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