1<?php
2
3/////////////////////////////////////////////////////////////////
4/// getID3() by James Heinrich <info@getid3.org> //
5// available at https://github.com/JamesHeinrich/getID3 //
6// or https://www.getid3.org //
7// or http://getid3.sourceforge.net //
8// see readme.txt for more details //
9/////////////////////////////////////////////////////////////////
10// //
11// module.audio.ac3.php //
12// module for analyzing AC-3 (aka Dolby Digital) audio files //
13// dependencies: NONE //
14// ///
15/////////////////////////////////////////////////////////////////
16
17if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers
18 exit;
19}
20
21class getid3_ac3 extends getid3_handler
22{
23 /**
24 * @var array
25 */
26 private $AC3header = array();
27
28 /**
29 * @var int
30 */
31 private $BSIoffset = 0;
32
33 const syncword = 0x0B77;
34
35 /**
36 * @return bool
37 */
38 public function Analyze() {
39 $info = &$this->getid3->info;
40
41 ///AH
42 $info['ac3']['raw']['bsi'] = array();
43 $thisfile_ac3 = &$info['ac3'];
44 $thisfile_ac3_raw = &$thisfile_ac3['raw'];
45 $thisfile_ac3_raw_bsi = &$thisfile_ac3_raw['bsi'];
46
47
48 // http://www.atsc.org/standards/a_52a.pdf
49
50 $info['fileformat'] = 'ac3';
51
52 // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames
53 // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256
54 // new audio samples per channel. A synchronization information (SI) header at the beginning
55 // of each frame contains information needed to acquire and maintain synchronization. A
56 // bit stream information (BSI) header follows SI, and contains parameters describing the coded
57 // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the
58 // end of each frame is an error check field that includes a CRC word for error detection. An
59 // additional CRC word is located in the SI header, the use of which, by a decoder, is optional.
60 //
61 // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC
62
63 // syncinfo() {
64 // syncword 16
65 // crc1 16
66 // fscod 2
67 // frmsizecod 6
68 // } /* end of syncinfo */
69
70 $this->fseek($info['avdataoffset']);
71 $tempAC3header = $this->fread(100); // should be enough to cover all data, there are some variable-length fields...?
72 $this->AC3header['syncinfo'] = getid3_lib::BigEndian2Int(substr($tempAC3header, 0, 2));
73 $this->AC3header['bsi'] = getid3_lib::BigEndian2Bin(substr($tempAC3header, 2));
74 $thisfile_ac3_raw_bsi['bsid'] = (getid3_lib::LittleEndian2Int(substr($tempAC3header, 5, 1)) & 0xF8) >> 3; // AC3 and E-AC3 put the "bsid" version identifier in the same place, but unfortnately the 4 bytes between the syncword and the version identifier are interpreted differently, so grab it here so the following code structure can make sense
75 unset($tempAC3header);
76
77 if ($this->AC3header['syncinfo'] !== self::syncword) {
78 if (!$this->isDependencyFor('matroska')) {
79 unset($info['fileformat'], $info['ac3']);
80 return $this->error('Expecting "'.dechex(self::syncword).'" at offset '.$info['avdataoffset'].', found "'.dechex($this->AC3header['syncinfo']).'"');
81 }
82 }
83
84 $info['audio']['dataformat'] = 'ac3';
85 $info['audio']['bitrate_mode'] = 'cbr';
86 $info['audio']['lossless'] = false;
87
88 if ($thisfile_ac3_raw_bsi['bsid'] <= 8) {
89
90 $thisfile_ac3_raw_bsi['crc1'] = getid3_lib::Bin2Dec($this->readHeaderBSI(16));
91 $thisfile_ac3_raw_bsi['fscod'] = $this->readHeaderBSI(2); // 5.4.1.3
92 $thisfile_ac3_raw_bsi['frmsizecod'] = $this->readHeaderBSI(6); // 5.4.1.4
93 if ($thisfile_ac3_raw_bsi['frmsizecod'] > 37) { // binary: 100101 - see Table 5.18 Frame Size Code Table (1 word = 16 bits)
94 $this->warning('Unexpected ac3.bsi.frmsizecod value: '.$thisfile_ac3_raw_bsi['frmsizecod'].', bitrate not set correctly');
95 }
96
97 $thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5); // we already know this from pre-parsing the version identifier, but re-read it to let the bitstream flow as intended
98 $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3);
99 $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3);
100
101 if ($thisfile_ac3_raw_bsi['acmod'] & 0x01) {
102 // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream.
103 $thisfile_ac3_raw_bsi['cmixlev'] = $this->readHeaderBSI(2);
104 $thisfile_ac3['center_mix_level'] = self::centerMixLevelLookup($thisfile_ac3_raw_bsi['cmixlev']);
105 }
106
107 if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) {
108 // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream.
109 $thisfile_ac3_raw_bsi['surmixlev'] = $this->readHeaderBSI(2);
110 $thisfile_ac3['surround_mix_level'] = self::surroundMixLevelLookup($thisfile_ac3_raw_bsi['surmixlev']);
111 }
112
113 if ($thisfile_ac3_raw_bsi['acmod'] == 0x02) {
114 // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround.
115 $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2);
116 $thisfile_ac3['dolby_surround_mode'] = self::dolbySurroundModeLookup($thisfile_ac3_raw_bsi['dsurmod']);
117 }
118
119 $thisfile_ac3_raw_bsi['flags']['lfeon'] = (bool) $this->readHeaderBSI(1);
120
121 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31.
