On Fri, 5 Dec 2003, Ronald Bultje wrote: > Note that MPEG2 4:2:0 chroma ordering isn't the only valid 4:2:0. > Scanline dropping is perfectly valid in other 4:2:0 cases. I'd say that Thinking about this, aren't there two ways you could scanline drop? Say you have a frame made from two fields, with scanlines 1, 2, 3, 4, 5, etc. If you want to treat it as a single progressive frame (say because that's what the source material happens to be) it would make the most sense to drop the chroma from scanlines 2, 4, 6, etc. But if you want to treat it as two independent fields, you would want to drop chroma from scanlines 3, 7, 11,... from the odd field and 4, 8, 12,... from the even field. The bt848 hardware has the capability to do both. But it seems that the driver only supports the former and not the latter?
