Changed priority from "extra" to "optional".
Added line-breaks in "Build-Depends" field of d/control.
Upgraded to debhelper 9.
Removed useless comments from debian/rules.
Use DEB_BUILD_MAINT_OPTIONS variable instead of CPPFLAGS, CFLAGS, CXXFLAGS and LDFLAGS separately in debian/rules.
Updated changelog time.
Make sure the package compiles with both Libav 10 (in Debian testing and unstable) and Libav 9 (in some downstream distros like Ubuntu), the patch for Libav 10 compatibility (in commit 7bf48cda) broke the compilation with older Libav versions.