122 // 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.
123 $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5); // 5.4.2.8 dialnorm: Dialogue Normalization, 5 Bits
124
125 $thisfile_ac3_raw_bsi['flags']['compr'] = (bool) $this->readHeaderBSI(1); // 5.4.2.9 compre: Compression Gain Word Exists, 1 Bit
126 if ($thisfile_ac3_raw_bsi['flags']['compr']) {
127 $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8); // 5.4.2.10 compr: Compression Gain Word, 8 Bits
128 $thisfile_ac3['heavy_compression'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr']);
129 }
130
131 $thisfile_ac3_raw_bsi['flags']['langcod'] = (bool) $this->readHeaderBSI(1); // 5.4.2.11 langcode: Language Code Exists, 1 Bit
132 if ($thisfile_ac3_raw_bsi['flags']['langcod']) {
133 $thisfile_ac3_raw_bsi['langcod'] = $this->readHeaderBSI(8); // 5.4.2.12 langcod: Language Code, 8 Bits
134 }
135
136 $thisfile_ac3_raw_bsi['flags']['audprodinfo'] = (bool) $this->readHeaderBSI(1); // 5.4.2.13 audprodie: Audio Production Information Exists, 1 Bit
137 if ($thisfile_ac3_raw_bsi['flags']['audprodinfo']) {
138 $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5); // 5.4.2.14 mixlevel: Mixing Level, 5 Bits
139 $thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2); // 5.4.2.15 roomtyp: Room Type, 2 Bits
140
141 $thisfile_ac3['mixing_level'] = (80 + $thisfile_ac3_raw_bsi['mixlevel']).'dB';
142 $thisfile_ac3['room_type'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp']);
143 }
144
145
146 $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5); // 5.4.2.16 dialnorm2: Dialogue Normalization, ch2, 5 Bits
147 $thisfile_ac3['dialogue_normalization2'] = '-'.$thisfile_ac3_raw_bsi['dialnorm2'].'dB'; // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31. 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.
148
149 $thisfile_ac3_raw_bsi['flags']['compr2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.17 compr2e: Compression Gain Word Exists, ch2, 1 Bit
150 if ($thisfile_ac3_raw_bsi['flags']['compr2']) {
151 $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8); // 5.4.2.18 compr2: Compression Gain Word, ch2, 8 Bits
152 $thisfile_ac3['heavy_compression2'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr2']);
153 }
154
155 $thisfile_ac3_raw_bsi['flags']['langcod2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.19 langcod2e: Language Code Exists, ch2, 1 Bit
156 if ($thisfile_ac3_raw_bsi['flags']['langcod2']) {
157 $thisfile_ac3_raw_bsi['langcod2'] = $this->readHeaderBSI(8); // 5.4.2.20 langcod2: Language Code, ch2, 8 Bits
158 }
159
160 $thisfile_ac3_raw_bsi['flags']['audprodinfo2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.21 audprodi2e: Audio Production Information Exists, ch2, 1 Bit
161 if ($thisfile_ac3_raw_bsi['flags']['audprodinfo2']) {
162 $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5); // 5.4.2.22 mixlevel2: Mixing Level, ch2, 5 Bits
163 $thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2); // 5.4.2.23 roomtyp2: Room Type, ch2, 2 Bits
164
165 $thisfile_ac3['mixing_level2'] = (80 + $thisfile_ac3_raw_bsi['mixlevel2']).'dB';
166 $thisfile_ac3['room_type2'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp2']);
167 }
168
169 $thisfile_ac3_raw_bsi['copyright'] = (bool) $this->readHeaderBSI(1); // 5.4.2.24 copyrightb: Copyright Bit, 1 Bit
170
171 $thisfile_ac3_raw_bsi['original'] = (bool) $this->readHeaderBSI(1); // 5.4.2.25 origbs: Original Bit Stream, 1 Bit
172
173 $thisfile_ac3_raw_bsi['flags']['timecod1'] = $this->readHeaderBSI(2); // 5.4.2.26 timecod1e, timcode2e: Time Code (first and second) Halves Exist, 2 Bits
174 if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x01) {
175 $thisfile_ac3_raw_bsi['timecod1'] = $this->readHeaderBSI(14); // 5.4.2.27 timecod1: Time code first half, 14 bits
176 $thisfile_ac3['timecode1'] = 0;
177 $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x3E00) >> 9) * 3600; // The first 5 bits of this 14-bit field represent the time in hours, with valid values of 0�23
178 $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x01F8) >> 3) * 60; // The next 6 bits represent the time in minutes, with valid values of 0�59
179 $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x0003) >> 0) * 8; // The final 3 bits represents the time in 8 second increments, with valid values of 0�7 (representing 0, 8, 16, ... 56 seconds)
180 }
181 if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x02) {
182 $thisfile_ac3_raw_bsi['timecod2'] = $this->readHeaderBSI(14); // 5.4.2.28 timecod2: Time code second half, 14 bits
183 $thisfile_ac3['timecode2'] = 0;
184 $thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x3800) >> 11) * 1; // The first 3 bits of this 14-bit field represent the time in seconds, with valid values from 0�7 (representing 0-7 seconds)
185 $thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x07C0) >> 6) * (1 / 30); // The next 5 bits represents the time in frames, with valid values from 0�29 (one frame = 1/30th of a second)
186 $thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x003F) >> 0) * ((1 / 30) / 60); // The final 6 bits represents fractions of 1/64 of a frame, with valid values from 0�63
187 }
188
189 $thisfile_ac3_raw_bsi['flags']['addbsi'] = (bool) $this->readHeaderBSI(1);
190 if ($thisfile_ac3_raw_bsi['flags']['addbsi']) {
191 $thisfile_ac3_raw_bsi['addbsi_length'] = $this->readHeaderBSI(6) + 1; // This 6-bit code, which exists only if addbside is a 1, indicates the length in bytes of additional bit stream information. The valid range of addbsil is 0�63, indicating 1�64 additional bytes, respectively.
