<?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.ogg.php                                        //
// module for analyzing Ogg Vorbis, OggFLAC and Speex files    //
// dependencies: module.audio.flac.php                         //
//                                                            ///
/////////////////////////////////////////////////////////////////

getid3_lib::IncludeDependency(GETID3_INCLUDEPATH.'module.audio.flac.php', __FILE__, true);

class getid3_ogg
{

    function getid3_ogg(&$fd, &$ThisFileInfo) {

        $ThisFileInfo['fileformat'] = 'ogg';

        // Warn about illegal tags - only vorbiscomments are allowed
        if (isset($ThisFileInfo['id3v2'])) {
            $ThisFileInfo['warning'][] = 'Illegal ID3v2 tag present.';
        }
        if (isset($ThisFileInfo['id3v1'])) {
            $ThisFileInfo['warning'][] = 'Illegal ID3v1 tag present.';
        }
        if (isset($ThisFileInfo['ape'])) {
            $ThisFileInfo['warning'][] = 'Illegal APE tag present.';
        }


        // Page 1 - Stream Header

        fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);

        $oggpageinfo = getid3_ogg::ParseOggPageHeader($fd);
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']] = $oggpageinfo;

        if (ftell($fd) >= GETID3_FREAD_BUFFER_SIZE) {
            $ThisFileInfo['error'][] = 'Could not find start of Ogg page in the first '.GETID3_FREAD_BUFFER_SIZE.' bytes (this might not be an Ogg-Vorbis file?)';
            unset($ThisFileInfo['fileformat']);
            unset($ThisFileInfo['ogg']);
            return false;
        }

        $filedata = fread($fd, $oggpageinfo['page_length']);
        $filedataoffset = 0;

        if (substr($filedata, 0, 4) == 'fLaC') {

            $ThisFileInfo['audio']['dataformat']   = 'flac';
            $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
            $ThisFileInfo['audio']['lossless']     = true;

        } elseif (substr($filedata, 1, 6) == 'vorbis') {

            $ThisFileInfo['audio']['dataformat'] = 'vorbis';
            $ThisFileInfo['audio']['lossless']   = false;

            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['packet_type'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1));
            $filedataoffset += 1;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['stream_type'] = substr($filedata, $filedataoffset, 6); // hard-coded to 'vorbis'
            $filedataoffset += 6;
            $ThisFileInfo['ogg']['bitstreamversion'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['numberofchannels'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1));
            $filedataoffset += 1;
            $ThisFileInfo['audio']['channels']                = $ThisFileInfo['ogg']['numberofchannels'];
            $ThisFileInfo['ogg']['samplerate']       = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            if ($ThisFileInfo['ogg']['samplerate'] == 0) {
                $ThisFileInfo['error'][] = 'Corrupt Ogg file: sample rate == zero';
                return false;
            }
            $ThisFileInfo['audio']['sample_rate']               = $ThisFileInfo['ogg']['samplerate'];
            $ThisFileInfo['ogg']['samples']          = 0; // filled in later
            $ThisFileInfo['ogg']['bitrate_average']  = 0; // filled in later
            $ThisFileInfo['ogg']['bitrate_max']      = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['bitrate_nominal']  = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['bitrate_min']      = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['blocksize_small']  = pow(2,  getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1)) & 0x0F);
            $ThisFileInfo['ogg']['blocksize_large']  = pow(2, (getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1)) & 0xF0) >> 4);
            $ThisFileInfo['ogg']['stop_bit']         = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1)); // must be 1, marks end of packet

            $ThisFileInfo['audio']['bitrate_mode'] = 'vbr'; // overridden if actually abr
            if ($ThisFileInfo['ogg']['bitrate_max'] == 0xFFFFFFFF) {
                unset($ThisFileInfo['ogg']['bitrate_max']);
                $ThisFileInfo['audio']['bitrate_mode'] = 'abr';
            }
            if ($ThisFileInfo['ogg']['bitrate_nominal'] == 0xFFFFFFFF) {
                unset($ThisFileInfo['ogg']['bitrate_nominal']);
            }
            if ($ThisFileInfo['ogg']['bitrate_min'] == 0xFFFFFFFF) {
                unset($ThisFileInfo['ogg']['bitrate_min']);
                $ThisFileInfo['audio']['bitrate_mode'] = 'abr';
            }

