When reading ’The Snowman’ DVD from 2004, I get this output:

jani@saegusa:DVD$ dvdbackup -i /dev/sr0 -M
libdvdread: Using libdvdcss version 1.2.12 for DVD access

libdvdread: Attempting to retrieve all CSS keys
libdvdread: This can take a _long_ time, please be patient

libdvdread: Get key for /VIDEO_TS/VIDEO_TS.VOB at 0x0000015a
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_01_0.VOB at 0x000001c1
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_01_1.VOB at 0x00023749
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_02_0.VOB at 0x000241f0
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_02_1.VOB at 0x0002423d
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_03_0.VOB at 0x00024f03
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_03_1.VOB at 0x00024f50
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_04_0.VOB at 0x00025d8f
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_04_1.VOB at 0x00025ddc
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_05_0.VOB at 0x000e2c65
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_05_1.VOB at 0x000e2cb2
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_06_0.VOB at 0x000eb4df
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_06_1.VOB at 0x000eb52c
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_07_0.VOB at 0x000f7617
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_07_1.VOB at 0x000f7664
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_08_0.VOB at 0x00128eb1
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_08_1.VOB at 0x00128efe
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_09_0.VOB at 0x001da296
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_09_1.VOB at 0x001da2e3
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_10_0.VOB at 0x001e3856
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_10_1.VOB at 0x001e38a3
libdvdread: Elapsed time 0
libdvdread: Found 10 VTS’s
libdvdread: Elapsed time 0
*** Zero check failed in /build/buildd/libdvdread-4.2.0/src/ifo_read.c:904
for pgc->subp_control[i] = 0x00000001
*** Zero check failed in /build/buildd/libdvdread-4.2.0/src/ifo_read.c:904
for pgc->subp_control[i] = 0x00000001
*** Zero check failed in /build/buildd/libdvdread-4.2.0/src/ifo_read.c:904
for pgc->subp_control[i] = 0x00000001

This doesn’t prevent dvdbackup from finishing up, and the resulting copy looks to be fine (on cursory inspection). While dvdbackup is running, the issue also doesn’t cause an OOM as in Bug #377414. Still, I tested libdvdread4_4.2.0+20130428-0ubuntu0~bryce~precise1_amd64.deb from Bryce Harrington’s PPA [1], but it just slightly changed the ”Zero check failed” output:

*** Zero check failed in ifo_read.c:904
for pgc->subp_control[i] = 0x00000001
*** Zero check failed in ifo_read.c:904
for pgc->subp_control[i] = 0x00000001
*** Zero check failed in ifo_read.c:904
for pgc->subp_control[i] = 0x00000001

This DVD is the only one I’ve come across manifesting this, and I’ve backed up some 40 DVDs so far on this same setup.

*[1] https://launchpad.net/~bryce/+archive/lp377414/+build/4542681