192
193 $this->AC3header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($thisfile_ac3_raw_bsi['addbsi_length']));
194
195 $thisfile_ac3_raw_bsi['addbsi_data'] = substr($this->AC3header['bsi'], $this->BSIoffset, $thisfile_ac3_raw_bsi['addbsi_length'] * 8);
196 $this->BSIoffset += $thisfile_ac3_raw_bsi['addbsi_length'] * 8;
197 }
198
199
200 } elseif ($thisfile_ac3_raw_bsi['bsid'] <= 16) { // E-AC3
201
202
203 $this->error('E-AC3 parsing is incomplete and experimental in this version of getID3 ('.$this->getid3->version().'). Notably the bitrate calculations are wrong -- value might (or not) be correct, but it is not calculated correctly. Email info@getid3.org if you know how to calculate EAC3 bitrate correctly.');
204 $info['audio']['dataformat'] = 'eac3';
205
206 $thisfile_ac3_raw_bsi['strmtyp'] = $this->readHeaderBSI(2);
207 $thisfile_ac3_raw_bsi['substreamid'] = $this->readHeaderBSI(3);
208 $thisfile_ac3_raw_bsi['frmsiz'] = $this->readHeaderBSI(11);
209 $thisfile_ac3_raw_bsi['fscod'] = $this->readHeaderBSI(2);
210 if ($thisfile_ac3_raw_bsi['fscod'] == 3) {
211 $thisfile_ac3_raw_bsi['fscod2'] = $this->readHeaderBSI(2);
212 $thisfile_ac3_raw_bsi['numblkscod'] = 3; // six blocks per syncframe
213 } else {
214 $thisfile_ac3_raw_bsi['numblkscod'] = $this->readHeaderBSI(2);
215 }
216 $thisfile_ac3['bsi']['blocks_per_sync_frame'] = self::blocksPerSyncFrame($thisfile_ac3_raw_bsi['numblkscod']);
217 $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3);
218 $thisfile_ac3_raw_bsi['flags']['lfeon'] = (bool) $this->readHeaderBSI(1);
219 $thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5); // we already know this from pre-parsing the version identifier, but re-read it to let the bitstream flow as intended
220 $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5);
221 $thisfile_ac3_raw_bsi['flags']['compr'] = (bool) $this->readHeaderBSI(1);
222 if ($thisfile_ac3_raw_bsi['flags']['compr']) {
223 $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8);
224 }
225 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
226 $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5);
227 $thisfile_ac3_raw_bsi['flags']['compr2'] = (bool) $this->readHeaderBSI(1);
228 if ($thisfile_ac3_raw_bsi['flags']['compr2']) {
229 $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8);
230 }
231 }
232 if ($thisfile_ac3_raw_bsi['strmtyp'] == 1) { // if dependent stream
233 $thisfile_ac3_raw_bsi['flags']['chanmap'] = (bool) $this->readHeaderBSI(1);
234 if ($thisfile_ac3_raw_bsi['flags']['chanmap']) {
235 $thisfile_ac3_raw_bsi['chanmap'] = $this->readHeaderBSI(8);
236 }
237 }
238 $thisfile_ac3_raw_bsi['flags']['mixmdat'] = (bool) $this->readHeaderBSI(1);
239 if ($thisfile_ac3_raw_bsi['flags']['mixmdat']) { // Mixing metadata
240 if ($thisfile_ac3_raw_bsi['acmod'] > 2) { // if more than 2 channels
241 $thisfile_ac3_raw_bsi['dmixmod'] = $this->readHeaderBSI(2);
242 }
243 if (($thisfile_ac3_raw_bsi['acmod'] & 0x01) && ($thisfile_ac3_raw_bsi['acmod'] > 2)) { // if three front channels exist
244 $thisfile_ac3_raw_bsi['ltrtcmixlev'] = $this->readHeaderBSI(3);
245 $thisfile_ac3_raw_bsi['lorocmixlev'] = $this->readHeaderBSI(3);
246 }
247 if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) { // if a surround channel exists
248 $thisfile_ac3_raw_bsi['ltrtsurmixlev'] = $this->readHeaderBSI(3);
249 $thisfile_ac3_raw_bsi['lorosurmixlev'] = $this->readHeaderBSI(3);
250 }
251 if ($thisfile_ac3_raw_bsi['flags']['lfeon']) { // if the LFE channel exists
252 $thisfile_ac3_raw_bsi['flags']['lfemixlevcod'] = (bool) $this->readHeaderBSI(1);
253 if ($thisfile_ac3_raw_bsi['flags']['lfemixlevcod']) {
254 $thisfile_ac3_raw_bsi['lfemixlevcod'] = $this->readHeaderBSI(5);
255 }
256 }
257 if ($thisfile_ac3_raw_bsi['strmtyp'] == 0) { // if independent stream
258 $thisfile_ac3_raw_bsi['flags']['pgmscl'] = (bool) $this->readHeaderBSI(1);
259 if ($thisfile_ac3_raw_bsi['flags']['pgmscl']) {
260 $thisfile_ac3_raw_bsi['pgmscl'] = $this->readHeaderBSI(6);
261 }
262 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
263 $thisfile_ac3_raw_bsi['flags']['pgmscl2'] = (bool) $this->readHeaderBSI(1);
264 if ($thisfile_ac3_raw_bsi['flags']['pgmscl2']) {
265 $thisfile_ac3_raw_bsi['pgmscl2'] = $this->readHeaderBSI(6);
266 }
267 }
268 $thisfile_ac3_raw_bsi['flags']['extpgmscl'] = (bool) $this->readHeaderBSI(1);
269 if ($thisfile_ac3_raw_bsi['flags']['extpgmscl']) {
270 $thisfile_ac3_raw_bsi['extpgmscl'] = $this->readHeaderBSI(6);
