Wordpress 3.6
[autoinstalls/wordpress.git] / wp-includes / ID3 / module.audio.ac3.php
1 <?php
2 /////////////////////////////////////////////////////////////////
3 /// getID3() by James Heinrich <info@getid3.org>               //
4 //  available at http://getid3.sourceforge.net                 //
5 //            or http://www.getid3.org                         //
6 /////////////////////////////////////////////////////////////////
7 // See readme.txt for more details                             //
8 /////////////////////////////////////////////////////////////////
9 //                                                             //
10 // module.audio.ac3.php                                        //
11 // module for analyzing AC-3 (aka Dolby Digital) audio files   //
12 // dependencies: NONE                                          //
13 //                                                            ///
14 /////////////////////////////////////////////////////////////////
15
16
17 class getid3_ac3 extends getid3_handler
18 {
19     private $AC3header = array();
20     private $BSIoffset = 0;
21
22     const syncword = "\x0B\x77";
23
24         public function Analyze() {
25                 $info = &$this->getid3->info;
26
27                 ///AH
28                 $info['ac3']['raw']['bsi'] = array();
29                 $thisfile_ac3              = &$info['ac3'];
30                 $thisfile_ac3_raw          = &$thisfile_ac3['raw'];
31                 $thisfile_ac3_raw_bsi      = &$thisfile_ac3_raw['bsi'];
32
33
34                 // http://www.atsc.org/standards/a_52a.pdf
35
36                 $info['fileformat'] = 'ac3';
37
38                 // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames
39                 // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256
40                 // new audio samples per channel. A synchronization information (SI) header at the beginning
41                 // of each frame contains information needed to acquire and maintain synchronization. A
42                 // bit stream information (BSI) header follows SI, and contains parameters describing the coded
43                 // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the
44                 // end of each frame is an error check field that includes a CRC word for error detection. An
45                 // additional CRC word is located in the SI header, the use of which, by a decoder, is optional.
46                 //
47                 // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC
48
49                 // syncinfo() {
50                 //       syncword    16
51                 //       crc1        16
52                 //       fscod        2
53                 //       frmsizecod   6
54                 // } /* end of syncinfo */
55
56                 $this->fseek($info['avdataoffset']);
57                 $this->AC3header['syncinfo'] = $this->fread(5);
58
59                 if (strpos($this->AC3header['syncinfo'], self::syncword) === 0) {
60                         $thisfile_ac3_raw['synchinfo']['synchword'] = self::syncword;
61                         $offset = 2;
62                 } else {
63                         if (!$this->isDependencyFor('matroska')) {
64                                 unset($info['fileformat'], $info['ac3']);
65                                 return $this->error('Expecting "'.getid3_lib::PrintHexBytes(self::syncword).'" at offset '.$info['avdataoffset'].', found "'.getid3_lib::PrintHexBytes(substr($this->AC3header['syncinfo'], 0, 2)).'"');
66                         }
67                         $offset = 0;
68                         $this->fseek(-2, SEEK_CUR);
69                 }
70
71                 $info['audio']['dataformat']   = 'ac3';
72                 $info['audio']['bitrate_mode'] = 'cbr';
73                 $info['audio']['lossless']     = false;
74
75                 $thisfile_ac3_raw['synchinfo']['crc1']       = getid3_lib::LittleEndian2Int(substr($this->AC3header['syncinfo'], $offset, 2));
76                 $ac3_synchinfo_fscod_frmsizecod              = getid3_lib::LittleEndian2Int(substr($this->AC3header['syncinfo'], ($offset + 2), 1));
77                 $thisfile_ac3_raw['synchinfo']['fscod']      = ($ac3_synchinfo_fscod_frmsizecod & 0xC0) >> 6;
78                 $thisfile_ac3_raw['synchinfo']['frmsizecod'] = ($ac3_synchinfo_fscod_frmsizecod & 0x3F);
79
80                 $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup($thisfile_ac3_raw['synchinfo']['fscod']);
81                 if ($thisfile_ac3_raw['synchinfo']['fscod'] <= 3) {
82                         $info['audio']['sample_rate'] = $thisfile_ac3['sample_rate'];
83                 }
84
85                 $thisfile_ac3['frame_length'] = self::frameSizeLookup($thisfile_ac3_raw['synchinfo']['frmsizecod'], $thisfile_ac3_raw['synchinfo']['fscod']);
86                 $thisfile_ac3['bitrate']      = self::bitrateLookup($thisfile_ac3_raw['synchinfo']['frmsizecod']);
87                 $info['audio']['bitrate'] = $thisfile_ac3['bitrate'];
88
89                 $this->AC3header['bsi'] = getid3_lib::BigEndian2Bin($this->fread(15));
90                 $ac3_bsi_offset = 0;
91
92                 $thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5);
93                 if ($thisfile_ac3_raw_bsi['bsid'] > 8) {
94                         // Decoders which can decode version 8 will thus be able to decode version numbers less than 8.
