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