ILIAS  release_5-4 Revision v5.4.26-12-gabc799a52e6
module.audio.aac.php
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1 <?php
4 // available at http://getid3.sourceforge.net //
5 // or http://www.getid3.org //
6 // also https://github.com/JamesHeinrich/getID3 //
8 // See readme.txt for more details //
10 // //
11 // module.audio.aac.php //
12 // module for analyzing AAC Audio files //
13 // dependencies: NONE //
14 // ///
16 
17 
18 class getid3_aac extends getid3_handler
19 {
20  public function Analyze() {
21  $info = &$this->getid3->info;
22  $this->fseek($info['avdataoffset']);
23  if ($this->fread(4) == 'ADIF') {
24  $this->getAACADIFheaderFilepointer();
25  } else {
26  $this->getAACADTSheaderFilepointer();
27  }
28  return true;
29  }
30 
31 
32 
33  public function getAACADIFheaderFilepointer() {
34  $info = &$this->getid3->info;
35  $info['fileformat'] = 'aac';
36  $info['audio']['dataformat'] = 'aac';
37  $info['audio']['lossless'] = false;
38 
39  $this->fseek($info['avdataoffset']);
40  $AACheader = $this->fread(1024);
41  $offset = 0;
42 
43  if (substr($AACheader, 0, 4) == 'ADIF') {
44 
45  // http://faac.sourceforge.net/wiki/index.php?page=ADIF
46 
47  // http://libmpeg.org/mpeg4/doc/w2203tfs.pdf
48  // adif_header() {
49  // adif_id 32
50  // copyright_id_present 1
51  // if( copyright_id_present )
52  // copyright_id 72
53  // original_copy 1
54  // home 1
55  // bitstream_type 1
56  // bitrate 23
57  // num_program_config_elements 4
58  // for (i = 0; i < num_program_config_elements + 1; i++ ) {
59  // if( bitstream_type == '0' )
60  // adif_buffer_fullness 20
61  // program_config_element()
62  // }
63  // }
64 
65  $AACheaderBitstream = getid3_lib::BigEndian2Bin($AACheader);
66  $bitoffset = 0;
67 
68  $info['aac']['header_type'] = 'ADIF';
69  $bitoffset += 32;
70  $info['aac']['header']['mpeg_version'] = 4;
71 
72  $info['aac']['header']['copyright'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
73  $bitoffset += 1;
74  if ($info['aac']['header']['copyright']) {
75  $info['aac']['header']['copyright_id'] = getid3_lib::Bin2String(substr($AACheaderBitstream, $bitoffset, 72));
76  $bitoffset += 72;
77  }
78  $info['aac']['header']['original_copy'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
79  $bitoffset += 1;
80  $info['aac']['header']['home'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
81  $bitoffset += 1;
82  $info['aac']['header']['is_vbr'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
83  $bitoffset += 1;
84  if ($info['aac']['header']['is_vbr']) {
85  $info['audio']['bitrate_mode'] = 'vbr';
86  $info['aac']['header']['bitrate_max'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 23));
87  $bitoffset += 23;
88  } else {
89  $info['audio']['bitrate_mode'] = 'cbr';
90  $info['aac']['header']['bitrate'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 23));
91  $bitoffset += 23;
92  $info['audio']['bitrate'] = $info['aac']['header']['bitrate'];
93  }
94  if ($info['audio']['bitrate'] == 0) {
95  $this->error('Corrupt AAC file: bitrate_audio == zero');
96  return false;
97  }
98  $info['aac']['header']['num_program_configs'] = 1 + getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
99  $bitoffset += 4;
100 
101  for ($i = 0; $i < $info['aac']['header']['num_program_configs']; $i++) {
102  // http://www.audiocoding.com/wiki/index.php?page=program_config_element
103 
104  // buffer_fullness 20
105 
106  // element_instance_tag 4
107  // object_type 2
108  // sampling_frequency_index 4
109  // num_front_channel_elements 4
110  // num_side_channel_elements 4
111  // num_back_channel_elements 4
112  // num_lfe_channel_elements 2
113  // num_assoc_data_elements 3
114  // num_valid_cc_elements 4
115  // mono_mixdown_present 1
116  // mono_mixdown_element_number 4 if mono_mixdown_present == 1
117  // stereo_mixdown_present 1
118  // stereo_mixdown_element_number 4 if stereo_mixdown_present == 1
119  // matrix_mixdown_idx_present 1
120  // matrix_mixdown_idx 2 if matrix_mixdown_idx_present == 1
121  // pseudo_surround_enable 1 if matrix_mixdown_idx_present == 1
