Tips & Tweaks: Lx3, Lx4, Lx5 modes

[Harrumph]

Well, I understand why you went this route to achieve apparent 4:3 image, but technically it’s actually not correct. This is because the analog image from consoles is not exactly 4:3, and the 4:3 is achieved by cropping overscan by the frame of the screen itself.

Consider consoles outputting 256 or 320 dot active widths (eg SNES and MD/Genesis, respectively). They use 8:7 and 32:35 pixel aspect ratios. In both cases the horizontal width, when converted to square pixels (as we need to on a fixed pixel LCD display), is roughly 293:
256*8/7 = 292.57
320*32/35 = 292.57

This equates to the full line being multiples of 390 H samples (as is already the case for Lx3 and Lx4 at default settings):
341*8/7 = 389.7
427*32/35 = 390.4

Now if we want this to cover the entire horizontal space of 4:3 area, by necessity the image height needs to be
292.57/4*3 = 219.4 lines

So the ”most correct” 4:3 image is achieved by zooming on your TV so that the visible image is cropped to a multiple of 219-220 lines. If your display allows it, it could also be achieved by setting V.Active to those values on the OSSC.

https://pineight.com/mw/index.php?title=Dot_clock_rates
https://en.m.wikipedia.org/wiki/Pixel_aspect_ratio

[James-F]

Okay having the OSSC enough time to understand how Generic mode (best mode IMO) works, so I’ll try to explain.

The multiplier (3x,,3x,4x,5x) in generic mode refers only to the vertical plane while the horizontal plane is adjusted without a multiplier, so if you look at the advanced timing of generic modes you’ll see 960×240 (3x), 1280×240 (4x) and 1536×240 (5x).
V.samplerate which is not show in advanced timing is the 263p (314p, etc..) value you see on the main input display.

From what I observed the monitor/TV will try to choose resolution from its database according to the ACTIVE resolution the OSSC sends.
Generic Line3x mode that sends 960×720 makes my monitor go into 1280×720 mode and will display all content in 4:3 format.
So it appears that the monitor/TV is much less picky about the samplerate (total) pixels, but very sensitive to active pixels.
PC monitors seem to accept practically any active resolution, even 811×643 since they designed to accept all kinds of computers.

Here is a 240p Generic Line2x mode to try that results in a perfect 640×480 4:3 image with no underscan.
It might be more compatible with some TVs than the default Line2x 720×240 with standard NTSC timing.

H.samplerate 846
S.synclen 62 (default)
H.backporch 96
H.active 640
V.synclen 3 (default)
V.backporch 15 (default)
V.active 240 (default)

[Harrumph]

Sorry, didn’t explain myself first time around, see my edited post.

[James-F]

@Harrumph

Well I don’t think there is a ‘correct’ resolution when sampling an analog signal in Generic mode since the sampling rate can be anything really, just like with audio, we can sample 44kHz or 192kHz from the same analog signal.
Yes, I realize that 4:3 aspect is achieved by adjusting the image on a CRT, but most consoles from that era have more or less the same output in terms of borders and active area, that is why I had success using this method of adjusting the Generic mode.

I set my OSSC in Generic mode just like I set my Sony Trinitron CRT to accept all consoles without much overscan or underscan.
The CRT obviously has 4:3 aspect ratio and that’s what I go for with the OSSC, and it looks excellent.
I do realize that there is technically a correct calculated aspect ratio for each console but I rather have 4:3 like on my CRT which most games are designed to look correct on.

[hardyhell]

Hello,

i have a sony beamer that supports the following input singnals:

480/60p, 576/50p, 720/60p, 720/50p, 1.080/60i, 1.080/50i, 1.080/60p, 1.080/50p, 1.080/24p, 3.840 x 2.160/24p, 3.840 x 2.160/25p, 3.840 x 2.160/30p, 3.840 x 2.160/50p*4, 3.840 x 2.160/60p*4, 4.096 x 2.160/24p, 4.096 x 2.160/25p, 4.096 x 2.160/30p, 4.096 x 2.160/50p*4, 4.096 x 2.160/60p*4

with the ossc 2x seems to be ok but 3x and 5x the Picture moves down and is cut off at the bottom.
4x does not give me a useable Picture.

is there a way to move the Picture up in 3 and 5x mode so i have all visible again?

Thank you very much

[James-F]

V.backporch is your friend.
More moves picture up, less moves it down.

[hardyhell]

Thanks a lot.
But the option does not change the position of the picture and at about 19 it looses sync totally.
The hbackporch does shift the picture though

[GameJon]

Just in case anyone here has a GSCARTSW…
For a year I was unable to get a solid image at 5X on my Samsung UE32K5600.

I recently discovered that turning the Sync Stripper OFF on the GSCARTSW (original version with second VGA-Style output) fixed this problem, and allowed upto 5x without issue.

