File size: 5.75Kb
<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <[email protected]> //
// available at http://getid3.sourceforge.net //
// or http://www.getid3.org //
/////////////////////////////////////////////////////////////////
// See readme.txt for more details //
/////////////////////////////////////////////////////////////////
// //
// module.audio.lpac.php //
// module for analyzing LPAC Audio files //
// dependencies: module.audio-video.riff.php //
// ///
/////////////////////////////////////////////////////////////////
getid3_lib::IncludeDependency(GETID3_INCLUDEPATH.'module.audio-video.riff.php', __FILE__, true);
class getid3_lpac extends getid3_handler
{
function Analyze() {
$info = &$this->getid3->info;
fseek($this->getid3->fp, $info['avdataoffset'], SEEK_SET);
$LPACheader = fread($this->getid3->fp, 14);
if (substr($LPACheader, 0, 4) != 'LPAC') {
$info['error'][] = 'Expected "LPAC" at offset '.$info['avdataoffset'].', found "'.$StreamMarker.'"';
return false;
}
$info['avdataoffset'] += 14;
$info['fileformat'] = 'lpac';
$info['audio']['dataformat'] = 'lpac';
$info['audio']['lossless'] = true;
$info['audio']['bitrate_mode'] = 'vbr';
$info['lpac']['file_version'] = getid3_lib::BigEndian2Int(substr($LPACheader, 4, 1));
$flags['audio_type'] = getid3_lib::BigEndian2Int(substr($LPACheader, 5, 1));
$info['lpac']['total_samples']= getid3_lib::BigEndian2Int(substr($LPACheader, 6, 4));
$flags['parameters'] = getid3_lib::BigEndian2Int(substr($LPACheader, 10, 4));
$info['lpac']['flags']['is_wave'] = (bool) ($flags['audio_type'] & 0x40);
$info['lpac']['flags']['stereo'] = (bool) ($flags['audio_type'] & 0x04);
$info['lpac']['flags']['24_bit'] = (bool) ($flags['audio_type'] & 0x02);
$info['lpac']['flags']['16_bit'] = (bool) ($flags['audio_type'] & 0x01);
if ($info['lpac']['flags']['24_bit'] && $info['lpac']['flags']['16_bit']) {
$info['warning'][] = '24-bit and 16-bit flags cannot both be set';
}
$info['lpac']['flags']['fast_compress'] = (bool) ($flags['parameters'] & 0x40000000);
$info['lpac']['flags']['random_access'] = (bool) ($flags['parameters'] & 0x08000000);
$info['lpac']['block_length'] = pow(2, (($flags['parameters'] & 0x07000000) >> 24)) * 256;
$info['lpac']['flags']['adaptive_prediction_order'] = (bool) ($flags['parameters'] & 0x00800000);
$info['lpac']['flags']['adaptive_quantization'] = (bool) ($flags['parameters'] & 0x00400000);
$info['lpac']['flags']['joint_stereo'] = (bool) ($flags['parameters'] & 0x00040000);
$info['lpac']['quantization'] = ($flags['parameters'] & 0x00001F00) >> 8;
$info['lpac']['max_prediction_order'] = ($flags['parameters'] & 0x0000003F);
if ($info['lpac']['flags']['fast_compress'] && ($info['lpac']['max_prediction_order'] != 3)) {
$info['warning'][] = 'max_prediction_order expected to be "3" if fast_compress is true, actual value is "'.$info['lpac']['max_prediction_order'].'"';
}
switch ($info['lpac']['file_version']) {
case 6:
if ($info['lpac']['flags']['adaptive_quantization']) {
$info['warning'][] = 'adaptive_quantization expected to be false in LPAC file stucture v6, actually true';
}
if ($info['lpac']['quantization'] != 20) {
$info['warning'][] = 'Quantization expected to be 20 in LPAC file stucture v6, actually '.$info['lpac']['flags']['Q'];
}
break;
default:
//$info['warning'][] = 'This version of getID3() ['.$this->getid3->version().'] only supports LPAC file format version 6, this file is version '.$info['lpac']['file_version'].' - please report to [email protected]';
break;
}
$getid3_temp = new getID3();
$getid3_temp->openfile($this->getid3->filename);
$getid3_temp->info = $info;
$getid3_riff = new getid3_riff($getid3_temp);
$getid3_riff->Analyze();
$info['avdataoffset'] = $getid3_temp->info['avdataoffset'];
$info['riff'] = $getid3_temp->info['riff'];
$info['error'] = $getid3_temp->info['error'];
$info['warning'] = $getid3_temp->info['warning'];
$info['lpac']['comments']['comment'] = $getid3_temp->info['comments'];
$info['audio']['sample_rate'] = $getid3_temp->info['audio']['sample_rate'];
unset($getid3_temp, $getid3_riff);
$info['audio']['channels'] = ($info['lpac']['flags']['stereo'] ? 2 : 1);
if ($info['lpac']['flags']['24_bit']) {
$info['audio']['bits_per_sample'] = $info['riff']['audio'][0]['bits_per_sample'];
} elseif ($info['lpac']['flags']['16_bit']) {
$info['audio']['bits_per_sample'] = 16;
} else {
$info['audio']['bits_per_sample'] = 8;
}
if ($info['lpac']['flags']['fast_compress']) {
// fast
$info['audio']['encoder_options'] = '-1';
} else {
switch ($info['lpac']['max_prediction_order']) {
case 20: // simple
$info['audio']['encoder_options'] = '-2';
break;
case 30: // medium
$info['audio']['encoder_options'] = '-3';
break;
case 40: // high
$info['audio']['encoder_options'] = '-4';
break;
case 60: // extrahigh
$info['audio']['encoder_options'] = '-5';
break;
}
}
$info['playtime_seconds'] = $info['lpac']['total_samples'] / $info['audio']['sample_rate'];
$info['audio']['bitrate'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
return true;
}
}
?>