On Sat, 2005-02-26 at 02:14 -0500, David Kyle wrote: > hondaman wrote: > > > I have a backend running fc3/mythtv .17 on one box with a pvr-250 > > capture card, and a frontend box running fc3 with it outputting to my > > computer monitor. I noticed that the image quality on the frontend is > > quite poor... its blurry, not sharp like a tv thats not doing any kind > > of PVR stuff (DTV dish --> reciever --> tv) I would have expected the > > output to my monitor to be super crisp, being a better display than a tv. > > > > This brings me to a couple questions: > > > > Is my "blurry" display on my monitor normal? > > > > When I output to a tv (I havent done this yet) will the output be as > > good as a normal setup, i.e. DTV dish --> reciever --> tv? > > > > _______________________________________________ > > mythtv-users mailing list > > [email protected] > > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users > > > In my experience, TV output to a monitor looks bad. Once you start > sending it to the TV, it should look almost as good as straight TV. At > least, it does for me. I'm not sure why, but the TV seems to do a good > job of hidding problems with the encoding.
I'm a bit sleepy, but I should be able to answer this. First off the tv signal is bandlimited. I'm not sure of the exact range (6Mhz?) but if you have a horizontal pattern with sharp transitions they will be rounded off by the limited bandwidth. Another thing to consider on your pc monitor is your presumably taking a 480i or 480p image and sending it to your video card to have it scale it up to whatever your resolution is. Now if your video card uses a fairly simple method of interpolation you might get some bluring there. I.E. If I have say 3 values 0 100 50 and the video card needs to interpolate those values it might do 0 50 100 125 50. The explanation doesn't catch all the details, yet you get the idea. What you want to do when expanding is use some kind of higher order expansion algorithm like bicubic resizing, however if you have mpeg artifacts the expansion algorithm might make parts of it look worse. Of course if you have a normal CRT you can just set your monitor at 640x480 and see what that looks like. It should be closer to a tv type effect. In general if you do some small to moderate post processing to reduce mpeg artifacts and use a good method for expanding the picture the picture on your computer screen 'should' look better than that on your tv screen. If you want to examine this idea a bit take a look at the post processing and different ways of expanding the video in mplayer. Of course handling things this complex in software can require a lot of CPU time. Some video cards might do better at expanding the video image as well, so you will probably have to look at the technology involved if its an important factor. Sometimes newer is better, and sometimes its just more expensive. > > So... it won't look perfect, but it'll be close. > _______________________________________________ > mythtv-users mailing list > [email protected] > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users >
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