public function Analyze()
 {
     $info =& $this->getid3->info;
     $info['fileformat'] = 'ogg';
     // Warn about illegal tags - only vorbiscomments are allowed
     if (isset($info['id3v2'])) {
         $info['warning'][] = 'Illegal ID3v2 tag present.';
     }
     if (isset($info['id3v1'])) {
         $info['warning'][] = 'Illegal ID3v1 tag present.';
     }
     if (isset($info['ape'])) {
         $info['warning'][] = 'Illegal APE tag present.';
     }
     // Page 1 - Stream Header
     $this->fseek($info['avdataoffset']);
     $oggpageinfo = $this->ParseOggPageHeader();
     $info['ogg']['pageheader'][$oggpageinfo['page_seqno']] = $oggpageinfo;
     if ($this->ftell() >= $this->getid3->fread_buffer_size()) {
         $info['error'][] = 'Could not find start of Ogg page in the first ' . $this->getid3->fread_buffer_size() . ' bytes (this might not be an Ogg-Vorbis file?)';
         unset($info['fileformat']);
         unset($info['ogg']);
         return false;
     }
     $filedata = $this->fread($oggpageinfo['page_length']);
     $filedataoffset = 0;
     if (substr($filedata, 0, 4) == 'fLaC') {
         $info['audio']['dataformat'] = 'flac';
         $info['audio']['bitrate_mode'] = 'vbr';
         $info['audio']['lossless'] = true;
     } elseif (substr($filedata, 1, 6) == 'vorbis') {
         $this->ParseVorbisPageHeader($filedata, $filedataoffset, $oggpageinfo);
     } elseif (substr($filedata, 0, 8) == 'Speex   ') {
         // http://www.speex.org/manual/node10.html
         $info['audio']['dataformat'] = 'speex';
         $info['mime_type'] = 'audio/speex';
         $info['audio']['bitrate_mode'] = 'abr';
         $info['audio']['lossless'] = false;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['speex_string'] = substr($filedata, $filedataoffset, 8);
         // hard-coded to 'Speex   '
         $filedataoffset += 8;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['speex_version'] = substr($filedata, $filedataoffset, 20);
         $filedataoffset += 20;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['speex_version_id'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['header_size'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['rate'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['mode'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['mode_bitstream_version'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['nb_channels'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['bitrate'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['framesize'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['vbr'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['frames_per_packet'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['extra_headers'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['reserved1'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['reserved2'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['speex']['speex_version'] = trim($info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['speex_version']);
         $info['speex']['sample_rate'] = $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['rate'];
         $info['speex']['channels'] = $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['nb_channels'];
         $info['speex']['vbr'] = (bool) $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['vbr'];
         $info['speex']['band_type'] = $this->SpeexBandModeLookup($info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['mode']);
         $info['audio']['sample_rate'] = $info['speex']['sample_rate'];
         $info['audio']['channels'] = $info['speex']['channels'];
         if ($info['speex']['vbr']) {
             $info['audio']['bitrate_mode'] = 'vbr';
         }
     } elseif (substr($filedata, 0, 7) == "€" . 'theora') {
         // http://www.theora.org/doc/Theora.pdf (section 6.2)
         $info['ogg']['pageheader']['theora']['theora_magic'] = substr($filedata, $filedataoffset, 7);
         // hard-coded to "\x80.'theora'
         $filedataoffset += 7;
         $info['ogg']['pageheader']['theora']['version_major'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 1));
         $filedataoffset += 1;
         $info['ogg']['pageheader']['theora']['version_minor'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 1));
         $filedataoffset += 1;
         $info['ogg']['pageheader']['theora']['version_revision'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 1));
         $filedataoffset += 1;