122  // for (i = 0; i < num_front_channel_elements; i++) {
123  // front_element_is_cpe[i] 1
124  // front_element_tag_select[i] 4
125  // }
126  // for (i = 0; i < num_side_channel_elements; i++) {
127  // side_element_is_cpe[i] 1
128  // side_element_tag_select[i] 4
129  // }
130  // for (i = 0; i < num_back_channel_elements; i++) {
131  // back_element_is_cpe[i] 1
132  // back_element_tag_select[i] 4
133  // }
134  // for (i = 0; i < num_lfe_channel_elements; i++) {
135  // lfe_element_tag_select[i] 4
136  // }
137  // for (i = 0; i < num_assoc_data_elements; i++) {
138  // assoc_data_element_tag_select[i] 4
139  // }
140  // for (i = 0; i < num_valid_cc_elements; i++) {
141  // cc_element_is_ind_sw[i] 1
142  // valid_cc_element_tag_select[i] 4
143  // }
144  // byte_alignment() VAR
145  // comment_field_bytes 8
146  // for (i = 0; i < comment_field_bytes; i++) {
147  // comment_field_data[i] 8
148  // }
149 
150  if (!$info['aac']['header']['is_vbr']) {
151  $info['aac']['program_configs'][$i]['buffer_fullness'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 20));
152  $bitoffset += 20;
153  }
154  $info['aac']['program_configs'][$i]['element_instance_tag'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
155  $bitoffset += 4;
156  $info['aac']['program_configs'][$i]['object_type'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
157  $bitoffset += 2;
158  $info['aac']['program_configs'][$i]['sampling_frequency_index'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
159  $bitoffset += 4;
160  $info['aac']['program_configs'][$i]['num_front_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
161  $bitoffset += 4;
162  $info['aac']['program_configs'][$i]['num_side_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
163  $bitoffset += 4;
164  $info['aac']['program_configs'][$i]['num_back_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
165  $bitoffset += 4;
166  $info['aac']['program_configs'][$i]['num_lfe_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
167  $bitoffset += 2;
168  $info['aac']['program_configs'][$i]['num_assoc_data_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 3));
169  $bitoffset += 3;
170  $info['aac']['program_configs'][$i]['num_valid_cc_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
171  $bitoffset += 4;
172  $info['aac']['program_configs'][$i]['mono_mixdown_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
173  $bitoffset += 1;
174  if ($info['aac']['program_configs'][$i]['mono_mixdown_present']) {
175  $info['aac']['program_configs'][$i]['mono_mixdown_element_number'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
176  $bitoffset += 4;
177  }
178  $info['aac']['program_configs'][$i]['stereo_mixdown_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
179  $bitoffset += 1;
180  if ($info['aac']['program_configs'][$i]['stereo_mixdown_present']) {
181  $info['aac']['program_configs'][$i]['stereo_mixdown_element_number'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
182  $bitoffset += 4;
183  }
184  $info['aac']['program_configs'][$i]['matrix_mixdown_idx_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
185  $bitoffset += 1;
186  if ($info['aac']['program_configs'][$i]['matrix_mixdown_idx_present']) {
187  $info['aac']['program_configs'][$i]['matrix_mixdown_idx'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
188  $bitoffset += 2;
189  $info['aac']['program_configs'][$i]['pseudo_surround_enable'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
190  $bitoffset += 1;
191  }
192  for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_front_channel_elements']; $j++) {
193  $info['aac']['program_configs'][$i]['front_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
194  $bitoffset += 1;
195  $info['aac']['program_configs'][$i]['front_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
196  $bitoffset += 4;
197  }
198  for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_side_channel_elements']; $j++) {
199  $info['aac']['program_configs'][$i]['side_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
