ILIAS  release_5-4 Revision v5.4.26-12-gabc799a52e6
Public Member Functions | Static Public Member Functions | Data Fields | Private Member Functions | Private Attributes
getid3_ac3 Class Reference

getID3() by James Heinrich info@.nosp@m.geti.nosp@m.d3.or.nosp@m.g // More...

+ Inheritance diagram for getid3_ac3:
+ Collaboration diagram for getid3_ac3:

Public Member Functions

 Analyze ()
 
- Public Member Functions inherited from getid3_handler
 __construct (getID3 $getid3, $call_module=null)
 
 Analyze ()
 
 AnalyzeString ($string)
 
 setStringMode ($string)
 
 saveAttachment ($name, $offset, $length, $image_mime=null)
 

Static Public Member Functions

static sampleRateCodeLookup ($fscod)
 
static sampleRateCodeLookup2 ($fscod2)
 
static serviceTypeLookup ($bsmod, $acmod)
 
static audioCodingModeLookup ($acmod)
 
static centerMixLevelLookup ($cmixlev)
 
static surroundMixLevelLookup ($surmixlev)
 
static dolbySurroundModeLookup ($dsurmod)
 
static channelsEnabledLookup ($acmod, $lfeon)
 
static heavyCompression ($compre)
 
static roomTypeLookup ($roomtyp)
 
static frameSizeLookup ($frmsizecod, $fscod)
 
static bitrateLookup ($frmsizecod)
 
static blocksPerSyncFrame ($numblkscod)
 

Data Fields

const syncword = 0x0B77
 

Private Member Functions

 readHeaderBSI ($length)
 

Private Attributes

 $AC3header = array()
 
 $BSIoffset = 0
 

Additional Inherited Members

- Protected Member Functions inherited from getid3_handler
 ftell ()
 
 fread ($bytes)
 
 fseek ($bytes, $whence=SEEK_SET)
 
 feof ()
 
 isDependencyFor ($module)
 
 error ($text)
 
 warning ($text)
 
 notice ($text)
 
- Protected Attributes inherited from getid3_handler
 $getid3
 
 $data_string_flag = false
 
 $data_string = ''
 
 $data_string_position = 0
 
 $data_string_length = 0
 

Detailed Description

getID3() by James Heinrich info@.nosp@m.geti.nosp@m.d3.or.nosp@m.g //

Definition at line 18 of file module.audio.ac3.php.

Member Function Documentation

◆ Analyze()

getid3_ac3::Analyze ( )

AH

Reimplemented from getid3_handler.

Definition at line 25 of file module.audio.ac3.php.

