[mythtv-users] 23.976fps choppy playback

Sebastian Jambor crepels at gmx.net
Sun Jan 15 12:04:00 UTC 2012

On Saturday, January 14, 2012 22:37:42 Jean-Yves Avenard wrote:
> On Sunday, 15 January 2012, Wil <nodenet at hotmail.com> wrote:
> > I am interested to know when you say you are playing back the original
> > discs if they are older discs or not, as the mythtv wiki states that
> > playback is only supported for...
> > 
> > A disc protected by AACS MKB version 10 or lower, and not protected by
> > BD+

This information is a bit dated. There are keys available for MKBv25, and this 
is the latest version, as far as I know, which should allow you to play all 
discs not encrypted with BD+.

> Unfortunately, I can't play BD disks natively any longer. I played a disk
> once (dark side of the moon), that invalidated some keys. And none of the
> known ones now work. So no more BD playback on Linux for me without anydvd.

I assume you are talking about the certificates to get the volume ID? This 
part of the AACS scheme always seemed to be the most flawed to me. Any 
software player able to play blu ray discs has to communicate with the drive 
to get the volume ID. This communication can be intercepted, e.g. with strace. 
So what I do is the following: For each new blu ray I buy I run makemkv (but 
you should also be able to use anydvd or any other player), use strace to 
intercept the ioctl call where the volume ID is read, and put this information 
in the KEYDB.cfg. The downside is that you have to do this for each new disc. 
The upside is that you only have to do it _once_ for each disc, and then you 
can watch that disc forever, even if your certificates have been revoked. 
I wrote a small script which does this automatically, but I guess the mailing 
list policies prohibit me from posting it here.

There is another downside to this, which is BD+. Fortunately, it seems that 
only Fox uses BD+, and not even on all discs. Of the six Fox blu ray's I own, 
only three are additionally encrypted with BD+.


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