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comparison e2gallerypro/e2upload/Backend/Assets/getid3/module.audio.ac3.php @ 3:3f6b44aa6b35 judyates

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[svn r4] added ability to buy stuff, from a Prints page, but it doesn't work well with the css, and it also has not been fitted into the perl make system.
author rlm
date Mon, 22 Feb 2010 08:02:39 -0500
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2:670229c4eb4b 3:3f6b44aa6b35
1 <?php
2 // +----------------------------------------------------------------------+
3 // | PHP version 5 |
4 // +----------------------------------------------------------------------+
5 // | Copyright (c) 2002-2006 James Heinrich, Allan Hansen |
6 // +----------------------------------------------------------------------+
7 // | This source file is subject to version 2 of the GPL license, |
8 // | that is bundled with this package in the file license.txt and is |
9 // | available through the world-wide-web at the following url: |
10 // | http://www.gnu.org/copyleft/gpl.html |
11 // +----------------------------------------------------------------------+
12 // | getID3() - http://getid3.sourceforge.net or http://www.getid3.org |
13 // +----------------------------------------------------------------------+
14 // | Authors: James Heinrich <infoุgetid3*org> |
15 // | Allan Hansen <ahุartemis*dk> |
16 // +----------------------------------------------------------------------+
17 // | module.audio.ac3.php |
18 // | Module for analyzing AC-3 (aka Dolby Digital) audio files |
19 // | dependencies: NONE |
20 // +----------------------------------------------------------------------+
21 //
22 // $Id: module.audio.ac3.php,v 1.3 2006/11/02 10:48:01 ah Exp $
23
24
25
26 class getid3_ac3 extends getid3_handler
27 {
28
29 public function Analyze() {
30
31 $getid3 = $this->getid3;
32
33 // http://www.atsc.org/standards/a_52a.pdf
34
35 $getid3->info['fileformat'] = 'ac3';
36 $getid3->info['audio']['dataformat'] = 'ac3';
37 $getid3->info['audio']['bitrate_mode'] = 'cbr';
38 $getid3->info['audio']['lossless'] = false;
39
40 $getid3->info['ac3']['raw']['bsi'] = array ();
41 $info_ac3 = &$getid3->info['ac3'];
42 $info_ac3_raw = &$info_ac3['raw'];
43 $info_ac3_raw_bsi = &$info_ac3_raw['bsi'];
44
45
46 // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames
47 // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256
48 // new audio samples per channel. A synchronization information (SI) header at the beginning
49 // of each frame contains information needed to acquire and maintain synchronization. A
50 // bit stream information (BSI) header follows SI, and contains parameters describing the coded
51 // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the
52 // end of each frame is an error check field that includes a CRC word for error detection. An
53 // additional CRC word is located in the SI header, the use of which, by a decoder, is optional.
54 //
55 // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC
56
57 $this->fseek($getid3->info['avdataoffset'], SEEK_SET);
58 $ac3_header['syncinfo'] = $this->fread(5);
59 $info_ac3_raw['synchinfo']['synchword'] = substr($ac3_header['syncinfo'], 0, 2);
60
61 if ($info_ac3_raw['synchinfo']['synchword'] != "\x0B\x77") {
62 throw new getid3_exception('Expecting "\x0B\x77" at offset '.$getid3->info['avdataoffset'].', found \x'.strtoupper(dechex($ac3_header['syncinfo']{0})).'\x'.strtoupper(dechex($ac3_header['syncinfo']{1})).' instead');
63 }
64
65
66 // syncinfo() {
67 // syncword 16
68 // crc1 16
69 // fscod 2
70 // frmsizecod 6
71 // } /* end of syncinfo */
72
73 $info_ac3_raw['synchinfo']['crc1'] = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 2, 2));
74 $ac3_synchinfo_fscod_frmsizecod = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 4, 1));
75 $info_ac3_raw['synchinfo']['fscod'] = ($ac3_synchinfo_fscod_frmsizecod & 0xC0) >> 6;
76 $info_ac3_raw['synchinfo']['frmsizecod'] = ($ac3_synchinfo_fscod_frmsizecod & 0x3F);
77
78 $info_ac3['sample_rate'] = getid3_ac3::AC3sampleRateCodeLookup($info_ac3_raw['synchinfo']['fscod']);
79 if ($info_ac3_raw['synchinfo']['fscod'] <= 3) {
80 $getid3->info['audio']['sample_rate'] = $info_ac3['sample_rate'];
81 }
82
83 $info_ac3['frame_length'] = getid3_ac3::AC3frameSizeLookup($info_ac3_raw['synchinfo']['frmsizecod'], $info_ac3_raw['synchinfo']['fscod']);
84 $info_ac3['bitrate'] = getid3_ac3::AC3bitrateLookup($info_ac3_raw['synchinfo']['frmsizecod']);
85 $getid3->info['audio']['bitrate'] = $info_ac3['bitrate'];
86
87 $ac3_header['bsi'] = getid3_lib::BigEndian2Bin($this->fread(15));
88
89 $info_ac3_raw_bsi['bsid'] = bindec(substr($ac3_header['bsi'], 0, 5));
90 if ($info_ac3_raw_bsi['bsid'] > 8) {
91 // Decoders which can decode version 8 will thus be able to decode version numbers less than 8.