25 {
26 $info = &$this->getid3->info;
27
29 $info['ac3']['raw']['bsi'] = array();
30 $thisfile_ac3 = &$info['ac3'];
31 $thisfile_ac3_raw = &$thisfile_ac3['raw'];
32 $thisfile_ac3_raw_bsi = &$thisfile_ac3_raw['bsi'];
33
34
35 // http://www.atsc.org/standards/a_52a.pdf
36
37 $info['fileformat'] = 'ac3';
38
39 // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames
40 // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256
41 // new audio samples per channel. A synchronization information (SI) header at the beginning
42 // of each frame contains information needed to acquire and maintain synchronization. A
43 // bit stream information (BSI) header follows SI, and contains parameters describing the coded
44 // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the
45 // end of each frame is an error check field that includes a CRC word for error detection. An
46 // additional CRC word is located in the SI header, the use of which, by a decoder, is optional.
47 //
48 // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC
49
50 // syncinfo() {
51 // syncword 16
52 // crc1 16
53 // fscod 2
54 // frmsizecod 6
55 // } /* end of syncinfo */
56
57 $this->fseek($info['avdataoffset']);
58 $tempAC3header = $this->fread(100); // should be enough to cover all data, there are some variable-length fields...?
59 $this->AC3header['syncinfo'] = getid3_lib::BigEndian2Int(substr($tempAC3header, 0, 2));
60 $this->AC3header['bsi'] = getid3_lib::BigEndian2Bin(substr($tempAC3header, 2));
61 $thisfile_ac3_raw_bsi['bsid'] = (getid3_lib::LittleEndian2Int(substr($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
62 unset($tempAC3header);
63
64 if ($this->AC3header['syncinfo'] !== self::syncword) {
65 if (!$this->isDependencyFor('matroska')) {
66 unset($info['fileformat'], $info['ac3']);
67 return $this->error('Expecting "'.dechex(self::syncword).'" at offset '.$info['avdataoffset'].', found "'.dechex($this->AC3header['syncinfo']).'"');
68 }
69 }
70
71 $info['audio']['dataformat'] = 'ac3';
72 $info['audio']['bitrate_mode'] = 'cbr';
73 $info['audio']['lossless'] = false;
74
75 if ($thisfile_ac3_raw_bsi['bsid'] <= 8) {
76
77 $thisfile_ac3_raw_bsi['crc1'] = getid3_lib::Bin2Dec($this->readHeaderBSI(16));
78 $thisfile_ac3_raw_bsi['fscod'] = $this->readHeaderBSI(2); // 5.4.1.3
79 $thisfile_ac3_raw_bsi['frmsizecod'] = $this->readHeaderBSI(6); // 5.4.1.4
80 if ($thisfile_ac3_raw_bsi['frmsizecod'] > 37) { // binary: 100101 - see Table 5.18 Frame Size Code Table (1 word = 16 bits)
81 $this->warning('Unexpected ac3.bsi.frmsizecod value: '.$thisfile_ac3_raw_bsi['frmsizecod'].', bitrate not set correctly');
82 }
83
84 $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
85 $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3);
86 $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3);
87
88 if ($thisfile_ac3_raw_bsi['acmod'] & 0x01) {
89 // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream.
90 $thisfile_ac3_raw_bsi['cmixlev'] = $this->readHeaderBSI(2);
91 $thisfile_ac3['center_mix_level'] = self::centerMixLevelLookup($thisfile_ac3_raw_bsi['cmixlev']);
92 }
93
94 if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) {
95 // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream.
96 $thisfile_ac3_raw_bsi['surmixlev'] = $this->readHeaderBSI(2);
97 $thisfile_ac3['surround_mix_level'] = self::surroundMixLevelLookup($thisfile_ac3_raw_bsi['surmixlev']);
98 }
99
100 if ($thisfile_ac3_raw_bsi['acmod'] == 0x02) {
101 // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround.
102 $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2);
103 $thisfile_ac3['dolby_surround_mode'] = self::dolbySurroundModeLookup($thisfile_ac3_raw_bsi['dsurmod']);
104 }
105
106 $thisfile_ac3_raw_bsi['flags']['lfeon'] = (bool) $this->readHeaderBSI(1);
107
108 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31.
109 // 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.
110 $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5); // 5.4.2.8 dialnorm: Dialogue Normalization, 5 Bits
111
112 $thisfile_ac3_raw_bsi['flags']['compr'] = (bool) $this->readHeaderBSI(1); // 5.4.2.9 compre: Compression Gain Word Exists, 1 Bit
113 if ($thisfile_ac3_raw_bsi['flags']['compr']) {
114 $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8); // 5.4.2.10 compr: Compression Gain Word, 8 Bits
115 $thisfile_ac3['heavy_compression'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr']);
116 }
117
118 $thisfile_ac3_raw_bsi['flags']['langcod'] = (bool) $this->readHeaderBSI(1); // 5.4.2.11 langcode: Language Code Exists, 1 Bit
119 if ($thisfile_ac3_raw_bsi['flags']['langcod']) {
120 $thisfile_ac3_raw_bsi['langcod'] = $this->readHeaderBSI(8); // 5.4.2.12 langcod: Language Code, 8 Bits
121 }
122
123 $thisfile_ac3_raw_bsi['flags']['audprodinfo'] = (bool) $this->readHeaderBSI(1); // 5.4.2.13 audprodie: Audio Production Information Exists, 1 Bit
124 if ($thisfile_ac3_raw_bsi['flags']['audprodinfo']) {
125 $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5); // 5.4.2.14 mixlevel: Mixing Level, 5 Bits
126 $thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2); // 5.4.2.15 roomtyp: Room Type, 2 Bits
127
128 $thisfile_ac3['mixing_level'] = (80 + $thisfile_ac3_raw_bsi['mixlevel']).'dB';
129 $thisfile_ac3['room_type'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp']);
130 }
131
132
133 $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5); // 5.4.2.16 dialnorm2: Dialogue Normalization, ch2, 5 Bits
134 $thisfile_ac3['dialogue_normalization2'] = '-'.$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.
135
136 $thisfile_ac3_raw_bsi['flags']['compr2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.17 compr2e: Compression Gain Word Exists, ch2, 1 Bit
137 if ($thisfile_ac3_raw_bsi['flags']['compr2']) {
138 $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8); // 5.4.2.18 compr2: Compression Gain Word, ch2, 8 Bits
139 $thisfile_ac3['heavy_compression2'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr2']);
140 }
141
142 $thisfile_ac3_raw_bsi['flags']['langcod2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.19 langcod2e: Language Code Exists, ch2, 1 Bit
143 if ($thisfile_ac3_raw_bsi['flags']['langcod2']) {
144 $thisfile_ac3_raw_bsi['langcod2'] = $this->readHeaderBSI(8); // 5.4.2.20 langcod2: Language Code, ch2, 8 Bits
145 }
146
147 $thisfile_ac3_raw_bsi['flags']['audprodinfo2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.21 audprodi2e: Audio Production Information Exists, ch2, 1 Bit
148 if ($thisfile_ac3_raw_bsi['flags']['audprodinfo2']) {
149 $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5); // 5.4.2.22 mixlevel2: Mixing Level, ch2, 5 Bits
