<?php

define('INDSIZE', 2);  // number of dashes to indent sub-atoms

// list of container atoms
$AtomType = array("moov", "trak", "udta", "tref", "imap", "mdia",
    "minf", "stbl", "edts", "mdra", "rmra", "imag", "vnrp", "dinf");

$GenreList = array(
    "Blues", "Classic Rock", "Country", "Dance", "Disco", "Funk",
    "Grunge", "Hip-Hop", "Jazz", "Metal", "New Age", "Oldies",
    "Other", "Pop", "R&B", "Rap", "Reggae", "Rock",
    "Techno", "Industrial", "Alternative", "Ska", "Death Metal", "Pranks",
    "Soundtrack", "Euro-Techno", "Ambient", "Trip-Hop", "Vocal", "Jazz+Funk",
    "Fusion", "Trance", "Classical", "Instrumental", "Acid", "House",
    "Game", "Sound Clip", "Gospel", "Noise", "AlternRock", "Bass",
    "Soul", "Punk", "Space", "Meditative", "Instrumental Pop", "Instrumental Rock",
    "Ethnic", "Gothic", "Darkwave", "Techno-Industrial", "Electronic", "Pop-Folk",
    "Eurodance", "Dream", "Southern Rock", "Comedy", "Cult", "Gangsta",
    "Top 40", "Christian Rap", "Pop/Funk", "Jungle", "Native American", "Cabaret",
    "New Wave", "Psychadelic", "Rave", "Showtunes", "Trailer", "Lo-Fi",
    "Tribal", "Acid Punk", "Acid Jazz", "Polka", "Retro", "Musical",
    "Rock & Roll", "Hard Rock", "Folk", "Folk/Rock", "National Folk", "Swing",
    "Fast-Fusion", "Bebob", "Latin", "Revival", "Celtic", "Bluegrass", "Avantgarde",
    "Gothic Rock", "Progressive Rock", "Psychedelic Rock", "Symphonic Rock", "Slow Rock", "Big Band",
    "Chorus", "Easy Listening", "Acoustic", "Humour", "Speech", "Chanson",
    "Opera", "Chamber Music", "Sonata", "Symphony", "Booty Bass", "Primus",
    "Porn Groove", "Satire", "Slow Jam", "Club", "Tango", "Samba",
    "Folklore", "Ballad", "Power Ballad", "Rhythmic Soul", "Freestyle", "Duet",
    "Punk Rock", "Drum Solo", "A capella", "Euro-House", "Dance Hall",
    "Goa", "Drum & Bass", "Club House", "Hardcore", "Terror",
    "Indie", "BritPop", "NegerPunk", "Polsk Punk", "Beat",
    "Christian Gangsta", "Heavy Metal", "Black Metal", "Crossover", "Contemporary C",
    "Christian Rock", "Merengue", "Salsa", "Thrash Metal", "Anime", "JPop",
    "SynthPop");

$indent = 0;
$debug = 0;

function dprintf() {
    global $debug;

    if($debug) {
        $args = func_get_args();
        return call_user_func_array('printf', $args);
    }
}

function BigEndian2Int($byteword) {
    $intvalue = 0;
    $bytewordlen = strlen($byteword);
    for ($i = 0; $i < $bytewordlen; $i++) {
        $intvalue += ord($byteword{$i}) * pow(256, ($bytewordlen - 1 - $i));
    }
    return (int)$intvalue;
}

if (!function_exists('FixedPoint16_16')) {
	function FixedPoint16_16($rawdata) {
		return BigEndian2Int(substr($rawdata, 0, 2)) + (float) (BigEndian2Int(substr($rawdata, 2, 2)) / pow(2, 16));
	}
}

if (!function_exists('TimeString')) {
	function TimeString($seconds) {
		$mins = floor($seconds / 60);
		$secs = round((($seconds / 60) - $mins) * 60);
		if ($secs >= 60) {
			$secs -= 60;
			$mins++;
		}
		return sprintf("%d:%02d", $mins, $secs);
	}
}

function ind($n) {
    for ($i = INDSIZE; $i < $n; $i++) {
        dprintf("-");
    }
}

function ParseTag($metaItemKey, $metaItemData, &$tags) {
    global $indent;