92 // If this standard is extended by the addition of additional elements or features, a value of bsid greater than 8 will be used.
93 // Decoders built to this version of the standard will not be able to decode versions with bsid greater than 8.
94 throw new getid3_exception('Bit stream identification is version '.$info_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 8');
95 }
96
97 $info_ac3_raw_bsi['bsmod'] = bindec(substr($ac3_header['bsi'], 5, 3));
98 $info_ac3_raw_bsi['acmod'] = bindec(substr($ac3_header['bsi'], 8, 3));
99
100 $info_ac3['service_type'] = getid3_ac3::AC3serviceTypeLookup($info_ac3_raw_bsi['bsmod'], $info_ac3_raw_bsi['acmod']);
101 $ac3_coding_mode = getid3_ac3::AC3audioCodingModeLookup($info_ac3_raw_bsi['acmod']);
102 foreach($ac3_coding_mode as $key => $value) {
103 $info_ac3[$key] = $value;
104 }
105 switch ($info_ac3_raw_bsi['acmod']) {
106 case 0:
107 case 1:
108 $getid3->info['audio']['channelmode'] = 'mono';
109 break;
110 case 3:
111 case 4:
112 $getid3->info['audio']['channelmode'] = 'stereo';
113 break;
114 default:
115 $getid3->info['audio']['channelmode'] = 'surround';
116 break;
117 }
118 $getid3->info['audio']['channels'] = $info_ac3['num_channels'];
119
120 $offset = 11;
121
122 if ($info_ac3_raw_bsi['acmod'] & 0x01) {
123 // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream.
124 $info_ac3_raw_bsi['cmixlev'] = bindec(substr($ac3_header['bsi'], $offset, 2));
125 $info_ac3['center_mix_level'] = getid3_ac3::AC3centerMixLevelLookup($info_ac3_raw_bsi['cmixlev']);
126 $offset += 2;
127 }
128
129 if ($info_ac3_raw_bsi['acmod'] & 0x04) {
130 // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream.
131 $info_ac3_raw_bsi['surmixlev'] = bindec(substr($ac3_header['bsi'], $offset, 2));
132 $info_ac3['surround_mix_level'] = getid3_ac3::AC3surroundMixLevelLookup($info_ac3_raw_bsi['surmixlev']);
133 $offset += 2;
134 }
135
136 if ($info_ac3_raw_bsi['acmod'] == 0x02) {
137 // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround.
138 $info_ac3_raw_bsi['dsurmod'] = bindec(substr($ac3_header['bsi'], $offset, 2));
139 $info_ac3['dolby_surround_mode'] = getid3_ac3::AC3dolbySurroundModeLookup($info_ac3_raw_bsi['dsurmod']);
140 $offset += 2;
141 }
142
143 $info_ac3_raw_bsi['lfeon'] = $ac3_header['bsi']{$offset++} == '1';
144 $info_ac3['lfe_enabled'] = $info_ac3_raw_bsi['lfeon'];
145 if ($info_ac3_raw_bsi['lfeon']) {
146 $getid3->info['audio']['channels'] .= '.1';
147 }
148
149 $info_ac3['channels_enabled'] = getid3_ac3::AC3channelsEnabledLookup($info_ac3_raw_bsi['acmod'], $info_ac3_raw_bsi['lfeon']);
150
151 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1–31.