150 $thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2); // 5.4.2.23 roomtyp2: Room Type, ch2, 2 Bits
151
152 $thisfile_ac3['mixing_level2'] = (80 + $thisfile_ac3_raw_bsi['mixlevel2']).'dB';
153 $thisfile_ac3['room_type2'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp2']);
154 }
155
156 $thisfile_ac3_raw_bsi['copyright'] = (bool) $this->readHeaderBSI(1); // 5.4.2.24 copyrightb: Copyright Bit, 1 Bit
157
158 $thisfile_ac3_raw_bsi['original'] = (bool) $this->readHeaderBSI(1); // 5.4.2.25 origbs: Original Bit Stream, 1 Bit
159
160 $thisfile_ac3_raw_bsi['flags']['timecod1'] = $this->readHeaderBSI(2); // 5.4.2.26 timecod1e, timcode2e: Time Code (first and second) Halves Exist, 2 Bits
161 if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x01) {
162 $thisfile_ac3_raw_bsi['timecod1'] = $this->readHeaderBSI(14); // 5.4.2.27 timecod1: Time code first half, 14 bits
163 $thisfile_ac3['timecode1'] = 0;
164 $thisfile_ac3['timecode1'] += (($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
165 $thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x01F8) >> 3) * 60; // The next 6 bits represent the time in minutes, with valid values of 0–59
166 $thisfile_ac3['timecode1'] += (($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)
167 }
168 if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x02) {
169 $thisfile_ac3_raw_bsi['timecod2'] = $this->readHeaderBSI(14); // 5.4.2.28 timecod2: Time code second half, 14 bits
170 $thisfile_ac3['timecode2'] = 0;
171 $thisfile_ac3['timecode2'] += (($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)
172 $thisfile_ac3['timecode2'] += (($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)
173 $thisfile_ac3['timecode2'] += (($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
174 }
175
176 $thisfile_ac3_raw_bsi['flags']['addbsi'] = (bool) $this->readHeaderBSI(1);
177 if ($thisfile_ac3_raw_bsi['flags']['addbsi']) {
178 $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.
179
180 $this->AC3header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($thisfile_ac3_raw_bsi['addbsi_length']));
181
182 $thisfile_ac3_raw_bsi['addbsi_data'] = substr($this->AC3header['bsi'], $this->BSIoffset, $thisfile_ac3_raw_bsi['addbsi_length'] * 8);
183 $this->BSIoffset += $thisfile_ac3_raw_bsi['addbsi_length'] * 8;
184 }
185
186
187 } elseif ($thisfile_ac3_raw_bsi['bsid'] <= 16) { // E-AC3
188
189
190$this->error('E-AC3 parsing is incomplete and experimental in this version of getID3 ('.$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.');
191 $info['audio']['dataformat'] = 'eac3';
192
193 $thisfile_ac3_raw_bsi['strmtyp'] = $this->readHeaderBSI(2);
194 $thisfile_ac3_raw_bsi['substreamid'] = $this->readHeaderBSI(3);
195 $thisfile_ac3_raw_bsi['frmsiz'] = $this->readHeaderBSI(11);
196 $thisfile_ac3_raw_bsi['fscod'] = $this->readHeaderBSI(2);
197 if ($thisfile_ac3_raw_bsi['fscod'] == 3) {
198 $thisfile_ac3_raw_bsi['fscod2'] = $this->readHeaderBSI(2);
199 $thisfile_ac3_raw_bsi['numblkscod'] = 3; // six blocks per syncframe
200 } else {
201 $thisfile_ac3_raw_bsi['numblkscod'] = $this->readHeaderBSI(2);
202 }
203 $thisfile_ac3['bsi']['blocks_per_sync_frame'] = self::blocksPerSyncFrame($thisfile_ac3_raw_bsi['numblkscod']);
204 $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3);
205 $thisfile_ac3_raw_bsi['flags']['lfeon'] = (bool) $this->readHeaderBSI(1);
206 $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
207 $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5);
208 $thisfile_ac3_raw_bsi['flags']['compr'] = (bool) $this->readHeaderBSI(1);
209 if ($thisfile_ac3_raw_bsi['flags']['compr']) {
210 $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8);
211 }
212 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
213 $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5);
214 $thisfile_ac3_raw_bsi['flags']['compr2'] = (bool) $this->readHeaderBSI(1);
215 if ($thisfile_ac3_raw_bsi['flags']['compr2']) {
216 $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8);
217 }
218 }
219 if ($thisfile_ac3_raw_bsi['strmtyp'] == 1) { // if dependent stream
220 $thisfile_ac3_raw_bsi['flags']['chanmap'] = (bool) $this->readHeaderBSI(1);
221 if ($thisfile_ac3_raw_bsi['flags']['chanmap']) {
222 $thisfile_ac3_raw_bsi['chanmap'] = $this->readHeaderBSI(8);
223 }
224 }
225 $thisfile_ac3_raw_bsi['flags']['mixmdat'] = (bool) $this->readHeaderBSI(1);
226 if ($thisfile_ac3_raw_bsi['flags']['mixmdat']) { // Mixing metadata
227 if ($thisfile_ac3_raw_bsi['acmod'] > 2) { // if more than 2 channels
228 $thisfile_ac3_raw_bsi['dmixmod'] = $this->readHeaderBSI(2);
229 }
230 if (($thisfile_ac3_raw_bsi['acmod'] & 0x01) && ($thisfile_ac3_raw_bsi['acmod'] > 2)) { // if three front channels exist
231 $thisfile_ac3_raw_bsi['ltrtcmixlev'] = $this->readHeaderBSI(3);
232 $thisfile_ac3_raw_bsi['lorocmixlev'] = $this->readHeaderBSI(3);
233 }
234 if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) { // if a surround channel exists
235 $thisfile_ac3_raw_bsi['ltrtsurmixlev'] = $this->readHeaderBSI(3);
236 $thisfile_ac3_raw_bsi['lorosurmixlev'] = $this->readHeaderBSI(3);
237 }
238 if ($thisfile_ac3_raw_bsi['flags']['lfeon']) { // if the LFE channel exists
239 $thisfile_ac3_raw_bsi['flags']['lfemixlevcod'] = (bool) $this->readHeaderBSI(1);
240 if ($thisfile_ac3_raw_bsi['flags']['lfemixlevcod']) {
241 $thisfile_ac3_raw_bsi['lfemixlevcod'] = $this->readHeaderBSI(5);
242 }
243 }
244 if ($thisfile_ac3_raw_bsi['strmtyp'] == 0) { // if independent stream
245 $thisfile_ac3_raw_bsi['flags']['pgmscl'] = (bool) $this->readHeaderBSI(1);
246 if ($thisfile_ac3_raw_bsi['flags']['pgmscl']) {
247 $thisfile_ac3_raw_bsi['pgmscl'] = $this->readHeaderBSI(6);
248 }
249 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
250 $thisfile_ac3_raw_bsi['flags']['pgmscl2'] = (bool) $this->readHeaderBSI(1);
251 if ($thisfile_ac3_raw_bsi['flags']['pgmscl2']) {
252 $thisfile_ac3_raw_bsi['pgmscl2'] = $this->readHeaderBSI(6);
253 }
254 }
255 $thisfile_ac3_raw_bsi['flags']['extpgmscl'] = (bool) $this->readHeaderBSI(1);
256 if ($thisfile_ac3_raw_bsi['flags']['extpgmscl']) {
257 $thisfile_ac3_raw_bsi['extpgmscl'] = $this->readHeaderBSI(6);
258 }
259 $thisfile_ac3_raw_bsi['mixdef'] = $this->readHeaderBSI(2);
260 if ($thisfile_ac3_raw_bsi['mixdef'] == 1) { // mixing option 2
261 $thisfile_ac3_raw_bsi['premixcmpsel'] = (bool) $this->readHeaderBSI(1);
262 $thisfile_ac3_raw_bsi['drcsrc'] = (bool) $this->readHeaderBSI(1);
263 $thisfile_ac3_raw_bsi['premixcmpscl'] = $this->readHeaderBSI(3);
264 } elseif ($thisfile_ac3_raw_bsi['mixdef'] == 2) { // mixing option 3
265 $thisfile_ac3_raw_bsi['mixdata'] = $this->readHeaderBSI(12);
266 } elseif ($thisfile_ac3_raw_bsi['mixdef'] == 3) { // mixing option 4
