code snippet...
     read(IN, my $buff, 1 * 2**10);
     (substr($buff,0,4) eq "RIFF") || die "not a valid RIFF file";
     my $size = unpack ("V4",substr($buff,4,4));
     myprint (" RIFF segment size = $size");
     (substr($buff,50,4) eq "data")|| die "data segment not found";
     my $dsize = unpack ("V4",substr($buff,54,4));   
     myprint (" DATA Segment size = $dsize");