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module.audio.aac.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.aac.php //
11 // module for analyzing AAC Audio files //
12 // dependencies: NONE //
13 // ///
15 
16 
17 class getid3_aac
18 {
19 
20  // new combined constructor
21  function getid3_aac(&$fd, &$ThisFileInfo, $option) {
22 
23  if ($option === 'adif') {
24  $this->getAACADIFheaderFilepointer($fd, $ThisFileInfo);
25  }
26  elseif ($option === 'adts') {
27  $this->getAACADTSheaderFilepointer($fd, $ThisFileInfo);
28  }
29  }
30 
31 
32 
33  function getAACADIFheaderFilepointer(&$fd, &$ThisFileInfo) {
34  $ThisFileInfo['fileformat'] = 'aac';
35  $ThisFileInfo['audio']['dataformat'] = 'aac';
36  $ThisFileInfo['audio']['lossless'] = false;
37 
38  fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);
39  $AACheader = fread($fd, 1024);
40  $offset = 0;
41 
42  if (substr($AACheader, 0, 4) == 'ADIF') {
43 
44  // http://faac.sourceforge.net/wiki/index.php?page=ADIF
45 
46  // http://libmpeg.org/mpeg4/doc/w2203tfs.pdf
47  // adif_header() {
48  // adif_id 32
49  // copyright_id_present 1
50  // if( copyright_id_present )
51  // copyright_id 72
52  // original_copy 1
53  // home 1
54  // bitstream_type 1
55  // bitrate 23
56  // num_program_config_elements 4
57  // for (i = 0; i < num_program_config_elements + 1; i++ ) {
58  // if( bitstream_type == '0' )
59  // adif_buffer_fullness 20
60  // program_config_element()
61  // }
62  // }
63 
64  $AACheaderBitstream = getid3_lib::BigEndian2Bin($AACheader);
65  $bitoffset = 0;
66 
67  $ThisFileInfo['aac']['header_type'] = 'ADIF';
68  $bitoffset += 32;
69  $ThisFileInfo['aac']['header']['mpeg_version'] = 4;
70 
71  $ThisFileInfo['aac']['header']['copyright'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
72  $bitoffset += 1;
73  if ($ThisFileInfo['aac']['header']['copyright']) {
74  $ThisFileInfo['aac']['header']['copyright_id'] = getid3_lib::Bin2String(substr($AACheaderBitstream, $bitoffset, 72));
75  $bitoffset += 72;
76  }
77  $ThisFileInfo['aac']['header']['original_copy'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
78  $bitoffset += 1;
79  $ThisFileInfo['aac']['header']['home'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
80  $bitoffset += 1;
81  $ThisFileInfo['aac']['header']['is_vbr'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
82  $bitoffset += 1;
83  if ($ThisFileInfo['aac']['header']['is_vbr']) {
84  $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
85  $ThisFileInfo['aac']['header']['bitrate_max'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 23));
86  $bitoffset += 23;
87  } else {
88  $ThisFileInfo['audio']['bitrate_mode'] = 'cbr';
89  $ThisFileInfo['aac']['header']['bitrate'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 23));
90  $bitoffset += 23;
91  $ThisFileInfo['audio']['bitrate'] = $ThisFileInfo['aac']['header']['bitrate'];
92  }
93  if ($ThisFileInfo['audio']['bitrate'] == 0) {
94  $ThisFileInfo['error'][] = 'Corrupt AAC file: bitrate_audio == zero';
95  return false;
96  }
97  $ThisFileInfo['aac']['header']['num_program_configs'] = 1 + getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
98  $bitoffset += 4;
99 
100  for ($i = 0; $i < $ThisFileInfo['aac']['header']['num_program_configs']; $i++) {
101  // http://www.audiocoding.com/wiki/index.php?page=program_config_element
102 
103  // buffer_fullness 20
104 
105  // element_instance_tag 4
106  // object_type 2
107  // sampling_frequency_index 4
108  // num_front_channel_elements 4
109  // num_side_channel_elements 4
