source: extensions/charlies_content/getid3/getid3/module.audio.au.php

<?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.au.php                                         //
// module for analyzing AU files                               //
// dependencies: NONE                                          //
//                                                            ///
/////////////////////////////////////////////////////////////////


class getid3_au
{

        function getid3_au(&$fd, &$ThisFileInfo) {

                fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);
                $AUheader  = fread($fd, 8);

                if (substr($AUheader, 0, 4) != '.snd') {
                        $ThisFileInfo['error'][] = 'Expecting ".snd" at offset '.$ThisFileInfo['avdataoffset'].', found "'.substr($AUheader, 0, 4).'"';
                        return false;
                }

                // shortcut
                $ThisFileInfo['au'] = array();
                $thisfile_au        = &$ThisFileInfo['au'];

                $ThisFileInfo['fileformat']            = 'au';
                $ThisFileInfo['audio']['dataformat']   = 'au';
                $ThisFileInfo['audio']['bitrate_mode'] = 'cbr';
                $thisfile_au['encoding']               = 'ISO-8859-1';

                $thisfile_au['header_length']   = getid3_lib::BigEndian2Int(substr($AUheader,  4, 4));
                $AUheader .= fread($fd, $thisfile_au['header_length'] - 8);
                $ThisFileInfo['avdataoffset'] += $thisfile_au['header_length'];

                $thisfile_au['data_size']             = getid3_lib::BigEndian2Int(substr($AUheader,  8, 4));
                $thisfile_au['data_format_id']        = getid3_lib::BigEndian2Int(substr($AUheader, 12, 4));
                $thisfile_au['sample_rate']           = getid3_lib::BigEndian2Int(substr($AUheader, 16, 4));
                $thisfile_au['channels']              = getid3_lib::BigEndian2Int(substr($AUheader, 20, 4));
                $thisfile_au['comments']['comment'][] =                      trim(substr($AUheader, 24));

                $thisfile_au['data_format'] = $this->AUdataFormatNameLookup($thisfile_au['data_format_id']);
                $thisfile_au['used_bits_per_sample'] = $this->AUdataFormatUsedBitsPerSampleLookup($thisfile_au['data_format_id']);
                if ($thisfile_au['bits_per_sample'] = $this->AUdataFormatBitsPerSampleLookup($thisfile_au['data_format_id'])) {
                        $ThisFileInfo['audio']['bits_per_sample'] = $thisfile_au['bits_per_sample'];
                } else {
                        unset($thisfile_au['bits_per_sample']);
                }

                $ThisFileInfo['audio']['sample_rate']  = $thisfile_au['sample_rate'];
                $ThisFileInfo['audio']['channels']     = $thisfile_au['channels'];

                if (($ThisFileInfo['avdataoffset'] + $thisfile_au['data_size']) > $ThisFileInfo['avdataend']) {
                        $ThisFileInfo['warning'][] = 'Possible truncated file - expecting "'.$thisfile_au['data_size'].'" bytes of audio data, only found '.($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']).' bytes"';
                }

                $ThisFileInfo['playtime_seconds'] = $thisfile_au['data_size'] / ($thisfile_au['sample_rate'] * $thisfile_au['channels'] * ($thisfile_au['used_bits_per_sample'] / 8));
                $ThisFileInfo['audio']['bitrate'] = ($thisfile_au['data_size'] * 8) / $ThisFileInfo['playtime_seconds'];

                return true;
        }

        function AUdataFormatNameLookup($id) {
                static $AUdataFormatNameLookup = array(
                        0  => 'unspecified format',
                        1  => '8-bit mu-law',
                        2  => '8-bit linear',
                        3  => '16-bit linear',
                        4  => '24-bit linear',
                        5  => '32-bit linear',
                        6  => 'floating-point',
                        7  => 'double-precision float',
                        8  => 'fragmented sampled data',
                        9  => 'SUN_FORMAT_NESTED',
                        10 => 'DSP program',
                        11 => '8-bit fixed-point',
                        12 => '16-bit fixed-point',
                        13 => '24-bit fixed-point',
                        14 => '32-bit fixed-point',

                        16 => 'non-audio display data',
                        17 => 'SND_FORMAT_MULAW_SQUELCH',
                        18 => '16-bit linear with emphasis',
                        19 => '16-bit linear with compression',
                        20 => '16-bit linear with emphasis + compression',
                        21 => 'Music Kit DSP commands',
                        22 => 'SND_FORMAT_DSP_COMMANDS_SAMPLES',
                        23 => 'CCITT g.721 4-bit ADPCM',
                        24 => 'CCITT g.722 ADPCM',
                        25 => 'CCITT g.723 3-bit ADPCM',
                        26 => 'CCITT g.723 5-bit ADPCM',
                        27 => 'A-Law 8-bit'
                );
                return (isset($AUdataFormatNameLookup[$id]) ? $AUdataFormatNameLookup[$id] : false);
        }

        function AUdataFormatBitsPerSampleLookup($id) {
                static $AUdataFormatBitsPerSampleLookup = array(
                        1  => 8,
                        2  => 8,
                        3  => 16,
                        4  => 24,
                        5  => 32,
                        6  => 32,
                        7  => 64,

                        11 => 8,
                        12 => 16,
                        13 => 24,
                        14 => 32,

                        18 => 16,
                        19 => 16,
                        20 => 16,

                        23 => 16,

                        25 => 16,
                        26 => 16,
                        27 => 8
                );
                return (isset($AUdataFormatBitsPerSampleLookup[$id]) ? $AUdataFormatBitsPerSampleLookup[$id] : false);
        }

        function AUdataFormatUsedBitsPerSampleLookup($id) {
                static $AUdataFormatUsedBitsPerSampleLookup = array(
                        1  => 8,
                        2  => 8,
                        3  => 16,
                        4  => 24,
                        5  => 32,
                        6  => 32,
                        7  => 64,

                        11 => 8,
                        12 => 16,
                        13 => 24,
                        14 => 32,

                        18 => 16,
                        19 => 16,
                        20 => 16,

                        23 => 4,

                        25 => 3,
                        26 => 5,
                        27 => 8,
                );
                return (isset($AUdataFormatUsedBitsPerSampleLookup[$id]) ? $AUdataFormatUsedBitsPerSampleLookup[$id] : false);
        }

}


?>