A GST_VIDEO_FORMAT_* could be mapped to only one pair of DRM_FORMAT_*
and DRM_FORMAT_MOD_*. Until now only DRM_FORMAT_MOD_LINEAR was used.
To be able to add other modifiers add a modidier field in struct FormatMap.
Create a helper functions the allow turning a GstVideoFormat into a pair
of DRM fourcc and modifier and vis-versa.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7849>
The current way of dma caps uses the drm-format to replace the orginal
format field. The absence of format field means it can accept all formats.
It causes problems when clipping with other old DMA or video/x-raw(ANY)
caps, the result will contain both format field and drm-format field,
which is not valid DMA caps.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4981>
In gst_video_info_dma_drm_to_caps() the caps are newly created, so there's no
need for make it writable. In gst_video_info_dma_drm_from_caps() a copy of the
caps is done, which implies a gst_caps_make_writable().
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4195>