271 }
272 $thisfile_ac3_raw_bsi['mixdef'] = $this->readHeaderBSI(2);
273 if ($thisfile_ac3_raw_bsi['mixdef'] == 1) { // mixing option 2
274 $thisfile_ac3_raw_bsi['premixcmpsel'] = (bool) $this->readHeaderBSI(1);
275 $thisfile_ac3_raw_bsi['drcsrc'] = (bool) $this->readHeaderBSI(1);
276 $thisfile_ac3_raw_bsi['premixcmpscl'] = $this->readHeaderBSI(3);
277 } elseif ($thisfile_ac3_raw_bsi['mixdef'] == 2) { // mixing option 3
278 $thisfile_ac3_raw_bsi['mixdata'] = $this->readHeaderBSI(12);
279 } elseif ($thisfile_ac3_raw_bsi['mixdef'] == 3) { // mixing option 4
280 $mixdefbitsread = 0;
281 $thisfile_ac3_raw_bsi['mixdeflen'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
282 $thisfile_ac3_raw_bsi['flags']['mixdata2'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
283 if ($thisfile_ac3_raw_bsi['flags']['mixdata2']) {
284 $thisfile_ac3_raw_bsi['premixcmpsel'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
285 $thisfile_ac3_raw_bsi['drcsrc'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
286 $thisfile_ac3_raw_bsi['premixcmpscl'] = $this->readHeaderBSI(3); $mixdefbitsread += 3;
287 $thisfile_ac3_raw_bsi['flags']['extpgmlscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
288 if ($thisfile_ac3_raw_bsi['flags']['extpgmlscl']) {
289 $thisfile_ac3_raw_bsi['extpgmlscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
290 }
291 $thisfile_ac3_raw_bsi['flags']['extpgmcscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
292 if ($thisfile_ac3_raw_bsi['flags']['extpgmcscl']) {
293 $thisfile_ac3_raw_bsi['extpgmcscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
294 }
295 $thisfile_ac3_raw_bsi['flags']['extpgmrscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
296 if ($thisfile_ac3_raw_bsi['flags']['extpgmrscl']) {
297 $thisfile_ac3_raw_bsi['extpgmrscl'] = $this->readHeaderBSI(4);
298 }
299 $thisfile_ac3_raw_bsi['flags']['extpgmlsscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
300 if ($thisfile_ac3_raw_bsi['flags']['extpgmlsscl']) {
301 $thisfile_ac3_raw_bsi['extpgmlsscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
302 }
303 $thisfile_ac3_raw_bsi['flags']['extpgmrsscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
304 if ($thisfile_ac3_raw_bsi['flags']['extpgmrsscl']) {
305 $thisfile_ac3_raw_bsi['extpgmrsscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
306 }
307 $thisfile_ac3_raw_bsi['flags']['extpgmlfescl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
308 if ($thisfile_ac3_raw_bsi['flags']['extpgmlfescl']) {
309 $thisfile_ac3_raw_bsi['extpgmlfescl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
310 }
311 $thisfile_ac3_raw_bsi['flags']['dmixscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
312 if ($thisfile_ac3_raw_bsi['flags']['dmixscl']) {
313 $thisfile_ac3_raw_bsi['dmixscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
314 }
315 $thisfile_ac3_raw_bsi['flags']['addch'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
316 if ($thisfile_ac3_raw_bsi['flags']['addch']) {
317 $thisfile_ac3_raw_bsi['flags']['extpgmaux1scl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
318 if ($thisfile_ac3_raw_bsi['flags']['extpgmaux1scl']) {
319 $thisfile_ac3_raw_bsi['extpgmaux1scl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
320 }
321 $thisfile_ac3_raw_bsi['flags']['extpgmaux2scl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
322 if ($thisfile_ac3_raw_bsi['flags']['extpgmaux2scl']) {
323 $thisfile_ac3_raw_bsi['extpgmaux2scl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
324 }
325 }
326 }
327 $thisfile_ac3_raw_bsi['flags']['mixdata3'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
328 if ($thisfile_ac3_raw_bsi['flags']['mixdata3']) {
329 $thisfile_ac3_raw_bsi['spchdat'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
330 $thisfile_ac3_raw_bsi['flags']['addspchdat'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
331 if ($thisfile_ac3_raw_bsi['flags']['addspchdat']) {
332 $thisfile_ac3_raw_bsi['spchdat1'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
333 $thisfile_ac3_raw_bsi['spchan1att'] = $this->readHeaderBSI(2); $mixdefbitsread += 2;
334 $thisfile_ac3_raw_bsi['flags']['addspchdat1'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
335 if ($thisfile_ac3_raw_bsi['flags']['addspchdat1']) {
336 $thisfile_ac3_raw_bsi['spchdat2'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
337 $thisfile_ac3_raw_bsi['spchan2att'] = $this->readHeaderBSI(3); $mixdefbitsread += 3;