95                         // If this standard is extended by the addition of additional elements or features, a value of bsid greater than 8 will be used.
96                         // Decoders built to this version of the standard will not be able to decode versions with bsid greater than 8.
97                         $this->error('Bit stream identification is version '.$thisfile_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 8');
98                     unset($info['ac3']);
99                         return false;
100                 }
101
102                 $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3);
103                 $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3);
104
105                 $thisfile_ac3['service_type'] = self::serviceTypeLookup($thisfile_ac3_raw_bsi['bsmod'], $thisfile_ac3_raw_bsi['acmod']);
106                 $ac3_coding_mode = self::audioCodingModeLookup($thisfile_ac3_raw_bsi['acmod']);
107                 foreach($ac3_coding_mode as $key => $value) {
108                         $thisfile_ac3[$key] = $value;
109                 }
110                 switch ($thisfile_ac3_raw_bsi['acmod']) {
111                         case 0:
112                         case 1:
113                                 $info['audio']['channelmode'] = 'mono';
114                                 break;
115                         case 3:
116                         case 4:
117                                 $info['audio']['channelmode'] = 'stereo';
118                                 break;
119                         default:
120                                 $info['audio']['channelmode'] = 'surround';
121                                 break;
122                 }
123                 $info['audio']['channels'] = $thisfile_ac3['num_channels'];
124
125                 if ($thisfile_ac3_raw_bsi['acmod'] & 0x01) {
126                         // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream.
127                         $thisfile_ac3_raw_bsi['cmixlev'] = $this->readHeaderBSI(2);
128                         $thisfile_ac3['center_mix_level'] = self::centerMixLevelLookup($thisfile_ac3_raw_bsi['cmixlev']);
129                 }
130
131                 if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) {
132                         // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream.
133                         $thisfile_ac3_raw_bsi['surmixlev'] = $this->readHeaderBSI(2);
134                         $thisfile_ac3['surround_mix_level'] = self::surroundMixLevelLookup($thisfile_ac3_raw_bsi['surmixlev']);
135                 }
136
137                 if ($thisfile_ac3_raw_bsi['acmod'] == 0x02) {
138                         // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround.
139                         $thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2);
140                         $thisfile_ac3['dolby_surround_mode'] = self::dolbySurroundModeLookup($thisfile_ac3_raw_bsi['dsurmod']);
141                 }
142
143                 $thisfile_ac3_raw_bsi['lfeon'] = (bool) $this->readHeaderBSI(1);
144                 $thisfile_ac3['lfe_enabled'] = $thisfile_ac3_raw_bsi['lfeon'];
145                 if ($thisfile_ac3_raw_bsi['lfeon']) {
146                         //$info['audio']['channels']++;
147                         $info['audio']['channels'] .= '.1';
148                 }
149
150                 $thisfile_ac3['channels_enabled'] = self::channelsEnabledLookup($thisfile_ac3_raw_bsi['acmod'], $thisfile_ac3_raw_bsi['lfeon']);
151
152                 // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31.
153                 // 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.
154                 $thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5);
155                 $thisfile_ac3['dialogue_normalization'] = '-'.$thisfile_ac3_raw_bsi['dialnorm'].'dB';
156
157                 $thisfile_ac3_raw_bsi['compre_flag'] = (bool) $this->readHeaderBSI(1);
158                 if ($thisfile_ac3_raw_bsi['compre_flag']) {
159                         $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8);
160                         $thisfile_ac3['heavy_compression'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr']);
161                 }
162
163                 $thisfile_ac3_raw_bsi['langcode_flag'] = (bool) $this->readHeaderBSI(1);
164                 if ($thisfile_ac3_raw_bsi['langcode_flag']) {
165                         $thisfile_ac3_raw_bsi['langcod'] = $this->readHeaderBSI(8);
166                 }
167
168                 $thisfile_ac3_raw_bsi['audprodie'] = (bool) $this->readHeaderBSI(1);
169                 if ($thisfile_ac3_raw_bsi['audprodie']) {
170                         $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5);
171                         $thisfile_ac3_raw_bsi['roomtyp']  = $this->readHeaderBSI(2);
172
173                         $thisfile_ac3['mixing_level'] = (80 + $thisfile_ac3_raw_bsi['mixlevel']).'dB';
174                         $thisfile_ac3['room_type']    = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp']);
175                 }
176
177                 if ($thisfile_ac3_raw_bsi['acmod'] == 0x00) {
178                         // If acmod is 0, then two completely independent program channels (dual mono)
179                         // are encoded into the bit stream, and are referenced as Ch1, Ch2. In this case,
180                         // a number of additional items are present in BSI or audblk to fully describe Ch2.