267 $mixdefbitsread = 0;
268 $thisfile_ac3_raw_bsi['mixdeflen'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
269 $thisfile_ac3_raw_bsi['flags']['mixdata2'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
270 if ($thisfile_ac3_raw_bsi['flags']['mixdata2']) {
271 $thisfile_ac3_raw_bsi['premixcmpsel'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
272 $thisfile_ac3_raw_bsi['drcsrc'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
273 $thisfile_ac3_raw_bsi['premixcmpscl'] = $this->readHeaderBSI(3); $mixdefbitsread += 3;
274 $thisfile_ac3_raw_bsi['flags']['extpgmlscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
275 if ($thisfile_ac3_raw_bsi['flags']['extpgmlscl']) {
276 $thisfile_ac3_raw_bsi['extpgmlscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
277 }
278 $thisfile_ac3_raw_bsi['flags']['extpgmcscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
279 if ($thisfile_ac3_raw_bsi['flags']['extpgmcscl']) {
280 $thisfile_ac3_raw_bsi['extpgmcscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
281 }
282 $thisfile_ac3_raw_bsi['flags']['extpgmrscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
283 if ($thisfile_ac3_raw_bsi['flags']['extpgmrscl']) {
284 $thisfile_ac3_raw_bsi['extpgmrscl'] = $this->readHeaderBSI(4);
285 }
286 $thisfile_ac3_raw_bsi['flags']['extpgmlsscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
287 if ($thisfile_ac3_raw_bsi['flags']['extpgmlsscl']) {
288 $thisfile_ac3_raw_bsi['extpgmlsscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
289 }
290 $thisfile_ac3_raw_bsi['flags']['extpgmrsscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
291 if ($thisfile_ac3_raw_bsi['flags']['extpgmrsscl']) {
292 $thisfile_ac3_raw_bsi['extpgmrsscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
293 }
294 $thisfile_ac3_raw_bsi['flags']['extpgmlfescl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
295 if ($thisfile_ac3_raw_bsi['flags']['extpgmlfescl']) {
296 $thisfile_ac3_raw_bsi['extpgmlfescl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
297 }
298 $thisfile_ac3_raw_bsi['flags']['dmixscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
299 if ($thisfile_ac3_raw_bsi['flags']['dmixscl']) {
300 $thisfile_ac3_raw_bsi['dmixscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
301 }
302 $thisfile_ac3_raw_bsi['flags']['addch'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
303 if ($thisfile_ac3_raw_bsi['flags']['addch']) {
304 $thisfile_ac3_raw_bsi['flags']['extpgmaux1scl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
305 if ($thisfile_ac3_raw_bsi['flags']['extpgmaux1scl']) {
306 $thisfile_ac3_raw_bsi['extpgmaux1scl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
307 }
308 $thisfile_ac3_raw_bsi['flags']['extpgmaux2scl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
309 if ($thisfile_ac3_raw_bsi['flags']['extpgmaux2scl']) {
310 $thisfile_ac3_raw_bsi['extpgmaux2scl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
311 }
312 }
313 }
314 $thisfile_ac3_raw_bsi['flags']['mixdata3'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
315 if ($thisfile_ac3_raw_bsi['flags']['mixdata3']) {
316 $thisfile_ac3_raw_bsi['spchdat'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
317 $thisfile_ac3_raw_bsi['flags']['addspchdat'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
318 if ($thisfile_ac3_raw_bsi['flags']['addspchdat']) {
319 $thisfile_ac3_raw_bsi['spchdat1'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
320 $thisfile_ac3_raw_bsi['spchan1att'] = $this->readHeaderBSI(2); $mixdefbitsread += 2;
321 $thisfile_ac3_raw_bsi['flags']['addspchdat1'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
322 if ($thisfile_ac3_raw_bsi['flags']['addspchdat1']) {
323 $thisfile_ac3_raw_bsi['spchdat2'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
324 $thisfile_ac3_raw_bsi['spchan2att'] = $this->readHeaderBSI(3); $mixdefbitsread += 3;
325 }
326 }
327 }
328 $mixdata_bits = (8 * ($thisfile_ac3_raw_bsi['mixdeflen'] + 2)) - $mixdefbitsread;
329 $mixdata_fill = (($mixdata_bits % 8) ? 8 - ($mixdata_bits % 8) : 0);
330 $thisfile_ac3_raw_bsi['mixdata'] = $this->readHeaderBSI($mixdata_bits);
331 $thisfile_ac3_raw_bsi['mixdatafill'] = $this->readHeaderBSI($mixdata_fill);
332 unset($mixdefbitsread, $mixdata_bits, $mixdata_fill);
333 }
334 if ($thisfile_ac3_raw_bsi['acmod'] < 2) { // if mono or dual mono source
335 $thisfile_ac3_raw_bsi['flags']['paninfo'] = (bool) $this->readHeaderBSI(1);
336 if ($thisfile_ac3_raw_bsi['flags']['paninfo']) {
337 $thisfile_ac3_raw_bsi['panmean'] = $this->readHeaderBSI(8);
338 $thisfile_ac3_raw_bsi['paninfo'] = $this->readHeaderBSI(6);
339 }
340 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
341 $thisfile_ac3_raw_bsi['flags']['paninfo2'] = (bool) $this->readHeaderBSI(1);
342 if ($thisfile_ac3_raw_bsi['flags']['paninfo2']) {
343 $thisfile_ac3_raw_bsi['panmean2'] = $this->readHeaderBSI(8);
344 $thisfile_ac3_raw_bsi['paninfo2'] = $this->readHeaderBSI(6);
345 }
346 }
347 }
348 $thisfile_ac3_raw_bsi['flags']['frmmixcfginfo'] = (bool) $this->readHeaderBSI(1);
349 if ($thisfile_ac3_raw_bsi['flags']['frmmixcfginfo']) { // mixing configuration information
350 if ($thisfile_ac3_raw_bsi['numblkscod'] == 0) {
351 $thisfile_ac3_raw_bsi['blkmixcfginfo'][0] = $this->readHeaderBSI(5);
352 } else {
353 for ($blk = 0; $blk < $thisfile_ac3_raw_bsi['numblkscod']; $blk++) {
354 $thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk] = (bool) $this->readHeaderBSI(1);
355 if ($thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk]) { // mixing configuration information
356 $thisfile_ac3_raw_bsi['blkmixcfginfo'][$blk] = $this->readHeaderBSI(5);
357 }
358 }
359 }
360 }
361 }
362 }
363 $thisfile_ac3_raw_bsi['flags']['infomdat'] = (bool) $this->readHeaderBSI(1);
364 if ($thisfile_ac3_raw_bsi['flags']['infomdat']) { // Informational metadata
365 $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3);
366 $thisfile_ac3_raw_bsi['flags']['copyrightb'] = (bool) $this->readHeaderBSI(1);
367 $thisfile_ac3_raw_bsi['flags']['origbs'] = (bool) $this->readHeaderBSI(1);
368 if ($thisfile_ac3_raw_bsi['acmod'] == 2) { // if in 2/0 mode
369 $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2);
370 $thisfile_ac3_raw_bsi['dheadphonmod'] = $this->readHeaderBSI(2);
371 }
372 if ($thisfile_ac3_raw_bsi['acmod'] >= 6) { // if both surround channels exist
373 $thisfile_ac3_raw_bsi['dsurexmod'] = $this->readHeaderBSI(2);
374 }
375 $thisfile_ac3_raw_bsi['flags']['audprodi'] = (bool) $this->readHeaderBSI(1);
376 if ($thisfile_ac3_raw_bsi['flags']['audprodi']) {
377 $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5);