[hardyhell]

could anybody please help me with the vbackporch Problem?

thanks a lot

[guut]

I have received my OSSC Today and already tried different consoles with it. Unfortunately I have a Sony kdl W-series TV, which seems to be very picky if it comes to anything above lx2.
Is there any “Trick”, or did anyone manage to get above lx2 with a W-series Sony?
I have bought that TV because of very low lag not that long ago. Would be a pity if I do need another TV 🙁

[Gummi]

Can’t help you with your TV but in case you can’t get the other modes working, I would suggesting trying out the optimized modes. If your TV can display them, and you have the means to properly dial in H. samplerate and sample phase (or use another user’s setting, FirebrandX will also publish his someday), then it will look noticeably sharper than the generic mode, even at x2. Using scanlines will also help make the image look a bit sharper.

[guut]

Thanks for your reply. Didn’t tried to play around with the advanced timing settings. But my TV didn’t display any image with any mode beside of generic 4:3

Can someone tell me settings I can test for lx3/lx4 mode?
When I choose lx3/lx4 I can at leasr hear the ingame sound but without any image.
On lx5 there is no sound, and no image.

Is that a sign I could get lx3/lx4 working when I found out the correct timing settings?

[CastingDreams]

Any advice for the owner of a Sony KDL-55W800B? Like dadjumper and MiserablePixels I’ve been unable to get 3x and above to work, I keep getting a message about an invalid signal (sound still plays though). I’ve tried with my PS2 running in 240p, 480p and 480i. In Sampling Options, I’ve increased V.Active to 256 as per the instructions, but even when V.Backporch is 1 I don’t get a picture. I’ve tried changing the TX mode to DVI. I’ve set my TV to “Graphics” mode and Wide Mode to “Full”, as per this section of the manual on PC input signals:

• 640 x 480, 31.5 kHz/60 Hz
• 800 x 600, 37.9 kHz/60 Hz
• 1024 x 768, 48.4 kHz/60 Hz
• 1280 x 768, 47.4 kHz/60 Hz and 47.8 kHz/60 Hz
• 1360 x 768, 47.7 kHz/60 Hz
• 1280 x 1024, 64.0 kHz/60 Hz (Full HD model only)
• 1920 x 1080, 67.5 kHz/60 Hz (Full HD model only)*

* The 1080p timing, when applied to the HDMI input, will be treated as a video timing and not a PC timing. This will affect the [Preferences] and [Picture & Display] settings. To view PC content, set [Scene Select] to [Graphics], [Wide Mode] to [Full], and [Display Area] to [Full Pixel]. ([Display Area] is configurable only when [Auto Display Area] is set to [Off].)

Is there anything obvious that I might be missing? Thanks.

[Anonymous]

I was having problems getting CPS1 and CPS2 game boards to display properly. They were displaying with top and bottom edges off the screen. Capturing from the camlink would have it shifted down, and about 1/8 of the bottom of the image being cut off.
I found the below settings to work for CPS1/CPS2 , to get it to display fully on screen in line5x @ 1920×1080, and perfectly centered within capture software.

Start OSSC and game. Set OSSC to:

Output Opt:
240p/288p proc
Line5x

Line5x Mode
Generic 4:3

Line5x format
1920×1080

Sampling Opt:
<Adv Timing>
1536×240

V. synclen 1
V. backporch 1
V. active 300
H. samplerate 2046
H. synclen 150
H. Backporch 231
H. active 1538

If it gets close to centered, but not perfectly centered, then v./h. backporch should be your first attempts to center, and use v./h. synclen if those don’t work or some additional fine tuning is needed.

Both devices see it as a 1920×1235, whatever the heck that is.

I hope this is helpful to others.

:edit: I just tested the above with MVS also, and it solved my problem of not being able to the grid pattern fully on the screen. That of course, includes the standard tweaks necessary to get MVS syncing (and the one tweak to Analog LPF that I found to be necessary, for me at least):

Sync OPT. -> H-PLL Post-Coast – 2 lines
Sync OPT. -> Hsync Tolerance – 8.30us
Sync OPT. -> Analog LPF – 10MHz

[Anonymous]

I believe I found a sweet spot for PS1 line5x. Generic 4:3, line5x mode set to 1920×1080. It outputs as 1920×1200, but allows the image to be centered and not cropping/overscanning – this is true for both my screen and the camlink (camlink in OBS only, GCHD would throw a “not supported” message).

Line5x 1600×1200 mode works, displays as 1600×1285*
Line5x 1920×1200 mode works, displays as 1920×1285*
*Both of these were not perfectly stable in my testing. May need some minor tweaking to the
backporches and/or synclens to get 100% stable

Sample Opt
<Adv Timing>
1536×240

V. Synclen 4
V. Backporch 1
V. Active 264
H. Samplerate 2046
H. Synclen 150
H. Backporch 234
H. Active 1536

I tested on multiple games, all look good. This SFEX2@ just happens to be my fixation momentarily. :p

Some side by side comparisons of scanlines vs. no scanlines.

[Author]

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