200  $bitoffset += 1;
201  $info['aac']['program_configs'][$i]['side_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
202  $bitoffset += 4;
203  }
204  for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_back_channel_elements']; $j++) {
205  $info['aac']['program_configs'][$i]['back_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
206  $bitoffset += 1;
207  $info['aac']['program_configs'][$i]['back_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
208  $bitoffset += 4;
209  }
210  for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_lfe_channel_elements']; $j++) {
211  $info['aac']['program_configs'][$i]['lfe_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
212  $bitoffset += 4;
213  }
214  for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_assoc_data_elements']; $j++) {
215  $info['aac']['program_configs'][$i]['assoc_data_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
216  $bitoffset += 4;
217  }
218  for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_valid_cc_elements']; $j++) {
219  $info['aac']['program_configs'][$i]['cc_element_is_ind_sw'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
220  $bitoffset += 1;
221  $info['aac']['program_configs'][$i]['valid_cc_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
222  $bitoffset += 4;
223  }
224 
225  $bitoffset = ceil($bitoffset / 8) * 8;
226 
227  $info['aac']['program_configs'][$i]['comment_field_bytes'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 8));
228  $bitoffset += 8;
229  $info['aac']['program_configs'][$i]['comment_field'] = getid3_lib::Bin2String(substr($AACheaderBitstream, $bitoffset, 8 * $info['aac']['program_configs'][$i]['comment_field_bytes']));
230  $bitoffset += 8 * $info['aac']['program_configs'][$i]['comment_field_bytes'];
231 
232 
233  $info['aac']['header']['profile'] = self::AACprofileLookup($info['aac']['program_configs'][$i]['object_type'], $info['aac']['header']['mpeg_version']);
234  $info['aac']['program_configs'][$i]['sampling_frequency'] = self::AACsampleRateLookup($info['aac']['program_configs'][$i]['sampling_frequency_index']);
235  $info['audio']['sample_rate'] = $info['aac']['program_configs'][$i]['sampling_frequency'];
236  $info['audio']['channels'] = self::AACchannelCountCalculate($info['aac']['program_configs'][$i]);
237  if ($info['aac']['program_configs'][$i]['comment_field']) {
238  $info['aac']['comments'][] = $info['aac']['program_configs'][$i]['comment_field'];
239  }
240  }
241  $info['playtime_seconds'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['audio']['bitrate'];
242 
243  $info['audio']['encoder_options'] = $info['aac']['header_type'].' '.$info['aac']['header']['profile'];
244 
245 
246 
247  return true;
248 
249  } else {
250 
251  unset($info['fileformat']);
252  unset($info['aac']);
253  $this->error('AAC-ADIF synch not found at offset '.$info['avdataoffset'].' (expected "ADIF", found "'.substr($AACheader, 0, 4).'" instead)');
254  return false;
255 
256  }
257 
258  }
259 
260 
261  public function getAACADTSheaderFilepointer($MaxFramesToScan=1000000, $ReturnExtendedInfo=false) {
262  $info = &$this->getid3->info;
263 
264  // based loosely on code from AACfile by Jurgen Faul <jfaulØgmx.de>
265  // http://jfaul.de/atl or http://j-faul.virtualave.net/atl/atl.html
266 
267 
268  // http://faac.sourceforge.net/wiki/index.php?page=ADTS // dead link
269  // http://wiki.multimedia.cx/index.php?title=ADTS
270 
271  // * ADTS Fixed Header: these don't change from frame to frame
272  // syncword 12 always: '111111111111'
273  // ID 1 0: MPEG-4, 1: MPEG-2
274  // MPEG layer 2 If you send AAC in MPEG-TS, set to 0
275  // protection_absent 1 0: CRC present; 1: no CRC
276  // profile 2 0: AAC Main; 1: AAC LC (Low Complexity); 2: AAC SSR (Scalable Sample Rate); 3: AAC LTP (Long Term Prediction)
277  // sampling_frequency_index 4 15 not allowed
278  // private_bit 1 usually 0
279  // channel_configuration 3
280  // original/copy 1 0: original; 1: copy
281  // home 1 usually 0
282  // emphasis 2 only if ID == 0 (ie MPEG-4) // not present in some documentation?
