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

I think we should actually report this to the company resposible for the 
software as a bug. 

Cheers Olaf

On Wednesday 28 August 2002 11:31, James Tappin wrote:
> There would appear to be at least 1 dvd authoring package out there that
> is generating DVDs with off-by-one errors in the lengths of some fields.
> Since the validity of these fields is check by an assert in libdvdread, to
> play said DVDs I have had to comment out the relevant assertions (and
> print the values instead).
>
> Line numbers refer to release 0.93.
>
> The first is at line 950 of ifo_read.c:
>  assert(n > 0 && (n % 4) == 0;
> These DVDs have n=61
>
> the other is at line 184 of nav_read.c:
>  assert(dsi->dsi_gi.zero1 == 0);
> these have dsi->dsi_gi.zero1 == 1
>
> 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.
>
> 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.
>
> Best regards,
> 	James