MiSTer + OSSC

https://github.com/MiSTer-devel/Main_MiSTer/wiki

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MiSTer + OSSC

Postby jdubs » Mon Nov 05, 2018 6:39 pm

Hey guys, I’m assuming some of you are using this combo to get lag-free upscaled hdmi output? Of course, only if your display is ossc compatible.

Waiting on my i/o board to try it out.

-Jim

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Re: MiSTer + OSSC

Postby flain » Tue Nov 06, 2018 9:50 am

I don't think the OSSC will really add much for you here. MiSTer can already do basically the same thing, if you set vsync_adjust=1 in the ini file. However your display needs to be able to handle the pixel clock. This is the same as with the OSSC though, since the OSSC has no frame buffer.

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Re: MiSTer + OSSC

Postby ijor » Tue Nov 06, 2018 12:08 pm

A few people here posted that they do use OSSC. However this is probably not the ideal setup for MiSTer. And unless you actually want to use a CRT, soon might not be been even needed. There is a new HDMI scaler being developed right now. It is not yet implemented, but the new scaler should be able to output scaled video with lag (almost) as short as OSCC.

flain wrote:I don't think the OSSC will really add much for you here. MiSTer can already do basically the same thing, if you set vsync_adjust=1 in the ini file. However your display needs to be able to handle the pixel clock. This is the same as with the OSSC though, since the OSSC has no frame buffer.


Vsync, at least by itself, won't reduce the lag. It will only remove tear and artifacts produced by the frame rate conversion. But, once we have the new scaler, it would allow to scale without frame buffering. And then yes, lag will be very small.

The monitor would need to support non standard pixel clock rates on the HDMI input. Not every monitor does. Even if it supports those pixel rates on the VGA input, it might not support them on the HDMI input.
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Re: MiSTer + OSSC

Postby flain » Tue Nov 06, 2018 1:35 pm

ijor wrote:There is a new HDMI scaler being developed right now. It is not yet implemented, but the new scaler should be able to output scaled video with lag (almost) as short as OSCC.

Vsync, at least by itself, won't reduce the lag. It will only remove tear and artifacts produced by the frame rate conversion. But, once we have the new scaler, it would allow to scale without frame buffering. And then yes, lag will be very small.

The monitor would need to support non standard pixel clock rates on the HDMI input. Not every monitor does. Even if it supports those pixel rates on the VGA input, it might not support them on the HDMI input.


Thanks this is good to know. I actually use OSSC (not with MiSTer) with a neogeo arcade board and a CPS2 board to display on a gaming LCD monitor. Good news is the newer LCD TVs seem to be accepting non standard refresh more than the older ones. Some of the TVs released in the last year support 120hz at 1080p which means that 60.098hz that some consoles output is no longer above the max rate (but is still out of spec).

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Re: MiSTer + OSSC

Postby jdubs » Thu Nov 08, 2018 5:42 am

I've read this thread already:

viewtopic.php?f=117&t=34564

...but I didn't get the impression that there is too much focus on a low / no lag HDMI solution. Did I read that wrong?

I mean, it seems like there are more and more TVs / monitors accepting of non-standard HDMI input. I mean, my TCL has no problem with an OSSC upsampling my NES and SNES at 5x. LG OLED has no problem with it either. Just a couple of examples.

-Jim

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Re: MiSTer + OSSC

Postby Sorgelig » Thu Nov 08, 2018 6:18 am

Many people jump from modern consoles and windows FPS games where low lag is key to win.
So they jump to retro consoles and computers with primitive graphics where term lag wasn't exist as there was no such quick movements. People don't understand that 20 years old consoles checked the gamepad only once per frame or even once per 2(!) frames.

It's in vain to explain that 1-2 frames lag has no meaning for retro systems.. This is kind of obsession, OCD - nothing more.