        } elseif (substr($filedata, 0, 8) == 'Speex   ') {

            // http://www.speex.org/manual/node10.html

            $ThisFileInfo['audio']['dataformat']   = 'speex';
            $ThisFileInfo['mime_type']             = 'audio/speex';
            $ThisFileInfo['audio']['bitrate_mode'] = 'abr';
            $ThisFileInfo['audio']['lossless']     = false;

            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['speex_string']           =                  substr($filedata, $filedataoffset, 8); // hard-coded to 'Speex   '
            $filedataoffset += 8;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['speex_version']          =                  substr($filedata, $filedataoffset, 20);
            $filedataoffset += 20;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['speex_version_id']       = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['header_size']            = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['rate']                   = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['mode']                   = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['mode_bitstream_version'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['nb_channels']            = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['bitrate']                = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['framesize']              = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['vbr']                    = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['frames_per_packet']      = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['extra_headers']          = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['reserved1']              = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['reserved2']              = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
            $filedataoffset += 4;

            $ThisFileInfo['speex']['speex_version'] = trim($ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['speex_version']);
            $ThisFileInfo['speex']['sample_rate']   = $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['rate'];
            $ThisFileInfo['speex']['channels']      = $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['nb_channels'];
            $ThisFileInfo['speex']['vbr']           = (bool) $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['vbr'];
            $ThisFileInfo['speex']['band_type']     = getid3_ogg::SpeexBandModeLookup($ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['mode']);

            $ThisFileInfo['audio']['sample_rate']   = $ThisFileInfo['speex']['sample_rate'];
            $ThisFileInfo['audio']['channels']      = $ThisFileInfo['speex']['channels'];
            if ($ThisFileInfo['speex']['vbr']) {
                $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
            }

        } else {

            $ThisFileInfo['error'][] = 'Expecting either "Speex   " or "vorbis" identifier strings, found neither';
            unset($ThisFileInfo['ogg']);
            unset($ThisFileInfo['mime_type']);
            return false;

        }


        // Page 2 - Comment Header

        $oggpageinfo = getid3_ogg::ParseOggPageHeader($fd);
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']] = $oggpageinfo;

        switch ($ThisFileInfo['audio']['dataformat']) {

            case 'vorbis':
                $filedata = fread($fd, $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length']);
                $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['packet_type'] = getid3_lib::LittleEndian2Int(substr($filedata, 0, 1));
                $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['stream_type'] =                  substr($filedata, 1, 6); // hard-coded to 'vorbis'

                getid3_ogg::ParseVorbisCommentsFilepointer($fd, $ThisFileInfo);
                break;

            case 'flac':
                if (!getid3_flac::FLACparseMETAdata($fd, $ThisFileInfo)) {
                    $ThisFileInfo['error'][] = 'Failed to parse FLAC headers';
                    return false;
                }
                break;

            case 'speex':
                fseek($fd, $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length'], SEEK_CUR);
                getid3_ogg::ParseVorbisCommentsFilepointer($fd, $ThisFileInfo);
                break;

        }



        // Last Page - Number of Samples

        fseek($fd, max($ThisFileInfo['avdataend'] - GETID3_FREAD_BUFFER_SIZE, 0), SEEK_SET);
        $LastChunkOfOgg = strrev(fread($fd, GETID3_FREAD_BUFFER_SIZE));
        if ($LastOggSpostion = strpos($LastChunkOfOgg, 'SggO')) {
            fseek($fd, $ThisFileInfo['avdataend'] - ($LastOggSpostion + strlen('SggO')), SEEK_SET);
            $ThisFileInfo['avdataend'] = ftell($fd);
            $ThisFileInfo['ogg']['pageheader']['eos'] = getid3_ogg::ParseOggPageHeader($fd);
            $ThisFileInfo['ogg']['samples']   = $ThisFileInfo['ogg']['pageheader']['eos']['pcm_abs_position'];
            if ($ThisFileInfo['ogg']['samples'] == 0) {
                $ThisFileInfo['error'][] = 'Corrupt Ogg file: eos.number of samples == zero';
                return false;
            }
            $ThisFileInfo['ogg']['bitrate_average'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / ($ThisFileInfo['ogg']['samples'] / $ThisFileInfo['audio']['sample_rate']);
        }

