[videogameperfectionrocks]

Doesn’t Garegga look vertically compressed on my screen?

View post on imgur.com

That is in 384×240 optim mode (thanks @marqs!). It looks normal in Generic mode.

[videogameperfectionrocks]

Ah I see. I’m actually on Linux but still concerned about bricking the OSSC.

[videogameperfectionrocks]

What problems were you running into without a USB blaster?

[videogameperfectionrocks]

Truxton has samplerate 450 so not possible to use optim mode there either.

270 lines
57.6Hz
7Mhz dotclk (according to https://pineight.com/mw/index.php?title=Dot_clock_rates)

7000000 / ( 270 * 57.6 ) = 450.10288

Is it normal for OSSC to report the number of lines and refresh rate inconsistently? For example trying this again I get 269 lines and 57.78Hz.

[videogameperfectionrocks]

Gunbird 2 has a samplerate of 456 which puts it in the difficult 423-532 range so will have to wait for 384×240 optim mode to get it dialed in but OSSC reports 261 lines and 60.14Hz. The dotclk is 57.2727Mhz / 8 = 7.1590875Mhz.

[videogameperfectionrocks]

Fantastic!

Will post data from a Psikyo board next…

[videogameperfectionrocks]

Thank you kind sir!

[videogameperfectionrocks]

It’s tough to go back to Generic after getting used to optim mode which looks incredible. 4x isn’t an option due to higher lag (surely from my monitor).

Strangely, dropping h.synclen any lower than 75 or h.backporch any lower than 77 kills the video output from the OSSC if h.active is 320. I wish I could get a small image in optim mode while still sending my monitor 1600×1200 to keep lag low.

Is a 4x horizontal multiplier possible for Line5x mode in the future?

[videogameperfectionrocks]

This would also be great for any game with a samplerate that lies within a certain difficult range. In my case that is 423-532. My monitor’s max samplerate is 2110 so I can’t multiply 423 and up by 5x and my monitor’s resolution is 1600×1200 so I can’t multiply 532 and down by 3x.

[videogameperfectionrocks]

Is there anything I can do to get a board with samplerate 432 (or anything between 423-532) working in a Line5x optim mode on a 1600×1200 monitor with 2110 maximum samplerate?

Also if multiplying this board’s image by 5x vertically and 3x horizontally throws off the aspect ratio, why does it retain the correct aspect ratio with other boards (Espgaluda for example)?

[videogameperfectionrocks]

I think I have definitive evidence that the problem I’m having with Battle Garegga is an OSSC bug.

The following settings display the full image but it is squashed vertically:

Line5x mode 512×240 optim.
Sampling phase 202 deg
H. samplerate 432
H. synclen 41
H. backporch 46
H. active 450

Lowering h.active causes the OSSC to stop outputting an image at all, unless I increase h.synclen and h.backporch like this (although then about 25% of the image is cropped from the bottom and it is still squashed vertically):

Line5x mode 512×240 optim.
Sampling phase 202 deg
H. samplerate 432
H. synclen 75
H. backporch 77
H. active 320

In both cases my 1600×1200 monitor reports it is receiving 1280×1200 resolution which should never be the case in Line5x mode:

“With Line5x, horizontal active and mask are adjusted internally so that frame width of 1600 or 1920 (depending on “Line5x format”) is always generated.”

http://junkerhq.net/xrgb/index.php?title=Optimal_timings#Horizontal_multiplication_factors

Can we agree this is an OSSC bug?

[videogameperfectionrocks]

I have Raiden looking perfect like this:

Line5x mode 320×240 optim.
Sampling phase 202 deg
H. samplerate 384
H. backporch 24
v. backporch 8

I stumbled upon that samplerate accidentally. I think this means the dotclk is 6Mhz:

6000000 / ( 258 × 60.49 ) = 384.457

But how could that dotclk have been calculated from the MAME sources?

https://github.com/mamedev/mame/blob/master/src/mame/drivers/raiden.cpp

[videogameperfectionrocks]

Got it, thank you. That all makes sense to me.

The OSSC not putting out a signal at lower h.active values in 512×240 optim is blocking this project. Could it be an OSSC bug? How can I unblock this and get back to posting PCB data?

[videogameperfectionrocks]

I turned on the crosshatch test pattern in Raiden (reset while holding both start buttons) and with the samplerate at 432 and sampling phase at 157 I don’t see any issues except for positioning. I can’t use 320×240 optim because the samplerate will multiply too high for my monitor and in 512×240 optim I tried to lower h.active from 512 to fix the positioning but I get no image below 364. Very similar behavior to Battle Garegga in 512×240 optim which leaves me at another dead end unfortunately.

[videogameperfectionrocks]

Regarding the trouble with Battle Garegga, h.active 320 works in all of these modes:

2x 256×240 (horizontal multiplier: 3x)
4x 512×240 (horizontal multiplier: 2x)
4x 320×240 (horizontal multiplier: 4x)
4x 256×240 (horizontal multiplier: 5x)
5x 320×240 (horizontal multiplier: 5x) <– unstable with samplerate above 422
5x Generic

I don’t see why h.active 320 works in 2x 256×240 and doesn’t work in 5x 512×240 since both have horizontal multiplier 3x.

I also don’t see why the image becomes unstable above samplerate 422 in 5x 320×240 and works fine at the correct samplerate 432 in 4x 256×240 since both have horizontal multiplier 5x.

I’m trying to get Raiden to work too. The only samplerates that make sense to me there are these:

( 20000000 / 2 ) / ( 258 × 60.49 ) = 640
( 20000000 / 3 ) / ( 258 × 60.49 ) = 427
( 20000000 / 4 ) / ( 258 × 60.49 ) = 320

But I can see some blinking and out of place pixels in all three samplerates at every sampling phase setting. What am I missing?

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