338 }
339 }
340 }
341 $mixdata_bits = (8 * ($thisfile_ac3_raw_bsi['mixdeflen'] + 2)) - $mixdefbitsread;
342 $mixdata_fill = (($mixdata_bits % 8) ? 8 - ($mixdata_bits % 8) : 0);
343 $thisfile_ac3_raw_bsi['mixdata'] = $this->readHeaderBSI($mixdata_bits);
344 $thisfile_ac3_raw_bsi['mixdatafill'] = $this->readHeaderBSI($mixdata_fill);
345 unset($mixdefbitsread, $mixdata_bits, $mixdata_fill);
346 }
347 if ($thisfile_ac3_raw_bsi['acmod'] < 2) { // if mono or dual mono source
348 $thisfile_ac3_raw_bsi['flags']['paninfo'] = (bool) $this->readHeaderBSI(1);
349 if ($thisfile_ac3_raw_bsi['flags']['paninfo']) {
350 $thisfile_ac3_raw_bsi['panmean'] = $this->readHeaderBSI(8);
351 $thisfile_ac3_raw_bsi['paninfo'] = $this->readHeaderBSI(6);
352 }
353 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
354 $thisfile_ac3_raw_bsi['flags']['paninfo2'] = (bool) $this->readHeaderBSI(1);
355 if ($thisfile_ac3_raw_bsi['flags']['paninfo2']) {
356 $thisfile_ac3_raw_bsi['panmean2'] = $this->readHeaderBSI(8);
357 $thisfile_ac3_raw_bsi['paninfo2'] = $this->readHeaderBSI(6);
358 }
359 }
360 }
361 $thisfile_ac3_raw_bsi['flags']['frmmixcfginfo'] = (bool) $this->readHeaderBSI(1);
362 if ($thisfile_ac3_raw_bsi['flags']['frmmixcfginfo']) { // mixing configuration information
363 if ($thisfile_ac3_raw_bsi['numblkscod'] == 0) {
364 $thisfile_ac3_raw_bsi['blkmixcfginfo'][0] = $this->readHeaderBSI(5);
365 } else {
366 for ($blk = 0; $blk < $thisfile_ac3_raw_bsi['numblkscod']; $blk++) {
367 $thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk] = (bool) $this->readHeaderBSI(1);
368 if ($thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk]) { // mixing configuration information
369 $thisfile_ac3_raw_bsi['blkmixcfginfo'][$blk] = $this->readHeaderBSI(5);
370 }
371 }
372 }
373 }
374 }
375 }
376 $thisfile_ac3_raw_bsi['flags']['infomdat'] = (bool) $this->readHeaderBSI(1);
377 if ($thisfile_ac3_raw_bsi['flags']['infomdat']) { // Informational metadata
378 $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3);
379 $thisfile_ac3_raw_bsi['flags']['copyrightb'] = (bool) $this->readHeaderBSI(1);
380 $thisfile_ac3_raw_bsi['flags']['origbs'] = (bool) $this->readHeaderBSI(1);
381 if ($thisfile_ac3_raw_bsi['acmod'] == 2) { // if in 2/0 mode
382 $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2);
383 $thisfile_ac3_raw_bsi['dheadphonmod'] = $this->readHeaderBSI(2);
384 }
385 if ($thisfile_ac3_raw_bsi['acmod'] >= 6) { // if both surround channels exist
386 $thisfile_ac3_raw_bsi['dsurexmod'] = $this->readHeaderBSI(2);
387 }
388 $thisfile_ac3_raw_bsi['flags']['audprodi'] = (bool) $this->readHeaderBSI(1);
389 if ($thisfile_ac3_raw_bsi['flags']['audprodi']) {
390 $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5);
391 $thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2);
392 $thisfile_ac3_raw_bsi['flags']['adconvtyp'] = (bool) $this->readHeaderBSI(1);
393 }
394 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
395 $thisfile_ac3_raw_bsi['flags']['audprodi2'] = (bool) $this->readHeaderBSI(1);
396 if ($thisfile_ac3_raw_bsi['flags']['audprodi2']) {
397 $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5);
398 $thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2);
399 $thisfile_ac3_raw_bsi['flags']['adconvtyp2'] = (bool) $this->readHeaderBSI(1);
400 }
401 }
402 if ($thisfile_ac3_raw_bsi['fscod'] < 3) { // if not half sample rate
403 $thisfile_ac3_raw_bsi['flags']['sourcefscod'] = (bool) $this->readHeaderBSI(1);
404 }
405 }
406 if (($thisfile_ac3_raw_bsi['strmtyp'] == 0) && ($thisfile_ac3_raw_bsi['numblkscod'] != 3)) { // if both surround channels exist
407 $thisfile_ac3_raw_bsi['flags']['convsync'] = (bool) $this->readHeaderBSI(1);
408 }
409 if ($thisfile_ac3_raw_bsi['strmtyp'] == 2) { // if bit stream converted from AC-3
410 if ($thisfile_ac3_raw_bsi['numblkscod'] != 3) { // 6 blocks per syncframe
411 $thisfile_ac3_raw_bsi['flags']['blkid'] = 1;
412 } else {
413 $thisfile_ac3_raw_bsi['flags']['blkid'] = (bool) $this->readHeaderBSI(1);
414 }
415 if ($thisfile_ac3_raw_bsi['flags']['blkid']) {
416 $thisfile_ac3_raw_bsi['frmsizecod'] = $this->readHeaderBSI(6);
417 }
418 }
419 $thisfile_ac3_raw_bsi['flags']['addbsi'] = (bool) $this->readHeaderBSI(1);
420 if ($thisfile_ac3_raw_bsi['flags']['addbsi']) {
421 $thisfile_ac3_raw_bsi['addbsil'] = $this->readHeaderBSI(6);
422 $thisfile_ac3_raw_bsi['addbsi'] = $this->readHeaderBSI(($thisfile_ac3_raw_bsi['addbsil'] + 1) * 8);