152 // The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
153 $info_ac3_raw_bsi['dialnorm'] = bindec(substr($ac3_header['bsi'], $offset, 5));
154 $offset += 5;
155 $info_ac3['dialogue_normalization'] = '-'.$info_ac3_raw_bsi['dialnorm'].'dB';
156
157 $info_ac3_raw_bsi['compre_flag'] = $ac3_header['bsi']{$offset++} == '1';
158 if ($info_ac3_raw_bsi['compre_flag']) {
159 $info_ac3_raw_bsi['compr'] = bindec(substr($ac3_header['bsi'], $offset, 8));
160 $offset += 8;
161
162 $info_ac3['heavy_compression'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr']);
163 }
164
165 $info_ac3_raw_bsi['langcode_flag'] = $ac3_header['bsi']{$offset++} == '1';
166 if ($info_ac3_raw_bsi['langcode_flag']) {
167 $info_ac3_raw_bsi['langcod'] = bindec(substr($ac3_header['bsi'], $offset, 8));
168 $offset += 8;
169 }
170
171 $info_ac3_raw_bsi['audprodie'] = $ac3_header['bsi']{$offset++} == '1';
172 if ($info_ac3_raw_bsi['audprodie']) {
173 $info_ac3_raw_bsi['mixlevel'] = bindec(substr($ac3_header['bsi'], $offset, 5));
174 $offset += 5;
175
176 $info_ac3_raw_bsi['roomtyp'] = bindec(substr($ac3_header['bsi'], $offset, 2));
177 $offset += 2;
178
179 $info_ac3['mixing_level'] = (80 + $info_ac3_raw_bsi['mixlevel']).'dB';
180 $info_ac3['room_type'] = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp']);
181 }
182
183 if ($info_ac3_raw_bsi['acmod'] == 0x00) {
184 // If acmod is 0, then two completely independent program channels (dual mono)
185 // are encoded into the bit stream, and are referenced as Ch1, Ch2. In this case,
186 // a number of additional items are present in BSI or audblk to fully describe Ch2.
187
188
189 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1–31.
190 // The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
191 $info_ac3_raw_bsi['dialnorm2'] = bindec(substr($ac3_header['bsi'], $offset, 5));
192 $offset += 5;
193
194 $info_ac3['dialogue_normalization2'] = '-'.$info_ac3_raw_bsi['dialnorm2'].'dB';
195
196 $info_ac3_raw_bsi['compre_flag2'] = $ac3_header['bsi']{$offset++} == '1';
197 if ($info_ac3_raw_bsi['compre_flag2']) {
198 $info_ac3_raw_bsi['compr2'] = bindec(substr($ac3_header['bsi'], $offset, 8));
199 $offset += 8;
200
201 $info_ac3['heavy_compression2'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr2']);
202 }
203
204 $info_ac3_raw_bsi['langcode_flag2'] = $ac3_header['bsi']{$offset++} == '1';
205 if ($info_ac3_raw_bsi['langcode_flag2']) {
206 $info_ac3_raw_bsi['langcod2'] = bindec(substr($ac3_header['bsi'], $offset, 8));
207 $offset += 8;
208 }
209
210 $info_ac3_raw_bsi['audprodie2'] = $ac3_header['bsi']{$offset++} == '1';
211 if ($info_ac3_raw_bsi['audprodie2']) {
212 $info_ac3_raw_bsi['mixlevel2'] = bindec(substr($ac3_header['bsi'], $offset, 5));
213 $offset += 5;
214
215 $info_ac3_raw_bsi['roomtyp2'] = bindec(substr($ac3_header['bsi'], $offset, 2));
216 $offset += 2;
217
218 $info_ac3['mixing_level2'] = (80 + $info_ac3_raw_bsi['mixlevel2']).'dB';
219 $info_ac3['room_type2'] = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp2']);
220 }
221
222 }
223
224 $info_ac3_raw_bsi['copyright'] = $ac3_header['bsi']{$offset++} == '1';
225
226 $info_ac3_raw_bsi['original'] = $ac3_header['bsi']{$offset++} == '1';
227
228 $info_ac3_raw_bsi['timecode1_flag'] = $ac3_header['bsi']{$offset++} == '1';
229 if ($info_ac3_raw_bsi['timecode1_flag']) {
230 $info_ac3_raw_bsi['timecode1'] = bindec(substr($ac3_header['bsi'], $offset, 14));
231 $offset += 14;
232 }
233
234 $info_ac3_raw_bsi['timecode2_flag'] = $ac3_header['bsi']{$offset++} == '1';
235 if ($info_ac3_raw_bsi['timecode2_flag']) {
236 $info_ac3_raw_bsi['timecode2'] = bindec(substr($ac3_header['bsi'], $offset, 14));
237 $offset += 14;
238 }
239
240 $info_ac3_raw_bsi['addbsi_flag'] = $ac3_header['bsi']{$offset++} == '1';
241 if ($info_ac3_raw_bsi['addbsi_flag']) {
242 $info_ac3_raw_bsi['addbsi_length'] = bindec(substr($ac3_header['bsi'], $offset, 6));