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Re: MiSTer + OSSC

Postby cacophony » Thu Nov 08, 2018 7:24 am

Sorgelig wrote:Many people jump from modern consoles and windows FPS games where low lag is key to win.
So they jump to retro consoles and computers with primitive graphics where term lag wasn't exist as there was no such quick movements. People don't understand that 20 years old consoles checked the gamepad only once per frame or even once per 2(!) frames.

It's in vain to explain that 1-2 frames lag has no meaning for retro systems.. This is kind of obsession, OCD - nothing more.


The problem is that lag is cumulative and once you reach a certain amount many of these older 8 and 16 bit games become far more difficult. Most people have at least 1-2 frames of lag from their TV, and controllers can add lag too. So if you're going to add 1-2 frames of unnecessary lag from the console then you're already at 4+ frames of lag.

If lag doesn't bother you then you're probably not playing games where it matters much.

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Re: MiSTer + OSSC

Postby Sorgelig » Thu Nov 08, 2018 8:10 am

cacophony wrote: unnecessary lag

who decide it's unnecessary? controllers lad is necessary, tv lag is necessary, but this is unnecessary?
So, i just can return your words: if you think it's unnecessary then you don't understand the technical details.

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Re: MiSTer + OSSC

Postby hyperterminal » Thu Nov 08, 2018 11:20 am

Let's not argue which lag is necessary or not. I think we can all agree that less lag is better. Sorgelig and the other volunteers are already working on a new scaler that might produce less lag. Until then, you can use the OSSC or an old CRT display.

Besides the scaler, is there anything that can be done to further reduce the lag? Increase the USB polling interval perhaps?

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Re: MiSTer + OSSC

Postby ijor » Thu Nov 08, 2018 12:06 pm

hyperterminal wrote:Besides the scaler, is there anything that can be done to further reduce the lag? Increase the USB polling interval perhaps?


I wonder how much lag we get from the controllers. Somebody performed any measurements as that guy did with the HDMI video output lag?

If the lag is significant, and probably is, it might be worth to add a DB-9 connector to the I/O board. Personally I'll remove the extra SD Card connector. I can offer to contribute developing a SD Card server, assuming there isn't one already, if that makes a difference for adapting those cores that use it.

I also wonder if it wouldn't possible to approach a small LCD panel manufacturer. May be we could integrate at the low level and get a display with almost zero lag. This won't work for those gamers that like to play with, say, a huge Samsung display. But for those smaller portables displays, it might be possible.
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Re: MiSTer + OSSC

Postby kitrinx » Thu Nov 08, 2018 1:30 pm

I used a scope with a Mc Cthulu arcade board to the mister. For testing, the genesis core was modified to light the user LED when it received input. One probe was on the button itself, the other probe on the user LED. Counting only tests that had low bounce, the average latency I saw on the scope between the button closing and the LED lighting was around 8-9ms. Bear in mind that some of this may have been from the Mc Cthulu itself which is known to have some latency. It was a little hard to follow all the polling, but based on that number it makes me wonder if it was polling once per frame. That is a very acceptable input latency in any circumstance, and probably not a lot different than you would end up getting with a real controller on an older system that polls infrequently.

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Re: MiSTer + OSSC

Postby flain » Thu Nov 08, 2018 1:55 pm

ElectronAsh from these forums was working on a low latency controller board

http://retrorgb.com/mister-ll-cool-joy- ... pdate.html

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Re: MiSTer + OSSC

Postby ijor » Thu Nov 08, 2018 2:01 pm

kitrinx wrote:I used a scope with a Mc Cthulu arcade board to the mister. For testing, the genesis core was modified to light the user LED when it received input. One probe was on the button itself, the other probe on the user LED. Counting only tests that had low bounce, the average latency I saw on the scope between the button closing and the LED lighting was around 8-9ms. Bear in mind that some of this may have been from the Mc Cthulu itself which is known to have some latency. It was a little hard to follow all the polling, but based on that number it makes me wonder if it was polling once per frame. That is a very acceptable input latency in any circumstance, and probably not a lot different than you would end up getting with a real controller on an older system that polls infrequently.