423 }
424
425 } else {
426
427 $this->error('Bit stream identification is version '.$thisfile_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 16. Please submit a support ticket with a sample file.');
428 unset($info['ac3']);
429 return false;
430
431 }
432
433 if (isset($thisfile_ac3_raw_bsi['fscod2'])) {
434 $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup2($thisfile_ac3_raw_bsi['fscod2']);
435 } else {
436 $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup($thisfile_ac3_raw_bsi['fscod']);
437 }
438 if ($thisfile_ac3_raw_bsi['fscod'] <= 3) {
439 $info['audio']['sample_rate'] = $thisfile_ac3['sample_rate'];
440 } else {
441 $this->warning('Unexpected ac3.bsi.fscod value: '.$thisfile_ac3_raw_bsi['fscod']);
442 }
443 if (isset($thisfile_ac3_raw_bsi['frmsizecod'])) {
444 $thisfile_ac3['frame_length'] = self::frameSizeLookup($thisfile_ac3_raw_bsi['frmsizecod'], $thisfile_ac3_raw_bsi['fscod']);
445 $thisfile_ac3['bitrate'] = self::bitrateLookup($thisfile_ac3_raw_bsi['frmsizecod']);
446 } elseif (!empty($thisfile_ac3_raw_bsi['frmsiz'])) {
447 // this isn't right, but it's (usually) close, roughly 5% less than it should be.
448 // but WHERE is the actual bitrate value stored in EAC3?? email info@getid3.org if you know!
449 $thisfile_ac3['bitrate'] = ($thisfile_ac3_raw_bsi['frmsiz'] + 1) * 16 * 30; // The frmsiz field shall contain a value one less than the overall size of the coded syncframe in 16-bit words. That is, this field may assume a value ranging from 0 to 2047, and these values correspond to syncframe sizes ranging from 1 to 2048.
450 // kludge-fix to make it approximately the expected value, still not "right":
451 $thisfile_ac3['bitrate'] = round(($thisfile_ac3['bitrate'] * 1.05) / 16000) * 16000;
452 }
453 $info['audio']['bitrate'] = $thisfile_ac3['bitrate'];
454
455 if (isset($thisfile_ac3_raw_bsi['bsmod']) && isset($thisfile_ac3_raw_bsi['acmod'])) {
456 $thisfile_ac3['service_type'] = self::serviceTypeLookup($thisfile_ac3_raw_bsi['bsmod'], $thisfile_ac3_raw_bsi['acmod']);
457 }
458 $ac3_coding_mode = self::audioCodingModeLookup($thisfile_ac3_raw_bsi['acmod']);
459 foreach($ac3_coding_mode as $key => $value) {
460 $thisfile_ac3[$key] = $value;
461 }
462 switch ($thisfile_ac3_raw_bsi['acmod']) {
463 case 0:
464 case 1:
465 $info['audio']['channelmode'] = 'mono';
466 break;
467 case 3:
468 case 4:
469 $info['audio']['channelmode'] = 'stereo';
470 break;
471 default:
472 $info['audio']['channelmode'] = 'surround';
473 break;
474 }
475 $info['audio']['channels'] = $thisfile_ac3['num_channels'];
476
477 $thisfile_ac3['lfe_enabled'] = $thisfile_ac3_raw_bsi['flags']['lfeon'];
478 if ($thisfile_ac3_raw_bsi['flags']['lfeon']) {
479 $info['audio']['channels'] .= '.1';
480 }
481
482 $thisfile_ac3['channels_enabled'] = self::channelsEnabledLookup($thisfile_ac3_raw_bsi['acmod'], $thisfile_ac3_raw_bsi['flags']['lfeon']);
483 $thisfile_ac3['dialogue_normalization'] = '-'.$thisfile_ac3_raw_bsi['dialnorm'].'dB';
484
485 return true;
486 }
487
488 /**
489 * @param int $length
490 *
491 * @return int
492 */
493 private function readHeaderBSI($length) {
494 $data = substr($this->AC3header['bsi'], $this->BSIoffset, $length);
495 $this->BSIoffset += $length;
496
497 return bindec($data);
498 }
499
500 /**
501 * @param int $fscod
502 *
503 * @return int|string|false
504 */
505 public static function sampleRateCodeLookup($fscod) {
506 static $sampleRateCodeLookup = array(
507 0 => 48000,
508 1 => 44100,
509 2 => 32000,
510 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
511 );
512 return (isset($sampleRateCodeLookup[$fscod]) ? $sampleRateCodeLookup[$fscod] : false);
513 }
514
515 /**
516 * @param int $fscod2
517 *
518 * @return int|string|false
519 */
520 public static function sampleRateCodeLookup2($fscod2) {
521 static $sampleRateCodeLookup2 = array(
522 0 => 24000,
523 1 => 22050,
524 2 => 16000,
525 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
526 );
527 return (isset($sampleRateCodeLookup2[$fscod2]) ? $sampleRateCodeLookup2[$fscod2] : false);
528 }
529
530 /**
531 * @param int $bsmod
532 * @param int $acmod
533 *
534 * @return string|false
535 */
536 public static function serviceTypeLookup($bsmod, $acmod) {
537 static $serviceTypeLookup = array();
538 if (empty($serviceTypeLookup)) {
539 for ($i = 0; $i <= 7; $i++) {
540 $serviceTypeLookup[0][$i] = 'main audio service: complete main (CM)';
