The VideoLAN Forums

Posted: **22 Jul 2019 19:25**

I regularly need to convert DVDs for various purposes. Most are not encrypted, so I can just copy the .VOB files and convert them with ffmpeg. But some DVDs use CSS copy protection, and I realize it only after doing all the transcoding.

Is there a quick and easy way in VLC to find out if a DVD uses CSS?

There is code in VLC which does check that, but I don't really know C or C++, so I'm not able to extract and rewrap it into a simple "csscheck" command-line tool.

Posted: **26 Jul 2019 13:44**

Well it seems I just have to try playing a single VOB instead of the whole DVD or DVD-folder. The scrambling is immediately visible. For some reason, I had he impression that VLC would also de-CSS a single VOB, but apparently it doesn't.

Before realizing that, I had made a Perl script which seems to correctly detect it too, so here it is in case it's useful to someone:

Code: Select all

#!/usr/bin/perl

my $VERSION=0.02;

my $sector_size = 2048;
my $count       = 1000;

use strict;
use autodie;


my $file = shift;
die "Not found: $file\n" unless (-f $file);

if (-s $file < $count * $sector_size) {
	$count = int( (-s $file)/$sector_size );
	warn "File too small. Checking $count sectors only ($file)\n";
}

my $protected = 0;

open my $fh, '<:raw', $file;

for (my $s=0; $s<$count; $s++) {
	my $bytes_read = read($fh, my $bytes, $sector_size);
	die "Got $bytes_read but expected $sector_size from $file\n" unless ($bytes_read == $sector_size);

	my @sectors = unpack("C*", $bytes);
	if ( ($sectors[ ($sectors[13] & 7)+20 ] & 48) != 0 ) {
		$protected++;
	}
}

if ($protected) {
	print "CSS-protected (on $protected of $count sectors) : $file\n";
} else {
	print "NOT protected : $file\n";
}

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How to check if DVD uses CSS copy protection

How to check if DVD uses CSS copy protection

Re: How to check if DVD uses CSS copy protection