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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-video.flv.php                                  //
// module for analyzing Shockwave Flash Video files            //
// dependencies: NONE                                          //
//                                                             //
/////////////////////////////////////////////////////////////////
//                                                             //
//  FLV module by Seth Kaufman <sethØwhirl-i-gig*com>          //
//                                                             //
//  * version 0.1 (26 June 2005)                               //
//                                                             //
//  * version 0.1.1 (15 July 2005)                             //
//  minor modifications by James Heinrich <info@getid3.org>    //
//                                                             //
//  * version 0.2 (22 February 2006)                           //
//  Support for On2 VP6 codec and meta information             //
//    by Steve Webster <steve.websterØfeaturecreep*com>        //
//                                                             //
//  * version 0.3 (15 June 2006)                               //
//  Modified to not read entire file into memory               //
//    by James Heinrich <info@getid3.org>                      //
//                                                             //
//  * version 0.4 (07 December 2007)                           //
//  Bugfixes for incorrectly parsed FLV dimensions             //
//    and incorrect parsing of onMetaTag                       //
//    by Evgeny Moysevich <moysevichØgmail*com>                //
//                                                             //
//  * version 0.5 (21 May 2009)                                //
//  Fixed parsing of audio tags and added additional codec     //
//    details. The duration is now read from onMetaTag (if     //
//    exists), rather than parsing whole file                  //
//    by Nigel Barnes <ngbarnesØhotmail*com>                   //
//                                                             //
//  * version 0.6 (24 May 2009)                                //
//  Better parsing of files with h264 video                    //
//    by Evgeny Moysevich <moysevichØgmail*com>                //
//                                                             //
//  * version 0.6.1 (30 May 2011)                              //
//    prevent infinite loops in expGolombUe()                  //
//                                                             //
//  * version 0.7.0 (16 Jul 2013)                              //
//  handle GETID3_FLV_VIDEO_VP6FLV_ALPHA                       //
//  improved AVCSequenceParameterSetReader::readData()         //
//    by Xander Schouwerwou <schouwerwouØgmail*com>            //
//                                                            ///
/////////////////////////////////////////////////////////////////

if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers
    exit;
}

define('GETID3_FLV_TAG_AUDIO',          8);
define('GETID3_FLV_TAG_VIDEO',          9);
define('GETID3_FLV_TAG_META',          18);

define('GETID3_FLV_VIDEO_H263',         2);
define('GETID3_FLV_VIDEO_SCREEN',       3);
define('GETID3_FLV_VIDEO_VP6FLV',       4);
define('GETID3_FLV_VIDEO_VP6FLV_ALPHA', 5);
define('GETID3_FLV_VIDEO_SCREENV2',     6);
define('GETID3_FLV_VIDEO_H264',         7);

define('H264_AVC_SEQUENCE_HEADER',          0);
define('H264_PROFILE_BASELINE',            66);
define('H264_PROFILE_MAIN',                77);
define('H264_PROFILE_EXTENDED',            88);
define('H264_PROFILE_HIGH',               100);
define('H264_PROFILE_HIGH10',             110);
define('H264_PROFILE_HIGH422',            122);
define('H264_PROFILE_HIGH444',            144);
define('H264_PROFILE_HIGH444_PREDICTIVE', 244);

class getid3_flv extends getid3_handler
{
    const magic = 'FLV';

    /**
     * Break out of the loop if too many frames have been scanned; only scan this
     * many if meta frame does not contain useful duration.
     *
     * @var int
     */
    public $max_frames = 100000;

    /**
     * @return bool
     */
    public function Analyze() {
        $info = &$this->getid3->info;

        $this->fseek($info['avdataoffset']);

        $FLVdataLength = $info['avdataend'] - $info['avdataoffset'];
        $FLVheader = $this->fread(5);