283 
284  // * ADTS Variable Header: these can change from frame to frame
285  // copyright_identification_bit 1
286  // copyright_identification_start 1
287  // aac_frame_length 13 length of the frame including header (in bytes)
288  // adts_buffer_fullness 11 0x7FF indicates VBR
289  // no_raw_data_blocks_in_frame 2
290 
291  // * ADTS Error check
292  // crc_check 16 only if protection_absent == 0
293 
294  $byteoffset = $info['avdataoffset'];
295  $framenumber = 0;
296 
297  // Init bit pattern array
298  static $decbin = array();
299 
300  // Populate $bindec
301  for ($i = 0; $i < 256; $i++) {
302  $decbin[chr($i)] = str_pad(decbin($i), 8, '0', STR_PAD_LEFT);
303  }
304 
305  // used to calculate bitrate below
306  $BitrateCache = array();
307 
308 
309  while (true) {
310  // breaks out when end-of-file encountered, or invalid data found,
311  // or MaxFramesToScan frames have been scanned
312 
313  if (!getid3_lib::intValueSupported($byteoffset)) {
314  $this->warning('Unable to parse AAC file beyond '.$this->ftell().' (PHP does not support file operations beyond '.round(PHP_INT_MAX / 1073741824).'GB)');
315  return false;
316  }
317  $this->fseek($byteoffset);
318 
319  // First get substring
320  $substring = $this->fread(9); // header is 7 bytes (or 9 if CRC is present)
321  $substringlength = strlen($substring);
322  if ($substringlength != 9) {
323  $this->error('Failed to read 7 bytes at offset '.($this->ftell() - $substringlength).' (only read '.$substringlength.' bytes)');
324  return false;
325  }
326  // this would be easier with 64-bit math, but split it up to allow for 32-bit:
327  $header1 = getid3_lib::BigEndian2Int(substr($substring, 0, 2));
328  $header2 = getid3_lib::BigEndian2Int(substr($substring, 2, 4));
329  $header3 = getid3_lib::BigEndian2Int(substr($substring, 6, 1));
330 
331  $info['aac']['header']['raw']['syncword'] = ($header1 & 0xFFF0) >> 4;
332  if ($info['aac']['header']['raw']['syncword'] != 0x0FFF) {
333  $this->error('Synch pattern (0x0FFF) not found at offset '.($this->ftell() - $substringlength).' (found 0x0'.strtoupper(dechex($info['aac']['header']['raw']['syncword'])).' instead)');
334  //if ($info['fileformat'] == 'aac') {
335  // return true;
336  //}
337  unset($info['aac']);
338  return false;
339  }
340 
341  // Gather info for first frame only - this takes time to do 1000 times!
342  if ($framenumber == 0) {
343  $info['aac']['header_type'] = 'ADTS';
344  $info['fileformat'] = 'aac';
345  $info['audio']['dataformat'] = 'aac';
346 
347  $info['aac']['header']['raw']['mpeg_version'] = ($header1 & 0x0008) >> 3;
348  $info['aac']['header']['raw']['mpeg_layer'] = ($header1 & 0x0006) >> 1;
349  $info['aac']['header']['raw']['protection_absent'] = ($header1 & 0x0001) >> 0;
350 
351  $info['aac']['header']['raw']['profile_code'] = ($header2 & 0xC0000000) >> 30;
352  $info['aac']['header']['raw']['sample_rate_code'] = ($header2 & 0x3C000000) >> 26;
353  $info['aac']['header']['raw']['private_stream'] = ($header2 & 0x02000000) >> 25;
354  $info['aac']['header']['raw']['channels_code'] = ($header2 & 0x01C00000) >> 22;
355  $info['aac']['header']['raw']['original'] = ($header2 & 0x00200000) >> 21;
356  $info['aac']['header']['raw']['home'] = ($header2 & 0x00100000) >> 20;
357  $info['aac']['header']['raw']['copyright_stream'] = ($header2 & 0x00080000) >> 19;
358  $info['aac']['header']['raw']['copyright_start'] = ($header2 & 0x00040000) >> 18;
359  $info['aac']['header']['raw']['frame_length'] = ($header2 & 0x0003FFE0) >> 5;
360 
361  $info['aac']['header']['mpeg_version'] = ($info['aac']['header']['raw']['mpeg_version'] ? 2 : 4);
362  $info['aac']['header']['crc_present'] = ($info['aac']['header']['raw']['protection_absent'] ? false: true);
