unpack() function generates Fatal error

[santrooper]

Hello all,
I am trying to unpack big wav file (more than 10 mb), because i want to generate Visualization of an wav file, for smaller files (less than 2 mb) it works fine, but for bigger files it gives
Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 35 bytes) in /var/www/phptest/mp3processor/thescript.php on line 64
I am pesting the code below
PLEASE HELP
====================

<?
class wavVisualization{
    var $afiles = array();        
    var $arrData = array();
    var $wavs = array();
 
    function wavVisualization(){}
 
    function loadFile($filenam){
        $content = file_get_contents($filenam) or die("HALT");
        $this->getStructure($content);
        $this->afiles['structure'] = $this->wavs;
        $this->unpackData($this->wavs['Data']);
    }
 
    //== Get structure of wav file ==//
    function getStructure($binstr){
        $this->wavs['ChunkID'] = substr($binstr,0,4); 
        $this->wavs['ChunkSize'] = $this->unpackHeader(substr($binstr,4,4));
        $this->wavs['Format'] = substr($binstr,8,4); 
        $this->wavs['Subchunk1ID'] = substr($binstr,12,4);
        $this->wavs['SubChunk1Size'] = $this->unpackHeader(substr($binstr,16,4));
        $this->wavs['AudioFormat'] = $this->unpackHeader(substr($binstr,20,2));
        $this->wavs['NumChannels'] = $this->unpackHeader(substr($binstr,22,2));
        $this->wavs['SampleRate']  = $this->unpackHeader(substr($binstr,24,4));
        $this->wavs['ByteRate'] = $this->unpackHeader(substr($binstr,28,4));
        $this->wavs['BlockAlign'] = $this->unpackHeader(substr($binstr,32,2));
        $this->wavs['BitsPerSample'] = $this->unpackHeader(substr($binstr,34,2));
 
        //check extra format bytes
        if($this->wavs['SubChunk1Size']==16){
            $this->wavs['Subchunk2ID'] = substr($binstr,36,4);
            $this->wavs['SubChunk2Size'] = $this->unpackHeader(substr($binstr,40,4));
            $this->wavs['Data']= substr($binstr,44,strlen($binstr));
        }
        elseif($this->wavs['SubChunk1Size']==18){
            $this->wavs['ExtraFormatBytes'] = substr($binstr,36,2);
            $this->wavs['Subchunk2ID'] = substr($binstr,38,4);
            $this->wavs['SubChunk2Size'] = $this->unpackHeader(substr($binstr,42,4));
            $this->wavs['Data']= substr($binstr,46,strlen($binstr));
        }
        $this->wavs['NumberSamples']= ($this->wavs['SubChunk2Size']*8)/($this->wavs['NumChannels']*$this->wavs['BitsPerSample']);
    }
 
 
    //== Get Decimal Values ==//
    function unpackHeader($str,$opt=""){
        if(strlen($str)>2){
            $arr = unpack("V*",$str);
        }
        else{
            $arr = unpack("v*",$str);
        }
        return $arr[1];
    }
 
 
    //== unpackData ==//
    function unpackData($strbin){
        if($this->wavs['BlockAlign']==1){
            return unpack("C*",$strbin);                //unsign Character
        }
        else{
            return unpack("s*",$strbin);                //sign int16 //error occuring here//
        }
    }
}
?>
<?php
$srcaudio="temp_audio_store/lal_1192620354.wav"; //==An WAV file more than 10 mb==//
$audViz = new wavVisualization();
$audViz->loadFile($srcaudio);
?>

[pbmods]

Heya, santrooper. Welcome to TSDN!

You're getting an out-of-memory error.

Probably the best way to circumvent this would be to load the file in 2 MB chunks using the fread() function.

Of course, in order to avoid out-of-memory errors, you'll also need to keep writing your temporary data to a file as you process. This will slow down your script significantly, so be sure to check the size of the file first.