[libdvdcss-devel] Unscrambling ISO file - questions

[jrvirwty]

Attached is a simple program that I wrote to unscramble DVD ISO files.
I
hope to use this program, along with dd_rescue, to create unscrambled
ISO
files of the latest Disney (and other) DVDs. It appears to work in
initial "smoke testing" with a Tropic Thunder DVD that happened to be
lying around.

A have several questions:

1) This program is *SLOW* -- 4 hours or more to unscramble the 8 GB
Tropic Thunder ISO. Is there any way to use the library more
intelligently to speed it up?

(Note that I do want to stick with a block-by-block approach,
avoiding the file system-level shenanigans that some copy
protection
systems use.)

2) The ISO file contains 4 blocks that could not be unscrambled.
dvdcss_seek returns a "fatal error in vts css key". I am assuming
that this is yet another copy protection "trick", and the fact that
the unscrambled ISO appears to work seems to bear this out.

Have others seen this?

3) Just to confirm, there does not appear to be any sort of error code
or similar when a library function fails, so there's no way for my
program to know if dvdcss_seek has encountered the "fatal error in
vts css key" problem or some other error. Correct?

4) I am checking for a scrambled sectors using

if (buffer[0x14] & 0x30)

which I found in csstest.c.

Is this what dvdcss_is_scrambled does?

Thanks!

[jrvirwty]

Post by jrvirwty
1) This program is *SLOW* -- 4 hours or more to unscramble the 8 GB
Tropic Thunder ISO. Is there any way to use the library more
intelligently to speed it up?
(Note that I do want to stick with a block-by-block approach,
avoiding the file system-level shenanigans that some copy
protection
systems use.)

Aargh! Forgot one question.

Is libdvdcss thread-safe? I'd like to use multiple threads to speed up
unscrambling an ISO file. I'm hoping that I can call dvdcss_open from
each thread (all on the same source file) and use the returned handles
independently.

Will this work?

Thanks!

(BTW, sorry about the binary MIME type on the last post. Anyone know
how to get Tor Mail's "roundcube" web UI to use a text/plain type?)

[G.raud]

----- Original Message -----
From: jrvirwty
Sent: 07/15/13 07:09 PM
Subject: [libdvdcss-devel] Unscrambling ISO file - questions
Attached is a simple program that I wrote to unscramble DVD ISO files.
I hope to use this program, along with dd_rescue, to create unscrambled
ISO files of the latest Disney (and other) DVDs. It appears to work in
initial "smoke testing" with a Tropic Thunder DVD that happened to be
lying around.

It seems that what you are trying to achieve is exactly the same as a program
that I wrote 6 months ago, dvdimgdecss, and that I officilay released a few
weeks ago as part of CDimg|tools; see <https://gna.org/projects/cdimgtools>.
Let me know whether it can help do what you want.

[jrvirwty]

Post by G.raud
It seems that what you are trying to achieve is exactly the same as a program
that I wrote 6 months ago, dvdimgdecss, and that I officilay released a few
weeks ago as part of CDimg|tools; see
<https://gna.org/projects/cdimgtools>.
Let me know whether it can help do what you want.

You're correct. dvdimgdecss does exactly what I want (and much faster)
than my version, even after I parallelized it.

Thank you!