Tips & Tweaks: Lx3, Lx4, Lx5 modes

[b0nz0beavis]

OSSC settings guide for Panasonic VT60

This linked google doc contains my latest settings for Panasonic VT60. They might also apply to other Panasonic TVs.

The green cell indicates whether the section is for optim or generic modes. The optim section contains specific settings for Capcom fighting games on the Saturn and also for SNES 8:7 AR (only at Lx3 though, there are some issues with Lx4 – see the notes column)

The very first adjustment should be to increase V.active to 256. Then reduce V.backporch until an image appears on screen. Then do all the other adjustments, and finally, reduce V.active to 240. You should now be looking at some sweet-arse graphics.

[Harrumph]

Thanks a lot for your contributions BonzoBits!

The interesting thing is that Lx4 mode might actually be one of the more compatible modes. This is because, due to how the scanline count works out, it’s actually really close to VESA timings from the start. Here is the VESA timings for 1280×1024 (non-reduced blanking):

VESA 1280x1024
H.Samplerate | 1712 | V.Total  | 1063 |
H.Active     | 1280 | V.Active | 1024 |
H.FrontP     |   80 | V.FrontP |    3 |
H.Sync       |  136 | V.Sync   |    7 |
H.BackP      |  216 | V.BackP  |   29 |

Note that LO in linex4 is 4×262= 1048 or 4×263= 1052, which is pretty close to 1063 (e.g. a lot closer than in Lx5).
And both optimized modes work as 427×4= 1708, and 341×5= 1705, apparently within tolerance also.

[CobraKing]

@Harrumph, do you recommend trying those settings on our SONY TV sets?

[b0nz0beavis]

Np. It gets a bit exhausting after 2-3 hours late at night, but if we can come up with some sort of succinct guide to OSSC timing tweaker manipulation, and settings for users to plug straight in, hopefully this can help get more retro enthusiasts (obsessives ;-)) on-board.

When I searched for the CVT 1.2 doc I didn’t find it. Can you link me the on you’re using?

Now I’m looking at your table in your latest post, it’s got me inspired to try for Lx5 again. And since my body seems to have had enough sleep for the night, I guess I’ll make use of these three hours before work and do some investigating.

[Harrumph]

@BonzoBits CVT spreadsheet What I wonder is if x5 is only possible with a 1920×1200 panel. On closer look of my manual, it’s stated as a W-UXGA panel (1920×1200), although it scales down 1200 to 1080 for some reason. Could see this cos managed to display 1600×1200 (same settings as 1920×1080), it would then scale down at a 10/9 ratio, fitting the full 240 lines.

@CobraKing Sure, won’t hurt. On the vertical you probably still need the lower Backporch though, as described earlier. Would be really cool if we could break that Sony barrier!

[b0nz0beavis]

Dude, I can’t figure out that spreadsheet for the life of me. Can you post the specs for 1920 x 1080. Maybe the other 5x modes also?

I now understand the relationship between all the H. settings, so if you can hook me up with those specs, I should be able to find out if the panny can do 5x. Tried to hit 5x in 1280 x 1024 this morning, but I think the required adjustments are incompatible.

Thanks again for the help.

[Harrumph]

Sorry for the delay. Wanted to tidy up my spreadsheet, but in the end I just pasted my reference table in google docs.
VESA and CEA (HDMI) timings

[b0nz0beavis]

That’s cool. Thanks for getting them up.

Had a bit of a play around yesterday, I think I need to ask Marqs of the upper limit for backporch can be increased.

Also, going over my posts in this thread, there are a few times I’ve written stuff that I thought was accurate at the time but now know is incorrect. When I get the time I’ll go back and correct those posts. Might even start a separate thread also, seeing as my stuff is all VT60 focussed. Have probs diluted your message a tad 🙂

[Flappyraccoon]

I have a question if anyone has an experience with this scenario. 4:3 works fine with 480p x2 mode. I can enable dot by dot mode on my display and everything is as crisp as can be. But when I change the game to 16:9 the OSSC squishes the image. Is there a way in the sampling settings to expand the screen so it is the proper ratio? I don’t know what I’m really doing yet and either I lose the option to use dot by dot or the image is all wonky. Cheers!

[b0nz0beavis]

Adjusting H.samplerate (Sampling opt > Advanced timing tweaker > H.samplerate) changes the width of the image, on my TV at least.

[marqs]

Generally it’s best to keep H.samplerate as 858 for 480p sources since that usually matches their DAC output. Modification on H/V active should be tried first although many displays do not care about them. 16:9 480p games are more problematic since their pixel aspect ratio is far from square. Displays can typically stretch 720×480 signal but not necessarily 480Px2 1440×960 signal.

[Harrumph]

Indeed, my Philips TV does not change aspect due to H.Active at all, although it has some limited tolerance to how small/large the H.Active can be (I’m thinking because of limits to the H.Blank in relation to Active). The only way for me to affect aspect is to increase/decrease H.Samplerate.
EDIT: I found an exception to this, which concerns H.Active of 720 vs 640 (with 480 active height), which makes sense for these resolutions. The former will be treated as 480p, the latter VGA, and they are identical unscaled, but different when scaled to fullscreen (due to different pixel aspect ratio). Annoyingly though, my TV does not scale 480p properly, it seems (screen is too narrow).

[funny_mikey]

I have a question about Lx5 mode. My display is a Samsung UN46C6300. At first I could only get line double mode to work but I was able to get Lx3 and Lx4 working by using the timing tweak suggestions from this forum. What I cant seem to get working is Lx5. I was wondering if anyone had any suggestions based on the information (taken from the manual) provided below:

Mode: VESA DMT / DTV CEA
Resolution: 1920 x 1080 @ 60 Hz
Horizontal frequency (Khz): 67.500
Vertical frequency (Hz): 60.00
Pixel clock frequency (MHz): 148.500
Sync Polarity: + / +

All of my testing was with an RGB amp modified snes mini over hdretrovision component cables. Also, on lx3 my TV does not display the resolution but it does on lx4, not sure why. Both lx3 and lx4 are windowed within a black frame all the way around. I have not been able to get it to take up all of the window vertically. Any suggestions are greatly appreciated.

[Harrumph]

Probably won’t work in Lx5 mode because the CEA spec is quite unflexible, and there doesn’t seem to be any modes for higher pixel clocks/resolutions on your display.
You could try to match the pixel clock, but I highly doubt it would work. For SNES, that would be a H.Samplerate around 1887, if you then set H.Active to 1440, H.Sync & H.BackP should be around 120 & 240 respectively.

[funny_mikey]

Thank you for the feedback. I’ll try it out tonight and see if it works. Assuming it doesn’t work how can I get lx3 and lx4 to take up the rest of the screen vertically? I’m actually pretty happy with lx4 it’d just be nice to get it to fit the rest of the screen vertically. I have the TV set to the 4:3 aspect ratio and have a picture within a black frame. Is there any way to get it to take up the rest of the box? Also in looking at the manual it says under VESA DMT it can output to 1680 x 1050. Is this a resolution the ossc can output to? My current resolution is 1280 x 1024 so it would be a bit higher of a resolution. Just a thought. Thanks again for the feedback, I look forward to trying it out!

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