378 $thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2);
379 $thisfile_ac3_raw_bsi['flags']['adconvtyp'] = (bool) $this->readHeaderBSI(1);
380 }
381 if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
382 $thisfile_ac3_raw_bsi['flags']['audprodi2'] = (bool) $this->readHeaderBSI(1);
383 if ($thisfile_ac3_raw_bsi['flags']['audprodi2']) {
384 $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5);
385 $thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2);
386 $thisfile_ac3_raw_bsi['flags']['adconvtyp2'] = (bool) $this->readHeaderBSI(1);
387 }
388 }
389 if ($thisfile_ac3_raw_bsi['fscod'] < 3) { // if not half sample rate
390 $thisfile_ac3_raw_bsi['flags']['sourcefscod'] = (bool) $this->readHeaderBSI(1);
391 }
392 }
393 if (($thisfile_ac3_raw_bsi['strmtyp'] == 0) && ($thisfile_ac3_raw_bsi['numblkscod'] != 3)) { // if both surround channels exist
394 $thisfile_ac3_raw_bsi['flags']['convsync'] = (bool) $this->readHeaderBSI(1);
395 }
396 if ($thisfile_ac3_raw_bsi['strmtyp'] == 2) { // if bit stream converted from AC-3
397 if ($thisfile_ac3_raw_bsi['numblkscod'] != 3) { // 6 blocks per syncframe
398 $thisfile_ac3_raw_bsi['flags']['blkid'] = 1;
399 } else {
400 $thisfile_ac3_raw_bsi['flags']['blkid'] = (bool) $this->readHeaderBSI(1);
401 }
402 if ($thisfile_ac3_raw_bsi['flags']['blkid']) {
403 $thisfile_ac3_raw_bsi['frmsizecod'] = $this->readHeaderBSI(6);
404 }
405 }
406 $thisfile_ac3_raw_bsi['flags']['addbsi'] = (bool) $this->readHeaderBSI(1);
407 if ($thisfile_ac3_raw_bsi['flags']['addbsi']) {
408 $thisfile_ac3_raw_bsi['addbsil'] = $this->readHeaderBSI(6);
409 $thisfile_ac3_raw_bsi['addbsi'] = $this->readHeaderBSI(($thisfile_ac3_raw_bsi['addbsil'] + 1) * 8);
410 }
411
412 } else {
413
414 $this->error('Bit stream identification is version '.$thisfile_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 16. Please submit a support ticket with a sample file.');
415 unset($info['ac3']);
416 return false;
417
418 }
419
420 if (isset($thisfile_ac3_raw_bsi['fscod2'])) {
421 $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup2($thisfile_ac3_raw_bsi['fscod2']);
422 } else {
423 $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup($thisfile_ac3_raw_bsi['fscod']);
424 }
425 if ($thisfile_ac3_raw_bsi['fscod'] <= 3) {
426 $info['audio']['sample_rate'] = $thisfile_ac3['sample_rate'];
427 } else {
428 $this->warning('Unexpected ac3.bsi.fscod value: '.$thisfile_ac3_raw_bsi['fscod']);
429 }
430 if (isset($thisfile_ac3_raw_bsi['frmsizecod'])) {
431 $thisfile_ac3['frame_length'] = self::frameSizeLookup($thisfile_ac3_raw_bsi['frmsizecod'], $thisfile_ac3_raw_bsi['fscod']);
432 $thisfile_ac3['bitrate'] = self::bitrateLookup($thisfile_ac3_raw_bsi['frmsizecod']);
433 } elseif (!empty($thisfile_ac3_raw_bsi['frmsiz'])) {
434// this isn't right, but it's (usually) close, roughly 5% less than it should be.
435// but WHERE is the actual bitrate value stored in EAC3?? email info@getid3.org if you know!
436 $thisfile_ac3['bitrate'] = ($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.
437// kludge-fix to make it approximately the expected value, still not "right":
438$thisfile_ac3['bitrate'] = round(($thisfile_ac3['bitrate'] * 1.05) / 16000) * 16000;
439 }
440 $info['audio']['bitrate'] = $thisfile_ac3['bitrate'];
441
442 $thisfile_ac3['service_type'] = self::serviceTypeLookup($thisfile_ac3_raw_bsi['bsmod'], $thisfile_ac3_raw_bsi['acmod']);
443 $ac3_coding_mode = self::audioCodingModeLookup($thisfile_ac3_raw_bsi['acmod']);
444 foreach($ac3_coding_mode as $key => $value) {
445 $thisfile_ac3[$key] = $value;
446 }
447 switch ($thisfile_ac3_raw_bsi['acmod']) {
448 case 0:
449 case 1:
450 $info['audio']['channelmode'] = 'mono';
451 break;
452 case 3:
453 case 4:
454 $info['audio']['channelmode'] = 'stereo';
455 break;
456 default:
457 $info['audio']['channelmode'] = 'surround';
458 break;
459 }
460 $info['audio']['channels'] = $thisfile_ac3['num_channels'];
461
462 $thisfile_ac3['lfe_enabled'] = $thisfile_ac3_raw_bsi['flags']['lfeon'];
463 if ($thisfile_ac3_raw_bsi['flags']['lfeon']) {
464 $info['audio']['channels'] .= '.1';
465 }
466
467 $thisfile_ac3['channels_enabled'] = self::channelsEnabledLookup($thisfile_ac3_raw_bsi['acmod'], $thisfile_ac3_raw_bsi['flags']['lfeon']);
468 $thisfile_ac3['dialogue_normalization'] = '-'.$thisfile_ac3_raw_bsi['dialnorm'].'dB';
469
470 return true;
471 }
getid3_ac3\channelsEnabledLookup
static channelsEnabledLookup($acmod, $lfeon)
Definition: module.audio.ac3.php:572
getid3_ac3\heavyCompression
static heavyCompression($compre)
Definition: module.audio.ac3.php:597
getid3_ac3\sampleRateCodeLookup2
static sampleRateCodeLookup2($fscod2)
Definition: module.audio.ac3.php:490
getid3_ac3\blocksPerSyncFrame
static blocksPerSyncFrame($numblkscod)
Definition: module.audio.ac3.php:722
getid3_ac3\surroundMixLevelLookup
static surroundMixLevelLookup($surmixlev)
Definition: module.audio.ac3.php:549
getid3_ac3\sampleRateCodeLookup
static sampleRateCodeLookup($fscod)
Definition: module.audio.ac3.php:480
getid3_ac3\audioCodingModeLookup
static audioCodingModeLookup($acmod)
Definition: module.audio.ac3.php:521
getid3_ac3\dolbySurroundModeLookup
static dolbySurroundModeLookup($dsurmod)
Definition: module.audio.ac3.php:562
getid3_ac3\serviceTypeLookup
static serviceTypeLookup($bsmod, $acmod)
Definition: module.audio.ac3.php:500
getid3_ac3\readHeaderBSI
readHeaderBSI($length)
Definition: module.audio.ac3.php:473
getid3_ac3\roomTypeLookup
static roomTypeLookup($roomtyp)
Definition: module.audio.ac3.php:647
getid3_ac3\bitrateLookup
static bitrateLookup($frmsizecod)
Definition: module.audio.ac3.php:693
getid3_ac3\frameSizeLookup
static frameSizeLookup($frmsizecod, $fscod)
Definition: module.audio.ac3.php:657
getid3_ac3\centerMixLevelLookup
static centerMixLevelLookup($cmixlev)
Definition: module.audio.ac3.php:536
getid3_handler\fseek
fseek($bytes, $whence=SEEK_SET)
Definition: getid3.php:1711
getid3_handler\isDependencyFor
isDependencyFor($module)
Definition: getid3.php:1748
getid3_handler\fread
fread($bytes)
Definition: getid3.php:1683
getid3_handler\warning
warning($text)
Definition: getid3.php:1758
getid3_handler\error
error($text)
Definition: getid3.php:1752
getid3_lib\LittleEndian2Int
static LittleEndian2Int($byteword, $signed=false)
Definition: getid3.lib.php:292
getid3_lib\BigEndian2Bin
static BigEndian2Bin($byteword)
Definition: getid3.lib.php:297
getid3_lib\Bin2Dec
static Bin2Dec($binstring, $signed=false)
Definition: getid3.lib.php:342
getid3_lib\BigEndian2Int
static BigEndian2Int($byteword, $synchsafe=false, $signed=false)
Definition: getid3.lib.php:263
$key
$key
Definition: croninfo.php:18
$info
$info
Definition: index.php:5