         $info['ogg']['pageheader']['theora']['frame_width_macroblocks'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 2));
         $filedataoffset += 2;
         $info['ogg']['pageheader']['theora']['frame_height_macroblocks'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 2));
         $filedataoffset += 2;
         $info['ogg']['pageheader']['theora']['resolution_x'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 3));
         $filedataoffset += 3;
         $info['ogg']['pageheader']['theora']['resolution_y'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 3));
         $filedataoffset += 3;
         $info['ogg']['pageheader']['theora']['picture_offset_x'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 1));
         $filedataoffset += 1;
         $info['ogg']['pageheader']['theora']['picture_offset_y'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 1));
         $filedataoffset += 1;
         $info['ogg']['pageheader']['theora']['frame_rate_numerator'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader']['theora']['frame_rate_denominator'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 4));
         $filedataoffset += 4;
         $info['ogg']['pageheader']['theora']['pixel_aspect_numerator'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 3));
         $filedataoffset += 3;
         $info['ogg']['pageheader']['theora']['pixel_aspect_denominator'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 3));
         $filedataoffset += 3;
         $info['ogg']['pageheader']['theora']['color_space_id'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 1));
         $filedataoffset += 1;
         $info['ogg']['pageheader']['theora']['nominal_bitrate'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 3));
         $filedataoffset += 3;
         $info['ogg']['pageheader']['theora']['flags'] = getid3_lib::BigEndian2Int(substr($filedata, $filedataoffset, 2));
         $filedataoffset += 2;
         $info['ogg']['pageheader']['theora']['quality'] = ($info['ogg']['pageheader']['theora']['flags'] & 0xfc00) >> 10;
         $info['ogg']['pageheader']['theora']['kfg_shift'] = ($info['ogg']['pageheader']['theora']['flags'] & 0x3e0) >> 5;
         $info['ogg']['pageheader']['theora']['pixel_format_id'] = ($info['ogg']['pageheader']['theora']['flags'] & 0x18) >> 3;
         $info['ogg']['pageheader']['theora']['reserved'] = ($info['ogg']['pageheader']['theora']['flags'] & 0x7) >> 0;
         // should be 0
         $info['ogg']['pageheader']['theora']['color_space'] = self::TheoraColorSpace($info['ogg']['pageheader']['theora']['color_space_id']);
         $info['ogg']['pageheader']['theora']['pixel_format'] = self::TheoraPixelFormat($info['ogg']['pageheader']['theora']['pixel_format_id']);
         $info['video']['dataformat'] = 'theora';
         $info['mime_type'] = 'video/ogg';
         //$info['audio']['bitrate_mode'] = 'abr';
         //$info['audio']['lossless']     = false;
         $info['video']['resolution_x'] = $info['ogg']['pageheader']['theora']['resolution_x'];
         $info['video']['resolution_y'] = $info['ogg']['pageheader']['theora']['resolution_y'];
         if ($info['ogg']['pageheader']['theora']['frame_rate_denominator'] > 0) {
             $info['video']['frame_rate'] = (double) $info['ogg']['pageheader']['theora']['frame_rate_numerator'] / $info['ogg']['pageheader']['theora']['frame_rate_denominator'];
         }
         if ($info['ogg']['pageheader']['theora']['pixel_aspect_denominator'] > 0) {
             $info['video']['pixel_aspect_ratio'] = (double) $info['ogg']['pageheader']['theora']['pixel_aspect_numerator'] / $info['ogg']['pageheader']['theora']['pixel_aspect_denominator'];
         }
         $info['warning'][] = 'Ogg Theora (v3) not fully supported in this version of getID3 [' . $this->getid3->version() . '] -- bitrate, playtime and all audio data are currently unavailable';
     } elseif (substr($filedata, 0, 8) == "fishead") {
         // Ogg Skeleton version 3.0 Format Specification
         // http://xiph.org/ogg/doc/skeleton.html
         $filedataoffset += 8;
         $info['ogg']['skeleton']['fishead']['raw']['version_major'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 2));
         $filedataoffset += 2;
         $info['ogg']['skeleton']['fishead']['raw']['version_minor'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 2));
         $filedataoffset += 2;
         $info['ogg']['skeleton']['fishead']['raw']['presentationtime_numerator'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 8));
