On Sat, Jan 01, 2005 at 10:42:53PM +1100, William Uther wrote: > I've been building a MythTV box. I have a VisionPlus digital DVB-T > capture card (giving me a PAL, MPEG2, 16:9, 50Hz, interlaced video > stream). I'm trying to find the best way to get a picture on my TV (a > 4:3 aspect ratio, 100 Mhz Grundig with vga, scart, svideo and composite > interfaces). I'd like to be able to watch the 16:9 signal both > letterboxed (see the whole thing with top and bottom black stripes) and > zoomed (just grab the middle 4:3 section out of the 16:9 signal - lose > the left and right edges of the video stream). > > I've tried two methods so far, but neither is entirely satisfactory. > Can anyone suggest a good approach?
I'm using TV out from a Geforce4 MX440 card. I have a 720x576 50Hz modeline for X. Then use the TV out overscan controls to have the picture fill the TV. By default, the 16:9 picture is letterboxed to fit the 4:3 TV. You can use the '16:9 Zoom' mode to get the central 4:3 portion to fill the screen. My TV is a plain Panasonic 4:3 with nothing but composite/S-Video/component inputs, so I haven't tried VGA output. > Here is what I've tried: > > i) Use VGA out on the myth box at 640x480x60Hz into the vga in port > on the TV. You should be able to use 50 Hz, which would be better. You need interlaced output also, which your video card might not support. > I then tried the modeline on that website, and the one posted by > Stephen Williams on this list: > > Modeline "768x576pali" 14.76 768 789 858 944 576 580 583 625 -hsync > -vsync interlace > ModeLine "720x576pali" 13.875 720 744 808 888 576 581 586 625 -hsync > -vsync interlace > > Both of these generate an image that is too large for the TV screen. > More than that, changing the mode line by small amounts doesn't seem to > help - I'm beginning to wonder if the TV has some auto-centering > circuitry that is throwing things off. sigh. You might be able to fix this with 'xvidtune', though it might be the same as the adjustments you already tried by hand. > The other problem is that the 'interlace' part of the modeline seems > to turn off Xv support (Savage drivers). This in turn switches off the > ability to zoom in Myth - I only get the 16:9 image squished into 4:3. > I don't like the stretching. Again, sigh. It sounds like a better VGA card is in order. regards Hamish -- Hamish Moffatt VK3SB <[EMAIL PROTECTED]> <[EMAIL PROTECTED]>
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