References $info, $key, audioCodingModeLookup(), getid3_lib\BigEndian2Bin(), getid3_lib\BigEndian2Int(), getid3_lib\Bin2Dec(), bitrateLookup(), blocksPerSyncFrame(), centerMixLevelLookup(), channelsEnabledLookup(), dolbySurroundModeLookup(), getid3_handler\error(), frameSizeLookup(), getid3_handler\fread(), getid3_handler\fseek(), heavyCompression(), getid3_handler\isDependencyFor(), getid3_lib\LittleEndian2Int(), readHeaderBSI(), roomTypeLookup(), sampleRateCodeLookup(), sampleRateCodeLookup2(), serviceTypeLookup(), surroundMixLevelLookup(), and getid3_handler\warning().

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◆ audioCodingModeLookup()

static getid3_ac3::audioCodingModeLookup (   $acmod)
static

Definition at line 521 of file module.audio.ac3.php.

521 {
522 // array(channel configuration, # channels (not incl LFE), channel order)
523 static $audioCodingModeLookup = array (
524 0 => array('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'),
525 1 => array('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'),
526 2 => array('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'),
527 3 => array('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'),
528 4 => array('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'),
529 5 => array('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'),
530 6 => array('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'),
531 7 => array('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR'),
532 );
533 return (isset($audioCodingModeLookup[$acmod]) ? $audioCodingModeLookup[$acmod] : false);
534 }

Referenced by Analyze().

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◆ bitrateLookup()

static getid3_ac3::bitrateLookup (   $frmsizecod)
static

Definition at line 693 of file module.audio.ac3.php.

693 {
694 // LSB is whether padding is used or not
695 $padding = (bool) ($frmsizecod & 0x01);
696 $framesizeid = ($frmsizecod & 0x3E) >> 1;
697
698 static $bitrateLookup = array(
699 0 => 32000,
700 1 => 40000,
701 2 => 48000,
702 3 => 56000,
703 4 => 64000,
704 5 => 80000,
705 6 => 96000,
706 7 => 112000,
707 8 => 128000,
708 9 => 160000,
709 10 => 192000,
710 11 => 224000,
711 12 => 256000,
712 13 => 320000,
713 14 => 384000,
714 15 => 448000,
715 16 => 512000,
716 17 => 576000,
717 18 => 640000,
718 );
719 return (isset($bitrateLookup[$framesizeid]) ? $bitrateLookup[$framesizeid] : false);
720 }

Referenced by Analyze().