    ind($indent+INDSIZE);
    switch($metaItemKey) {
    case "Šnam":
        dprintf("title:  %s\n",$metaItemData);
        $tags['title'] = $metaItemData;
        break;
    case "ŠART":
        dprintf("artist: %s\n",$metaItemData);
        $tags['artist'] = $metaItemData;
        break;
    case "Šalb":
        dprintf("album:  %s\n",$metaItemData);
        $tags['album'] = $metaItemData;
        break;
    case "gnre":
        $tags['genrename'] = DecodeGenre(ord($metaItemData{1}));
        $tags['genrenum'] = ord($metaItemData{1});
        dprintf("genre:  %s (%d)\n", $tags['genrename'], $tags['genrenum']);
        break;
    case "trkn":
        dprintf("track:  %d\n",ord($metaItemData{3}));
        $tags['track'] = ord($metaItemData{3});
        break;
    case "disk":
        dprintf("disk:   %d of %d\n",ord($metaItemData{3}), ord($metaItemData{5}));
        break;
    case "Šday":
        dprintf("year:   %s\n",$metaItemData);
        $tags['year'] = $metaItemData;
        break;
    default:
        $commanumber = number_format(strlen($metaItemData));
        dprintf("other:  %s: %s (%s bytes)\n", $metaItemKey, substr($metaItemData, 0, 10), $commanumber);
        break;
    } // switch
} // parsetag

function DecodeGenre($num) {
    global $GenreList;

    return (isset($GenreList[$num-1]) ? $GenreList[$num-1] : "unknown");
}

function ParseAtom($f, $firstOff, $stopAt, &$tags) {
    global $AtomType;
    global $indent;

    $indent += INDSIZE;

    fseek($f, 0, SEEK_END);
    $end = ftell($f);

    $off = $firstOff;
    while($off < $stopAt) {
        fseek($f, $off, SEEK_SET);

        $AtomHeader = fread($f, 8);
        $atomsize = BigEndian2Int(substr($AtomHeader, 0, 4));
        $atomname =               substr($AtomHeader, 4, 4);

        ind($indent);
        dprintf("%s (%s bytes)\n", $atomname, number_format($atomsize));

        if(($off + $atomsize) > $end) {
            printf("atom at %d claims %d bytes, end = %d)\n", $off, $atomsize, $end);
            return FALSE;
        }

        $tags['atoms'][] = array('name'  => $atomname, 
                                 'size'  => $atomsize, 
                                 'pos'   => ftell($f)-8,
                                 'level' => $indent/2 > 0 ? $indent/2 : 0);
        if(strcmp($atomname, "moov") == 0)
            $tags['moovpos'] = ftell($f) - 8;
        if(strcmp($atomname, "free") == 0) {
            $tags['freepos'][]  = ftell($f) - 8;
            $tags['freesize'][] = $atomsize;
        }
        if(strcmp($atomname, "udta") == 0) {
            $tags['udtapos'][] = ftell($f) - 8;
            $tags['udtasize'][] = $atomsize;
        }
        if(strcmp($atomname, "mdat") == 0) {
            $tags['mdatsize'] = $atomsize;
        }

// if it's a container atom, parse the contents of the atom
        if(in_array($atomname, $AtomType)) {
            ParseAtom($f, ftell($f), $off+$atomsize, $tags);
        }

// meta atom contains tags and some other data
        if(strcmp($atomname, "meta") == 0) {
            $atomdata = fread($f, $atomsize-4);
            $NextTagPosition = strpos($atomdata, 'Š');
            while ($NextTagPosition < strlen($atomdata)) {
                $metaItemSize = BigEndian2Int(substr($atomdata, $NextTagPosition - 4, 4)) - 4;
                $metaItemRaw  = substr($atomdata, $NextTagPosition, $metaItemSize);
                $metaItemKey  = substr($metaItemRaw, 0, 4);
                $metaItemData = substr($metaItemRaw, 20);
                $NextTagPosition += $metaItemSize + 4;

                ParseTag($metaItemKey, $metaItemData, $tags);
            } // while
        } // if meta

// mdhd has data for calculating playtime
        if(strcmp($atomname, "mdhd") == 0) {
            $atomdata   = fread($f, 20);
			$time_scale = BigEndian2Int(substr($atomdata, 12, 4));
			$duration   = BigEndian2Int(substr($atomdata, 16, 4));
			$tags['playtime'] = $duration / $time_scale;
        } // if mdhd

// stsd has data for sample, channels and codec
        if(strcmp($atomname, "stsd") == 0) {
            $atomdata = fread($f, $atomsize-8);
            stsd($tags, $atomdata);
        }

// bump offest and continue
        if($atomsize == 0) {  // a 0 byte atom is the end
            $off = $stopAt;
        }
        else {
            $off += $atomsize;
        }

    } // while

    $indent -= INDSIZE;
    return TRUE;
} // parseatom


function stsd(&$tags, $atomdata) {

    $num = BigEndian2Int(substr($atomdata,  4, 4));
    $stsdOff = 8;
    for ($i = 0; $i < $num; $i++) {
    	$size = BigEndian2Int(substr($atomdata, $stsdOff, 4));
    	$stsdOff += 4;
        $data_format = substr($atomdata, $stsdOff, 4);
    	$stsdOff += 12;
    	$data = substr($atomdata, $stsdOff, ($size - 4 - 12));
    	$stsdOff += ($size - 4 - 12);