        if (!empty($ThisFileInfo['ogg']['bitrate_average'])) {
            $ThisFileInfo['audio']['bitrate'] = $ThisFileInfo['ogg']['bitrate_average'];
        } elseif (!empty($ThisFileInfo['ogg']['bitrate_nominal'])) {
            $ThisFileInfo['audio']['bitrate'] = $ThisFileInfo['ogg']['bitrate_nominal'];
        } elseif (!empty($ThisFileInfo['ogg']['bitrate_min']) && !empty($ThisFileInfo['ogg']['bitrate_max'])) {
            $ThisFileInfo['audio']['bitrate'] = ($ThisFileInfo['ogg']['bitrate_min'] + $ThisFileInfo['ogg']['bitrate_max']) / 2;
        }
        if (isset($ThisFileInfo['audio']['bitrate']) && !isset($ThisFileInfo['playtime_seconds'])) {
            if ($ThisFileInfo['audio']['bitrate'] == 0) {
                $ThisFileInfo['error'][] = 'Corrupt Ogg file: bitrate_audio == zero';
                return false;
            }
            $ThisFileInfo['playtime_seconds'] = (float) ((($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / $ThisFileInfo['audio']['bitrate']);
        }

        if (isset($ThisFileInfo['ogg']['vendor'])) {
            $ThisFileInfo['audio']['encoder'] = preg_replace('/^Encoded with /', '', $ThisFileInfo['ogg']['vendor']);

            // Vorbis only
            if ($ThisFileInfo['audio']['dataformat'] == 'vorbis') {

                // Vorbis 1.0 starts with Xiph.Org
                if  (preg_match('/^Xiph.Org/', $ThisFileInfo['audio']['encoder'])) {

                    if ($ThisFileInfo['audio']['bitrate_mode'] == 'abr') {

                        // Set -b 128 on abr files
                        $ThisFileInfo['audio']['encoder_options'] = '-b '.round($ThisFileInfo['ogg']['bitrate_nominal'] / 1000);

                    } elseif (($ThisFileInfo['audio']['bitrate_mode'] == 'vbr') && ($ThisFileInfo['audio']['channels'] == 2) && ($ThisFileInfo['audio']['sample_rate'] >= 44100) && ($ThisFileInfo['audio']['sample_rate'] <= 48000)) {
                        // Set -q N on vbr files
                        $ThisFileInfo['audio']['encoder_options'] = '-q '.$this->get_quality_from_nominal_bitrate($ThisFileInfo['ogg']['bitrate_nominal']);

                    }
                }

                if (empty($ThisFileInfo['audio']['encoder_options']) && !empty($ThisFileInfo['ogg']['bitrate_nominal'])) {
                    $ThisFileInfo['audio']['encoder_options'] = 'Nominal bitrate: '.intval(round($ThisFileInfo['ogg']['bitrate_nominal'] / 1000)).'kbps';
                }
            }
        }

        return true;
    }


    function ParseOggPageHeader(&$fd) {
        // http://xiph.org/ogg/vorbis/doc/framing.html
        $oggheader['page_start_offset'] = ftell($fd); // where we started from in the file

        $filedata = fread($fd, GETID3_FREAD_BUFFER_SIZE);
        $filedataoffset = 0;
        while ((substr($filedata, $filedataoffset++, 4) != 'OggS')) {
            if ((ftell($fd) - $oggheader['page_start_offset']) >= GETID3_FREAD_BUFFER_SIZE) {
                // should be found before here
                return false;
            }
            if ((($filedataoffset + 28) > strlen($filedata)) || (strlen($filedata) < 28)) {
                if (feof($fd) || (($filedata .= fread($fd, GETID3_FREAD_BUFFER_SIZE)) === false)) {
                    // get some more data, unless eof, in which case fail
                    return false;
                }
            }
        }
        $filedataoffset += strlen('OggS') - 1; // page, delimited by 'OggS'