541 $serviceTypeLookup[1][$i] = 'main audio service: music and effects (ME)';
542 $serviceTypeLookup[2][$i] = 'associated service: visually impaired (VI)';
543 $serviceTypeLookup[3][$i] = 'associated service: hearing impaired (HI)';
544 $serviceTypeLookup[4][$i] = 'associated service: dialogue (D)';
545 $serviceTypeLookup[5][$i] = 'associated service: commentary (C)';
546 $serviceTypeLookup[6][$i] = 'associated service: emergency (E)';
547 }
548
549 $serviceTypeLookup[7][1] = 'associated service: voice over (VO)';
550 for ($i = 2; $i <= 7; $i++) {
551 $serviceTypeLookup[7][$i] = 'main audio service: karaoke';
552 }
553 }
554 return (isset($serviceTypeLookup[$bsmod][$acmod]) ? $serviceTypeLookup[$bsmod][$acmod] : false);
555 }
556
557 /**
558 * @param int $acmod
559 *
560 * @return array|false
561 */
562 public static function audioCodingModeLookup($acmod) {
563 // array(channel configuration, # channels (not incl LFE), channel order)
564 static $audioCodingModeLookup = array (
565 0 => array('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'),
566 1 => array('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'),
567 2 => array('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'),
568 3 => array('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'),
569 4 => array('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'),
570 5 => array('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'),
571 6 => array('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'),
572 7 => array('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR'),
573 );
574 return (isset($audioCodingModeLookup[$acmod]) ? $audioCodingModeLookup[$acmod] : false);
575 }
576
577 /**
578 * @param int $cmixlev
579 *
580 * @return int|float|string|false
581 */
582 public static function centerMixLevelLookup($cmixlev) {
583 static $centerMixLevelLookup;
584 if (empty($centerMixLevelLookup)) {
585 $centerMixLevelLookup = array(
586 0 => pow(2, -3.0 / 6), // 0.707 (-3.0 dB)
587 1 => pow(2, -4.5 / 6), // 0.595 (-4.5 dB)
588 2 => pow(2, -6.0 / 6), // 0.500 (-6.0 dB)
589 3 => 'reserved'
590 );
591 }
592 return (isset($centerMixLevelLookup[$cmixlev]) ? $centerMixLevelLookup[$cmixlev] : false);
593 }
594
595 /**
596 * @param int $surmixlev
597 *
598 * @return int|float|string|false
599 */
600 public static function surroundMixLevelLookup($surmixlev) {
601 static $surroundMixLevelLookup;
602 if (empty($surroundMixLevelLookup)) {
603 $surroundMixLevelLookup = array(
604 0 => pow(2, -3.0 / 6),
605 1 => pow(2, -6.0 / 6),
606 2 => 0,
607 3 => 'reserved'
608 );
609 }
610 return (isset($surroundMixLevelLookup[$surmixlev]) ? $surroundMixLevelLookup[$surmixlev] : false);
611 }
612
613 /**
614 * @param int $dsurmod
615 *
616 * @return string|false
617 */
618 public static function dolbySurroundModeLookup($dsurmod) {
619 static $dolbySurroundModeLookup = array(
620 0 => 'not indicated',
621 1 => 'Not Dolby Surround encoded',
622 2 => 'Dolby Surround encoded',
623 3 => 'reserved'
624 );
625 return (isset($dolbySurroundModeLookup[$dsurmod]) ? $dolbySurroundModeLookup[$dsurmod] : false);
626 }
627
628 /**
629 * @param int $acmod
630 * @param bool $lfeon
631 *
632 * @return array
633 */
634 public static function channelsEnabledLookup($acmod, $lfeon) {
635 $lookup = array(
636 'ch1'=>($acmod == 0),
637 'ch2'=>($acmod == 0),
638 'left'=>($acmod > 1),
639 'right'=>($acmod > 1),
640 'center'=>(bool) ($acmod & 0x01),
641 'surround_mono'=>false,
642 'surround_left'=>false,
643 'surround_right'=>false,
644 'lfe'=>$lfeon);
645 switch ($acmod) {
646 case 4:
647 case 5:
648 $lookup['surround_mono'] = true;
649 break;
650 case 6:
651 case 7:
652 $lookup['surround_left'] = true;
653 $lookup['surround_right'] = true;
654 break;
655 }
656 return $lookup;
657 }
658
659 /**
660 * @param int $compre
661 *
662 * @return float|int
663 */
664 public static function heavyCompression($compre) {
665 // The first four bits indicate gain changes in 6.02dB increments which can be
666 // implemented with an arithmetic shift operation. The following four bits
667 // indicate linear gain changes, and require a 5-bit multiply.
668 // We will represent the two 4-bit fields of compr as follows:
669 // X0 X1 X2 X3 . Y4 Y5 Y6 Y7
670 // The meaning of the X values is most simply described by considering X to represent a 4-bit
671 // signed integer with values from -8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The
672 // following table shows this in detail.
