libva 2.xx introduce big improvment for intel hardware encoder and decoder,unfortunately the slackware 15.0 release use the 2.13 branch because the 2.14 was published too late.
libva2.14.0, libva-intel-driver2.4.1, libva-utils-2.14.0 fix encoding problems and more.

What is the best way to use for fixing the problem? (salix repository, sourcery, individual slackbuild...)