function getFLACHeaderFilepointer(&$fd, &$ThisFileInfo)
{
    // http://flac.sourceforge.net/format.html
    fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);
    $StreamMarker = fread($fd, 4);
    if ($StreamMarker != 'fLaC') {
        $ThisFileInfo['error'] .= "\n" . 'Invalid stream_marker - expected "fLaC", found "' . $StreamMarker . '"';
        return false;
    }
    $ThisFileInfo['fileformat'] = 'flac';
    $ThisFileInfo['audio']['dataformat'] = 'flac';
    $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
    return FLACparseMETAdata($fd, $ThisFileInfo);
}
function getOggHeaderFilepointer(&$fd, &$ThisFileInfo)
{
    $ThisFileInfo['fileformat'] = 'ogg';
    // Warn about illegal tags - only vorbiscomments are allowed
    if (isset($ThisFileInfo['id3v2'])) {
        $ThisFileInfo['warning'] .= "\n" . 'Illegal ID3v2 tag present.';
    }
    if (isset($ThisFileInfo['id3v1'])) {
        $ThisFileInfo['warning'] .= "\n" . 'Illegal ID3v1 tag present.';
    }
    if (isset($ThisFileInfo['ape'])) {
        $ThisFileInfo['warning'] .= "\n" . 'Illegal APE tag present.';
    }
    // Page 1 - Stream Header
    fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);
    $oggpageinfo = ParseOggPageHeader($fd);
    $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']] = $oggpageinfo;
    if (ftell($fd) >= FREAD_BUFFER_SIZE) {
        $ThisFileInfo['error'] .= "\n" . 'Could not find start of Ogg page in the first ' . FREAD_BUFFER_SIZE . ' bytes (this might not be an Ogg-Vorbis file?)';
        unset($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';
        $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
    } elseif (substr($filedata, 1, 6) == 'vorbis') {
        $ThisFileInfo['audio']['dataformat'] = 'vorbis';
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['packet_type'] = 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;
        $ThisFileInfo['ogg']['bitstreamversion'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['numberofchannels'] = LittleEndian2Int(substr($filedata, $filedataoffset, 1));
        $filedataoffset += 1;
        $ThisFileInfo['audio']['channels'] = $ThisFileInfo['ogg']['numberofchannels'];
        $ThisFileInfo['ogg']['samplerate'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        if ($ThisFileInfo['ogg']['samplerate'] == 0) {
            $ThisFileInfo['error'] .= "\n" . '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
        $ThisFileInfo['ogg']['bitrate_max'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['bitrate_nominal'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['bitrate_min'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['blocksize_small'] = pow(2, LittleEndian2Int(substr($filedata, $filedataoffset, 1)) & 0xf);
        $ThisFileInfo['ogg']['blocksize_large'] = pow(2, (LittleEndian2Int(substr($filedata, $filedataoffset, 1)) & 0xf0) >> 4);
        $ThisFileInfo['ogg']['stop_bit'] = LittleEndian2Int(substr($filedata, $filedataoffset, 1));
        // must be 1, marks end of packet
        $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
        // overridden if actually abr
        if ($ThisFileInfo['ogg']['bitrate_max'] == 4294967295.0) {
            unset($ThisFileInfo['ogg']['bitrate_max']);
            $ThisFileInfo['audio']['bitrate_mode'] = 'abr';
        }
        if ($ThisFileInfo['ogg']['bitrate_nominal'] == 4294967295.0) {
            unset($ThisFileInfo['ogg']['bitrate_nominal']);
        }
        if ($ThisFileInfo['ogg']['bitrate_min'] == 4294967295.0) {
            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';
        $ThisFileInfo['ogg']['pageheader'][$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'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['header_size'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['rate'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['mode'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['mode_bitstream_version'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['nb_channels'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['bitrate'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['framesize'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['vbr'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['frames_per_packet'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['extra_headers'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['reserved1'] = LittleEndian2Int(substr($filedata, $filedataoffset, 4));
        $filedataoffset += 4;
        $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['reserved2'] = 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'];
        $ThisFileInfo['speex']['band_type'] = SpeexBandModeLookup($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 {
        $ThisFileInfo['error'] .= "\n" . 'Expecting either "Speex   " or "vorbis" identifier strings, found neither';
        unset($ThisFileInfo['ogg']);
        unset($ThisFileInfo['mime_type']);
        return false;
    }
    // Page 2 - Comment Header
    $oggpageinfo = ParseOggPageHeader($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'] = LittleEndian2Int(substr($filedata, 0, 1));
            $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['stream_type'] = substr($filedata, 1, 6);
            // hard-coded to 'vorbis'
            ParseVorbisCommentsFilepointer($fd, $ThisFileInfo);
            break;
        case 'flac':
            require_once GETID3_INCLUDEPATH . 'getid3.flac.php';
            if (!FLACparseMETAdata($fd, $ThisFileInfo)) {
                $ThisFileInfo['error'] .= "\n" . 'Failed to parse FLAC headers';
                return false;
            }
            break;
        case 'speex':
            fseek($fd, $ThisFileInfo['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length'], SEEK_CUR);
            ParseVorbisCommentsFilepointer($fd, $ThisFileInfo);
            break;
    }
    // Last Page - Number of Samples
    fseek($fd, max($ThisFileInfo['avdataend'] - FREAD_BUFFER_SIZE, 0), SEEK_SET);
    $LastChunkOfOgg = strrev(fread($fd, FREAD_BUFFER_SIZE));
    if ($LastOggSpostion = strpos($LastChunkOfOgg, 'SggO')) {
        fseek($fd, 0 - ($LastOggSpostion + strlen('SggO')), SEEK_END);
        $ThisFileInfo['avdataend'] = ftell($fd);
        $ThisFileInfo['ogg']['pageheader']['eos'] = ParseOggPageHeader($fd);
        $ThisFileInfo['ogg']['samples'] = $ThisFileInfo['ogg']['pageheader']['eos']['pcm_abs_position'];
        if ($ThisFileInfo['ogg']['samples'] == 0) {
            $ThisFileInfo['error'] .= "\n" . 'Corrupt Ogg file: eos.number of samples == zero';
            return false;
        }
        $ThisFileInfo['ogg']['bitrate_average'] = ($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8 / ($ThisFileInfo['ogg']['samples'] / $ThisFileInfo['audio']['sample_rate']);
    }
    if (isset($ThisFileInfo['ogg']['bitrate_average']) && $ThisFileInfo['ogg']['bitrate_average'] > 0) {
        $ThisFileInfo['audio']['bitrate'] = $ThisFileInfo['ogg']['bitrate_average'];
    } elseif (isset($ThisFileInfo['ogg']['bitrate_nominal']) && $ThisFileInfo['ogg']['bitrate_nominal'] > 0) {
        $ThisFileInfo['audio']['bitrate'] = $ThisFileInfo['ogg']['bitrate_nominal'];
    } elseif (isset($ThisFileInfo['ogg']['bitrate_min']) && isset($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'] .= "\n" . 'Corrupt Ogg file: bitrate_audio == zero';
            return false;
        }
        $ThisFileInfo['playtime_seconds'] = (double) (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8 / $ThisFileInfo['audio']['bitrate']);
    }
    if (isset($ThisFileInfo['ogg']['vendor'])) {
        $ThisFileInfo['audio']['encoder'] = preg_replace('/^Encoded with /', '', $ThisFileInfo['ogg']['vendor']);
    }
    return true;
}