110  // num_back_channel_elements 4
111  // num_lfe_channel_elements 2
112  // num_assoc_data_elements 3
113  // num_valid_cc_elements 4
114  // mono_mixdown_present 1
115  // mono_mixdown_element_number 4 if mono_mixdown_present == 1
116  // stereo_mixdown_present 1
117  // stereo_mixdown_element_number 4 if stereo_mixdown_present == 1
118  // matrix_mixdown_idx_present 1
119  // matrix_mixdown_idx 2 if matrix_mixdown_idx_present == 1
120  // pseudo_surround_enable 1 if matrix_mixdown_idx_present == 1
121  // for (i = 0; i < num_front_channel_elements; i++) {
122  // front_element_is_cpe[i] 1
123  // front_element_tag_select[i] 4
124  // }
125  // for (i = 0; i < num_side_channel_elements; i++) {
126  // side_element_is_cpe[i] 1
127  // side_element_tag_select[i] 4
128  // }
129  // for (i = 0; i < num_back_channel_elements; i++) {
130  // back_element_is_cpe[i] 1
131  // back_element_tag_select[i] 4
132  // }
133  // for (i = 0; i < num_lfe_channel_elements; i++) {
134  // lfe_element_tag_select[i] 4
135  // }
136  // for (i = 0; i < num_assoc_data_elements; i++) {
137  // assoc_data_element_tag_select[i] 4
138  // }
139  // for (i = 0; i < num_valid_cc_elements; i++) {
140  // cc_element_is_ind_sw[i] 1
141  // valid_cc_element_tag_select[i] 4
142  // }
143  // byte_alignment() VAR
144  // comment_field_bytes 8
145  // for (i = 0; i < comment_field_bytes; i++) {
146  // comment_field_data[i] 8
147  // }
148 
149  if (!$ThisFileInfo['aac']['header']['is_vbr']) {
150  $ThisFileInfo['aac']['program_configs'][$i]['buffer_fullness'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 20));
151  $bitoffset += 20;
152  }
153  $ThisFileInfo['aac']['program_configs'][$i]['element_instance_tag'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
154  $bitoffset += 4;
155  $ThisFileInfo['aac']['program_configs'][$i]['object_type'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
156  $bitoffset += 2;
157  $ThisFileInfo['aac']['program_configs'][$i]['sampling_frequency_index'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
158  $bitoffset += 4;
159  $ThisFileInfo['aac']['program_configs'][$i]['num_front_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
160  $bitoffset += 4;
161  $ThisFileInfo['aac']['program_configs'][$i]['num_side_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
162  $bitoffset += 4;
163  $ThisFileInfo['aac']['program_configs'][$i]['num_back_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
164  $bitoffset += 4;
165  $ThisFileInfo['aac']['program_configs'][$i]['num_lfe_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
166  $bitoffset += 2;
167  $ThisFileInfo['aac']['program_configs'][$i]['num_assoc_data_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 3));
168  $bitoffset += 3;
169  $ThisFileInfo['aac']['program_configs'][$i]['num_valid_cc_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
170  $bitoffset += 4;
171  $ThisFileInfo['aac']['program_configs'][$i]['mono_mixdown_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
172  $bitoffset += 1;
173  if ($ThisFileInfo['aac']['program_configs'][$i]['mono_mixdown_present']) {
174  $ThisFileInfo['aac']['program_configs'][$i]['mono_mixdown_element_number'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
175  $bitoffset += 4;
176  }
177  $ThisFileInfo['aac']['program_configs'][$i]['stereo_mixdown_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
178  $bitoffset += 1;
179  if ($ThisFileInfo['aac']['program_configs'][$i]['stereo_mixdown_present']) {
180  $ThisFileInfo['aac']['program_configs'][$i]['stereo_mixdown_element_number'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