673
674 // Meaning of 4 msb of compr
675 // 7 +48.16 dB
676 // 6 +42.14 dB
677 // 5 +36.12 dB
678 // 4 +30.10 dB
679 // 3 +24.08 dB
680 // 2 +18.06 dB
681 // 1 +12.04 dB
682 // 0 +6.02 dB
683 // -1 0 dB
684 // -2 -6.02 dB
685 // -3 -12.04 dB
686 // -4 -18.06 dB
687 // -5 -24.08 dB
688 // -6 -30.10 dB
689 // -7 -36.12 dB
690 // -8 -42.14 dB
691
692 $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT);
693 if ($fourbit[0] == '1') {
694 $log_gain = -8 + bindec(substr($fourbit, 1));
695 } else {
696 $log_gain = bindec(substr($fourbit, 1));
697 }
698 $log_gain = ($log_gain + 1) * getid3_lib::RGADamplitude2dB(2);
699
700 // The value of Y is a linear representation of a gain change of up to -6 dB. Y is considered to
701 // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can
702 // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain
703 // changes from -0.28 dB to -6.02 dB.
704
705 $lin_gain = (16 + ($compre & 0x0F)) / 32;
706
707 // The combination of X and Y values allows compr to indicate gain changes from
708 // 48.16 - 0.28 = +47.89 dB, to
709 // -42.14 - 6.02 = -48.16 dB.
710
711 return $log_gain - $lin_gain;
712 }
713
714 /**
715 * @param int $roomtyp
716 *
717 * @return string|false
718 */
719 public static function roomTypeLookup($roomtyp) {
720 static $roomTypeLookup = array(
721 0 => 'not indicated',
722 1 => 'large room, X curve monitor',
723 2 => 'small room, flat monitor',
724 3 => 'reserved'
725 );
726 return (isset($roomTypeLookup[$roomtyp]) ? $roomTypeLookup[$roomtyp] : false);
727 }
728
729 /**
730 * @param int $frmsizecod
731 * @param int $fscod
732 *
733 * @return int|false
734 */
735 public static function frameSizeLookup($frmsizecod, $fscod) {
736 // LSB is whether padding is used or not
737 $padding = (bool) ($frmsizecod & 0x01);
738 $framesizeid = ($frmsizecod & 0x3E) >> 1;
739
740 static $frameSizeLookup = array();
741 if (empty($frameSizeLookup)) {
742 $frameSizeLookup = array (
743 0 => array( 128, 138, 192), // 32 kbps
744 1 => array( 160, 174, 240), // 40 kbps
745 2 => array( 192, 208, 288), // 48 kbps
746 3 => array( 224, 242, 336), // 56 kbps
747 4 => array( 256, 278, 384), // 64 kbps
748 5 => array( 320, 348, 480), // 80 kbps
749 6 => array( 384, 416, 576), // 96 kbps
750 7 => array( 448, 486, 672), // 112 kbps
751 8 => array( 512, 556, 768), // 128 kbps
752 9 => array( 640, 696, 960), // 160 kbps
753 10 => array( 768, 834, 1152), // 192 kbps
754 11 => array( 896, 974, 1344), // 224 kbps
755 12 => array(1024, 1114, 1536), // 256 kbps
756 13 => array(1280, 1392, 1920), // 320 kbps
757 14 => array(1536, 1670, 2304), // 384 kbps
758 15 => array(1792, 1950, 2688), // 448 kbps
759 16 => array(2048, 2228, 3072), // 512 kbps
760 17 => array(2304, 2506, 3456), // 576 kbps
761 18 => array(2560, 2786, 3840) // 640 kbps
762 );
763 }
764 $paddingBytes = 0;
765 if (($fscod == 1) && $padding) {
766 // frame lengths are padded by 1 word (16 bits) at 44100
767 // (fscode==1) means 44100Hz (see sampleRateCodeLookup)
768 $paddingBytes = 2;
769 }
770 return (isset($frameSizeLookup[$framesizeid][$fscod]) ? $frameSizeLookup[$framesizeid][$fscod] + $paddingBytes : false);
771 }
772
773 /**
774 * @param int $frmsizecod
775 *
776 * @return int|false
777 */
778 public static function bitrateLookup($frmsizecod) {
779 // LSB is whether padding is used or not
780 $padding = (bool) ($frmsizecod & 0x01);
781 $framesizeid = ($frmsizecod & 0x3E) >> 1;
782
783 static $bitrateLookup = array(
784 0 => 32000,
785 1 => 40000,
786 2 => 48000,
787 3 => 56000,
788 4 => 64000,
789 5 => 80000,
790 6 => 96000,
791 7 => 112000,
792 8 => 128000,
793 9 => 160000,
794 10 => 192000,
795 11 => 224000,
796 12 => 256000,
797 13 => 320000,
798 14 => 384000,
799 15 => 448000,
800 16 => 512000,
801 17 => 576000,
802 18 => 640000,
803 );
804 return (isset($bitrateLookup[$framesizeid]) ? $bitrateLookup[$framesizeid] : false);
805 }
806
807 /**
808 * @param int $numblkscod
809 *
810 * @return int|false
811 */
812 public static function blocksPerSyncFrame($numblkscod) {
813 static $blocksPerSyncFrameLookup = array(
814 0 => 1,
815 1 => 2,
816 2 => 3,
817 3 => 6,
818 );
819 return (isset($blocksPerSyncFrameLookup[$numblkscod]) ? $blocksPerSyncFrameLookup[$numblkscod] : false);
820 }
821
822
823}
824