        $info['fileformat'] = 'flv';
        $info['flv']['header']['signature'] =                           substr($FLVheader, 0, 3);
        $info['flv']['header']['version']   = getid3_lib::BigEndian2Int(substr($FLVheader, 3, 1));
        $TypeFlags                          = getid3_lib::BigEndian2Int(substr($FLVheader, 4, 1));

        if ($info['flv']['header']['signature'] != self::magic) {
            $this->error('Expecting "'.getid3_lib::PrintHexBytes(self::magic).'" at offset '.$info['avdataoffset'].', found "'.getid3_lib::PrintHexBytes($info['flv']['header']['signature']).'"');
            unset($info['flv'], $info['fileformat']);
            return false;
        }

        $info['flv']['header']['hasAudio'] = (bool) ($TypeFlags & 0x04);
        $info['flv']['header']['hasVideo'] = (bool) ($TypeFlags & 0x01);

        $FrameSizeDataLength = getid3_lib::BigEndian2Int($this->fread(4));
        $FLVheaderFrameLength = 9;
        if ($FrameSizeDataLength > $FLVheaderFrameLength) {
            $this->fseek($FrameSizeDataLength - $FLVheaderFrameLength, SEEK_CUR);
        }
        $Duration = 0;
        $found_video = false;
        $found_audio = false;
        $found_meta  = false;
        $found_valid_meta_playtime = false;
        $tagParseCount = 0;
        $info['flv']['framecount'] = array('total'=>0, 'audio'=>0, 'video'=>0);
        $flv_framecount = &$info['flv']['framecount'];
        while ((($this->ftell() + 16) < $info['avdataend']) && (($tagParseCount++ <= $this->max_frames) || !$found_valid_meta_playtime))  {
            $ThisTagHeader = $this->fread(16);

            $PreviousTagLength = getid3_lib::BigEndian2Int(substr($ThisTagHeader,  0, 4));
            $TagType           = getid3_lib::BigEndian2Int(substr($ThisTagHeader,  4, 1));
            $DataLength        = getid3_lib::BigEndian2Int(substr($ThisTagHeader,  5, 3));
            $Timestamp         = getid3_lib::BigEndian2Int(substr($ThisTagHeader,  8, 3));
            $LastHeaderByte    = getid3_lib::BigEndian2Int(substr($ThisTagHeader, 15, 1));
            $NextOffset = $this->ftell() - 1 + $DataLength;
            if ($Timestamp > $Duration) {
                $Duration = $Timestamp;
            }

            $flv_framecount['total']++;
            switch ($TagType) {
                case GETID3_FLV_TAG_AUDIO:
                    $flv_framecount['audio']++;
                    if (!$found_audio) {
                        $found_audio = true;
                        $info['flv']['audio']['audioFormat']     = ($LastHeaderByte >> 4) & 0x0F;
                        $info['flv']['audio']['audioRate']       = ($LastHeaderByte >> 2) & 0x03;
                        $info['flv']['audio']['audioSampleSize'] = ($LastHeaderByte >> 1) & 0x01;
                        $info['flv']['audio']['audioType']       =  $LastHeaderByte       & 0x01;
                    }
                    break;

                case GETID3_FLV_TAG_VIDEO:
                    $flv_framecount['video']++;
                    if (!$found_video) {
                        $found_video = true;
                        $info['flv']['video']['videoCodec'] = $LastHeaderByte & 0x07;

                        $FLVvideoHeader = $this->fread(11);

                        if ($info['flv']['video']['videoCodec'] == GETID3_FLV_VIDEO_H264) {
                            // this code block contributed by: moysevichØgmail*com

                            $AVCPacketType = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 0, 1));
                            if ($AVCPacketType == H264_AVC_SEQUENCE_HEADER) {
                                //  read AVCDecoderConfigurationRecord
                                $configurationVersion       = getid3_lib::BigEndian2Int(substr($FLVvideoHeader,  4, 1));
                                $AVCProfileIndication       = getid3_lib::BigEndian2Int(substr($FLVvideoHeader,  5, 1));
                                $profile_compatibility      = getid3_lib::BigEndian2Int(substr($FLVvideoHeader,  6, 1));
                                $lengthSizeMinusOne         = getid3_lib::BigEndian2Int(substr($FLVvideoHeader,  7, 1));
                                $numOfSequenceParameterSets = getid3_lib::BigEndian2Int(substr($FLVvideoHeader,  8, 1));