181  $bitoffset += 4;
182  }
183  $ThisFileInfo['aac']['program_configs'][$i]['matrix_mixdown_idx_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
184  $bitoffset += 1;
185  if ($ThisFileInfo['aac']['program_configs'][$i]['matrix_mixdown_idx_present']) {
186  $ThisFileInfo['aac']['program_configs'][$i]['matrix_mixdown_idx'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
187  $bitoffset += 2;
188  $ThisFileInfo['aac']['program_configs'][$i]['pseudo_surround_enable'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
189  $bitoffset += 1;
190  }
191  for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_front_channel_elements']; $j++) {
192  $ThisFileInfo['aac']['program_configs'][$i]['front_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
193  $bitoffset += 1;
194  $ThisFileInfo['aac']['program_configs'][$i]['front_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
195  $bitoffset += 4;
196  }
197  for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_side_channel_elements']; $j++) {
198  $ThisFileInfo['aac']['program_configs'][$i]['side_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
199  $bitoffset += 1;
200  $ThisFileInfo['aac']['program_configs'][$i]['side_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
201  $bitoffset += 4;
202  }
203  for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_back_channel_elements']; $j++) {
204  $ThisFileInfo['aac']['program_configs'][$i]['back_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
205  $bitoffset += 1;
206  $ThisFileInfo['aac']['program_configs'][$i]['back_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
207  $bitoffset += 4;
208  }
209  for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_lfe_channel_elements']; $j++) {
210  $ThisFileInfo['aac']['program_configs'][$i]['lfe_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
211  $bitoffset += 4;
212  }
213  for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_assoc_data_elements']; $j++) {
214  $ThisFileInfo['aac']['program_configs'][$i]['assoc_data_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
215  $bitoffset += 4;
216  }
217  for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_valid_cc_elements']; $j++) {
218  $ThisFileInfo['aac']['program_configs'][$i]['cc_element_is_ind_sw'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
219  $bitoffset += 1;
220  $ThisFileInfo['aac']['program_configs'][$i]['valid_cc_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
221  $bitoffset += 4;
222  }
223 
224  $bitoffset = ceil($bitoffset / 8) * 8;
225 
226  $ThisFileInfo['aac']['program_configs'][$i]['comment_field_bytes'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 8));
227  $bitoffset += 8;
228  $ThisFileInfo['aac']['program_configs'][$i]['comment_field'] = getid3_lib::Bin2String(substr($AACheaderBitstream, $bitoffset, 8 * $ThisFileInfo['aac']['program_configs'][$i]['comment_field_bytes']));
229  $bitoffset += 8 * $ThisFileInfo['aac']['program_configs'][$i]['comment_field_bytes'];
230 
231 
232  $ThisFileInfo['aac']['header']['profile_text'] = $this->AACprofileLookup($ThisFileInfo['aac']['program_configs'][$i]['object_type'], $ThisFileInfo['aac']['header']['mpeg_version']);
233  $ThisFileInfo['aac']['program_configs'][$i]['sampling_frequency'] = $this->AACsampleRateLookup($ThisFileInfo['aac']['program_configs'][$i]['sampling_frequency_index']);
234  $ThisFileInfo['audio']['sample_rate'] = $ThisFileInfo['aac']['program_configs'][$i]['sampling_frequency'];
