This adds a cogl-gst renderer to decode NV12 data. NV12 is split into
two buffers, one for the luma component and another for the two
chrominance components at a quarter of the resolution. The second
buffer is uploaded to a two-component RG texture. RG-component
textures are only supported if COGL_FEATURE_ID_TEXTURE_RG is
advertised by Cogl so the NV12 cap is also only advertised when that
is available.
Based on a patch by Lionel Landwerlin which was in turn based on a
patch from Edward Hervey and Matthieu Bouron for Clutter-Gst:
https://bugzilla.gnome.org/show_bug.cgi?id=712832
Reviewed-by: Robert Bragg <robert@linux.intel.com>
Reviewed-by: Lionel Landwerlin <llandwerlin@gmail.com>
(cherry picked from commit 2c619216964b46aab313be3ef1c405dfc720d258)
23044a1047