Simple php function to parse an audio or video file and find if it has the right signature (magic number) according to its extension

check_AVfile_signature.php

<?php
/*
 * Reads some part of the bytes of an audio|video file and checks if its signature are true|false for that file extension
 *
 * @param actual $file
 * @param string $fileExtension
 * @return boolean
**/
function check_AVfile_signature($file, $fileExtension) {
    
    $fileExtension = strtolower($fileExtension);
    
    //https://en.wikipedia.org/wiki/List_of_file_signatures
    //https://filesignatures.net
    //https://www.garykessler.net/library/file_sigs.html
    //signatures encoded in ISO 8859-1 or HEX and written as regex. The signature array may contain different signatureS for the same format e.g.mp3
    $videos = array("avi"=>["signature"=>["^(RIFF).*(AVI)"], "offset"=>0, "encode"=>"ISO" ],
                    "asf"=>["signature"=>["^(3026b2758e66cf11a6d900aa0062ce6c)"], "offset"=>0, "encode"=>"HEX" ],
                    "flv"=>["signature"=>["^(FLV)"], "offset"=>0, "encode"=>"ISO" ],
                    "wmv"=>["signature"=>["^(3026b2758e66cf11a6d900aa0062ce6c)"], "offset"=>0, "encode"=>"HEX" ],
                    "mpeg"=>["signature"=>["^(000001ba)"], "offset"=>0, "encode"=>"HEX" ],
                    "mpg"=>["signature"=>["^(000001ba)"], "offset"=>0, "encode"=>"HEX" ],
                    "mp4"=>["signature"=>["(FTYP)"], "offset"=>4, "encode"=>"ISO" ],
                    "mkv"=>["signature"=>["^(1a45dfa3)"], "offset"=>0, "encode"=>"HEX" ],
                    "webm"=>["signature"=>["^(1a45dfa3)"], "offset"=>0, "encode"=>"HEX" ]
                   );
    $audios = array("mp3"=>["signature"=>["^(ÿû)", "^(ID3)"], "offset"=>0, "encode"=>"ISO" ],
                    "wav"=>["signature"=>["^(RIFF).*(WAVE)"], "offset"=>0, "encode"=>"ISO" ],
                    "ogg"=>["signature"=>["^(OggS)"], "offset"=>0, "encode"=>"ISO" ],
                    "mid"=>["signature"=>["^(MThd)"], "offset"=>0, "encode"=>"ISO" ],
                    "wma"=>["signature"=>["^(3026b2758e66cf11a6d900aa0062ce6c)"], "offset"=>0, "encode"=>"HEX" ]
                   );
    $audioVideo = array_merge($audios,$videos);
    
    if ( ! array_key_exists($fileExtension, $audioVideo) ) return false;
    
    
    foreach ($audioVideo[$fileExtension]["signature"] as $index=>$fileSignature) {
        
        $byte_offset = $audioVideo[$fileExtension]["offset"];
        //read 100 bytes after the offset
        $byte_lenght = 100;
        
        $filecontent = file_get_contents($file, FALSE, NULL, $byte_offset, $byte_lenght);
        
        if ( $audioVideo[$fileExtension]["encode"] == "ISO" ) 
            //if the web page is in UTF-8, it will convert the file from ISO-8859-1 to UTF-8
            $filecontent = mb_convert_encoding($filecontent, "UTF-8", "ISO-8859-1");
        
        if ( $audioVideo[$fileExtension]["encode"] == "HEX" ) 
            $filecontent = bin2hex($filecontent);
        
        
        if ( preg_match("/$fileSignature/i", $filecontent) ) return true;
    }
    
    return false;
}
?>