Mark Vojkovich ([EMAIL PROTECTED]): > > I'd be worried about scaling. The Xv driver can't ensure the > > spacial position makes sense. I guess it could be up to the > > application to align it nicely. > > I don't understand what you're worried about. If you say top or > bottom that seems pretty clear to me. I don't see what there is to > mess up. This is pretty much the only way you're going to get > field-only display in Xv.
It's just something silly, I guess, but important for preserving the spacial position of the fields. Say you're scaling from 720x480 to 1024x768. 768/480 = 1.6, so, you want to scale up each field from 240 lines up to 766.4 lines. This gives a scaling of: [top field] y=0 to y=766.4 [bot field] y=1.6 to y=768 So, if the card can scale to non-integer scanlines, cool, but I doubt most cards can do this. So, someone has to choose a scale factor such that the start scanline of the bottom field, and the bottom scanline of the top field, are integer values so that the spacial position of the data in the field will make sense. Alternatively, you put a black scanline at top and bottom of the input, i.e., scale from 482 instead of 480, and then the Xv driver has to do that logic when copying into video memory. That's going to suck for cards which DMA it over though. Haven't thought that option through. Thoughts? -- Billy Biggs [EMAIL PROTECTED] _______________________________________________ Xpert mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xpert