                                if (($numOfSequenceParameterSets & 0x1F) != 0) {
                                    //  there is at least one SequenceParameterSet
                                    //  read size of the first SequenceParameterSet
                                    //$spsSize = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 9, 2));
                                    $spsSize = getid3_lib::LittleEndian2Int(substr($FLVvideoHeader, 9, 2));
                                    //  read the first SequenceParameterSet
                                    $sps = $this->fread($spsSize);
                                    if (strlen($sps) == $spsSize) { //  make sure that whole SequenceParameterSet was red
                                        $spsReader = new AVCSequenceParameterSetReader($sps);
                                        $spsReader->readData();
                                        $info['video']['resolution_x'] = $spsReader->getWidth();
                                        $info['video']['resolution_y'] = $spsReader->getHeight();
                                    }
                                }
                            }
                            // end: moysevichØgmail*com

                        } elseif ($info['flv']['video']['videoCodec'] == GETID3_FLV_VIDEO_H263) {

                            $PictureSizeType = (getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 3, 2))) >> 7;
                            $PictureSizeType = $PictureSizeType & 0x0007;
                            $info['flv']['header']['videoSizeType'] = $PictureSizeType;
                            switch ($PictureSizeType) {
                                case 0:
                                    //$PictureSizeEnc = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 5, 2));
                                    //$PictureSizeEnc <<= 1;
                                    //$info['video']['resolution_x'] = ($PictureSizeEnc & 0xFF00) >> 8;
                                    //$PictureSizeEnc = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 6, 2));
                                    //$PictureSizeEnc <<= 1;
                                    //$info['video']['resolution_y'] = ($PictureSizeEnc & 0xFF00) >> 8;

                                    $PictureSizeEnc['x'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 4, 2)) >> 7;
                                    $PictureSizeEnc['y'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 5, 2)) >> 7;
                                    $info['video']['resolution_x'] = $PictureSizeEnc['x'] & 0xFF;
                                    $info['video']['resolution_y'] = $PictureSizeEnc['y'] & 0xFF;
                                    break;

                                case 1:
                                    $PictureSizeEnc['x'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 4, 3)) >> 7;
                                    $PictureSizeEnc['y'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 6, 3)) >> 7;
                                    $info['video']['resolution_x'] = $PictureSizeEnc['x'] & 0xFFFF;
                                    $info['video']['resolution_y'] = $PictureSizeEnc['y'] & 0xFFFF;
                                    break;

                                case 2:
                                    $info['video']['resolution_x'] = 352;
                                    $info['video']['resolution_y'] = 288;
                                    break;

                                case 3:
                                    $info['video']['resolution_x'] = 176;
                                    $info['video']['resolution_y'] = 144;
                                    break;

                                case 4:
                                    $info['video']['resolution_x'] = 128;
                                    $info['video']['resolution_y'] = 96;
                                    break;

                                case 5:
                                    $info['video']['resolution_x'] = 320;
                                    $info['video']['resolution_y'] = 240;
                                    break;

                                case 6:
                                    $info['video']['resolution_x'] = 160;
                                    $info['video']['resolution_y'] = 120;
                                    break;

                                default:
                                    $info['video']['resolution_x'] = 0;
                                    $info['video']['resolution_y'] = 0;
                                    break;

                            }

                        } elseif ($info['flv']['video']['videoCodec'] ==  GETID3_FLV_VIDEO_VP6FLV_ALPHA) {

                            /* contributed by schouwerwouØgmail*com */
                            if (!isset($info['video']['resolution_x'])) { // only when meta data isn't set
                                $PictureSizeEnc['x'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 6, 2));
                                $PictureSizeEnc['y'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 7, 2));
                                $info['video']['resolution_x'] = ($PictureSizeEnc['x'] & 0xFF) << 3;
                                $info['video']['resolution_y'] = ($PictureSizeEnc['y'] & 0xFF) << 3;
                            }
                            /* end schouwerwouØgmail*com */

                        }
                        if (!empty($info['video']['resolution_x']) && !empty($info['video']['resolution_y'])) {
                            $info['video']['pixel_aspect_ratio'] = $info['video']['resolution_x'] / $info['video']['resolution_y'];
                        }
                    }
                    break;