363  $info['aac']['header']['profile'] = self::AACprofileLookup($info['aac']['header']['raw']['profile_code'], $info['aac']['header']['mpeg_version']);
364  $info['aac']['header']['sample_frequency'] = self::AACsampleRateLookup($info['aac']['header']['raw']['sample_rate_code']);
365  $info['aac']['header']['private'] = (bool) $info['aac']['header']['raw']['private_stream'];
366  $info['aac']['header']['original'] = (bool) $info['aac']['header']['raw']['original'];
367  $info['aac']['header']['home'] = (bool) $info['aac']['header']['raw']['home'];
368  $info['aac']['header']['channels'] = (($info['aac']['header']['raw']['channels_code'] == 7) ? 8 : $info['aac']['header']['raw']['channels_code']);
369  if ($ReturnExtendedInfo) {
370  $info['aac'][$framenumber]['copyright_id_bit'] = (bool) $info['aac']['header']['raw']['copyright_stream'];
371  $info['aac'][$framenumber]['copyright_id_start'] = (bool) $info['aac']['header']['raw']['copyright_start'];
372  }
373 
374  if ($info['aac']['header']['raw']['mpeg_layer'] != 0) {
375  $this->warning('Layer error - expected "0", found "'.$info['aac']['header']['raw']['mpeg_layer'].'" instead');
376  }
377  if ($info['aac']['header']['sample_frequency'] == 0) {
378  $this->error('Corrupt AAC file: sample_frequency == zero');
379  return false;
380  }
381 
382  $info['audio']['sample_rate'] = $info['aac']['header']['sample_frequency'];
383  $info['audio']['channels'] = $info['aac']['header']['channels'];
384  }
385 
386  $FrameLength = ($header2 & 0x0003FFE0) >> 5;
387 
388  if (!isset($BitrateCache[$FrameLength])) {
389  $BitrateCache[$FrameLength] = ($info['aac']['header']['sample_frequency'] / 1024) * $FrameLength * 8;
390  }
391  getid3_lib::safe_inc($info['aac']['bitrate_distribution'][$BitrateCache[$FrameLength]], 1);
392 
393  $info['aac'][$framenumber]['aac_frame_length'] = $FrameLength;
394 
395  $info['aac'][$framenumber]['adts_buffer_fullness'] = (($header2 & 0x0000001F) << 6) & (($header3 & 0xFC) >> 2);
396  if ($info['aac'][$framenumber]['adts_buffer_fullness'] == 0x07FF) {
397  $info['audio']['bitrate_mode'] = 'vbr';
398  } else {
399  $info['audio']['bitrate_mode'] = 'cbr';
400  }
401  $info['aac'][$framenumber]['num_raw_data_blocks'] = (($header3 & 0x03) >> 0);
402 
403  if ($info['aac']['header']['crc_present']) {
404  //$info['aac'][$framenumber]['crc'] = getid3_lib::BigEndian2Int(substr($substring, 7, 2);
405  }
406 
407  if (!$ReturnExtendedInfo) {
408  unset($info['aac'][$framenumber]);
409  }
410 
411  /*
412  $rounded_precision = 5000;
413  $info['aac']['bitrate_distribution_rounded'] = array();
414  foreach ($info['aac']['bitrate_distribution'] as $bitrate => $count) {
415  $rounded_bitrate = round($bitrate / $rounded_precision) * $rounded_precision;
416  getid3_lib::safe_inc($info['aac']['bitrate_distribution_rounded'][$rounded_bitrate], $count);
417  }
418  ksort($info['aac']['bitrate_distribution_rounded']);
419  */
420 
421  $byteoffset += $FrameLength;
422  if ((++$framenumber < $MaxFramesToScan) && (($byteoffset + 10) < $info['avdataend'])) {
423 
424  // keep scanning
425 
426  } else {
427 
428  $info['aac']['frames'] = $framenumber;
429  $info['playtime_seconds'] = ($info['avdataend'] / $byteoffset) * (($framenumber * 1024) / $info['aac']['header']['sample_frequency']); // (1 / % of file scanned) * (samples / (samples/sec)) = seconds
430  if ($info['playtime_seconds'] == 0) {
431  $this->error('Corrupt AAC file: playtime_seconds == zero');
432  return false;
433  }
434  $info['audio']['bitrate'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
435  ksort($info['aac']['bitrate_distribution']);
436 
437  $info['audio']['encoder_options'] = $info['aac']['header_type'].' '.$info['aac']['header']['profile'];
438 
439  return true;
440 
441  }
442  }
443  // should never get here.