181
182                         // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31.
183                         // 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.
184                         $thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5);
185                         $thisfile_ac3['dialogue_normalization2'] = '-'.$thisfile_ac3_raw_bsi['dialnorm2'].'dB';
186
187                         $thisfile_ac3_raw_bsi['compre_flag2'] = (bool) $this->readHeaderBSI(1);
188                         if ($thisfile_ac3_raw_bsi['compre_flag2']) {
189                                 $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8);
190                                 $thisfile_ac3['heavy_compression2'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr2']);
191                         }
192
193                         $thisfile_ac3_raw_bsi['langcode_flag2'] = (bool) $this->readHeaderBSI(1);
194                         if ($thisfile_ac3_raw_bsi['langcode_flag2']) {
195                                 $thisfile_ac3_raw_bsi['langcod2'] = $this->readHeaderBSI(8);
196                         }
197
198                         $thisfile_ac3_raw_bsi['audprodie2'] = (bool) $this->readHeaderBSI(1);
199                         if ($thisfile_ac3_raw_bsi['audprodie2']) {
200                                 $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5);
201                                 $thisfile_ac3_raw_bsi['roomtyp2']  = $this->readHeaderBSI(2);
202
203                                 $thisfile_ac3['mixing_level2'] = (80 + $thisfile_ac3_raw_bsi['mixlevel2']).'dB';
204                                 $thisfile_ac3['room_type2']    = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp2']);
205                         }
206
207                 }
208
209                 $thisfile_ac3_raw_bsi['copyright'] = (bool) $this->readHeaderBSI(1);
210
211                 $thisfile_ac3_raw_bsi['original']  = (bool) $this->readHeaderBSI(1);
212
213                 $thisfile_ac3_raw_bsi['timecode1_flag'] = (bool) $this->readHeaderBSI(1);
214                 if ($thisfile_ac3_raw_bsi['timecode1_flag']) {
215                         $thisfile_ac3_raw_bsi['timecode1'] = $this->readHeaderBSI(14);
216                 }
217
218                 $thisfile_ac3_raw_bsi['timecode2_flag'] = (bool) $this->readHeaderBSI(1);
219                 if ($thisfile_ac3_raw_bsi['timecode2_flag']) {
220                         $thisfile_ac3_raw_bsi['timecode2'] = $this->readHeaderBSI(14);
221                 }
222
223                 $thisfile_ac3_raw_bsi['addbsi_flag'] = (bool) $this->readHeaderBSI(1);
224                 if ($thisfile_ac3_raw_bsi['addbsi_flag']) {
225                         $thisfile_ac3_raw_bsi['addbsi_length'] = $this->readHeaderBSI(6);
226
227                         $this->AC3header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($thisfile_ac3_raw_bsi['addbsi_length']));
228
229                         $thisfile_ac3_raw_bsi['addbsi_data'] = substr($this->AC3header['bsi'], $this->BSIoffset, $thisfile_ac3_raw_bsi['addbsi_length'] * 8);
230                         $this->BSIoffset += $thisfile_ac3_raw_bsi['addbsi_length'] * 8;
231                 }
232
233                 return true;
234         }
235
236         private function readHeaderBSI($length) {
237                 $data = substr($this->AC3header['bsi'], $this->BSIoffset, $length);
238                 $this->BSIoffset += $length;
239
240                 return bindec($data);
241         }
242
243         public static function sampleRateCodeLookup($fscod) {
244                 static $sampleRateCodeLookup = array(
245                         0 => 48000,
246                         1 => 44100,
247                         2 => 32000,
248                         3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
249                 );
250                 return (isset($sampleRateCodeLookup[$fscod]) ? $sampleRateCodeLookup[$fscod] : false);
251         }
252
253         public static function serviceTypeLookup($bsmod, $acmod) {
254                 static $serviceTypeLookup = array();
255                 if (empty($serviceTypeLookup)) {
256                         for ($i = 0; $i <= 7; $i++) {
257                                 $serviceTypeLookup[0][$i] = 'main audio service: complete main (CM)';
258                                 $serviceTypeLookup[1][$i] = 'main audio service: music and effects (ME)';
259                                 $serviceTypeLookup[2][$i] = 'associated service: visually impaired (VI)';
260                                 $serviceTypeLookup[3][$i] = 'associated service: hearing impaired (HI)';
261                                 $serviceTypeLookup[4][$i] = 'associated service: dialogue (D)';
262                                 $serviceTypeLookup[5][$i] = 'associated service: commentary (C)';
263                                 $serviceTypeLookup[6][$i] = 'associated service: emergency (E)';
264                         }
265
266                         $serviceTypeLookup[7][1]      = 'associated service: voice over (VO)';
267                         for ($i = 2; $i <= 7; $i++) {