        $oggheader['stream_structver']  = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1));
        $filedataoffset += 1;
        $oggheader['flags_raw']         = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1));
        $filedataoffset += 1;
        $oggheader['flags']['fresh']    = (bool) ($oggheader['flags_raw'] & 0x01); // fresh packet
        $oggheader['flags']['bos']      = (bool) ($oggheader['flags_raw'] & 0x02); // first page of logical bitstream (bos)
        $oggheader['flags']['eos']      = (bool) ($oggheader['flags_raw'] & 0x04); // last page of logical bitstream (eos)

        $oggheader['pcm_abs_position']  = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 8));
        $filedataoffset += 8;
        $oggheader['stream_serialno']   = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $oggheader['page_seqno']        = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $oggheader['page_checksum']     = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $oggheader['page_segments']     = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1));
        $filedataoffset += 1;
        $oggheader['page_length'] = 0;
        for ($i = 0; $i < $oggheader['page_segments']; $i++) {
            $oggheader['segment_table'][$i] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset, 1));
            $filedataoffset += 1;
            $oggheader['page_length'] += $oggheader['segment_table'][$i];
        }
        $oggheader['header_end_offset'] = $oggheader['page_start_offset'] + $filedataoffset;
        $oggheader['page_end_offset']   = $oggheader['header_end_offset'] + $oggheader['page_length'];
        fseek($fd, $oggheader['header_end_offset'], SEEK_SET);

        return $oggheader;
    }


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

        $OriginalOffset = ftell($fd);
        $CommentStartOffset = $OriginalOffset;
        $commentdataoffset = 0;
        $VorbisCommentPage = 1;

        switch ($ThisFileInfo['audio']['dataformat']) {
            case 'vorbis':
                $CommentStartOffset = $ThisFileInfo['ogg']['pageheader'][$VorbisCommentPage]['page_start_offset'];  // Second Ogg page, after header block
                fseek($fd, $CommentStartOffset, SEEK_SET);
                $commentdataoffset = 27 + $ThisFileInfo['ogg']['pageheader'][$VorbisCommentPage]['page_segments'];
                $commentdata = fread($fd, getid3_ogg::OggPageSegmentLength($ThisFileInfo['ogg']['pageheader'][$VorbisCommentPage], 1) + $commentdataoffset);

                $commentdataoffset += (strlen('vorbis') + 1);
                break;

            case 'flac':
                fseek($fd, $ThisFileInfo['flac']['VORBIS_COMMENT']['raw']['offset'] + 4, SEEK_SET);
                $commentdata = fread($fd, $ThisFileInfo['flac']['VORBIS_COMMENT']['raw']['block_length']);
                break;

            case 'speex':
                $CommentStartOffset = $ThisFileInfo['ogg']['pageheader'][$VorbisCommentPage]['page_start_offset'];  // Second Ogg page, after header block
                fseek($fd, $CommentStartOffset, SEEK_SET);
                $commentdataoffset = 27 + $ThisFileInfo['ogg']['pageheader'][$VorbisCommentPage]['page_segments'];
                $commentdata = fread($fd, getid3_ogg::OggPageSegmentLength($ThisFileInfo['ogg']['pageheader'][$VorbisCommentPage], 1) + $commentdataoffset);
                break;

            default:
                return false;
                break;
        }

        $VendorSize = getid3_lib::LittleEndian2Int(substr($commentdata, $commentdataoffset, 4));
        $commentdataoffset += 4;

        $ThisFileInfo['ogg']['vendor'] = substr($commentdata, $commentdataoffset, $VendorSize);
        $commentdataoffset += $VendorSize;

        $CommentsCount = getid3_lib::LittleEndian2Int(substr($commentdata, $commentdataoffset, 4));
        $commentdataoffset += 4;
        $ThisFileInfo['avdataoffset'] = $CommentStartOffset + $commentdataoffset;

