BaseTransform.setPreferPassthrough

If prefer_passthrough is true (the default), trans will check and prefer passthrough caps from the list of caps returned by the transform_caps vmethod.

If set to false, the element must order the caps returned from the transform_caps function in such a way that the preferred format is first in the list. This can be interesting for transforms that can do passthrough transforms but prefer to do something else, like a capsfilter.

MT safe.