         $filedataoffset += 8;
         $info['ogg']['skeleton']['fishead']['raw']['presentationtime_denominator'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 8));
         $filedataoffset += 8;
         $info['ogg']['skeleton']['fishead']['raw']['basetime_numerator'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 8));
         $filedataoffset += 8;
         $info['ogg']['skeleton']['fishead']['raw']['basetime_denominator'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 8));
         $filedataoffset += 8;
         $info['ogg']['skeleton']['fishead']['raw']['utc'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 20));
         $filedataoffset += 20;
         $info['ogg']['skeleton']['fishead']['version'] = $info['ogg']['skeleton']['fishead']['raw']['version_major'] . '.' . $info['ogg']['skeleton']['fishead']['raw']['version_minor'];
         $info['ogg']['skeleton']['fishead']['presentationtime'] = $info['ogg']['skeleton']['fishead']['raw']['presentationtime_numerator'] / $info['ogg']['skeleton']['fishead']['raw']['presentationtime_denominator'];
         $info['ogg']['skeleton']['fishead']['basetime'] = $info['ogg']['skeleton']['fishead']['raw']['basetime_numerator'] / $info['ogg']['skeleton']['fishead']['raw']['basetime_denominator'];
         $info['ogg']['skeleton']['fishead']['utc'] = $info['ogg']['skeleton']['fishead']['raw']['utc'];
         $counter = 0;
         do {
             $oggpageinfo = $this->ParseOggPageHeader();
             $info['ogg']['pageheader'][$oggpageinfo['page_seqno'] . '.' . $counter++] = $oggpageinfo;
             $filedata = $this->fread($oggpageinfo['page_length']);
             $this->fseek($oggpageinfo['page_end_offset']);
             if (substr($filedata, 0, 8) == "fisbone") {
                 $filedataoffset = 8;
                 $info['ogg']['skeleton']['fisbone']['raw']['message_header_offset'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
                 $filedataoffset += 4;
                 $info['ogg']['skeleton']['fisbone']['raw']['serial_number'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
                 $filedataoffset += 4;
                 $info['ogg']['skeleton']['fisbone']['raw']['number_header_packets'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
                 $filedataoffset += 4;
                 $info['ogg']['skeleton']['fisbone']['raw']['granulerate_numerator'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 8));
                 $filedataoffset += 8;
                 $info['ogg']['skeleton']['fisbone']['raw']['granulerate_denominator'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 8));
                 $filedataoffset += 8;
                 $info['ogg']['skeleton']['fisbone']['raw']['basegranule'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 8));
                 $filedataoffset += 8;
                 $info['ogg']['skeleton']['fisbone']['raw']['preroll'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
                 $filedataoffset += 4;
                 $info['ogg']['skeleton']['fisbone']['raw']['granuleshift'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1));
                 $filedataoffset += 1;
                 $info['ogg']['skeleton']['fisbone']['raw']['padding'] = substr($filedata, $filedataoffset, 3);
                 $filedataoffset += 3;
             } elseif (substr($filedata, 1, 6) == 'theora') {
                 $info['video']['dataformat'] = 'theora1';
                 $info['error'][] = 'Ogg Theora (v1) not correctly handled in this version of getID3 [' . $this->getid3->version() . ']';
                 //break;
             } elseif (substr($filedata, 1, 6) == 'vorbis') {
                 $this->ParseVorbisPageHeader($filedata, $filedataoffset, $oggpageinfo);
             } else {
                 $info['error'][] = 'unexpected';
                 //break;
             }
             //} while ($oggpageinfo['page_seqno'] == 0);
         } while ($oggpageinfo['page_seqno'] == 0 && substr($filedata, 0, 8) != "fisbone");
         $this->fseek($oggpageinfo['page_start_offset']);
         $info['error'][] = 'Ogg Skeleton not correctly handled in this version of getID3 [' . $this->getid3->version() . ']';
         //return false;
     } else {
         $info['error'][] = 'Expecting either "Speex   " or "vorbis" identifier strings, found "' . substr($filedata, 0, 8) . '"';
         unset($info['ogg']);
         unset($info['mime_type']);
         return false;
     }
