[libdvdnav-devel] Cannot watch DVD (segmentation fault)

[Andrew Clayton]

On Tue, 21 Jul 2015 20:57:43 +0200, Francesco Turco wrote:

> Hello.
> 
> Note: this is a follow up of a message I sent to this mailing list on
> May 7th. Jean-Baptiste Kempf asked me more informations but I somewhat
> missed his message.
> 
> I have a DVD that I can't watch with the mpv video player because of a
> segmentation fault, and I think the issue is with libdvdnav. The movie
> is Jurassic Park. Other DVDs can be played just fine. The DVD is in
> very good conditions and it is not scratched.

Yeah, I've had plenty of DVD's that caused numerous problems, could
usually hack around the code enough to just be able to get the thing
ripped.

If I'm reading the gdb log right then the problem is here

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffd6d41700 (LWP 25336)]
0x00007ffff0b48b17 in dvdnav_describe_title_chapters (this=0x7fffcc000f20, 
    title=15, times=0x7fffd6d40c80, duration=0x7fffd6d40c88)
    at src/searching.c:650
650	    if (ptt[i].pgcn == 0 || ptt[i].pgcn > ifo->vts_pgcit->nr_of_pgci_srp) {

Probably one of these things is coming through as NULL for one or more
titles.

Stick in some printf's and see...

There was some place (possibly here) that I had to put in hacks
for certain dvd's that had one title that caused issues that I would
need to just skip (most of the time I'm just interested in ripping the
main title onto the computer).

Yeah, DVD's can be a real PITA. Just the other day I was watching a DVD
and the player (VLC) just stopped/hung about half way through. Looking
at dmesg I saw various errors from the DVD drive including something
about failure to read authenticated sector or some such. Restart VLC
skip through the chapters to where it should have been and no problems.
Crazy.

Andrew