243 $offset += 6;
244
245 $ac3_header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($info_ac3_raw_bsi['addbsi_length']));
246
247 $info_ac3_raw_bsi['addbsi_data'] = substr($ac3_header['bsi'], 119, $info_ac3_raw_bsi['addbsi_length'] * 8);
248 }
249
250 return true;
251 }
252
253
254
255 public static function AC3sampleRateCodeLookup($fscod) {
256
257 static $lookup = array (
258 0 => 48000,
259 1 => 44100,
260 2 => 32000,
261 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
262 );
263 return (isset($lookup[$fscod]) ? $lookup[$fscod] : false);
264 }
265
266
267
268 public static function AC3serviceTypeLookup($bsmod, $acmod) {
269
270 static $lookup = array (
271 0 => 'main audio service: complete main (CM)',
272 1 => 'main audio service: music and effects (ME)',
273 2 => 'associated service: visually impaired (VI)',
274 3 => 'associated service: hearing impaired (HI)',
275 4 => 'associated service: dialogue (D)',
276 5 => 'associated service: commentary (C)',
277 6 => 'associated service: emergency (E)',
278 7 => 'main audio service: karaoke'
279 );
280
281 if ($bsmod == 7 && $acmod == 1) {
282 return 'associated service: voice over (VO)';
283 }
284
285 return (isset($lookup[$bsmod]) ? $lookup[$bsmod] : false);
286 }
287
288
289
290 public static function AC3audioCodingModeLookup($acmod) {
291
292 // array (channel configuration, # channels (not incl LFE), channel order)
293 static $lookup = array (
294 0 => array ('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'),
295 1 => array ('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'),
296 2 => array ('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'),
297 3 => array ('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'),
298 4 => array ('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'),
299 5 => array ('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'),
300 6 => array ('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'),
301 7 => array ('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR')
302 );
303 return (isset($lookup[$acmod]) ? $lookup[$acmod] : false);
304 }
305
306
307
308 public static function AC3centerMixLevelLookup($cmixlev) {
309
310 static $lookup;
311 if (!@$lookup) {
312 $lookup = array (
313 0 => pow(2, -3.0 / 6), // 0.707 (–3.0 dB)
314 1 => pow(2, -4.5 / 6), // 0.595 (–4.5 dB)
315 2 => pow(2, -6.0 / 6), // 0.500 (–6.0 dB)
316 3 => 'reserved'
317 );
318 }
319 return (isset($lookup[$cmixlev]) ? $lookup[$cmixlev] : false);
320 }
321
322
323
324 public static function AC3surroundMixLevelLookup($surmixlev) {
325
326 static $lookup;
327 if (!@$lookup) {
328 $lookup = array (
329 0 => pow(2, -3.0 / 6),
330 1 => pow(2, -6.0 / 6),
331 2 => 0,
332 3 => 'reserved'
333 );
334 }
335 return (isset($lookup[$surmixlev]) ? $lookup[$surmixlev] : false);
336 }
337
338
339
340 public static function AC3dolbySurroundModeLookup($dsurmod) {
341
342 static $lookup = array (
343 0 => 'not indicated',
344 1 => 'Not Dolby Surround encoded',
345 2 => 'Dolby Surround encoded',
346 3 => 'reserved'
347 );
348 return (isset($lookup[$dsurmod]) ? $lookup[$dsurmod] : false);
349 }
350
351
352
353 public static function AC3channelsEnabledLookup($acmod, $lfeon) {
354
355 return array (
356 'ch1' => $acmod == 0,
357 'ch2' => $acmod == 0,
358 'left' => $acmod > 1,
359 'right' => $acmod > 1,
360 'center' => (bool)($acmod & 0x01),
361 'surround_mono' => $acmod == 4 || $acmod == 5,
362 'surround_left' => $acmod == 6 || $acmod == 7,
363 'surround_right' => $acmod == 6 || $acmod == 7,
364 'lfe' => $lfeon
365 );
366 }
367
368
369
370 public static function AC3heavyCompression($compre) {
371
372 // The first four bits indicate gain changes in 6.02dB increments which can be
373 // implemented with an arithmetic shift operation. The following four bits
374 // indicate linear gain changes, and require a 5-bit multiply.
