1: <?php
  2: /////////////////////////////////////////////////////////////////
  3: /// getID3() by James Heinrich <info@getid3.org>               //
  4: //  available at http://getid3.sourceforge.net                 //
  5: //            or http://www.getid3.org                         //
  6: //          also https://github.com/JamesHeinrich/getID3       //
  7: /////////////////////////////////////////////////////////////////
  8: // See readme.txt for more details                             //
  9: /////////////////////////////////////////////////////////////////
 10: //                                                             //
 11: // module.audio.aac.php                                        //
 12: // module for analyzing AAC Audio files                        //
 13: // dependencies: NONE                                          //
 14: //                                                            ///
 15: /////////////////////////////////////////////////////////////////
 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:                 $info['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:             $info['error'][] = 'AAC-ADIF synch not found at offset '.$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:                 $info['warning'][] = 'Unable to parse AAC file beyond '.$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:                 $info['error'][] = 'Failed to read 7 bytes at offset '.($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:                 $info['error'][] = 'Synch pattern (0x0FFF) not found at offset '.($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:                     $info['warning'][] = 'Layer error - expected "0", found "'.$info['aac']['header']['raw']['mpeg_layer'].'" instead';
376:                 }
377:                 if ($info['aac']['header']['sample_frequency'] == 0) {
378:                     $info['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:                     $info['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: }
514: