Re: libdvdread -- off by 1 errors (not your fault)

On Thu, 29 Aug 2002 10:53:52 +0200
H}kan Hjort <[email protected]> wrote:

> > The first is at line 950 of ifo_read.c:
> >  assert(n > 0 && (n % 4) == 0;
> > These DVDs have n=61
> > 
> Haven't seen this before.  

This was actually the first one I found, but it only happens once, whereas the other is every "block".

> > the other is at line 184 of nav_read.c:
> >  assert(dsi->dsi_gi.zero1 == 0);
> > these have dsi->dsi_gi.zero1 == 1
> > 
> Have seen this, perhaps among others, it's produced by the MacOSX DVD
> creation software.  Which seems to becomming ever more popular as 
> more people burn their own DVD-R.
> 
> > This affects both ogle and xine-dvdnav playback (xine-dvdnav also fails
> > another assert in xine-lib that I've not yet tracked down in detail).
> > While it's pretty obvious to me that the author of the writing software
> > has double-allowed for the null at the  end of a string, this is probably
> > a commercial package for windows or mac so I doubt there's much chance of
> > exterminating it.
> > 
> If some one could confirm which program it is and at least report it as
> a bug... 

The problem here is that I only have a snail-mail address for the videographer responsible so, unless there is an indicator on the disc, it may take a while to find out.

> > Is it reasonable that these asserts be downgraded to some kind of warning
> > message as the DVD plays correctly in ogle when they are ignored.
> > 
> Yes, and I've been intending to do this for a while now.  It's not always
> as simple as to just remove the assert.  Ofthen it needs to be replaced
> by both a check to emit a warnings and some new code to patch up the values
> to some thing safe that won't crash or currupt memmory later.

Keep up the good work!
	James Tappin

-- 
James Tappin,               O__      "I forget the punishment for using
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