getid3_ogg::ParseOpusPageHeader( string $filedata, int $filedataoffset, array $oggpageinfo ): bool

477	public function ParseOpusPageHeader(&$filedata, &$filedataoffset, &$oggpageinfo) {478		$info = &$this->getid3->info;479		$info['audio']['dataformat']   = 'opus';480		$info['mime_type']             = 'audio/ogg; codecs=opus';481 482		/** @todo find a usable way to detect abr (vbr that is padded to be abr) */483		$info['audio']['bitrate_mode'] = 'vbr';484 485		$info['audio']['lossless']     = false;486 487		$info['ogg']['pageheader']['opus']['opus_magic'] = substr($filedata, $filedataoffset, 8); // hard-coded to 'OpusHead'488		$filedataoffset += 8;489		$info['ogg']['pageheader']['opus']['version']    = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  1));490		$filedataoffset += 1;491 492		if ($info['ogg']['pageheader']['opus']['version'] < 1 || $info['ogg']['pageheader']['opus']['version'] > 15) {493			$this->error('Unknown opus version number (only accepting 1-15)');494			return false;495		}496 497		$info['ogg']['pageheader']['opus']['out_channel_count'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  1));498		$filedataoffset += 1;499 500		if ($info['ogg']['pageheader']['opus']['out_channel_count'] == 0) {501			$this->error('Invalid channel count in opus header (must not be zero)');502			return false;503		}504 505		$info['ogg']['pageheader']['opus']['pre_skip'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  2));506		$filedataoffset += 2;507 508		$info['ogg']['pageheader']['opus']['input_sample_rate'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  4));509		$filedataoffset += 4;510 511		//$info['ogg']['pageheader']['opus']['output_gain'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  2));512		//$filedataoffset += 2;513 514		//$info['ogg']['pageheader']['opus']['channel_mapping_family'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  1));515		//$filedataoffset += 1;516 517		$info['opus']['opus_version']       = $info['ogg']['pageheader']['opus']['version'];518		$info['opus']['sample_rate_input']  = $info['ogg']['pageheader']['opus']['input_sample_rate'];519		$info['opus']['out_channel_count']  = $info['ogg']['pageheader']['opus']['out_channel_count'];520 521		$info['audio']['channels']          = $info['opus']['out_channel_count'];522		$info['audio']['sample_rate_input'] = $info['opus']['sample_rate_input'];523		$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.html524		return true;525	}