WIP: v4l2: Fix alternate interlacing caps and field values
Copied from https://gitlab.freedesktop.org//gstreamer/gst-plugins-good/-/merge_requests/665
Alternate interlacing was broken for v4l2sink element and had some issues in caps reporting. The caps negotiation was also broken in many ways.
ToDo:
- Ensure the following fails
v4l2src ! video/x-raw\(format:Interlaced\),interlaced-mode=progressive ! fakevideosink
- Ensure the following fails
v4l2src ! video/x-raw,interlaced-mode=alternate ! fakevideosink
- Investigate why all second fields are dropped with vivid
cc @gdesmott