Dreamcast OSSC + Toro Aspect Ratio Issue

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  • #25419
    BaskinRobinson
    Participant

    I’ve been using my Dreamcast with an OSSC + Toro (VGA) on my Dell U2414H monitor without issue—I set the sampling to 480p DTV and the horizontal active area to 640, and it gives me the correct 4:3 aspect ratio:

    http://www.firebrandx.com/OSSC/OSSC%20-%20Sega%20Dreamcast%20-%20Toro%20VGA%20Optimal%20Timing.txt

    I would like to use it on my TV, which is a Sony KDL-60W630B, but I’m unable to get it to display in the correct aspect ratio. Using the same settings as above, I get a much narrower than 4:3 image (using 480p DTV sampling). If I change the sampling to 640×480 VESA, it appears to show an aspect ratio closer to 4:3, but still a little too narrow, and it puts the TV in some kind of PC mode with very washed out colors and overall poor image quality. If adjust the H. active from 720 to 640, it simply cuts off an equivalent amount of the image on the right side. I can adjust the H. backporch to move the image to the left to show the entire image again, but the aspect ratio is no different—it’s the same narrow image, just shifted over to the left more.

    I’m not sure if it’s the OSSC settings, or if my TV is simply incompatible, but I was wondering if anyone ran into a similar issue and was able to correct it.

    Also, I should mention that the Dreamcast boot screen (the white background with animation) is shown in the correct aspect ratio. All games and the GDEMU menu are too narrow.

    #25429
    nmalinoski
    Participant

    How does the aspect ratio look when running the 240p Test Suite?

    Does the Dreamcast use 480i/576i for the boot splash and then switch to 480p, or is it 480p the whole time?

    Side note: You may want to consider picking up a SCART cable to connect the Toro to the OSSC; the Dreamcast can benefit from the low-pass filtering that is available on AV1 (also AV2) that isn’t present on AV3.

    #25431
    BaskinRobinson
    Participant

    How does the aspect ratio look when running the 240p Test Suite?

    I haven’t tried the 240p Test Suite—I’ll need to get that set up. Either way, the aspect ratio is definitely narrower than 4:3.

    Does the Dreamcast use 480i/576i for the boot splash and then switch to 480p, or is it 480p the whole time?

    I’m not actually sure. I think it’s 480p the entire time. How would I confirm?

    Side note: You may want to consider picking up a SCART cable to connect the Toro to the OSSC; the Dreamcast can benefit from the low-pass filtering that is available on AV1 (also AV2) that isn’t present on AV3.

    I tried this, but was not able to get a 480p signal, only 480i. I tried every combination of VGA/RBG and RGBHV/RGBS on the Toro, but the TV only accepted the signal when it was 480i, and it seemed like a very low-quality, shimmery 480i at that.

    #25433
    nmalinoski
    Participant

    Does the Dreamcast use 480i/576i for the boot splash and then switch to 480p, or is it 480p the whole time?

    I’m not actually sure. I think it’s 480p the entire time. How would I confirm?

    Watch the screen on the OSSC when you turn the console on. If it says 525p the entire time, it’s 480p. If it says 525i/625i, then it’s 480i/576i. (I also have a Dreamcast with a Toro and OSSC hooked up; I’m just not at home right now.)

    Side note: You may want to consider picking up a SCART cable to connect the Toro to the OSSC; the Dreamcast can benefit from the low-pass filtering that is available on AV1 (also AV2) that isn’t present on AV3.

    I tried this, but was not able to get a 480p signal, only 480i. I tried every combination of VGA/RBG and RGBHV/RGBS on the Toro, but the TV only accepted the signal when it was 480i, and it seemed like a very low-quality, shimmery 480i at that.

    On the Toro, you need to have the Dreamcast mode switch (the one in the bank of four closest to the console) set to ‘VGA’, so the console will output 31kHz RGBHV (480p). Then you need to run a fully-wired male-to-male SCART cable from the Toro to AV1, and change the input on the OSSC to AV1-RGBS. The other RGBHV/RGBS toggle, the one between the DE-15 and SCART outputs on the Toro, only changes between RGBHV and RGBS on the DE-15 output; the SCART output is full-time RGBS, regardless of what the console is outputting.

    That ugly, shimmery 480i is the OSSC bob-deinterlacing 480i to 480p. It’s never going to look good.

    #25435
    BaskinRobinson
    Participant

    On the Toro, you need to have the Dreamcast mode switch (the one in the bank of four closest to the console) set to ‘VGA’, so the console will output 31kHz RGBHV (480p). Then you need to run a fully-wired male-to-male SCART cable from the Toro to AV1, and change the input on the OSSC to AV1-RGBS. The other RGBHV/RGBS toggle, the one between the DE-15 and SCART outputs on the Toro, only changes between RGBHV and RGBS on the DE-15 output; the SCART output is full-time RGBS, regardless of what the console is outputting.

    Thanks for the clarification. I will double check when I get home later, but I recall getting a 480i signal regardless of the switch being set to “RBG” or “VGA”.

    #25440
    BaskinRobinson
    Participant

    Alright, so I tested the SCART cable again and was able to get a 480p signal working. However, it has the same aspect ratio problem as the VGA cable.

    The Dreamcast startup screen is close to 4:3, but it’s slightly narrow. Once the GDEMU loads up, and when I start a game, the image gets much narrower.

    At this point, I’m convinced my TV is simply incompatible.

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