Reply To: Dreamcast – VGA or DTV 480p confusion

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Hi, it says in my TVs manual that my TV HDMI/DVI input recognizes VESA mode in 640×480 with Horizontal Frequency 31.469 kHz, Vertical Frequency 59.940, Pixel Clock 25.175 and Sync Polarity -/- .

Does that so far look compatible with Dreamcast <VGA cable> OSSC 480p DV mode <DVItoHDMI> TV ?

Sorry guys, I am not a whiz when it comes to this stuff but I am trying to understand what is going on. I’m reading through this thread again and maybe the answer is already there, but I’m still trying to figure out where the 720×480 to 640×480 change happens. I was thinking the NTSC TV could be doing it automatically, but then it sounds like the DC might stick the black-bars on both sides of the original image like I thought, but then change that whole image to 640 x 480 by changing the PAR, and that’s how the 3:4 display ends up with a squashed image, nor will it upscale to 16:9 properly. Plus I started to realize that 3:2 is an odd ratio to output video in anyway unless you are recording film to process, but I also know that that ratio pops up somehow during 3:4/16:9 anamorphic wide-screen processing, so maybe that is part of why it does it at all.

I was figuring that my S-Video image in 16:9 is about 10% too wide based on comparing height and width of some circles on the screen, which sounds like PAR pixel aspect ratio difference might come into play as part of the problem there somehow. Then I was also thinking if the DC is narrowing the image by switching it to 640×480 with the intent of being stretched later, you would have to turn that back into the original 3:2 image and then turn that into anamorphic 3:2 (I guess as dictated by the 480pDV standard) in order to get proper 4:3, and consequently tv-up-scaled 16:9. Is that right or am I missing some stuff? Also was wondering more about those black bars, how DC decides to hang them, is it hardware or software? Personally I don’t give a hoot if they stay, as long as I have proper aspect ratio, but I think that there’re graphics under there. Just trying to figure out when things happen in this chain and why. If the OSSC can optimally utilize whatever is going on in the Dreamcast to give us proper aspect ratios in 480p 640×480, that would be awesome.