375 // We will represent the two 4-bit fields of compr as follows:
376 // X0 X1 X2 X3 . Y4 Y5 Y6 Y7
377 // The meaning of the X values is most simply described by considering X to represent a 4-bit
378 // signed integer with values from –8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The
379 // following table shows this in detail.
380
381 // Meaning of 4 msb of compr
382 // 7 +48.16 dB
383 // 6 +42.14 dB
384 // 5 +36.12 dB
385 // 4 +30.10 dB
386 // 3 +24.08 dB
387 // 2 +18.06 dB
388 // 1 +12.04 dB
389 // 0 +6.02 dB
390 // -1 0 dB
391 // -2 –6.02 dB
392 // -3 –12.04 dB
393 // -4 –18.06 dB
394 // -5 –24.08 dB
395 // -6 –30.10 dB
396 // -7 –36.12 dB
397 // -8 –42.14 dB
398
399 $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT);
400 if ($fourbit{0} == '1') {
401 $log_gain = -8 + bindec(substr($fourbit, 1));
402 } else {
403 $log_gain = bindec(substr($fourbit, 1));
404 }
405 $log_gain = ($log_gain + 1) * (20 * log10(2));
406
407 // The value of Y is a linear representation of a gain change of up to –6 dB. Y is considered to
408 // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can
409 // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain
410 // changes from –0.28 dB to –6.02 dB.
411
412 $lin_gain = (16 + ($compre & 0x0F)) / 32;
413
414 // The combination of X and Y values allows compr to indicate gain changes from
415 // 48.16 – 0.28 = +47.89 dB, to
416 // –42.14 – 6.02 = –48.16 dB.
417
418 return $log_gain - $lin_gain;
419 }
420
421
422
423 public static function AC3roomTypeLookup($roomtyp) {
424
425 static $lookup = array (
426 0 => 'not indicated',
427 1 => 'large room, X curve monitor',
428 2 => 'small room, flat monitor',
429 3 => 'reserved'
430 );
431 return (isset($lookup[$roomtyp]) ? $lookup[$roomtyp] : false);
432 }
433
434
435
436 public static function AC3frameSizeLookup($frmsizecod, $fscod) {
437
438 $padding = (bool)($frmsizecod % 2);
439 $frame_size_id = floor($frmsizecod / 2);
440
441 static $lookup = array (
442 0 => array (128, 138, 192),
443 1 => array (40, 160, 174, 240),
444 2 => array (48, 192, 208, 288),
445 3 => array (56, 224, 242, 336),
446 4 => array (64, 256, 278, 384),
447 5 => array (80, 320, 348, 480),
448 6 => array (96, 384, 416, 576),
449 7 => array (112, 448, 486, 672),
450 8 => array (128, 512, 556, 768),
451 9 => array (160, 640, 696, 960),
452 10 => array (192, 768, 834, 1152),
453 11 => array (224, 896, 974, 1344),
454 12 => array (256, 1024, 1114, 1536),
455 13 => array (320, 1280, 1392, 1920),
456 14 => array (384, 1536, 1670, 2304),
457 15 => array (448, 1792, 1950, 2688),
458 16 => array (512, 2048, 2228, 3072),
459 17 => array (576, 2304, 2506, 3456),
460 18 => array (640, 2560, 2786, 3840)
461 );
462 if (($fscod == 1) && $padding) {
463 // frame lengths are padded by 1 word (16 bits) at 44100
464 $lookup[$frmsizecod] += 2;
465 }
466 return (isset($lookup[$frame_size_id][$fscod]) ? $lookup[$frame_size_id][$fscod] : false);
467 }
468
469
470
471 public static function AC3bitrateLookup($frmsizecod) {
472
473 static $lookup = array (
474 0 => 32000,
475 1 => 40000,
476 2 => 48000,
477 3 => 56000,
478 4 => 64000,
479 5 => 80000,
480 6 => 96000,
481 7 => 112000,
482 8 => 128000,
483 9 => 160000,
484 10 => 192000,
485 11 => 224000,
486 12 => 256000,
487 13 => 320000,
488 14 => 384000,
489 15 => 448000,
490 16 => 512000,
491 17 => 576000,
492 18 => 640000
493 );
494 $frame_size_id = floor($frmsizecod / 2);
495 return (isset($lookup[$frame_size_id]) ? $lookup[$frame_size_id] : false);
496 }
497
498 }
499
500 ?>