Xvideo is displayed incorerctly on FX5200 PCI
I am using a FX5200 PCI card in an old I810 based system to drive an RBG scart TV directly from the VGA connector (couldn't use the integrated I810 graphics card as it didn't support interlacing).
Running X and Myth TV generally behaves fine and even watching TV is fine provided the vertical scaling is set such that the whole of the video stream is displayed on the whole of the display. However if I use the 'letterbox' modes to remove the horizontal bars from the top and bottom (I'm using a 16:9 TV), then the displayed image is offset vertically (off the top of the screen) and the bottom of the image is dispalyed once and then doesn't change. The magnitude of both of these effects depends on scaling factor.
Looking at the Myth TV code, it appears to do scaling by drawing onto a larger display area (starting at -ve y coordinates). This works fine on one of my PCs (with a Radeon chipset), but not with this system.
I have modiied the MythTV code to produce more debugging and all the src and dest co-ordinates look fine. I have even modified it to apply the letterboxing by reducing the area of the video to copy rather than expanding the display area and the results are the same.