[libdvdcss-devel] CSS authentication changes content returned from drive on some systems only?

[Diego Elio Pettenò]

Just a wild guess honestly, but if your DVD drive is set to region of the
disk you're reading, it will perform the auth in hardware, and libdvdcss
wouldn't be involved.

So I would check with the other developer whether you're using matching or
mismatching drives/discs.

Diego Elio Pettenò — Flameeyes
flameeyes at flameeyes.eu — http://blog.flameeyes.eu/


On Wed, Jul 10, 2013 at 9:24 AM, <libdvdcss at jmbreuer.net> wrote:

> I've run into an issue while taking care of DVD resume code in XBMC.
>
> A bit of background: XBMC computes a hash over the content of all .IFO
> files to use as a Disk Unique ID, to make it possible to identify the same
> disk when it is inserted again later and have per-disk persistent player
> state / resume bookmarks.
>
> XBMC uses libdvdnav/libdvdread/libdvdcss for DVD access.
>
>
> I've observed the following: On both of my systems (gentoo on x86_64 and
> OpenELEC on x86_64 [different HW]), performing CSS authentication (e.g.
> "starting playback") will cause a different hash value to be computed than
> before - see https://github.com/xbmc/xbmc/**issues/2936<https://github.com/xbmc/xbmc/issues/2936>
>
> So it seems that performing CSS (my guess: the drive authentication part)
> causes different data to be returned from the drive - FOR ME.
>
> The hashes returned "before" and "after" authentication each are stable,
> i.e. I always get the same two hashes for a given disc, one before auth,
> the other after.
>
>
> While discussing the issue with upstream, it turns out that another
> developer on Windows cannot reproduce the issue - he always gets the same
> content/hashes, although the logs show CSS authentication being performed
> against his drive as well.
> See https://github.com/xbmc/xbmc/**pull/2951<https://github.com/xbmc/xbmc/pull/2951>
>
>
> Can anyone shed some light on why our systems would behave differently as
> they do?
>
>
> Thanks a lot!
>
>
> So long,
>    Joe
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