235  $ThisFileInfo['audio']['channels'] = $this->AACchannelCountCalculate($ThisFileInfo['aac']['program_configs'][$i]);
236  if ($ThisFileInfo['aac']['program_configs'][$i]['comment_field']) {
237  $ThisFileInfo['aac']['comments'][] = $ThisFileInfo['aac']['program_configs'][$i]['comment_field'];
238  }
239  }
240  $ThisFileInfo['playtime_seconds'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / $ThisFileInfo['audio']['bitrate'];
241 
242  $ThisFileInfo['audio']['encoder_options'] = $ThisFileInfo['aac']['header_type'].' '.$ThisFileInfo['aac']['header']['profile_text'];
243 
244 
245 
246  return true;
247 
248  } else {
249 
250  unset($ThisFileInfo['fileformat']);
251  unset($ThisFileInfo['aac']);
252  $ThisFileInfo['error'][] = 'AAC-ADIF synch not found at offset '.$ThisFileInfo['avdataoffset'].' (expected "ADIF", found "'.substr($AACheader, 0, 4).'" instead)';
253  return false;
254 
255  }
256 
257  }
258 
259 
260  function getAACADTSheaderFilepointer(&$fd, &$ThisFileInfo, $MaxFramesToScan=1000000, $ReturnExtendedInfo=false) {
261  // based loosely on code from AACfile by Jurgen Faul <jfaulØgmx.de>
262  // http://jfaul.de/atl or http://j-faul.virtualave.net/atl/atl.html
263 
264 
265  // http://faac.sourceforge.net/wiki/index.php?page=ADTS
266 
267  // * ADTS Fixed Header: these don't change from frame to frame
268  // syncword 12 always: '111111111111'
269  // ID 1 0: MPEG-4, 1: MPEG-2
270  // layer 2 always: '00'
271  // protection_absent 1
272  // profile 2
273  // sampling_frequency_index 4
274  // private_bit 1
275  // channel_configuration 3
276  // original/copy 1
277  // home 1
278  // emphasis 2 only if ID == 0 (ie MPEG-4)
279 
280  // * ADTS Variable Header: these can change from frame to frame
281  // copyright_identification_bit 1
282  // copyright_identification_start 1
283  // aac_frame_length 13 length of the frame including header (in bytes)
284  // adts_buffer_fullness 11 0x7FF indicates VBR
285  // no_raw_data_blocks_in_frame 2
286 
287  // * ADTS Error check
288  // crc_check 16 only if protection_absent == 0
289 
290  $byteoffset = 0;
291  $framenumber = 0;
292 
293  // Init bit pattern array
294  static $decbin = array();
295 
296  // Populate $bindec
297  for ($i = 0; $i < 256; $i++) {
298  $decbin[chr($i)] = str_pad(decbin($i), 8, '0', STR_PAD_LEFT);
299  }
300 
301  // used to calculate bitrate below
302  $BitrateCache = array();
303 
304 
305  while (true) {
306  // breaks out when end-of-file encountered, or invalid data found,
307  // or MaxFramesToScan frames have been scanned
308 
309  fseek($fd, $byteoffset, SEEK_SET);
310 
311  // First get substring
312  $substring = fread($fd, 10);
313  $substringlength = strlen($substring);
314  if ($substringlength != 10) {
315  $ThisFileInfo['error'][] = 'Failed to read 10 bytes at offset '.(ftell($fd) - $substringlength).' (only read '.$substringlength.' bytes)';
316  return false;
317  }
318 
319  // Initialise $AACheaderBitstream
320  $AACheaderBitstream = '';
321 
322  // Loop thru substring chars
323  for ($i = 0; $i < 10; $i++) {
324  $AACheaderBitstream .= $decbin[$substring{$i}];
325  }
326 
327  $bitoffset = 0;
328 
329  $synctest = bindec(substr($AACheaderBitstream, $bitoffset, 12));
330 
331  $bitoffset += 12;
332  if ($synctest != 0x0FFF) {
333  $ThisFileInfo['error'][] = 'Synch pattern (0x0FFF) not found at offset '.(ftell($fd) - 10).' (found 0x0'.strtoupper(dechex($synctest)).' instead)';
334  if ($ThisFileInfo['fileformat'] == 'aac') {
335  return true;
336  }
337  return false;
338  }
339 
340  // Gather info for first frame only - this takes time to do 1000 times!