     // Page 2 - Comment Header
     $oggpageinfo = $this->ParseOggPageHeader();
     $info['ogg']['pageheader'][$oggpageinfo['page_seqno']] = $oggpageinfo;
     switch ($info['audio']['dataformat']) {
         case 'vorbis':
             $filedata = $this->fread($info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length']);
             $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['packet_type'] = getid3_lib::LittleEndian2Int(substr($filedata, 0, 1));
             $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['stream_type'] = substr($filedata, 1, 6);
             // hard-coded to 'vorbis'
             $this->ParseVorbisComments();
             break;
         case 'flac':
             $flac = new getid3_flac($this->getid3);
             if (!$flac->parseMETAdata()) {
                 $info['error'][] = 'Failed to parse FLAC headers';
                 return false;
             }
             unset($flac);
             break;
         case 'speex':
             $this->fseek($info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length'], SEEK_CUR);
             $this->ParseVorbisComments();
             break;
     }
     // Last Page - Number of Samples
     if (!getid3_lib::intValueSupported($info['avdataend'])) {
         $info['warning'][] = 'Unable to parse Ogg end chunk file (PHP does not support file operations beyond ' . round(PHP_INT_MAX / 1073741824) . 'GB)';
     } else {
         $this->fseek(max($info['avdataend'] - $this->getid3->fread_buffer_size(), 0));
         $LastChunkOfOgg = strrev($this->fread($this->getid3->fread_buffer_size()));
         if ($LastOggSpostion = strpos($LastChunkOfOgg, 'SggO')) {
             $this->fseek($info['avdataend'] - ($LastOggSpostion + strlen('SggO')));
             $info['avdataend'] = $this->ftell();
             $info['ogg']['pageheader']['eos'] = $this->ParseOggPageHeader();
             $info['ogg']['samples'] = $info['ogg']['pageheader']['eos']['pcm_abs_position'];
             if ($info['ogg']['samples'] == 0) {
                 $info['error'][] = 'Corrupt Ogg file: eos.number of samples == zero';
                 return false;
             }
             if (!empty($info['audio']['sample_rate'])) {
                 $info['ogg']['bitrate_average'] = ($info['avdataend'] - $info['avdataoffset']) * 8 / ($info['ogg']['samples'] / $info['audio']['sample_rate']);
             }
         }
     }
     if (!empty($info['ogg']['bitrate_average'])) {
         $info['audio']['bitrate'] = $info['ogg']['bitrate_average'];
     } elseif (!empty($info['ogg']['bitrate_nominal'])) {
         $info['audio']['bitrate'] = $info['ogg']['bitrate_nominal'];
     } elseif (!empty($info['ogg']['bitrate_min']) && !empty($info['ogg']['bitrate_max'])) {
         $info['audio']['bitrate'] = ($info['ogg']['bitrate_min'] + $info['ogg']['bitrate_max']) / 2;
     }
     if (isset($info['audio']['bitrate']) && !isset($info['playtime_seconds'])) {
         if ($info['audio']['bitrate'] == 0) {
             $info['error'][] = 'Corrupt Ogg file: bitrate_audio == zero';
             return false;
         }
         $info['playtime_seconds'] = (double) (($info['avdataend'] - $info['avdataoffset']) * 8 / $info['audio']['bitrate']);
     }
     if (isset($info['ogg']['vendor'])) {
         $info['audio']['encoder'] = preg_replace('/^Encoded with /', '', $info['ogg']['vendor']);
         // Vorbis only
         if ($info['audio']['dataformat'] == 'vorbis') {
             // Vorbis 1.0 starts with Xiph.Org
             if (preg_match('/^Xiph.Org/', $info['audio']['encoder'])) {
                 if ($info['audio']['bitrate_mode'] == 'abr') {
                     // Set -b 128 on abr files
                     $info['audio']['encoder_options'] = '-b ' . round($info['ogg']['bitrate_nominal'] / 1000);
                 } elseif ($info['audio']['bitrate_mode'] == 'vbr' && $info['audio']['channels'] == 2 && $info['audio']['sample_rate'] >= 44100 && $info['audio']['sample_rate'] <= 48000) {
                     // Set -q N on vbr files
                     $info['audio']['encoder_options'] = '-q ' . $this->get_quality_from_nominal_bitrate($info['ogg']['bitrate_nominal']);
                 }
             }
             if (empty($info['audio']['encoder_options']) && !empty($info['ogg']['bitrate_nominal'])) {
                 $info['audio']['encoder_options'] = 'Nominal bitrate: ' . intval(round($info['ogg']['bitrate_nominal'] / 1000)) . 'kbps';
             }
         }
     }
     return true;
 }