There are a number of options which modify ASS subtitle rendering. Most
of these do things that can interfere with the styling done by subtitle
scripts, resulting in incorrect rendering. Add the --ass-style-override
option to make it easy to disable all overrides. This helps trouble-
shooting, and makes it more practical to use the override features. (You
can simply toggle the ass-style-override property at runtime, should
one of the style override options break subtitle rendering at a certain
point.)
This mainly affects whether most --ass-* options are applied, as well
as --sub-pos. Some things, like explicit style overrides loaded with
--ass-force-style, can't be changed at runtime using the
ass-style-override property.
wm4