This allows specifying more dither algorithms without using up flags and
without ambiguities.
Also initialize the new field based on the flags and use it.
Note, improving the logic of the checks is left to subsequent
commits, this here only switches from flags to enum.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
The version number is useful to check the libavutil version against which
the library was compiled at run-time, which in turn may be useful to deal
with binary compatibility issues.
Refactoring mmx2/mmxext YASM code with cpuflags will force renames.
So switching to a consistent naming scheme beforehand is sensible.
The name "mmxext" is more official and widespread and also the name
of the CPU flag, as reported e.g. by the Linux kernel.