                // Meta tag
                case GETID3_FLV_TAG_META:
                    if (!$found_meta) {
                        $found_meta = true;
                        $this->fseek(-1, SEEK_CUR);
                        $datachunk = $this->fread($DataLength);
                        $AMFstream = new AMFStream($datachunk);
                        $reader = new AMFReader($AMFstream);
                        $eventName = $reader->readData();
                        $info['flv']['meta'][$eventName] = $reader->readData();
                        unset($reader);

                        $copykeys = array('framerate'=>'frame_rate', 'width'=>'resolution_x', 'height'=>'resolution_y', 'audiodatarate'=>'bitrate', 'videodatarate'=>'bitrate');
                        foreach ($copykeys as $sourcekey => $destkey) {
                            if (isset($info['flv']['meta']['onMetaData'][$sourcekey])) {
                                switch ($sourcekey) {
                                    case 'width':
                                    case 'height':
                                        $info['video'][$destkey] = intval(round($info['flv']['meta']['onMetaData'][$sourcekey]));
                                        break;
                                    case 'audiodatarate':
                                        $info['audio'][$destkey] = getid3_lib::CastAsInt(round($info['flv']['meta']['onMetaData'][$sourcekey] * 1000));
                                        break;
                                    case 'videodatarate':
                                    case 'frame_rate':
                                    default:
                                        $info['video'][$destkey] = $info['flv']['meta']['onMetaData'][$sourcekey];
                                        break;
                                }
                            }
                        }
                        if (!empty($info['flv']['meta']['onMetaData']['duration'])) {
                            $found_valid_meta_playtime = true;
                        }
                    }
                    break;

                default:
                    // noop
                    break;
            }
            $this->fseek($NextOffset);
        }

        $info['playtime_seconds'] = $Duration / 1000;
        if ($info['playtime_seconds'] > 0) {
            $info['bitrate'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
        }

        if ($info['flv']['header']['hasAudio']) {
            $info['audio']['codec']           =   self::audioFormatLookup($info['flv']['audio']['audioFormat']);
            $info['audio']['sample_rate']     =     self::audioRateLookup($info['flv']['audio']['audioRate']);
            $info['audio']['bits_per_sample'] = self::audioBitDepthLookup($info['flv']['audio']['audioSampleSize']);

            $info['audio']['channels']   =  $info['flv']['audio']['audioType'] + 1; // 0=mono,1=stereo
            $info['audio']['lossless']   = ($info['flv']['audio']['audioFormat'] ? false : true); // 0=uncompressed
            $info['audio']['dataformat'] = 'flv';
        }
        if (!empty($info['flv']['header']['hasVideo'])) {
            $info['video']['codec']      = self::videoCodecLookup($info['flv']['video']['videoCodec']);
            $info['video']['dataformat'] = 'flv';
            $info['video']['lossless']   = false;
        }

        // Set information from meta
        if (!empty($info['flv']['meta']['onMetaData']['duration'])) {
            $info['playtime_seconds'] = $info['flv']['meta']['onMetaData']['duration'];
            $info['bitrate'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
        }
        if (isset($info['flv']['meta']['onMetaData']['audiocodecid'])) {
            $info['audio']['codec'] = self::audioFormatLookup($info['flv']['meta']['onMetaData']['audiocodecid']);
        }
        if (isset($info['flv']['meta']['onMetaData']['videocodecid'])) {
            $info['video']['codec'] = self::videoCodecLookup($info['flv']['meta']['onMetaData']['videocodecid']);
        }
        return true;
    }

    /**
     * @param int $id
     *
     * @return string|false
     */
    public static function audioFormatLookup($id) {
        static $lookup = array(
            0  => 'Linear PCM, platform endian',
            1  => 'ADPCM',
            2  => 'mp3',
            3  => 'Linear PCM, little endian',
            4  => 'Nellymoser 16kHz mono',
            5  => 'Nellymoser 8kHz mono',
            6  => 'Nellymoser',
            7  => 'G.711A-law logarithmic PCM',
            8  => 'G.711 mu-law logarithmic PCM',
            9  => 'reserved',
            10 => 'AAC',
            11 => 'Speex',
            12 => false, // unknown?
            13 => false, // unknown?
            14 => 'mp3 8kHz',
            15 => 'Device-specific sound',
        );
        return (isset($lookup[$id]) ? $lookup[$id] : false);
    }

