the meta initialization function is provided *after* the base implementation
fields have been set so do *NOT* reset them otherwise it would result
in corrupted GstMeta.
Instead explicitely set our fields to the default values we actually want.
This commits add common elements for Ancillary Data and Closed
Caption support in GStreamer:
* A VBI (Video Blanking Interval) parser that supports detection
and extraction of Ancillary data according to the SMPTE S291M
specification. Currently supports the v210 and UYVY video
formats.
* A new GstMeta for Closed Caption : GstVideoCaptionMeta. This
supports the two types of CC : CEA-608 and CEA-708, along with
the 4 different ways they can be transported (other systems
are super-set of those).
https://bugzilla.gnome.org/show_bug.cgi?id=794901
