[MPlayer-users] Rescuing a scratched DVD

[Magnus Damm]

I think this is related:

I usually rent DVD:s and use mplayer to watch them on my media box.
This is a ok solution as long as the DVD is without scratches/finger-
prints. Sometimes (1 out of 10 maybe) the DVD is scratchy/dirty and
my DVD drive together with Linux and mplayer will totally slow down,
I guess trying to read the problematic area of the disc. 

I have found out that my Linux kernel likes to disable DMA when a
read error occurs and I have to manually use hdparm to re-enable 
it again. And this can only be done after all IO has completed,
I usually have to wait a while an look at the logs that tells me
that a certain sector/whatever of the disc was problematic. And
this takes a lot of time and is generally a PITA.

So how to people solve this? Rent VHS instead? =)
Buy a regular DVD player for 100 EUR? =)
Can I tell the kernel to keep DMA on even if errors occur while 
reading the DVD? Is there any way to stop the kernel from reading 
sector by sector very slow from the DVD?

This is probably a generic kernel/IDE problem, but I hope someone
knows a better solution than just wait and re-enable DMA...

Thanks!

/ magnus

On Sat, 6 Dec 2003 20:51:44 +0100
"HR" <haavroed at online.no> wrote:

> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> 
> I'm examining various ways of recovering as much as possible from a
> scratched DVD (my kid stomped on it and used it to wipe the floor...).
> Currently I do
> 
> dd if=/dev/dvd of=movie.iso conv=noerror
> 
> which takes a looong time now that it has hit one of the really bad
> parts.
> 
> I expect many of the frames in the ruined areas to be damaged, most
> probably beyond what can be read my most (all?) players. The question
> is, how do I best "repair" the vob's on the iso such that they can be
> played? Ofcourse, the frames will look really bad, with blocks,
> artifacts and much worse, but it'll still be playable... I really want
> the DVD menus/structur, so some kind of vob-fixer would be good. Can
> mplayer do any of the sort? If I have to sacrifice the structure, so be
> it. Would a -dumpstram stop once it hits errors, or can I force it to
> continue like with 'dd'? And if so, will mplayer write "readable" frames
> (garbaged, yes, but readable)?
> 
> I did a test on the vob in the unfinished iso with a player in win*2000,
> and got a player-crash followed by a win* blue screen when it got into a
> bad part... nice. I'm expecting the standalone DVD-player to choke on it
> as well, unless I manage to repair the vob's somehow.
> 
> HR
> 
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