I'm using mplaner and xine to play HDTV mpeg streams on my television, using the
built-in Radeon driver (NOT the binary proprietary driver), on a Radeon 9600,
using the Xv extension.  I have two video modes defined in my xorg.conf.  One of
them is 856x480 and the other is 1796x960 interlaced.  The problem is when I am
decoding a 1920x1080 signal in 1796x960 mode.  According to xvinfo, images up to
2048x2048 are supported (see below), so it ought to work.  But instead, the
video looks like a tiny scrunched up ribbon in the top 10% of my window, and the
rest is black.  This happens no matter what the actual window size is, whether
its fullscreen, or just a small window.

Other combinations are OK.  If I run in 856x480 res, the 1920x1080 image looks
OK.  If I am decoding a 720p stream (1280x720 resolution) it works no matter
what the screen resolution is.  The processor is an Athlon64, and I have both 64
and 32 bit versions of Gentoo installed, and the same problem happens in both
modes.  It is xorg X11 version 6.8.0.

Also, the image is OK if I use the Xshm driver, instead of Xv, although its too
slow to be a useful workaround.

Below is xvinfo.  Please leave a comment if I can provide more information that
would be useful.

--- xvinfo ---
X-Video Extension version 2.2
screen #0
  Adaptor #0: "ATI Radeon Video Overlay"
    number of ports: 1
    port base: 53
    operations supported: PutImage 
    supported visuals:
      depth 24, visualID 0x21
      depth 24, visualID 0x22
    number of attributes: 15
      "XV_SET_DEFAULTS" (range 0 to 1)
              client settable attribute
      "XV_AUTOPAINT_COLORKEY" (range 0 to 1)
              client settable attribute
              client gettable attribute (current value is 1)
      "XV_COLORKEY" (range 0 to -1)
              client settable attribute
              client gettable attribute (current value is 30)
      "XV_DOUBLE_BUFFER" (range 0 to 1)
              client settable attribute
              client gettable attribute (current value is 1)
      "XV_BRIGHTNESS" (range -1000 to 1000)
              client settable attribute
              client gettable attribute (current value is 0)
      "XV_CONTRAST" (range -1000 to 1000)
              client settable attribute
              client gettable attribute (current value is 0)
      "XV_SATURATION" (range -1000 to 1000)
              client settable attribute
              client gettable attribute (current value is 0)
      "XV_COLOR" (range -1000 to 1000)
              client settable attribute
              client gettable attribute (current value is 0)
      "XV_HUE" (range -1000 to 1000)
              client settable attribute
              client gettable attribute (current value is 0)
      "XV_RED_INTENSITY" (range -1000 to 1000)
              client settable attribute
              client gettable attribute (current value is 0)
      "XV_GREEN_INTENSITY" (range -1000 to 1000)
              client settable attribute
              client gettable attribute (current value is 0)
      "XV_BLUE_INTENSITY" (range -1000 to 1000)
              client settable attribute
              client gettable attribute (current value is 0)
      "XV_SWITCHCRT" (range 0 to 1)
              client settable attribute
              client gettable attribute (current value is 0)
      "XV_GAMMA" (range 100 to 10000)
              client settable attribute
              client gettable attribute (current value is 1000)
      "XV_COLORSPACE" (range 0 to 1)
              client settable attribute
              client gettable attribute (current value is 0)
    maximum XvImage size: 2048 x 2048
    Number of image formats: 4
      id: 0x32595559 (YUY2)
        guid: 59555932-0000-0010-8000-00aa00389b71
        bits per pixel: 16
        number of planes: 1
        type: YUV (packed)
      id: 0x59565955 (UYVY)
        guid: 55595659-0000-0010-8000-00aa00389b71
        bits per pixel: 16
        number of planes: 1
        type: YUV (packed)
      id: 0x32315659 (YV12)
        guid: 59563132-0000-0010-8000-00aa00389b71
        bits per pixel: 12
        number of planes: 3
        type: YUV (planar)
      id: 0x30323449 (I420)
        guid: 49343230-0000-0010-8000-00aa00389b71
        bits per pixel: 12
        number of planes: 3
        type: YUV (planar)