Interesting. 8-9 ms is not bad. I admit I expected more. But it is about half a frame and it is somewhat significant. Yes, most classic systems didn't poll the input more frequently than one per frame. But here it would be added one on top of the other. The console would still poll the virtual input at the same rate it originally did, but the virtual input would have that additional latency.

Question if this is a best or a worst case.
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Re: MiSTer + OSSC

Postby cacophony » Thu Nov 08, 2018 5:16 pm

Sorgelig wrote:
cacophony wrote: unnecessary lag

who decide it's unnecessary? controllers lad is necessary, tv lag is necessary, but this is unnecessary?
So, i just can return your words: if you think it's unnecessary then you don't understand the technical details.


it's unnecessary because it's something that can be solved through the code of this project as opposed to needing to purchasing a new TV or controller. And you know it's technically possible on many important cores because there are existing FPGA solutions that add zero additional lag beyond original hardware. Just look at the AVS, the 17 (?) cores for the Nt Mini and also the Super Nt. And the most important and valued aspects of those devices is accuracy and the ability to keep lag as close to zero as possible. That's what people who invest in an FPGA solution care about.
Last edited by cacophony on Thu Nov 08, 2018 5:24 pm, edited 1 time in total.

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Re: MiSTer + OSSC

Postby flain » Thu Nov 08, 2018 5:23 pm

Exactly why so many more people are looking to FPGA instead of software emulators, its mostly latency (accuracy too, but we have that in many software emulators already). If you look at a raspberry pi running SNES super mario world on a software emulator on a modern display:

Software emulator latency - at least 2 frames (sometimes 4+)
Inbuilt original system latency (for super mario world) - 2 frames minimum (includes input polling delay and game processing delay on a CRT screen)
Input lag on raspberry pi usb polling based controls - at least 1 frame sometimes more
Modern TV hdmi input latency in "game mode" - 30ms is considered "good" on rtings.com, bad is over 50-60ms (16ms = 1 frame at 60hz). Some TVs can do 10ms but only at 1080p 120hz input.
Latency added from modern tv post processing - at least 1 frame (eg any HDR tv that does local back light dimming has its own frame buffer to do it and most you can't turn off the feature)

It ends up a lot of frames that were never there on the old way of playing games. This isn't about FPS players, this is about mario players pressing jump then seeing mario fall to his death instead lol. Most FPS gamers don't even know wtf us old retro gamers are complaining about.

So thats super mario world - try doing it with mortal kombat 2 on SNES its really super bad on emulators (the game has lots of lag built into it) you basically can't play it properly even if you are really good at the game.. it makes it almost impossible to beat the AI that already seems to cheat a bit. Then i try it on super nt, and wow beat it easy.

This all adds up and some games you no longer can play properly. Kevtris seemed to figure this out so on Super nt there is basically 0 lag added on his cores that that wasn't already added by the original system.

Of course none of this is MiSTers fault - it's already lower latency than a software emulator, i'm just trying to articulate why people care about getting rid of latency in every place possible.

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Re: MiSTer + OSSC

Postby Sorgelig » Thu Nov 08, 2018 5:25 pm

no problem. Use those FPGA solutions and you are set.

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Re: MiSTer + OSSC

Postby Sorgelig » Thu Nov 08, 2018 5:32 pm

i only see people talking about it. I don't see people who are going to implement this.
I see just people punch and push me trying to explain that "good thing is definitely better than bad thing". So what? Do you really think i just sit and wait when someone start to push me? Show your master and release opensource perfect core which will suit needs of all users.

Talking is much easier than making.
That's my last post on this subject. I don't want to contradict anymore to "I just want this and i don't care how!"
Anyone who is not satisfied by MiSTer are free to choose other platforms perfect for them.

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