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◆ blocksPerSyncFrame()

static getid3_ac3::blocksPerSyncFrame (   $numblkscod)
static

Definition at line 722 of file module.audio.ac3.php.

722 {
723 static $blocksPerSyncFrameLookup = array(
724 0 => 1,
725 1 => 2,
726 2 => 3,
727 3 => 6,
728 );
729 return (isset($blocksPerSyncFrameLookup[$numblkscod]) ? $blocksPerSyncFrameLookup[$numblkscod] : false);
730 }

Referenced by Analyze().

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◆ centerMixLevelLookup()

static getid3_ac3::centerMixLevelLookup (   $cmixlev)
static

Definition at line 536 of file module.audio.ac3.php.

536 {
537 static $centerMixLevelLookup;
538 if (empty($centerMixLevelLookup)) {
539 $centerMixLevelLookup = array(
540 0 => pow(2, -3.0 / 6), // 0.707 (-3.0 dB)
541 1 => pow(2, -4.5 / 6), // 0.595 (-4.5 dB)
542 2 => pow(2, -6.0 / 6), // 0.500 (-6.0 dB)
543 3 => 'reserved'
544 );
545 }
546 return (isset($centerMixLevelLookup[$cmixlev]) ? $centerMixLevelLookup[$cmixlev] : false);
547 }

Referenced by Analyze().

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◆ channelsEnabledLookup()

static getid3_ac3::channelsEnabledLookup (   $acmod,
  $lfeon 
)
static

Definition at line 572 of file module.audio.ac3.php.

572 {
573 $lookup = array(
574 'ch1'=>(bool) ($acmod == 0),
575 'ch2'=>(bool) ($acmod == 0),
576 'left'=>(bool) ($acmod > 1),
577 'right'=>(bool) ($acmod > 1),
578 'center'=>(bool) ($acmod & 0x01),
579 'surround_mono'=>false,
580 'surround_left'=>false,
581 'surround_right'=>false,
582 'lfe'=>$lfeon);
583 switch ($acmod) {
584 case 4:
585 case 5:
586 $lookup['surround_mono'] = true;
587 break;
588 case 6:
589 case 7:
590 $lookup['surround_left'] = true;
591 $lookup['surround_right'] = true;
592 break;
593 }
594 return $lookup;
595 }

Referenced by Analyze().

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◆ dolbySurroundModeLookup()

static getid3_ac3::dolbySurroundModeLookup (   $dsurmod)
static

Definition at line 562 of file module.audio.ac3.php.

562 {
563 static $dolbySurroundModeLookup = array(
564 0 => 'not indicated',
565 1 => 'Not Dolby Surround encoded',
566 2 => 'Dolby Surround encoded',
567 3 => 'reserved'
568 );
569 return (isset($dolbySurroundModeLookup[$dsurmod]) ? $dolbySurroundModeLookup[$dsurmod] : false);
570 }

Referenced by Analyze().

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◆ frameSizeLookup()

static getid3_ac3::frameSizeLookup (   $frmsizecod,
  $fscod 
)
static

Definition at line 657 of file module.audio.ac3.php.

657 {
658 // LSB is whether padding is used or not
659 $padding = (bool) ($frmsizecod & 0x01);
660 $framesizeid = ($frmsizecod & 0x3E) >> 1;
661
662 static $frameSizeLookup = array();
663 if (empty($frameSizeLookup)) {
664 $frameSizeLookup = array (
665 0 => array( 128, 138, 192), // 32 kbps
666 1 => array( 160, 174, 240), // 40 kbps
667 2 => array( 192, 208, 288), // 48 kbps
668 3 => array( 224, 242, 336), // 56 kbps
669 4 => array( 256, 278, 384), // 64 kbps
670 5 => array( 320, 348, 480), // 80 kbps
671 6 => array( 384, 416, 576), // 96 kbps
672 7 => array( 448, 486, 672), // 112 kbps
673 8 => array( 512, 556, 768), // 128 kbps
674 9 => array( 640, 696, 960), // 160 kbps
675 10 => array( 768, 834, 1152), // 192 kbps
676 11 => array( 896, 974, 1344), // 224 kbps
677 12 => array(1024, 1114, 1536), // 256 kbps
678 13 => array(1280, 1392, 1920), // 320 kbps
679 14 => array(1536, 1670, 2304), // 384 kbps
680 15 => array(1792, 1950, 2688), // 448 kbps
681 16 => array(2048, 2228, 3072), // 512 kbps
682 17 => array(2304, 2506, 3456), // 576 kbps
683 18 => array(2560, 2786, 3840) // 640 kbps
684 );
685 }
686 if (($fscod == 1) && $padding) {
687 // frame lengths are padded by 1 word (16 bits) at 44100
688 $frameSizeLookup[$frmsizecod] += 2;
689 }
690 return (isset($frameSizeLookup[$framesizeid][$fscod]) ? $frameSizeLookup[$framesizeid][$fscod] : false);
691 }

Referenced by Analyze().

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◆ heavyCompression()

static getid3_ac3::heavyCompression (   $compre)
static

Definition at line 597 of file module.audio.ac3.php.