    	$encoder_vendor   = substr($data,  4, 4);
    	if ($encoder_vendor == chr(0).chr(0).chr(0).chr(0)) {
    		$tags['sample_rate'] = FixedPoint16_16(substr($data, 16,  4));
    		$tags['channels']    =   BigEndian2Int(substr($data,  8,  2));
            if(strcmp($data_format, "mp4a") == 0)
        		$tags['codec'] 	 = "AAC";
            else
                $tags['codec']   = $data_format;
    	} // if
    } // for

} //stsd

function printtags($tags) {
    printf("Format:  %s\n", $tags['codec']);
    printf("Details: ");
    if(isset($tags['sample_rate'])) {
        printf("%s Hz ", $tags['sample_rate']);
    }
    if(isset($tags['channels'])) {
        if($tags['channels'] == 2) {
            printf("Stereo, ");
        } else
        if($tags['channels'] == 1) {
            printf("Mono, ");
        } else
        if($tags['channels'] !== 0) {
            printf("%s, ", $tags['channels']);
        }
    }

    $bitrate = (($tags['mdatsize'] * 8) / $tags['playtime']) / 1000;
    printf("%d kbps, playtime %s\n", $bitrate, TimeString($tags['playtime']) );

    printf("Artist:  %s\n", $tags['artist']);
    printf("Album:   %s\n", $tags['album']);
    printf("Title:   %s\n", $tags['title']);
    printf("Track:   %d\n", $tags['track']);
    printf("Genre:   %s\n", $tags['genrename']);
    printf("Year:    %s\n", $tags['year']);
}


function OptFree($infile, &$tags) {
    
    $f = fopen($infile, "r+b");

    $top = "";
    $changed = 0;
    $num = count($tags['atoms']);
    for($i = 0; $i < $num; $i++) {
        if(($tags['atoms'][$i]['level']-1) == 0) {
            $top = $tags['atoms'][$i]['name'];
            continue;
        }
        if( (strcmp($top, "moov") == 0) && 
            (($tags['atoms'][$i]['level']-1) == 1) &&
            (strcmp($tags['atoms'][$i]['name'], "free") == 0) ) {
                    printf("free: %s bytes at %s\n", number_format($tags['atoms'][$i]['size']), 
                        number_format($tags['atoms'][$i]['pos']) );
                    if( ($i+1) < $num && (strcmp($tags['atoms'][$i+1]['name'], 'free') == 0)) {
                        $tags['atoms'][$i+1]['pos'] = $tags['atoms'][$i]['pos'];
                        $tags['atoms'][$i+1]['size'] += $tags['atoms'][$i]['size'];
                        $changed = 1;
                        $last = $i+1;
                    }
                }
    }

    if($changed) {
        fseek($f, $tags['atoms'][$last]['pos']);
        fwrite($f, pack("N", $tags['atoms'][$last]['size']));
// printf("wrote %d at %d\n", $tags['atoms'][$last]['size'], $tags['atoms'][$last]['pos']);
    }

    fclose($f);

} // OptFree

// main
if(0) {
global $debug;

if($argc > 2) {
    if(!strcmp($argv[2], "--debug")) {
        $debug = 1;
    }
}
else {
    $debug = 0;
}

$infile = $argv[1]; 
$f = fopen($infile, "rb");
fseek($f, 0, SEEK_END);
$end = ftell($f);

ParseAtom($f, 0, $end, $tags);

$num = count($tags['atoms']);
for($i = 0; $i < $num; $i++) 
    printf("%s%s: %s bytes at %s\n", str_repeat('-',$tags['atoms'][$i]['level']-1), 
        $tags['atoms'][$i]['name'], number_format($tags['atoms'][$i]['size']), 
        number_format($tags['atoms'][$i]['pos']) );

printf("\ntags:\n");
printf("Artist: %s\n", $tags['artist']);
printf("Album:  %s\n", $tags['album']);
printf("Title:  %s\n", $tags['title']);
printf("Track:  %d\n", $tags['track']);
printf("Genre:  %s\n", $tags['genrename']);
printf("Year:   %s\n", $tags['year']);
$bitrate = (($tags['mdatsize'] * 8) / $tags['playtime']) / 1000;
printf("%d kpbs, playtime %s\n", $bitrate, TimeString($tags['playtime']) );
printf("%s %d %d\n", $tags['codec'], $tags['sample_rate'], $tags['channels']);

fclose($f);
// OptFree($infile, $tags);

} // main
?>