Do it only for video (the only thing for type for which HDR10+
makes sense).
This effectively reverts changes to several FATE ref-files
made in bda44f0f39.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This is possible by using a dynamic buffer to write them;
said dynamic buffer is (re)used and reset as appropriate.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>