597 {
598 // The first four bits indicate gain changes in 6.02dB increments which can be
599 // implemented with an arithmetic shift operation. The following four bits
600 // indicate linear gain changes, and require a 5-bit multiply.
601 // We will represent the two 4-bit fields of compr as follows:
602 // X0 X1 X2 X3 . Y4 Y5 Y6 Y7
603 // The meaning of the X values is most simply described by considering X to represent a 4-bit
604 // signed integer with values from -8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The
605 // following table shows this in detail.
606
607 // Meaning of 4 msb of compr
608 // 7 +48.16 dB
609 // 6 +42.14 dB
610 // 5 +36.12 dB
611 // 4 +30.10 dB
612 // 3 +24.08 dB
613 // 2 +18.06 dB
614 // 1 +12.04 dB
615 // 0 +6.02 dB
616 // -1 0 dB
617 // -2 -6.02 dB
618 // -3 -12.04 dB
619 // -4 -18.06 dB
620 // -5 -24.08 dB
621 // -6 -30.10 dB
622 // -7 -36.12 dB
623 // -8 -42.14 dB
624
625 $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT);
626 if ($fourbit{0} == '1') {
627 $log_gain = -8 + bindec(substr($fourbit, 1));
628 } else {
629 $log_gain = bindec(substr($fourbit, 1));
630 }
631 $log_gain = ($log_gain + 1) * getid3_lib::RGADamplitude2dB(2);
632
633 // The value of Y is a linear representation of a gain change of up to -6 dB. Y is considered to
634 // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can
635 // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain
636 // changes from -0.28 dB to -6.02 dB.
637
638 $lin_gain = (16 + ($compre & 0x0F)) / 32;
639
640 // The combination of X and Y values allows compr to indicate gain changes from
641 // 48.16 - 0.28 = +47.89 dB, to
642 // -42.14 - 6.02 = -48.16 dB.
643
644 return $log_gain - $lin_gain;
645 }
getid3_lib\RGADamplitude2dB
static RGADamplitude2dB($amplitude)
Definition: getid3.lib.php:1174

References getid3_lib\RGADamplitude2dB().

Referenced by Analyze().

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◆ readHeaderBSI()

getid3_ac3::readHeaderBSI (   $length)
private

Definition at line 473 of file module.audio.ac3.php.

473 {
474 $data = substr($this->AC3header['bsi'], $this->BSIoffset, $length);
475 $this->BSIoffset += $length;
476
477 return bindec($data);
478 }
$data
$data
Definition: bench.php:6

References $data.

Referenced by Analyze().

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◆ roomTypeLookup()

static getid3_ac3::roomTypeLookup (   $roomtyp)
static

Definition at line 647 of file module.audio.ac3.php.

647 {
648 static $roomTypeLookup = array(
649 0 => 'not indicated',
650 1 => 'large room, X curve monitor',
651 2 => 'small room, flat monitor',
652 3 => 'reserved'
653 );
654 return (isset($roomTypeLookup[$roomtyp]) ? $roomTypeLookup[$roomtyp] : false);
655 }

Referenced by Analyze().

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◆ sampleRateCodeLookup()

static getid3_ac3::sampleRateCodeLookup (   $fscod)
static

Definition at line 480 of file module.audio.ac3.php.

480 {
481 static $sampleRateCodeLookup = array(
482 0 => 48000,
483 1 => 44100,
484 2 => 32000,
485 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
486 );
487 return (isset($sampleRateCodeLookup[$fscod]) ? $sampleRateCodeLookup[$fscod] : false);
488 }

Referenced by Analyze().

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◆ sampleRateCodeLookup2()

static getid3_ac3::sampleRateCodeLookup2 (   $fscod2)
static

Definition at line 490 of file module.audio.ac3.php.

490 {
491 static $sampleRateCodeLookup2 = array(
492 0 => 24000,
493 1 => 22050,
494 2 => 16000,
495 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
496 );
497 return (isset($sampleRateCodeLookup2[$fscod2]) ? $sampleRateCodeLookup2[$fscod2] : false);
498 }

Referenced by Analyze().

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◆ serviceTypeLookup()

static getid3_ac3::serviceTypeLookup (   $bsmod,
  $acmod 
)
static

Definition at line 500 of file module.audio.ac3.php.

500 {
501 static $serviceTypeLookup = array();
502 if (empty($serviceTypeLookup)) {
503 for ($i = 0; $i <= 7; $i++) {
504 $serviceTypeLookup[0][$i] = 'main audio service: complete main (CM)';
505 $serviceTypeLookup[1][$i] = 'main audio service: music and effects (ME)';
506 $serviceTypeLookup[2][$i] = 'associated service: visually impaired (VI)';
507 $serviceTypeLookup[3][$i] = 'associated service: hearing impaired (HI)';
508 $serviceTypeLookup[4][$i] = 'associated service: dialogue (D)';
509 $serviceTypeLookup[5][$i] = 'associated service: commentary (C)';
510 $serviceTypeLookup[6][$i] = 'associated service: emergency (E)';
511 }
512
513 $serviceTypeLookup[7][1] = 'associated service: voice over (VO)';
514 for ($i = 2; $i <= 7; $i++) {
515 $serviceTypeLookup[7][$i] = 'main audio service: karaoke';
516 }
517 }
518 return (isset($serviceTypeLookup[$bsmod][$acmod]) ? $serviceTypeLookup[$bsmod][$acmod] : false);
519 }
$i
$i
Definition: disco.tpl.php:19

References $i.

Referenced by Analyze().

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◆ surroundMixLevelLookup()

static getid3_ac3::surroundMixLevelLookup (   $surmixlev)
static

Definition at line 549 of file module.audio.ac3.php.

549 {
550 static $surroundMixLevelLookup;
551 if (empty($surroundMixLevelLookup)) {
552 $surroundMixLevelLookup = array(
553 0 => pow(2, -3.0 / 6),
554 1 => pow(2, -6.0 / 6),
555 2 => 0,
556 3 => 'reserved'
557 );
558 }
559 return (isset($surroundMixLevelLookup[$surmixlev]) ? $surroundMixLevelLookup[$surmixlev] : false);
560 }

Referenced by Analyze().

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Field Documentation

◆ $AC3header

getid3_ac3::$AC3header = array()
private

Definition at line 20 of file module.audio.ac3.php.

◆ $BSIoffset

getid3_ac3::$BSIoffset = 0
private

Definition at line 21 of file module.audio.ac3.php.

◆ syncword

const getid3_ac3::syncword = 0x0B77

Definition at line 23 of file module.audio.ac3.php.

Referenced by getid3_riff\ParseRIFF().

The documentation for this class was generated from the following file: