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<?php

/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <info@getid3.org>               //
//  available at https://github.com/JamesHeinrich/getID3       //
//            or https://www.getid3.org                        //
//            or http://getid3.sourceforge.net                 //
//  see readme.txt for more details                            //
/////////////////////////////////////////////////////////////////
//                                                             //
// module.audio.ogg.php                                        //
// module for analyzing Ogg Vorbis, OggFLAC and Speex files    //
// dependencies: module.audio.flac.php                         //
//                                                            ///
/////////////////////////////////////////////////////////////////

if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers
	exit;
}
getid3_lib::IncludeDependency(GETID3_INCLUDEPATH.'module.audio.flac.php', __FILE__, true);

class getid3_ogg extends getid3_handler
{
	/**
	 * @link http://xiph.org/vorbis/doc/Vorbis_I_spec.html
	 *
	 * @return bool
	 */
	public function Analyze() {
		$info = &$this->getid3->info;

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

		// Warn about illegal tags - only vorbiscomments are allowed
		if (isset($info['id3v2'])) {
			$this->warning('Illegal ID3v2 tag present.');
		}
		if (isset($info['id3v1'])) {
			$this->warning('Illegal ID3v1 tag present.');
		}
		if (isset($info['ape'])) {
			$this->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()) {
			$this->error('Could not find start of Ogg page in the first '.$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) == 'OpusHead') {

			if ($this->ParseOpusPageHeader($filedata, $filedataoffset, $oggpageinfo) === false) {
				return false;
			}

		} 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) == "\x80".'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'] & 0x03E0) >>  5;
			$info['ogg']['pageheader']['theora']['pixel_format_id'] = ($info['ogg']['pageheader']['theora']['flags'] & 0x0018) >>  3;
			$info['ogg']['pageheader']['theora']['reserved']        = ($info['ogg']['pageheader']['theora']['flags'] & 0x0007) >>  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'] = (float) $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'] = (float) $info['ogg']['pageheader']['theora']['pixel_aspect_numerator'] / $info['ogg']['pageheader']['theora']['pixel_aspect_denominator'];
			}
$this->warning('Ogg Theora (v3) not fully supported in this version of getID3 ['.$this->getid3->version().'] -- bitrate, playtime and all audio data are currently unavailable');


		} elseif (substr($filedata, 0, 8) == "fishead\x00") {

			// 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'];
			$info['ogg']['skeleton']['fishead']['presentationtime'] = getid3_lib::SafeDiv($info['ogg']['skeleton']['fishead']['raw']['presentationtime_numerator'], $info['ogg']['skeleton']['fishead']['raw']['presentationtime_denominator']);
			$info['ogg']['skeleton']['fishead']['basetime']         = getid3_lib::SafeDiv($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\x00") {

					$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';
					$this->error('Ogg Theora (v1) not correctly handled in this version of getID3 ['.$this->getid3->version().']');
					//break;

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

					$this->ParseVorbisPageHeader($filedata, $filedataoffset, $oggpageinfo);

				} else {
					$this->error('unexpected');
					//break;
				}
			//} while ($oggpageinfo['page_seqno'] == 0);
			} while (($oggpageinfo['page_seqno'] == 0) && (substr($filedata, 0, 8) != "fisbone\x00"));

			$this->fseek($oggpageinfo['page_start_offset']);

			$this->error('Ogg Skeleton not correctly handled in this version of getID3 ['.$this->getid3->version().']');
			//return false;

		} elseif (substr($filedata, 0, 5) == "\x7F".'FLAC') {
			// https://xiph.org/flac/ogg_mapping.html

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

			$info['ogg']['flac']['header']['version_major']  =                         ord(substr($filedata,  5, 1));
			$info['ogg']['flac']['header']['version_minor']  =                         ord(substr($filedata,  6, 1));
			$info['ogg']['flac']['header']['header_packets'] =   getid3_lib::BigEndian2Int(substr($filedata,  7, 2)) + 1; // "A two-byte, big-endian binary number signifying the number of header (non-audio) packets, not including this one. This number may be zero (0x0000) to signify 'unknown' but be aware that some decoders may not be able to handle such streams."
			$info['ogg']['flac']['header']['magic']          =                             substr($filedata,  9, 4);
			if ($info['ogg']['flac']['header']['magic'] != 'fLaC') {
				$this->error('Ogg-FLAC expecting "fLaC", found "'.$info['ogg']['flac']['header']['magic'].'" ('.trim(getid3_lib::PrintHexBytes($info['ogg']['flac']['header']['magic'])).')');
				return false;
			}
			$info['ogg']['flac']['header']['STREAMINFO_bytes'] = getid3_lib::BigEndian2Int(substr($filedata, 13, 4));
			$info['flac']['STREAMINFO'] = getid3_flac::parseSTREAMINFOdata(substr($filedata, 17, 34));
			if (!empty($info['flac']['STREAMINFO']['sample_rate'])) {
				$info['audio']['bitrate_mode']    = 'vbr';
				$info['audio']['sample_rate']     = $info['flac']['STREAMINFO']['sample_rate'];
				$info['audio']['channels']        = $info['flac']['STREAMINFO']['channels'];
				$info['audio']['bits_per_sample'] = $info['flac']['STREAMINFO']['bits_per_sample'];
				$info['playtime_seconds']         = getid3_lib::SafeDiv($info['flac']['STREAMINFO']['samples_stream'], $info['flac']['STREAMINFO']['sample_rate']);
			}

		} else {

			$this->error('Expecting one of "vorbis", "Speex", "OpusHead", "vorbis", "fishhead", "theora", "fLaC" identifier strings, found "'.substr($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()) {
					$this->error('Failed to parse FLAC headers');
					return false;
				}
				unset($flac);
				break;

			case 'speex':
				$this->fseek($info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length'], SEEK_CUR);
				$this->ParseVorbisComments();
				break;

			case 'opus':
				$filedata = $this->fread($info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length']);
				$info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['stream_type'] = substr($filedata, 0, 8); // hard-coded to 'OpusTags'
				if(substr($filedata, 0, 8)  != 'OpusTags') {
					$this->error('Expected "OpusTags" as header but got "'.substr($filedata, 0, 8).'"');
					return false;
				}

				$this->ParseVorbisComments();
				break;

		}

		// Last Page - Number of Samples
		if (!getid3_lib::intValueSupported($info['avdataend'])) {

			$this->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($LastChunkOfOgg, 'SggO')) {
				if (substr($LastChunkOfOgg, 13, 8) === "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF") {
					// https://github.com/JamesHeinrich/getID3/issues/450
					// "Sometimes, Opus encoders (WhatsApp voice registrations and others) add a special last header with a granule duration of 0xFFFFFFFFFFFFFF.
					// This value indicates "this is the end," but must be ignored; otherwise, it makes calculations wrong."
					$LastOggSpostion = strpos($LastChunkOfOgg, 'SggO', $LastOggSpostion + 1);
				}
				$this->fseek($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) {
					$this->error('Corrupt Ogg file: eos.number of samples == zero');
					return false;
				}
				if (!empty($info['audio']['sample_rate'])) {
					$info['ogg']['bitrate_average'] = (($info['avdataend'] - $info['avdataoffset']) * 8) * $info['audio']['sample_rate'] / $info['ogg']['samples'];
				}
			}

		}

		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) {
				$this->error('Corrupt Ogg file: bitrate_audio == zero');
				return false;
			}
			$info['playtime_seconds'] = (float) ((($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;
	}

	/**
	 * @param string $filedata
	 * @param int    $filedataoffset
	 * @param array  $oggpageinfo
	 *
	 * @return bool
	 */
	public function ParseVorbisPageHeader(&$filedata, &$filedataoffset, &$oggpageinfo) {
		$info = &$this->getid3->info;
		$info['audio']['dataformat'] = 'vorbis';
		$info['audio']['lossless']   = false;

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

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

	/**
	 * @link http://tools.ietf.org/html/draft-ietf-codec-oggopus-03
	 *
	 * @param string $filedata
	 * @param int    $filedataoffset
	 * @param array  $oggpageinfo
	 *
	 * @return bool
	 */
	public function ParseOpusPageHeader(&$filedata, &$filedataoffset, &$oggpageinfo) {
		$info = &$this->getid3->info;
		$info['audio']['dataformat']   = 'opus';
		$info['mime_type']             = 'audio/ogg; codecs=opus';

		/** @todo find a usable way to detect abr (vbr that is padded to be abr) */
		$info['audio']['bitrate_mode'] = 'vbr';

		$info['audio']['lossless']     = false;

		$info['ogg']['pageheader']['opus']['opus_magic'] = substr($filedata, $filedataoffset, 8); // hard-coded to 'OpusHead'
		$filedataoffset += 8;
		$info['ogg']['pageheader']['opus']['version']    = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  1));
		$filedataoffset += 1;

		if ($info['ogg']['pageheader']['opus']['version'] < 1 || $info['ogg']['pageheader']['opus']['version'] > 15) {
			$this->error('Unknown opus version number (only accepting 1-15)');
			return false;
		}

		$info['ogg']['pageheader']['opus']['out_channel_count'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  1));
		$filedataoffset += 1;

		if ($info['ogg']['pageheader']['opus']['out_channel_count'] == 0) {
			$this->error('Invalid channel count in opus header (must not be zero)');
			return false;
		}

		$info['ogg']['pageheader']['opus']['pre_skip'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  2));
		$filedataoffset += 2;

		$info['ogg']['pageheader']['opus']['input_sample_rate'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  4));
		$filedataoffset += 4;

		//$info['ogg']['pageheader']['opus']['output_gain'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  2));
		//$filedataoffset += 2;

		//$info['ogg']['pageheader']['opus']['channel_mapping_family'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  1));
		//$filedataoffset += 1;

		$info['opus']['opus_version']       = $info['ogg']['pageheader']['opus']['version'];
		$info['opus']['sample_rate_input']  = $info['ogg']['pageheader']['opus']['input_sample_rate'];
		$info['opus']['out_channel_count']  = $info['ogg']['pageheader']['opus']['out_channel_count'];

		$info['audio']['channels']          = $info['opus']['out_channel_count'];
		$info['audio']['sample_rate_input'] = $info['opus']['sample_rate_input'];
		$info['audio']['sample_rate']       = 48000; // "All Opus audio is coded at 48 kHz, and should also be decoded at 48 kHz for playback (unless the target hardware does not support this sampling rate). However, this field may be used to resample the audio back to the original sampling rate, for example, when saving the output to a file." -- https://mf4.xiph.org/jenkins/view/opus/job/opusfile-unix/ws/doc/html/structOpusHead.html
		return true;
	}

	/**
	 * @return array|false
	 */
	public function ParseOggPageHeader() {
		// http://xiph.org/ogg/vorbis/doc/framing.html
		$oggheader = array();
		$oggheader['page_start_offset'] = $this->ftell(); // where we started from in the file

		$filedata = $this->fread($this->getid3->fread_buffer_size());
		$filedataoffset = 0;
		while (substr($filedata, $filedataoffset++, 4) != 'OggS') {
			if (($this->ftell() - $oggheader['page_start_offset']) >= $this->getid3->fread_buffer_size()) {
				// should be found before here
				return false;
			}
			if (($filedataoffset + 28) > strlen($filedata)) {
				if ($this->feof() || (($filedata .= $this->fread($this->getid3->fread_buffer_size())) === '')) {
					// 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'];
		$this->fseek($oggheader['header_end_offset']);

		return $oggheader;
	}

	/**
	 * @link http://xiph.org/vorbis/doc/Vorbis_I_spec.html#x1-810005
	 *
	 * @return bool
	 */
	public function ParseVorbisComments() {
		$info = &$this->getid3->info;

		$OriginalOffset = $this->ftell();
		$commentdata = null;
		$commentdataoffset = 0;
		$VorbisCommentPage = 1;
		$CommentStartOffset = 0;

		switch ($info['audio']['dataformat']) {
			case 'vorbis':
			case 'speex':
			case 'opus':
				$CommentStartOffset = $info['ogg']['pageheader'][$VorbisCommentPage]['page_start_offset'];  // Second Ogg page, after header block
				$this->fseek($CommentStartOffset);
				$commentdataoffset = 27 + $info['ogg']['pageheader'][$VorbisCommentPage]['page_segments'];
				$commentdata = $this->fread(self::OggPageSegmentLength($info['ogg']['pageheader'][$VorbisCommentPage], 1) + $commentdataoffset);

				if ($info['audio']['dataformat'] == 'vorbis') {
					$commentdataoffset += (strlen('vorbis') + 1);
				}
				else if ($info['audio']['dataformat'] == 'opus') {
					$commentdataoffset += strlen('OpusTags');
				}

				break;

			case 'flac':
				$CommentStartOffset = $info['flac']['VORBIS_COMMENT']['raw']['offset'] + 4;
				$this->fseek($CommentStartOffset);
				$commentdata = $this->fread($info['flac']['VORBIS_COMMENT']['raw']['block_length']);
				break;

			default:
				return false;
		}

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

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

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

		$basicfields = array('TITLE', 'ARTIST', 'ALBUM', 'TRACKNUMBER', 'GENRE', 'DATE', 'DESCRIPTION', 'COMMENT');
		$ThisFileInfo_ogg_comments_raw = &$info['ogg']['comments_raw'];
		for ($i = 0; $i < $CommentsCount; $i++) {

			if ($i >= 10000) {
				// https://github.com/owncloud/music/issues/212#issuecomment-43082336
				$this->warning('Unexpectedly large number ('.$CommentsCount.') of Ogg comments - breaking after reading '.$i.' comments');
				break;
			}

			$ThisFileInfo_ogg_comments_raw[$i]['dataoffset'] = $CommentStartOffset + $commentdataoffset;

			if ($this->ftell() < ($ThisFileInfo_ogg_comments_raw[$i]['dataoffset'] + 4)) {
				if ($oggpageinfo = $this->ParseOggPageHeader()) {
					$info['ogg']['pageheader'][$oggpageinfo['page_seqno']] = $oggpageinfo;

					$VorbisCommentPage++;

					// 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 + $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_segments']);
					$commentdataoffset += (27 + $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_segments']);

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

					//$commentdata .= $this->fread($info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length']);
					$commentdata .= $this->fread($this->OggPageSegmentLength($info['ogg']['pageheader'][$VorbisCommentPage], 1));
				}

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

			// replace avdataoffset with position just after the last vorbiscomment
			$info['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'] > $info['avdataend']) || ($ThisFileInfo_ogg_comments_raw[$i]['size'] < 0)) {
					$this->warning('Invalid Ogg comment size (comment #'.$i.', claims to be '.number_format($ThisFileInfo_ogg_comments_raw[$i]['size']).' bytes) - aborting reading comments');
					break 2;
				}

				$VorbisCommentPage++;

				if ($oggpageinfo = $this->ParseOggPageHeader()) {
					$info['ogg']['pageheader'][$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 + $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_segments']);
					$commentdataoffset += (27 + $info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_segments']);

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

					//$commentdata .= $this->fread($info['ogg']['pageheader'][$oggpageinfo['page_seqno']]['page_length']);
					if (!isset($info['ogg']['pageheader'][$VorbisCommentPage])) {
						$this->warning('undefined Vorbis Comment page "'.$VorbisCommentPage.'" at offset '.$this->ftell());
						break;
					}
					$readlength = self::OggPageSegmentLength($info['ogg']['pageheader'][$VorbisCommentPage], 1);
					if ($readlength <= 0) {
						$this->warning('invalid length Vorbis Comment page "'.$VorbisCommentPage.'" at offset '.$this->ftell());
						break;
					}
					$commentdata .= $this->fread($readlength);

					//$filebaseoffset += $oggpageinfo['header_end_offset'] - $oggpageinfo['page_start_offset'];
				} else {
					$this->warning('failed to ParseOggPageHeader() at offset '.$this->ftell());
					break;
				}
			}
			$ThisFileInfo_ogg_comments_raw[$i]['offset'] = $commentdataoffset;
			$commentstring = substr($commentdata, $commentdataoffset, $ThisFileInfo_ogg_comments_raw[$i]['size']);
			$commentdataoffset += $ThisFileInfo_ogg_comments_raw[$i]['size'];

			if (!$commentstring) {

				// no comment?
				$this->warning('Blank Ogg comment ['.$i.']');

			} elseif (strstr($commentstring, '=')) {

				$commentexploded = explode('=', $commentstring, 2);
				$ThisFileInfo_ogg_comments_raw[$i]['key']   = strtoupper($commentexploded[0]);
				$ThisFileInfo_ogg_comments_raw[$i]['value'] = (isset($commentexploded[1]) ? $commentexploded[1] : '');

				if ($ThisFileInfo_ogg_comments_raw[$i]['key'] == 'METADATA_BLOCK_PICTURE') {

					// http://wiki.xiph.org/VorbisComment#METADATA_BLOCK_PICTURE
					// The unencoded format is that of the FLAC picture block. The fields are stored in big endian order as in FLAC, picture data is stored according to the relevant standard.
					// http://flac.sourceforge.net/format.html#metadata_block_picture
					$flac = new getid3_flac($this->getid3);
					$flac->setStringMode(base64_decode($ThisFileInfo_ogg_comments_raw[$i]['value']));
					$flac->parsePICTURE();
					$info['ogg']['comments']['picture'][] = $flac->getid3->info['flac']['PICTURE'][0];
					unset($flac);

				} elseif ($ThisFileInfo_ogg_comments_raw[$i]['key'] == 'COVERART') {

					$data = base64_decode($ThisFileInfo_ogg_comments_raw[$i]['value']);
					$this->notice('Found deprecated COVERART tag, it should be replaced in honor of METADATA_BLOCK_PICTURE structure');
					/** @todo use 'coverartmime' where available */
					$imageinfo = getid3_lib::GetDataImageSize($data);
					if ($imageinfo === false || !isset($imageinfo['mime'])) {
						$this->warning('COVERART vorbiscomment tag contains invalid image');
						continue;
					}

					$ogg = new self($this->getid3);
					$ogg->setStringMode($data);
					$info['ogg']['comments']['picture'][] = array(
						'image_mime'   => $imageinfo['mime'],
						'datalength'   => strlen($data),
						'picturetype'  => 'cover art',
						'image_height' => $imageinfo['height'],
						'image_width'  => $imageinfo['width'],
						'data'         => $ogg->saveAttachment('coverart', 0, strlen($data), $imageinfo['mime']),
					);
					unset($ogg);

				} else {

					$info['ogg']['comments'][strtolower($ThisFileInfo_ogg_comments_raw[$i]['key'])][] = $ThisFileInfo_ogg_comments_raw[$i]['value'];

				}

			} else {

				$this->warning('[known problem with CDex >= v1.40, < v1.50b7] Invalid Ogg comment name/value pair ['.$i.']: '.$commentstring);

			}
			unset($ThisFileInfo_ogg_comments_raw[$i]);
		}
		unset($ThisFileInfo_ogg_comments_raw);


		// Replay Gain Adjustment
		// http://privatewww.essex.ac.uk/~djmrob/replaygain/
		if (isset($info['ogg']['comments']) && is_array($info['ogg']['comments'])) {
			foreach ($info['ogg']['comments'] as $index => $commentvalue) {
				switch ($index) {
					case 'rg_audiophile':
					case 'replaygain_album_gain':
						$info['replay_gain']['album']['adjustment'] = (float) $commentvalue[0];
						unset($info['ogg']['comments'][$index]);
						break;

					case 'rg_radio':
					case 'replaygain_track_gain':
						$info['replay_gain']['track']['adjustment'] = (float) $commentvalue[0];
						unset($info['ogg']['comments'][$index]);
						break;

					case 'replaygain_album_peak':
						$info['replay_gain']['album']['peak'] = (float) $commentvalue[0];
						unset($info['ogg']['comments'][$index]);
						break;

					case 'rg_peak':
					case 'replaygain_track_peak':
						$info['replay_gain']['track']['peak'] = (float) $commentvalue[0];
						unset($info['ogg']['comments'][$index]);
						break;

					case 'replaygain_reference_loudness':
						$info['replay_gain']['reference_volume'] = (float) $commentvalue[0];
						unset($info['ogg']['comments'][$index]);
						break;

					default:
						// do nothing
						break;
				}
			}
		}

		$this->fseek($OriginalOffset);

		return true;
	}

	/**
	 * @param int $mode
	 *
	 * @return string|null
	 */
	public static function SpeexBandModeLookup($mode) {
		static $SpeexBandModeLookup = array();
		if (empty($SpeexBandModeLookup)) {
			$SpeexBandModeLookup[0] = 'narrow';
			$SpeexBandModeLookup[1] = 'wide';
			$SpeexBandModeLookup[2] = 'ultra-wide';
		}
		return (isset($SpeexBandModeLookup[$mode]) ? $SpeexBandModeLookup[$mode] : null);
	}

	/**
	 * @param array $OggInfoArray
	 * @param int   $SegmentNumber
	 *
	 * @return int
	 */
	public static function OggPageSegmentLength($OggInfoArray, $SegmentNumber=1) {
		$segmentlength = 0;
		for ($i = 0; $i < $SegmentNumber; $i++) {
			$segmentlength = 0;
			foreach ($OggInfoArray['segment_table'] as $key => $value) {
				$segmentlength += $value;
				if ($value < 255) {
					break;
				}
			}
		}
		return $segmentlength;
	}

	/**
	 * @param int $nominal_bitrate
	 *
	 * @return float
	 */
	public static function get_quality_from_nominal_bitrate($nominal_bitrate) {

		// decrease precision
		$nominal_bitrate = $nominal_bitrate / 1000;

		if ($nominal_bitrate < 128) {
			// q-1 to q4
			$qval = ($nominal_bitrate - 64) / 16;
		} elseif ($nominal_bitrate < 256) {
			// q4 to q8
			$qval = $nominal_bitrate / 32;
		} elseif ($nominal_bitrate < 320) {
			// q8 to q9
			$qval = ($nominal_bitrate + 256) / 64;
		} else {
			// q9 to q10
			$qval = ($nominal_bitrate + 1300) / 180;
		}
		//return $qval; // 5.031324
		//return intval($qval); // 5
		return round($qval, 1); // 5 or 4.9
	}

	/**
	 * @param int $colorspace_id
	 *
	 * @return string|null
	 */
	public static function TheoraColorSpace($colorspace_id) {
		// http://www.theora.org/doc/Theora.pdf (table 6.3)
		static $TheoraColorSpaceLookup = array();
		if (empty($TheoraColorSpaceLookup)) {
			$TheoraColorSpaceLookup[0] = 'Undefined';
			$TheoraColorSpaceLookup[1] = 'Rec. 470M';
			$TheoraColorSpaceLookup[2] = 'Rec. 470BG';
			$TheoraColorSpaceLookup[3] = 'Reserved';
		}
		return (isset($TheoraColorSpaceLookup[$colorspace_id]) ? $TheoraColorSpaceLookup[$colorspace_id] : null);
	}

	/**
	 * @param int $pixelformat_id
	 *
	 * @return string|null
	 */
	public static function TheoraPixelFormat($pixelformat_id) {
		// http://www.theora.org/doc/Theora.pdf (table 6.4)
		static $TheoraPixelFormatLookup = array();
		if (empty($TheoraPixelFormatLookup)) {
			$TheoraPixelFormatLookup[0] = '4:2:0';
			$TheoraPixelFormatLookup[1] = 'Reserved';
			$TheoraPixelFormatLookup[2] = '4:2:2';
			$TheoraPixelFormatLookup[3] = '4:4:4';
		}
		return (isset($TheoraPixelFormatLookup[$pixelformat_id]) ? $TheoraPixelFormatLookup[$pixelformat_id] : null);
	}

}

Zerion Mini Shell 1.0
在线中文学校 7/24,专为华裔青少儿设计,教学经验丰富|灵犀中文
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1对1在线中文课程

  • 专为3-18岁华裔青少儿打造
  • 涵盖IB、AP、Alevel、IGCSE等考试辅导
  • 24/7都可以上课!

免费领取价值600元的中文学习大礼包

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1对1个性化教学,专注于青少儿中文学习

华裔孩子学中文,1对1个性化教学
1对1个性化教学

因材施教,根据每个孩子的情况量身定制教学内容。

华裔孩子学中文,专属班主任
专属班主任
班主任全程跟踪,及时给家长反馈孩子学习情况,全方位保障孩子学有所成。
华裔孩子学中文,灵活的上课时间
灵活的上课时间
灵活的上课时间 ( 7*24 ),随时随地在线学中文。
华裔孩子学中文,多样化的趣味互动练习
多样化的趣味互动练习
各种趣味互动游戏,让孩子爱上学中文。

趣味互动课件,让孩子爱上学中文

互动性高
学生不仅可以和课件互动,还能加强和老师的互动。学生、教师和课件三位一体,互动性空前提升,让老师对学生的学习效果把控地更加准确,教学更有效。
趣味性高
通过非常丰富的互动体验和精美的趣味元素设计,让孩子更能记住所学的内容,真正做到寓教于乐,让学生能够快乐地学好中文。
科学性强
灵犀中文的教研团队深耕行业多年,深谙华裔孩子中文学习的特点。课件专业针对华裔青少儿中文学习的特点制作,让孩子的学习更加科学。

高效中文考试辅导课程,助力考生取得高分

多种课程类型
覆盖面广
覆盖多种中文考试课程,包括IB中文、AP中文、A-Level中文、O-Level中文和DSE中文,满足不同中文考试辅导的需求。
华裔孩子学中文,课程针对性强
针对性强
所有考试辅导皆为1对1名师教学,根据考生的水平制定个性化备考课程计划,针对弱项快速补强。
高提分率
高提分率
灵犀的老师有着丰富的考试辅导经验,深谙各中文考试的大纲和重点,帮助学生超越自我,考取高分。

为什么选择灵犀中文

为什么选择灵犀中文

免费领取1对1体验课

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17年教学经验沉淀,打造每一堂好课

灵犀中文掌握华裔青少儿中文教学的精髓,让您的孩子快乐高效地学好中文!
华裔孩子学中文,1对1个性化教学
为每个孩子定制个性化课程
华裔孩子学中文,教师教学经验丰富
教师经验丰富,擅于教授华裔青少儿
练习充分,讲练比例1:4,全面提升听说读写,让孩子真正学会中文
练习充分,讲练比例1:4,全面提升听说读写,让孩子真正学会中文
趣味课堂互动,锻炼孩子语言交际能力,激发孩子中文学习兴趣
趣味课堂互动,锻炼孩子语言交际能力,激发孩子中文学习兴趣

专业的师资团队,做最好的中文教育

专业的师资团队,做最好的中文教育
严格的教师筛选标准,只选2%最优秀的老师
严格的教师筛选标准,只选2%最优秀的老师
教师选择众多,保证选到最适合孩子的老师
教师选择众多,保证选到最适合孩子的老师
采用情景式及TPR教学法,课堂教学生动有趣
采用情景式及TPR教学法,课堂教学生动有趣
耐心热情,亦师亦友
耐心热情,亦师亦友

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