Disable STACK_FIELDS for SDI field mode
One way of dealing with interlaced video is to stack both fields vertically. We did that so that we were recording the full video resolution without introducing nasty combing artefacts.
Unfortunately, all processing of the field-stack is currently broken. Field order is arbitrarily flipped in various places. And doing this properly is quite involved, up to the point were I think it's not worth the effort as it will undermine the simplicity of SDI video handling provided by libvideo.
So disable/remove STACK_FIELDS. Only keep full-frame, and drop-one-field.