444  }
445 
446  public static function AACsampleRateLookup($samplerateid) {
447  static $AACsampleRateLookup = array();
448  if (empty($AACsampleRateLookup)) {
449  $AACsampleRateLookup[0] = 96000;
450  $AACsampleRateLookup[1] = 88200;
451  $AACsampleRateLookup[2] = 64000;
452  $AACsampleRateLookup[3] = 48000;
453  $AACsampleRateLookup[4] = 44100;
454  $AACsampleRateLookup[5] = 32000;
455  $AACsampleRateLookup[6] = 24000;
456  $AACsampleRateLookup[7] = 22050;
457  $AACsampleRateLookup[8] = 16000;
458  $AACsampleRateLookup[9] = 12000;
459  $AACsampleRateLookup[10] = 11025;
460  $AACsampleRateLookup[11] = 8000;
461  $AACsampleRateLookup[12] = 0;
462  $AACsampleRateLookup[13] = 0;
463  $AACsampleRateLookup[14] = 0;
464  $AACsampleRateLookup[15] = 0;
465  }
466  return (isset($AACsampleRateLookup[$samplerateid]) ? $AACsampleRateLookup[$samplerateid] : 'invalid');
467  }
468 
469  public static function AACprofileLookup($profileid, $mpegversion) {
470  static $AACprofileLookup = array();
471  if (empty($AACprofileLookup)) {
472  $AACprofileLookup[2][0] = 'Main profile';
473  $AACprofileLookup[2][1] = 'Low Complexity profile (LC)';
474  $AACprofileLookup[2][2] = 'Scalable Sample Rate profile (SSR)';
475  $AACprofileLookup[2][3] = '(reserved)';
476  $AACprofileLookup[4][0] = 'AAC_MAIN';
477  $AACprofileLookup[4][1] = 'AAC_LC';
478  $AACprofileLookup[4][2] = 'AAC_SSR';
479  $AACprofileLookup[4][3] = 'AAC_LTP';
480  }
481  return (isset($AACprofileLookup[$mpegversion][$profileid]) ? $AACprofileLookup[$mpegversion][$profileid] : 'invalid');
482  }
483 
484  public static function AACchannelCountCalculate($program_configs) {
485  $channels = 0;
486  for ($i = 0; $i < $program_configs['num_front_channel_elements']; $i++) {
487  $channels++;
488  if ($program_configs['front_element_is_cpe'][$i]) {
489  // each front element is channel pair (CPE = Channel Pair Element)
490  $channels++;
491  }
492  }
493  for ($i = 0; $i < $program_configs['num_side_channel_elements']; $i++) {
494  $channels++;
495  if ($program_configs['side_element_is_cpe'][$i]) {
496  // each side element is channel pair (CPE = Channel Pair Element)
497  $channels++;
498  }
499  }
500  for ($i = 0; $i < $program_configs['num_back_channel_elements']; $i++) {
501  $channels++;
502  if ($program_configs['back_element_is_cpe'][$i]) {
503  // each back element is channel pair (CPE = Channel Pair Element)
504  $channels++;
505  }
506  }
507  for ($i = 0; $i < $program_configs['num_lfe_channel_elements']; $i++) {
508  $channels++;
509  }
510  return $channels;
511  }
512 
513 }
getid3_lib\safe_inc
static safe_inc(&$variable, $increment=1)
Definition: getid3.lib.php:56
getid3_aac\AACchannelCountCalculate
static AACchannelCountCalculate($program_configs)
Definition: module.audio.aac.php:484
getid3_aac\AACprofileLookup
static AACprofileLookup($profileid, $mpegversion)
Definition: module.audio.aac.php:469
getid3_aac\getAACADIFheaderFilepointer
getAACADIFheaderFilepointer()
Definition: module.audio.aac.php:33
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getid3_lib\intValueSupported
static intValueSupported($num)
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getid3_handler\warning
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getid3_lib\Bin2Dec
static Bin2Dec($binstring, $signed=false)
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getid3_aac\Analyze
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Definition: module.audio.aac.php:20
getid3_lib\BigEndian2Bin
static BigEndian2Bin($byteword)
Definition: getid3.lib.php:297
getid3_aac
getID3() by James Heinrich info@getid3.org //
Definition: module.audio.aac.php:18
getid3_handler
Definition: getid3.php:1616
getid3_aac\getAACADTSheaderFilepointer
getAACADTSheaderFilepointer($MaxFramesToScan=1000000, $ReturnExtendedInfo=false)
Definition: module.audio.aac.php:261
getid3_lib\Bin2String
static Bin2String($binstring)
Definition: getid3.lib.php:358
getid3_handler\fread
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Definition: getid3.php:1683
getid3_aac\AACsampleRateLookup
static AACsampleRateLookup($samplerateid)
Definition: module.audio.aac.php:446
$i
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getid3_handler\fseek
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getid3_handler\ftell
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getid3_lib\BigEndian2Int
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Definition: getid3.lib.php:263