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<?php
/* vim:set tabstop=8 softtabstop=8 shiftwidth=8 noexpandtab: */
// +----------------------------------------------------------------------+
// | PHP version 5 |
// +----------------------------------------------------------------------+
// | Copyright (c) 2002-2006 James Heinrich, Allan Hansen |
// +----------------------------------------------------------------------+
// | This source file is subject to version 2 of the GPL license, |
// | that is bundled with this package in the file license.txt and is |
// | available through the world-wide-web at the following url: |
// | http://www.gnu.org/copyleft/gpl.html |
// +----------------------------------------------------------------------+
// | getID3() - http://getid3.sourceforge.net or http://www.getid3.org |
// +----------------------------------------------------------------------+
// | Authors: James Heinrich <info�getid3*org> |
// | Allan Hansen <ah�artemis*dk> |
// +----------------------------------------------------------------------+
// | module.audio.mpc_old.php |
// | Module for analyzing Musepack/MPEG+ Audio files - SV4-SV6 |
// | dependencies: NONE |
// +----------------------------------------------------------------------+
//
// $Id: module.audio.mpc_old.php,v 1.2 2006/11/02 10:48:01 ah Exp $
class getid3_mpc_old extends getid3_handler
{
public function Analyze() {
$getid3 = $this->getid3;
// http://www.uni-jena.de/~pfk/mpp/sv8/header.html
$getid3->info['mpc']['header'] = array ();
$info_mpc_header = &$getid3->info['mpc']['header'];
$getid3->info['fileformat'] = 'mpc';
$getid3->info['audio']['dataformat'] = 'mpc';
$getid3->info['audio']['bitrate_mode'] = 'vbr';
$getid3->info['audio']['channels'] = 2; // the format appears to be hardcoded for stereo only
$getid3->info['audio']['lossless'] = false;
fseek($getid3->fp, $getid3->info['avdataoffset'], SEEK_SET);
$info_mpc_header['size'] = 8;
$getid3->info['avdataoffset'] += $info_mpc_header['size'];
$mpc_header_data = fread($getid3->fp, $info_mpc_header['size']);
// Most of this code adapted from Jurgen Faul's MPEGplus source code - thanks Jurgen! :)
$header_dword[0] = getid3_lib::LittleEndian2Int(substr($mpc_header_data, 0, 4));
$header_dword[1] = getid3_lib::LittleEndian2Int(substr($mpc_header_data, 4, 4));
// DDDD DDDD CCCC CCCC BBBB BBBB AAAA AAAA
// aaaa aaaa abcd dddd dddd deee eeff ffff
//
// a = bitrate = anything
// b = IS = anything
// c = MS = anything
// d = streamversion = 0000000004 or 0000000005 or 0000000006
// e = maxband = anything
// f = blocksize = 000001 for SV5+, anything(?) for SV4
$info_mpc_header['target_bitrate'] = (($header_dword[0] & 0xFF800000) >> 23);
$info_mpc_header['intensity_stereo'] = (bool)(($header_dword[0] & 0x00400000) >> 22);
$info_mpc_header['mid-side_stereo'] = (bool)(($header_dword[0] & 0x00200000) >> 21);
$info_mpc_header['stream_major_version'] = ($header_dword[0] & 0x001FF800) >> 11;
$info_mpc_header['stream_minor_version'] = 0;
$info_mpc_header['max_band'] = ($header_dword[0] & 0x000007C0) >> 6; // related to lowpass frequency, not sure how it translates exactly
$info_mpc_header['block_size'] = ($header_dword[0] & 0x0000003F);
switch ($info_mpc_header['stream_major_version']) {
case 4:
$info_mpc_header['frame_count'] = ($header_dword[1] >> 16);
break;
case 5:
case 6:
$info_mpc_header['frame_count'] = $header_dword[1];
break;
default:
throw new getid3_exception('Expecting 4, 5 or 6 in version field, found '.$info_mpc_header['stream_major_version'].' instead');
}
if (($info_mpc_header['stream_major_version'] > 4) && ($info_mpc_header['block_size'] != 1)) {
$getid3->warning('Block size expected to be 1, actual value found: '.$info_mpc_header['block_size']);
}
$info_mpc_header['sample_rate'] = $getid3->info['audio']['sample_rate'] = 44100; // AB: used by all files up to SV7
$info_mpc_header['samples'] = $info_mpc_header['frame_count'] * 1152 * $getid3->info['audio']['channels'];
$getid3->info['audio']['bitrate_mode'] = $info_mpc_header['target_bitrate'] == 0 ? 'vbr' : 'cbr';
$getid3->info['mpc']['bitrate'] = ($getid3->info['avdataend'] - $getid3->info['avdataoffset']) * 8 * 44100 / $info_mpc_header['frame_count'] / 1152;
$getid3->info['audio']['bitrate'] = $getid3->info['mpc']['bitrate'];
$getid3->info['audio']['encoder'] = 'SV'.$info_mpc_header['stream_major_version'];
return true;
}
}
?>
|
