[MPlayer-users] Dealing with Copy Protection

Alexander Roalter roalter at cs.tum.edu
Wed Aug 31 21:09:29 CEST 2005

... and no, I'm not talking about CSS, but about the new thing used by 
Sony which is known under the name ARccOS.

This copy protection method marks some sectors as unreadable/with wrong 
checksums/whatsoever and uses the IFOs to navigate around it, so a 
regular player will never see these sectors.

Now mplayer still does this, though I'm not sure if it is for the 
caching (read ahead) or some other thing. To my knowledge some "cells" 
of the VOBs are usused and produce read errors with the cdrom driver, 
which causes sometimes even a complete system arrest, but still at least 
around 5 minutes of retry for the driver (in this time you cant put to 
death mplayer or any other software trying to access the drive) and the 
eject button of course is also blocked.

Now I wonder if it were possible to a) finetune DVD reading so that even 
with caches (I set mine at 8 MB) mplayer does not try to get fancy and 
reads only the sectors that are needed (may need some snooping to find 
the next cell in the stream rather than simply increasing the sector number

or b) changing the cdrom driver (which unfortunately resides in the 
kernel) in such a way that it is (maybe programmable) that these 
erroneous sectors won't be retried and so mplayer should read happily 
over them and at last find the next valid sector.

I don't think this is a small problem, since it seems that more and more 
DVDs (especially the Sony ones (includes Columbia Tristar titles)) get 
this treatment. Whilst other DVD forums generally focus on making 
runnable copies of these DVDs by using a lot of the usual windows click 
and point stuff, I'd be more interested in a solution which doesn't 
bring the need for reburning a complete DVD which I already bought - why 
should I care for this and spend even more money, if there should be a 
solution by simple changing the player software (i.e. mplayer). And I 
wouldn't have to start windows again (which is now away for ages).


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