    /**
     * @param int $id
     *
     * @return int|false
     */
    public static function audioRateLookup($id) {
        static $lookup = array(
            0 =>  5500,
            1 => 11025,
            2 => 22050,
            3 => 44100,
        );
        return (isset($lookup[$id]) ? $lookup[$id] : false);
    }

    /**
     * @param int $id
     *
     * @return int|false
     */
    public static function audioBitDepthLookup($id) {
        static $lookup = array(
            0 =>  8,
            1 => 16,
        );
        return (isset($lookup[$id]) ? $lookup[$id] : false);
    }

    /**
     * @param int $id
     *
     * @return string|false
     */
    public static function videoCodecLookup($id) {
        static $lookup = array(
            GETID3_FLV_VIDEO_H263         => 'Sorenson H.263',
            GETID3_FLV_VIDEO_SCREEN       => 'Screen video',
            GETID3_FLV_VIDEO_VP6FLV       => 'On2 VP6',
            GETID3_FLV_VIDEO_VP6FLV_ALPHA => 'On2 VP6 with alpha channel',
            GETID3_FLV_VIDEO_SCREENV2     => 'Screen video v2',
            GETID3_FLV_VIDEO_H264         => 'Sorenson H.264',
        );
        return (isset($lookup[$id]) ? $lookup[$id] : false);
    }
}

class AMFStream
{
    /**
     * @var string
     */
    public $bytes;

    /**
     * @var int
     */
    public $pos;

    /**
     * @param string $bytes
     */
    public function __construct(&$bytes) {
        $this->bytes =& $bytes;
        $this->pos = 0;
    }

    /**
     * @return int
     */
    public function readByte() { //  8-bit
        return ord(substr($this->bytes, $this->pos++, 1));
    }

    /**
     * @return int
     */
    public function readInt() { // 16-bit
        return ($this->readByte() << 8) + $this->readByte();
    }

    /**
     * @return int
     */
    public function readLong() { // 32-bit
        return ($this->readByte() << 24) + ($this->readByte() << 16) + ($this->readByte() << 8) + $this->readByte();
    }

    /**
     * @return float|false
     */
    public function readDouble() {
        return getid3_lib::BigEndian2Float($this->read(8));
    }

    /**
     * @return string
     */
    public function readUTF() {
        $length = $this->readInt();
        return $this->read($length);
    }

    /**
     * @return string
     */
    public function readLongUTF() {
        $length = $this->readLong();
        return $this->read($length);
    }

    /**
     * @param int $length
     *
     * @return string
     */
    public function read($length) {
        $val = substr($this->bytes, $this->pos, $length);
        $this->pos += $length;
        return $val;
    }

    /**
     * @return int
     */
    public function peekByte() {
        $pos = $this->pos;
        $val = $this->readByte();
        $this->pos = $pos;
        return $val;
    }

    /**
     * @return int
     */
    public function peekInt() {
        $pos = $this->pos;
        $val = $this->readInt();
        $this->pos = $pos;
        return $val;
    }

    /**
     * @return int
     */
    public function peekLong() {
        $pos = $this->pos;
        $val = $this->readLong();
        $this->pos = $pos;
        return $val;
    }

    /**
     * @return float|false
     */
    public function peekDouble() {
        $pos = $this->pos;
        $val = $this->readDouble();
        $this->pos = $pos;
        return $val;
    }

    /**
     * @return string
     */
    public function peekUTF() {
        $pos = $this->pos;
        $val = $this->readUTF();
        $this->pos = $pos;
        return $val;
    }

    /**
     * @return string
     */
    public function peekLongUTF() {
        $pos = $this->pos;
        $val = $this->readLongUTF();
        $this->pos = $pos;
        return $val;
    }
}

class AMFReader
{
    /**
    * @var AMFStream
    */
    public $stream;

    /**
     * @param AMFStream $stream
     */
    public function __construct(AMFStream $stream) {
        $this->stream = $stream;
    }

