#!/usr/bin/perl -w
#
# Note: Ensure the DivX codec is installed on the target Windows machine, else
# Windows Media Player won't be able to decompress the video rendering it
# blank.
#
$|++;

use strict;

use constant READSIZE => 1000*1024; # GVI file read blocksize

my $buf;

my $filename = shift || die "Need name of GVI file to convert";

open(IFILE, "${filename}.gvi") or
    die "Unable to open video file ${filename}.gvi: $!";

open(OFILE, ">${filename}.avi") or
    die "Unable to create output file ${filename}.avi: $!";

read IFILE, $buf, 16;
print OFILE $buf;

seek IFILE, 68, 0;  # Skip over Google's header

do {
    read IFILE, $buf, READSIZE;
    print OFILE $buf;
} while (!eof(IFILE));

close OFILE;
close IFILE;

exit 0;