Reply To: Dreamcast – VGA or DTV 480p confusion


Ok I am learning that within the 480p DV standard, the 2:3 ratio is mainly a pixel aspect ratio for conversion and storage from 16:9 to 4:3, so that the 16:9 image changed to 2:3 pixel aspect ratio and then stored in 4:3 will show up on a 16:9 screen properly. Not sure if that can be used somehow going the other way, but I think that’s what I was trying to determine when I came across the thread.

As show in the previous picture, DC outputs only 640×480 subsection (which is designed to fill whole 4:3 screen) within that area so it won’t result to correct aspect with modern displays by default.

Ok let me know if this is correct. Sounds like those black bars (that mark where to stop stretching the image on a 640×480 3:4 set) are put there by the DC, but do not affect the pixel aspect ratio coming out of the DC by being there. Is it correct to think that the DC hangs those black sidebars over the 720×480 rendered graphics and then sends all of that to the TV as 720x480p without changing the pixel aspect ratio, and then the 3:4 TV squishes it, black bars and all, and that is the first time the pixel aspect ratio gets affected? The chart is helpful, but I found myself wondering about pixel aspect ratio, what does the DC use initially, and does that change internally before it leaves the system via VGA-out, and what is it when it leaves the system? It seemed like if it is changing before it leaves and then the TV is affecting it again, that it would have been a lot tougher to resolve the issues.


However, recent OSSC fws have advanced timing tweaking option which can reduce the width of signal marked as active from 720 to 640, so monitors and compatible TVs can display only that area when scaling to 4:3 or 16:9 (widescreen games), resulting to exactly correct aspect ratio.

Sounds good, wouldn’t mind some more discussion about my above questions anyway.

With my possible setup below and reading about the OSSC, I see to set 480p line x2 to off for basic 480p passthrough, does using the DTV-480p setting or using the dvi-d-to-hdmi cable somehow cause the output to change to 480i?
( DC <> VGA cable <> OSSC <> dvid-to-hdmi cable <<still 480p here?>> TV )

I pretty much play three games, none burned, on my NTSC system. NTSC Shenmue, NTSC F355 Challenge, and UK-PAL Shenmue2 using a reindeer boot disk that I made to get it started. I know reindeer disk won’t display through VGA.

Has anyone tested these three games to see if the 16:9 aspect ratio setting works on all of them? I know that these should all boot into VGA, but do I have to worry about PAL format with Shenmue 2 conflicting with the the DV standard that I need to set for widescreen? The game appears to run OK on my TV through S-Video, so I am assuming that the game runs in “PAL-60” then.