    /**
     * @return mixed
     */
    public function readData() {
        $value = null;

        $type = $this->stream->readByte();
        switch ($type) {

            // Double
            case 0:
                $value = $this->readDouble();
            break;

            // Boolean
            case 1:
                $value = $this->readBoolean();
                break;

            // String
            case 2:
                $value = $this->readString();
                break;

            // Object
            case 3:
                $value = $this->readObject();
                break;

            // null
            case 6:
                return null;

            // Mixed array
            case 8:
                $value = $this->readMixedArray();
                break;

            // Array
            case 10:
                $value = $this->readArray();
                break;

            // Date
            case 11:
                $value = $this->readDate();
                break;

            // Long string
            case 13:
                $value = $this->readLongString();
                break;

            // XML (handled as string)
            case 15:
                $value = $this->readXML();
                break;

            // Typed object (handled as object)
            case 16:
                $value = $this->readTypedObject();
                break;

            // Long string
            default:
                $value = '(unknown or unsupported data type)';
                break;
        }

        return $value;
    }

    /**
     * @return float|false
     */
    public function readDouble() {
        return $this->stream->readDouble();
    }

    /**
     * @return bool
     */
    public function readBoolean() {
        return $this->stream->readByte() == 1;
    }

    /**
     * @return string
     */
    public function readString() {
        return $this->stream->readUTF();
    }

    /**
     * @return array
     */
    public function readObject() {
        // Get highest numerical index - ignored
//      $highestIndex = $this->stream->readLong();

        $data = array();
        $key = null;

        while ($key = $this->stream->readUTF()) {
            $data[$key] = $this->readData();
        }
        // Mixed array record ends with empty string (0x00 0x00) and 0x09
        if (($key == '') && ($this->stream->peekByte() == 0x09)) {
            // Consume byte
            $this->stream->readByte();
        }
        return $data;
    }

    /**
     * @return array
     */
    public function readMixedArray() {
        // Get highest numerical index - ignored
        $highestIndex = $this->stream->readLong();

        $data = array();
        $key = null;

        while ($key = $this->stream->readUTF()) {
            if (is_numeric($key)) {
                $key = (int) $key;
            }
            $data[$key] = $this->readData();
        }
        // Mixed array record ends with empty string (0x00 0x00) and 0x09
        if (($key == '') && ($this->stream->peekByte() == 0x09)) {
            // Consume byte
            $this->stream->readByte();
        }

        return $data;
    }

    /**
     * @return array
     */
    public function readArray() {
        $length = $this->stream->readLong();
        $data = array();

        for ($i = 0; $i < $length; $i++) {
            $data[] = $this->readData();
        }
        return $data;
    }

    /**
     * @return float|false
     */
    public function readDate() {
        $timestamp = $this->stream->readDouble();
        $timezone = $this->stream->readInt();
        return $timestamp;
    }

    /**
     * @return string
     */
    public function readLongString() {
        return $this->stream->readLongUTF();
    }

    /**
     * @return string
     */
    public function readXML() {
        return $this->stream->readLongUTF();
    }

    /**
     * @return array
     */
    public function readTypedObject() {
        $className = $this->stream->readUTF();
        return $this->readObject();
    }
}

class AVCSequenceParameterSetReader
{
    /**
     * @var string
     */
    public $sps;
    public $start = 0;
    public $currentBytes = 0;
    public $currentBits = 0;

    /**
     * @var int
     */
    public $width;

    /**
     * @var int
     */
    public $height;

    /**
     * @param string $sps
     */
    public function __construct($sps) {
        $this->sps = $sps;
    }

