Kodi used to embed dvdread and dvdnav in its source but the developers switched to
downloading it which is not an option for Debian source packages. The embedded
copy of both libraries is retrieved from VideoLAN upstream by watchfile and the
required Debian patches are applied (debian/patches/libdvd{read,nav}-*.patch).

Kodi replaced the default webinterface in 17.0 beta6 but the new interface contains
many generated files without providing the source for them. The web interface
is temporarily reverted to the one included in beta5 to restore GPL compliance.

The web interface is placed in debian patch folder (debian/webinterface-default)
and is copied in autoconf override because quilt patches can not handle git binary
diffs.

The cdatetime-std-chrono patch set, available as upstream PR:

    https://github.com/xbmc/xbmc/pull/18727

is a refactored date and time conversion logic in Kodi, that fixes the totally
broken current implementation for 32-bit architectures (i386, mipsel).
It should have been added to 19.0 but upstream authors decided to postpond it
until 20.0 development cycle starts. I decided to include it in Debian release
nonetheless along with embedded date library (embedded-libdate-tz) from Howard
Hinnant:

    https://github.com/Howardhinnant/date

It does not make sense to package libdate-tz separately because it is partially
accepted as upcoming C++20 standard and eventually kodi will move to C++20 in 
20.0 or 21.0. Upstream author also expects the library to be embedded in project,
reasoning of "poor CMake support" (see upstream issues).

 -- Vasyl Gello <vasek.gello@gmail.com>, Tue,  3 Jun 2020 10:30:00 +0300