268                                 $serviceTypeLookup[7][$i] = 'main audio service: karaoke';
269                         }
270                 }
271                 return (isset($serviceTypeLookup[$bsmod][$acmod]) ? $serviceTypeLookup[$bsmod][$acmod] : false);
272         }
273
274         public static function audioCodingModeLookup($acmod) {
275                 // array(channel configuration, # channels (not incl LFE), channel order)
276                 static $audioCodingModeLookup = array (
277                         0 => array('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'),
278                         1 => array('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'),
279                         2 => array('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'),
280                         3 => array('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'),
281                         4 => array('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'),
282                         5 => array('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'),
283                         6 => array('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'),
284                         7 => array('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR'),
285                 );
286                 return (isset($audioCodingModeLookup[$acmod]) ? $audioCodingModeLookup[$acmod] : false);
287         }
288
289         public static function centerMixLevelLookup($cmixlev) {
290                 static $centerMixLevelLookup;
291                 if (empty($centerMixLevelLookup)) {
292                         $centerMixLevelLookup = array(
293                                 0 => pow(2, -3.0 / 6), // 0.707 (-3.0 dB)
294                                 1 => pow(2, -4.5 / 6), // 0.595 (-4.5 dB)
295                                 2 => pow(2, -6.0 / 6), // 0.500 (-6.0 dB)
296                                 3 => 'reserved'
297                         );
298                 }
299                 return (isset($centerMixLevelLookup[$cmixlev]) ? $centerMixLevelLookup[$cmixlev] : false);
300         }
301
302         public static function surroundMixLevelLookup($surmixlev) {
303                 static $surroundMixLevelLookup;
304                 if (empty($surroundMixLevelLookup)) {
305                         $surroundMixLevelLookup = array(
306                                 0 => pow(2, -3.0 / 6),
307                                 1 => pow(2, -6.0 / 6),
308                                 2 => 0,
309                                 3 => 'reserved'
310                         );
311                 }
312                 return (isset($surroundMixLevelLookup[$surmixlev]) ? $surroundMixLevelLookup[$surmixlev] : false);
313         }
314
315         public static function dolbySurroundModeLookup($dsurmod) {
316                 static $dolbySurroundModeLookup = array(
317                         0 => 'not indicated',
318                         1 => 'Not Dolby Surround encoded',
319                         2 => 'Dolby Surround encoded',
320                         3 => 'reserved'
321                 );
322                 return (isset($dolbySurroundModeLookup[$dsurmod]) ? $dolbySurroundModeLookup[$dsurmod] : false);
323         }
324
325         public static function channelsEnabledLookup($acmod, $lfeon) {
326                 $lookup = array(
327                         'ch1'=>(bool) ($acmod == 0),
328                         'ch2'=>(bool) ($acmod == 0),
329                         'left'=>(bool) ($acmod > 1),
330                         'right'=>(bool) ($acmod > 1),
331                         'center'=>(bool) ($acmod & 0x01),
332                         'surround_mono'=>false,
333                         'surround_left'=>false,
334                         'surround_right'=>false,
335                         'lfe'=>$lfeon);
336                 switch ($acmod) {
337                         case 4:
338                         case 5:
339                                 $lookup['surround_mono']  = true;
340                                 break;
341                         case 6:
342                         case 7:
343                                 $lookup['surround_left']  = true;
344                                 $lookup['surround_right'] = true;
345                                 break;
346                 }
347                 return $lookup;
348         }
349
350         public static function heavyCompression($compre) {
351                 // The first four bits indicate gain changes in 6.02dB increments which can be
352                 // implemented with an arithmetic shift operation. The following four bits
353                 // indicate linear gain changes, and require a 5-bit multiply.
354                 // We will represent the two 4-bit fields of compr as follows:
355                 //   X0 X1 X2 X3 . Y4 Y5 Y6 Y7
356                 // The meaning of the X values is most simply described by considering X to represent a 4-bit
357                 // signed integer with values from -8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The
358                 // following table shows this in detail.
