Lpac.php

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<?php

namespace GetId3\Module\Audio;

use GetId3\Handler\BaseHandler;
use GetId3\Lib\Helper;
use GetId3\GetId3Core;
use GetId3\Module\AudioVideo\Riff;

//  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                   //
//                                                            ///

class Lpac extends BaseHandler
{

    public 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';

        $info['lpac']['file_version'] = Helper::BigEndian2Int(substr($LPACheader,  4, 1));
        $flags['audio_type']                  = Helper::BigEndian2Int(substr($LPACheader,  5, 1));
        $info['lpac']['total_samples']= Helper::BigEndian2Int(substr($LPACheader,  6, 4));
        $flags['parameters']                  = Helper::BigEndian2Int(substr($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:
                //$info['warning'][] = 'This version of GetId3Core() ['.$this->getid3->version().'] only supports LPAC file format version 6, this file is version '.$info['lpac']['file_version'].' - please report to info@getid3.org';
                break;
        }

        $getid3_temp = new GetId3Core();
        $getid3_temp->openfile($this->getid3->filename);
        $getid3_temp->info = $info;
        $getid3_riff = new Riff($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;
    }
}