_name'] = $this->VOCcompressionTypeLookup($ThisBlock['compression_type']);
80  if ($ThisBlock['compression_type'] <= 3) {
81  $thisfile_voc['compressed_bits_per_sample'] = getid3_lib::CastAsInt(str_replace('-bit', '', $ThisBlock['compression_name']));
82  }
83 
84  // Less accurate sample_rate calculation than the Extended block (#8) data (but better than nothing if Extended Block is not available)
85  if (empty($thisfile_audio['sample_rate'])) {
86  // SR byte = 256 - (1000000 / sample_rate)
87  $thisfile_audio['sample_rate'] = getid3_lib::trunc((1000000 / (256 - $ThisBlock['sample_rate_id'])) / $thisfile_audio['channels']);
88  }
89  break;
90 
91  case 2: // Sound continue
92  case 3: // Silence
93  case 4: // Marker
94  case 6: // Repeat
95  case 7: // End repeat
96  // nothing useful, just skip
97  fseek($fd, $BlockSize, SEEK_CUR);
98  break;
99 
100  case 8: // Extended
101  $BlockData .= fread($fd, 4);
102 
103  //00-01 Time Constant:
104  // Mono: 65536 - (256000000 / sample_rate)
105  // Stereo: 65536 - (256000000 / (sample_rate * 2))
106  $ThisBlock['time_constant'] = getid3_lib::LittleEndian2Int(substr($BlockData, 4, 2));
107  $ThisBlock['pack_method'] = getid3_lib::LittleEndian2Int(substr($BlockData, 6, 1));
108  $ThisBlock['stereo'] = (bool) getid3_lib::LittleEndian2Int(substr($BlockData, 7, 1));
109 
110  $thisfile_audio['channels'] = ($ThisBlock['stereo'] ? 2 : 1);
111  $thisfile_audio['sample_rate'] = getid3_lib::trunc((256000000 / (65536 - $ThisBlock['time_constant'])) / $thisfile_audio['channels']);
112  break;
113 
114  case 9: // data block that supersedes blocks 1 and 8. Used for stereo, 16 bit
115  $BlockData .= fread($fd, 12);
116  if ($ThisFileInfo['avdataoffset'] <= $OriginalAVdataOffset) {
117  $ThisFileInfo['avdataoffset'] = ftell($fd);
118  }
119  fseek($fd, $BlockSize - 12, SEEK_CUR);
120 
121  $ThisBlock['sample_rate'] = getid3_lib::LittleEndian2Int(substr($BlockData, 4, 4));
122  $ThisBlock['bits_per_sample'] = getid3_lib::LittleEndian2Int(substr($BlockData, 8, 1));
123  $ThisBlock['channels'] = getid3_lib::LittleEndian2Int(substr($BlockData, 9, 1));
124  $ThisBlock['wFormat'] = getid3_lib::LittleEndian2Int(substr($BlockData, 10, 2));
125 
126  $ThisBlock['compression_name'] = $this->VOCwFormatLookup($ThisBlock['wFormat']);
127  if ($this->VOCwFormatActualBitsPerSampleLookup($ThisBlock['wFormat'])) {
128  $thisfile_voc['compressed_bits_per_sample'] = $this->VOCwFormatActualBitsPerSampleLookup($ThisBlock['wFormat']);
129  }
130 
131  $thisfile_audio['sample_rate'] = $ThisBlock['sample_rate'];
132  $thisfile_audio['bits_per_sample'] = $ThisBlock['bits_per_sample'];
133  $thisfile_audio['channels'] = $ThisBlock['channels'];
134  break;
135 
136  default:
137  $ThisFileInfo['warning'][] = 'Unhandled block type "'.$BlockType.'" at offset '.$BlockOffset;
138  fseek($fd, $BlockSize, SEEK_CUR);
139  break;
140  }
141 
142  if (!empty($ThisBlock)) {
143  $ThisBlock['block_offset'] = $BlockOffset;
144  $ThisBlock['block_size'] = $BlockSize;
145  $ThisBlock['block_type_id'] = $BlockType;
146  $thisfile_voc['blocks'][] = $ThisBlock;
147  }
148 
149  } while (!feof($fd) && ($BlockType != 0));
150 
151  // Terminator block doesn't have size field, so seek back 3 spaces
152  fseek($fd, -3, SEEK_CUR);
153 
154  ksort($thisfile_voc['blocktypes']);
155 
156  if (!empty($thisfile_voc['compressed_bits_per_sample'])) {
157  $ThisFileInfo['playtime_seconds'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / ($thisfile_voc['compressed_bits_per_sample'] * $thisfile_audio['channels'] * $thisfile_audio['sample_rate']);
158  $thisfile_audio['bitrate'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / $ThisFileInfo['playtime_seconds'];
159  }
160 
161  return true;
162  }
163 
164  function VOCcompressionTypeLookup($index) {
165  static $VOCcompressionTypeLookup = array(
166  0 => '8-bit',
167  1 => '4-bit',
168  2 => '2.6-bit',
169  3 => '2-bit'
170  );
171  return (isset($VOCcompressionTypeLookup[$index]) ? $VOCcompressionTypeLookup[$index] : 'Multi DAC ('.($index - 3).') channels');
172  }
173 
174  function VOCwFormatLookup($index) {
175  static $VOCwFormatLookup = array(
176  0x0000 => '8-bit unsigned PCM',
177  0x0001 => 'Creative 8-bit to 4-bit ADPCM',
178  0x0002 => 'Creative 8-bit to 3-bit ADPCM',
179  0x0003 => 'Creative 8-bit to 2-bit ADPCM',
180  0x0004 => '16-bit signed PCM',
181  0x0006 => 'CCITT a-Law',
182  0x0007 => 'CCITT u-Law',
183  0x2000 => 'Creative 16-bit to 4-bit ADPCM'
184  );
185  return (isset($VOCwFormatLookup[$index]) ? $VOCwFormatLookup[$index] : false);
186  }
187 
188  function VOCwFormatActualBitsPerSampleLookup($index) {
189  static $VOCwFormatLookup = array(
190  0x0000 => 8,
191  0x0001 => 4,
192  0x0002 => 3,
193  0x0003 => 2,
194  0x0004 => 16,
195  0x0006 => 8,
196  0x0007 => 8,
197  0x2000 => 4
198  );
199  return (isset($VOCwFormatLookup[$index]) ? $VOCwFormatLookup[$index] : false);
200  }
201 
202 }
203 
204 
205 ?>