Creating slideshow of large number of images fails due to inode exhaustion in default /tmp

[Ryan C. Underwood]

Creating a DVD image with several thousand (4000+) images fails, with this in the final log line:
Error while writing video frame: Operation not permitted

After much useless debugging and wasted time, I found:
Filesystem Inodes IUsed IFree IUse% Mounted on
udev 998714 621 998093 1% /dev
tmpfs 1006983 1194 1005789 1% /run
/dev/mapper/ubuntu-root 53043200 646110 52397090 2% /
tmpfs 1006983 37 1006946 1% /dev/shm
tmpfs 1006983 6 1006977 1% /run/lock
tmpfs 1006983 18 1006965 1% /sys/fs/cgroup
/dev/loop0 35 35 0 100% /snap/canonical-livepatch/50
/dev/loop1 1269 1269 0 100% /snap/gnome-calculator/260
/dev/loop5 1598 1598 0 100% /snap/gnome-characters/139
/dev/loop6 12783 12783 0 100% /snap/core/5742
/dev/loop2 31 31 0 100% /snap/canonical-livepatch/49
/dev/loop7 27345 27345 0 100% /snap/gtk-common-themes/818
/dev/loop8 12783 12783 0 100% /snap/core/5662
/dev/loop9 12810 12810 0 100% /snap/core/6130
/dev/loop3 35 35 0 100% /snap/canonical-livepatch/54
/dev/loop4 747 747 0 100% /snap/gnome-system-monitor/57
/dev/loop10 27631 27631 0 100% /snap/gnome-3-26-1604/74
/dev/loop11 1720 1720 0 100% /snap/gnome-logs/45
/dev/sda4 59520 303 59217 1% /boot
/dev/sda1 0 0 0 - /boot/efi
AFS 2147483647 0 2147483647 0% /afs
tmpfs 1006983 1006983 0 100% /run/user/1000

Note the last line.

DVDStyler should statfs() on encoding failure to help the user triage simple problems like "out of disk space" and "out of inodes" instead of bubbling opaque FFmpeg error messages to the user.