[vdr] sxfe and vsync

When using NVidia graphics cards and the proprietary driver I find vdr-sxfe looks quite smooth even with a monitor that only supports 60Hz. I think it's been syncing to the vertical blank "automagically". But with other graphics cards I get a lot of tearing which is marring my viewing pleasure. This is happening both with Intel Sandy Bridge (normal monitor) and a Radeon 5450 with fglrx connected to a TV. The free ati driver isn't a practical option on that because the HDMI audio doesn't work with it. I'm using the xv output in each case. Is there a way to make vdr-sxfe sync to the vertical blank with these cards/drivers?