341  if ($framenumber > 0) {
342 
343  if (!$AACheaderBitstream[$bitoffset]) {
344 
345  // MPEG-4
346  $bitoffset += 20;
347 
348  } else {
349 
350  // MPEG-2
351  $bitoffset += 18;
352 
353  }
354 
355  } else {
356 
357  $ThisFileInfo['aac']['header_type'] = 'ADTS';
358  $ThisFileInfo['aac']['header']['synch'] = $synctest;
359  $ThisFileInfo['fileformat'] = 'aac';
360  $ThisFileInfo['audio']['dataformat'] = 'aac';
361 
362  $ThisFileInfo['aac']['header']['mpeg_version'] = ((substr($AACheaderBitstream, $bitoffset, 1) == '0') ? 4 : 2);
363  $bitoffset += 1;
364  $ThisFileInfo['aac']['header']['layer'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
365  $bitoffset += 2;
366  if ($ThisFileInfo['aac']['header']['layer'] != 0) {
367  $ThisFileInfo['error'][] = 'Layer error - expected 0x00, found 0x'.dechex($ThisFileInfo['aac']['header']['layer']).' instead';
368  return false;
369  }
370  $ThisFileInfo['aac']['header']['crc_present'] = ((substr($AACheaderBitstream, $bitoffset, 1) == '0') ? true : false);
371  $bitoffset += 1;
372  $ThisFileInfo['aac']['header']['profile_id'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
373  $bitoffset += 2;
374  $ThisFileInfo['aac']['header']['profile_text'] = $this->AACprofileLookup($ThisFileInfo['aac']['header']['profile_id'], $ThisFileInfo['aac']['header']['mpeg_version']);
375 
376  $ThisFileInfo['aac']['header']['sample_frequency_index'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
377  $bitoffset += 4;
378  $ThisFileInfo['aac']['header']['sample_frequency'] = $this->AACsampleRateLookup($ThisFileInfo['aac']['header']['sample_frequency_index']);
379  if ($ThisFileInfo['aac']['header']['sample_frequency'] == 0) {
380  $ThisFileInfo['error'][] = 'Corrupt AAC file: sample_frequency == zero';
381  return false;
382  }
383  $ThisFileInfo['audio']['sample_rate'] = $ThisFileInfo['aac']['header']['sample_frequency'];
384 
385  $ThisFileInfo['aac']['header']['private'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
386  $bitoffset += 1;
387  $ThisFileInfo['aac']['header']['channel_configuration'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 3));
388  $bitoffset += 3;
389  $ThisFileInfo['audio']['channels'] = $ThisFileInfo['aac']['header']['channel_configuration'];
390  $ThisFileInfo['aac']['header']['original'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
391  $bitoffset += 1;
392  $ThisFileInfo['aac']['header']['home'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
393  $bitoffset += 1;
394 
395  if ($ThisFileInfo['aac']['header']['mpeg_version'] == 4) {
396  $ThisFileInfo['aac']['header']['emphasis'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
397  $bitoffset += 2;
398  }
399 
400  if ($ReturnExtendedInfo) {
401 
402  $ThisFileInfo['aac'][$framenumber]['copyright_id_bit'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
403  $bitoffset += 1;
404  $ThisFileInfo['aac'][$framenumber]['copyright_id_start'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
405  $bitoffset += 1;
406 
407  } else {
408 
409  $bitoffset += 2;
410 
411  }
412 
413  }
414 
415  $FrameLength = bindec(substr($AACheaderBitstream, $bitoffset, 13));
416 
417  if (!isset($BitrateCache[$FrameLength])) {
418  $BitrateCache[$FrameLength] = ($ThisFileInfo['aac']['header']['sample_frequency'] / 1024) * $FrameLength * 8;
419  }
420  @$ThisFileInfo['aac']['bitrate_distribution'][$BitrateCache[$FrameLength]]++;
421 
422  $ThisFileInfo['aac'][$framenumber]['aac_frame_length'] = $FrameLength;
423  $bitoffset += 13;
424  $ThisFileInfo['aac'][$framenumber]['adts_buffer_fullness'] = bindec(substr($AACheaderBitstream, $bitoffset, 11));
425  $bitoffset += 11;
426  if ($ThisFileInfo['aac'][$framenumber]['adts_buffer_fullness'] == 0x07FF) {
427  $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
428  } else {
429  $ThisFileInfo['audio']['bitrate_mode'] = 'cbr';
430  }
431  $ThisFileInfo['aac'][$framenumber]['num_raw_data_blocks'] = bindec(substr($AACheaderBitstream, $bitoffset, 2));
432  $bitoffset += 2;
433 
434  if ($ThisFileInfo['aac']['header']['crc_present']) {
435  //$ThisFileInfo['aac'][$framenumber]['crc'] = bindec(substr($AACheaderBitstream, $bitoffset, 16));
436  $bitoffset += 16;
437  }
438 
439  if (!$ReturnExtendedInfo) {
440  unset($ThisFileInfo['aac'][$framenumber]);
441  }
442 
443  $byteoffset += $FrameLength;
444  if ((++$framenumber < $MaxFramesToScan) && (($byteoffset + 10) < $ThisFileInfo['avdataend'])) {
445 
446  // keep scanning
447 
448  } else {
449 
450  $ThisFileInfo['aac']['frames'] = $framenumber;
451  $ThisFileInfo['playtime_seconds'] = ($ThisFileInfo['avdataend'] / $byteoffset) * (($framenumber * 1024) / $ThisFileInfo['aac']['header']['sample_frequency']); // (1 / % of file scanned) * (samples / (samples/sec)) = seconds
452  if ($ThisFileInfo['playtime_seconds'] == 0) {
453  $ThisFileInfo['error'][] = 'Corrupt AAC file: playtime_seconds == zero';
454  return false;
455  }
456  $ThisFileInfo['audio']['bitrate'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / $ThisFileInfo['playtime_seconds'];
457  ksort($ThisFileInfo['aac']['bitrate_distribution']);
458 
459  $ThisFileInfo['audio']['encoder_options'] = $ThisFileInfo['aac']['header_type'].' '.$ThisFileInfo['aac']['header']['profile_text'];
460 
461  return true;
462 
463  }
464  }
465  // should never get here.
