Originally Posted by Commodore 64
What about upscaling? Currently I use Mediaportal, but i will be setting up a MythTV backend and hopefully MythTV Frontend. Right now I output to a CRT HDTV at 1920 x 1080, and for whatever reason (I think VMR9 plus my 6600GT) the upscale is handled by the hardware.
Myth handles it the same way. Depending on your video card and drivers, it uses an overlay or a texture for the accelerated video playback. Part of the video card's capabilities are to scale the video to match the size/resolution of the output window. THis includes scaling up to a higher resolution, like your 1080i CRT, or down to a lower resolution like a 480i SD display.
You can test this by opening a video in VLC. Check its CPU usage at its native resolution, then expand it to full screen, and see if the CPU usage has changed.
You can get programs that do sophisticated scaling in software to get the best possible quality. Such as the popular "DScaler". They can use a lot of CPU power. But, most apps, including MythTV, just let the video hardware do the scaling.
So, for the original question - you shouldn't need to change anything in your configuration. The video will be scaled to display on your SDTV output. But, decoding the HD MPEG2 data will be a lot more CPU intensive. Depending on the speed of your Celerons, and if you can get XvMC working reliably, you might be able to display HD on your existing frontends.