    public function readData() {
        $this->skipBits(8);
        $this->skipBits(8);
        $profile = $this->getBits(8);                               // read profile
        if ($profile > 0) {
            $this->skipBits(8);
            $level_idc = $this->getBits(8);                         // level_idc
            $this->expGolombUe();                                   // seq_parameter_set_id // sps
            $this->expGolombUe();                                   // log2_max_frame_num_minus4
            $picOrderType = $this->expGolombUe();                   // pic_order_cnt_type
            if ($picOrderType == 0) {
                $this->expGolombUe();                               // log2_max_pic_order_cnt_lsb_minus4
            } elseif ($picOrderType == 1) {
                $this->skipBits(1);                                 // delta_pic_order_always_zero_flag
                $this->expGolombSe();                               // offset_for_non_ref_pic
                $this->expGolombSe();                               // offset_for_top_to_bottom_field
                $num_ref_frames_in_pic_order_cnt_cycle = $this->expGolombUe(); // num_ref_frames_in_pic_order_cnt_cycle
                for ($i = 0; $i < $num_ref_frames_in_pic_order_cnt_cycle; $i++) {
                    $this->expGolombSe();                           // offset_for_ref_frame[ i ]
                }
            }
            $this->expGolombUe();                                   // num_ref_frames
            $this->skipBits(1);                                     // gaps_in_frame_num_value_allowed_flag
            $pic_width_in_mbs_minus1 = $this->expGolombUe();        // pic_width_in_mbs_minus1
            $pic_height_in_map_units_minus1 = $this->expGolombUe(); // pic_height_in_map_units_minus1

            $frame_mbs_only_flag = $this->getBits(1);               // frame_mbs_only_flag
            if ($frame_mbs_only_flag == 0) {
                $this->skipBits(1);                                 // mb_adaptive_frame_field_flag
            }
            $this->skipBits(1);                                     // direct_8x8_inference_flag
            $frame_cropping_flag = $this->getBits(1);               // frame_cropping_flag

            $frame_crop_left_offset   = 0;
            $frame_crop_right_offset  = 0;
            $frame_crop_top_offset    = 0;
            $frame_crop_bottom_offset = 0;

            if ($frame_cropping_flag) {
                $frame_crop_left_offset   = $this->expGolombUe();   // frame_crop_left_offset
                $frame_crop_right_offset  = $this->expGolombUe();   // frame_crop_right_offset
                $frame_crop_top_offset    = $this->expGolombUe();   // frame_crop_top_offset
                $frame_crop_bottom_offset = $this->expGolombUe();   // frame_crop_bottom_offset
            }
            $this->skipBits(1);                                     // vui_parameters_present_flag
            // etc

            $this->width  = (($pic_width_in_mbs_minus1 + 1) * 16) - ($frame_crop_left_offset * 2) - ($frame_crop_right_offset * 2);
            $this->height = ((2 - $frame_mbs_only_flag) * ($pic_height_in_map_units_minus1 + 1) * 16) - ($frame_crop_top_offset * 2) - ($frame_crop_bottom_offset * 2);
        }
    }

    /**
     * @param int $bits
     */
    public function skipBits($bits) {
        $newBits = $this->currentBits + $bits;
        $this->currentBytes += (int)floor($newBits / 8);
        $this->currentBits = $newBits % 8;
    }

    /**
     * @return int
     */
    public function getBit() {
        $result = (getid3_lib::BigEndian2Int(substr($this->sps, $this->currentBytes, 1)) >> (7 - $this->currentBits)) & 0x01;
        $this->skipBits(1);
        return $result;
    }

    /**
     * @param int $bits
     *
     * @return int
     */
    public function getBits($bits) {
        $result = 0;
        for ($i = 0; $i < $bits; $i++) {
            $result = ($result << 1) + $this->getBit();
        }
        return $result;
    }

    /**
     * @return int
     */
    public function expGolombUe() {
        $significantBits = 0;
        $bit = $this->getBit();
        while ($bit == 0) {
            $significantBits++;
            $bit = $this->getBit();

            if ($significantBits > 31) {
                // something is broken, this is an emergency escape to prevent infinite loops
                return 0;
            }
        }
        return (1 << $significantBits) + $this->getBits($significantBits) - 1;
    }

    /**
     * @return int
     */
    public function expGolombSe() {
        $result = $this->expGolombUe();
        if (($result & 0x01) == 0) {
            return -($result >> 1);
        } else {
            return ($result + 1) >> 1;
        }
    }

    /**
     * @return int
     */
    public function getWidth() {
        return $this->width;
    }

    /**
     * @return int
     */
    public function getHeight() {
        return $this->height;
    }
}