466  }
467 
468  function AACsampleRateLookup($samplerateid) {
469  static $AACsampleRateLookup = array();
470  if (empty($AACsampleRateLookup)) {
471  $AACsampleRateLookup[0] = 96000;
472  $AACsampleRateLookup[1] = 88200;
473  $AACsampleRateLookup[2] = 64000;
474  $AACsampleRateLookup[3] = 48000;
475  $AACsampleRateLookup[4] = 44100;
476  $AACsampleRateLookup[5] = 32000;
477  $AACsampleRateLookup[6] = 24000;
478  $AACsampleRateLookup[7] = 22050;
479  $AACsampleRateLookup[8] = 16000;
480  $AACsampleRateLookup[9] = 12000;
481  $AACsampleRateLookup[10] = 11025;
482  $AACsampleRateLookup[11] = 8000;
483  $AACsampleRateLookup[12] = 0;
484  $AACsampleRateLookup[13] = 0;
485  $AACsampleRateLookup[14] = 0;
486  $AACsampleRateLookup[15] = 0;
487  }
488  return (isset($AACsampleRateLookup[$samplerateid]) ? $AACsampleRateLookup[$samplerateid] : 'invalid');
489  }
490 
491  function AACprofileLookup($profileid, $mpegversion) {
492  static $AACprofileLookup = array();
493  if (empty($AACprofileLookup)) {
494  $AACprofileLookup[2][0] = 'Main profile';
495  $AACprofileLookup[2][1] = 'Low Complexity profile (LC)';
496  $AACprofileLookup[2][2] = 'Scalable Sample Rate profile (SSR)';
497  $AACprofileLookup[2][3] = '(reserved)';
498  $AACprofileLookup[4][0] = 'AAC_MAIN';
499  $AACprofileLookup[4][1] = 'AAC_LC';
500  $AACprofileLookup[4][2] = 'AAC_SSR';
501  $AACprofileLookup[4][3] = 'AAC_LTP';
502  }
503  return (isset($AACprofileLookup[$mpegversion][$profileid]) ? $AACprofileLookup[$mpegversion][$profileid] : 'invalid');
504  }
505 
506  function AACchannelCountCalculate($program_configs) {
507  $channels = 0;
508  for ($i = 0; $i < $program_configs['num_front_channel_elements']; $i++) {
509  $channels++;
510  if ($program_configs['front_element_is_cpe'][$i]) {
511  // each front element is channel pair (CPE = Channel Pair Element)
512  $channels++;
513  }
514  }
515  for ($i = 0; $i < $program_configs['num_side_channel_elements']; $i++) {
516  $channels++;
517  if ($program_configs['side_element_is_cpe'][$i]) {
518  // each side element is channel pair (CPE = Channel Pair Element)
519  $channels++;
520  }
521  }
522  for ($i = 0; $i < $program_configs['num_back_channel_elements']; $i++) {
523  $channels++;
524  if ($program_configs['back_element_is_cpe'][$i]) {
525  // each back element is channel pair (CPE = Channel Pair Element)
526  $channels++;
527  }
528  }
529  for ($i = 0; $i < $program_configs['num_lfe_channel_elements']; $i++) {
530  $channels++;
531  }
532  return $channels;
533  }
534 
535 }
536 
537 
538 ?>