        $basicfields = array('TITLE', 'ARTIST', 'ALBUM', 'TRACKNUMBER', 'GENRE', 'DATE', 'DESCRIPTION', 'COMMENT');
        for ($i = 0; $i < $CommentsCount; $i++) {

            $ThisFileInfo['ogg']['comments_raw'][$i]['dataoffset'] = $CommentStartOffset + $commentdataoffset;

            if (ftell($fd) < ($ThisFileInfo['ogg']['comments_raw'][$i]['dataoffset'] + 4)) {
                $VorbisCommentPage++;

                $oggpageinfo = getid3_ogg::ParseOggPageHeader($fd);
                $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']] = $oggpageinfo;

                // First, save what we haven't read yet
                $AsYetUnusedData = substr($commentdata, $commentdataoffset);

                // Then take that data off the end
                $commentdata     = substr($commentdata, 0, $commentdataoffset);

                // Add [headerlength] bytes of dummy data for the Ogg Page Header, just to keep absolute offsets correct
                $commentdata .= str_repeat("\x00", 27 + $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_segments']);
                $commentdataoffset += (27 + $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_segments']);

                // Finally, stick the unused data back on the end
                $commentdata .= $AsYetUnusedData;

                //$commentdata .= fread($fd, $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length']);
                $commentdata .= fread($fd, getid3_ogg::OggPageSegmentLength($ThisFileInfo['ogg']['pageheader'][$VorbisCommentPage], 1));

            }
            $ThisFileInfo['ogg']['comments_raw'][$i]['size']       = getid3_lib::LittleEndian2Int(substr($commentdata, $commentdataoffset, 4));

            // replace avdataoffset with position just after the last vorbiscomment
            $ThisFileInfo['avdataoffset'] = $ThisFileInfo['ogg']['comments_raw'][$i]['dataoffset'] + $ThisFileInfo['ogg']['comments_raw'][$i]['size'] + 4;

            $commentdataoffset += 4;
            while ((strlen($commentdata) - $commentdataoffset) < $ThisFileInfo['ogg']['comments_raw'][$i]['size']) {
                if (($ThisFileInfo['ogg']['comments_raw'][$i]['size'] > $ThisFileInfo['avdataend']) || ($ThisFileInfo['ogg']['comments_raw'][$i]['size'] < 0)) {
                    $ThisFileInfo['error'][] = 'Invalid Ogg comment size (comment #'.$i.', claims to be '.number_format($ThisFileInfo['ogg']['comments_raw'][$i]['size']).' bytes) - aborting reading comments';
                    break 2;
                }

                $VorbisCommentPage++;

                $oggpageinfo = getid3_ogg::ParseOggPageHeader($fd);
                $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']] = $oggpageinfo;

                // First, save what we haven't read yet
                $AsYetUnusedData = substr($commentdata, $commentdataoffset);

                // Then take that data off the end
                $commentdata     = substr($commentdata, 0, $commentdataoffset);

                // Add [headerlength] bytes of dummy data for the Ogg Page Header, just to keep absolute offsets correct
                $commentdata .= str_repeat("\x00", 27 + $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_segments']);
                $commentdataoffset += (27 + $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_segments']);

                // Finally, stick the unused data back on the end
                $commentdata .= $AsYetUnusedData;

                //$commentdata .= fread($fd, $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length']);
                $commentdata .= fread($fd, getid3_ogg::OggPageSegmentLength($ThisFileInfo['ogg']['pageheader'][$VorbisCommentPage], 1));

                //$filebaseoffset += $oggpageinfo['header_end_offset'] - $oggpageinfo['page_start_offset'];
            }
            $commentstring = substr($commentdata, $commentdataoffset, $ThisFileInfo['ogg']['comments_raw'][$i]['size']);
            $commentdataoffset += $ThisFileInfo['ogg']['comments_raw'][$i]['size'];

            if (!$commentstring) {

                // no comment?
                $ThisFileInfo['warning'][] = 'Blank Ogg comment ['.$i.