359
360                 // Meaning of 4 msb of compr
361                 //  7    +48.16 dB
362                 //  6    +42.14 dB
363                 //  5    +36.12 dB
364                 //  4    +30.10 dB
365                 //  3    +24.08 dB
366                 //  2    +18.06 dB
367                 //  1    +12.04 dB
368                 //  0     +6.02 dB
369                 // -1         0 dB
370                 // -2     -6.02 dB
371                 // -3    -12.04 dB
372                 // -4    -18.06 dB
373                 // -5    -24.08 dB
374                 // -6    -30.10 dB
375                 // -7    -36.12 dB
376                 // -8    -42.14 dB
377
378                 $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT);
379                 if ($fourbit{0} == '1') {
380                         $log_gain = -8 + bindec(substr($fourbit, 1));
381                 } else {
382                         $log_gain = bindec(substr($fourbit, 1));
383                 }
384                 $log_gain = ($log_gain + 1) * getid3_lib::RGADamplitude2dB(2);
385
386                 // The value of Y is a linear representation of a gain change of up to -6 dB. Y is considered to
387                 // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can
388                 // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain
389                 // changes from -0.28 dB to -6.02 dB.
390
391                 $lin_gain = (16 + ($compre & 0x0F)) / 32;
392
393                 // The combination of X and Y values allows compr to indicate gain changes from
394                 //  48.16 - 0.28 = +47.89 dB, to
395                 // -42.14 - 6.02 = -48.16 dB.
396
397                 return $log_gain - $lin_gain;
398         }
399
400         public static function roomTypeLookup($roomtyp) {
401                 static $roomTypeLookup = array(
402                         0 => 'not indicated',
403                         1 => 'large room, X curve monitor',
404                         2 => 'small room, flat monitor',
405                         3 => 'reserved'
406                 );
407                 return (isset($roomTypeLookup[$roomtyp]) ? $roomTypeLookup[$roomtyp] : false);
408         }
409
410         public static function frameSizeLookup($frmsizecod, $fscod) {
411                 $padding     = (bool) ($frmsizecod % 2);
412                 $framesizeid =   floor($frmsizecod / 2);
413
414                 static $frameSizeLookup = array();
415                 if (empty($frameSizeLookup)) {
416                         $frameSizeLookup = array (
417                                 0  => array(128, 138, 192),
418                                 1  => array(40, 160, 174, 240),
419                                 2  => array(48, 192, 208, 288),
420                                 3  => array(56, 224, 242, 336),
421                                 4  => array(64, 256, 278, 384),
422                                 5  => array(80, 320, 348, 480),
423                                 6  => array(96, 384, 416, 576),
424                                 7  => array(112, 448, 486, 672),
425                                 8  => array(128, 512, 556, 768),
426                                 9  => array(160, 640, 696, 960),
427                                 10 => array(192, 768, 834, 1152),
428                                 11 => array(224, 896, 974, 1344),
429                                 12 => array(256, 1024, 1114, 1536),
430                                 13 => array(320, 1280, 1392, 1920),
431                                 14 => array(384, 1536, 1670, 2304),
432                                 15 => array(448, 1792, 1950, 2688),
433                                 16 => array(512, 2048, 2228, 3072),
434                                 17 => array(576, 2304, 2506, 3456),
435                                 18 => array(640, 2560, 2786, 3840)
436                         );
437                 }
438                 if (($fscod == 1) && $padding) {
439                         // frame lengths are padded by 1 word (16 bits) at 44100
440                         $frameSizeLookup[$frmsizecod] += 2;
441                 }
442                 return (isset($frameSizeLookup[$framesizeid][$fscod]) ? $frameSizeLookup[$framesizeid][$fscod] : false);
443         }
444
445         public static function bitrateLookup($frmsizecod) {
446                 $framesizeid =   floor($frmsizecod / 2);
447
448                 static $bitrateLookup = array(
449                         0  => 32000,
450                         1  => 40000,
451                         2  => 48000,
452                         3  => 56000,
453                         4  => 64000,
454                         5  => 80000,
455                         6  => 96000,
456                         7  => 112000,
457                         8  => 128000,
458                         9  => 160000,
459                         10 => 192000,
460                         11 => 224000,
461                         12 => 256000,
462                         13 => 320000,
463                         14 => 384000,
464                         15 => 448000,
465                         16 => 512000,
466                         17 => 576000,
467                         18 => 640000
468                 );
469                 return (isset($bitrateLookup[$framesizeid]) ? $bitrateLookup[$framesizeid] : false);
470         }
471
472
473 }