OSSC (DIY video digitizer & scandoubler)

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nmalinoski
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Re: OSSC (DIY video digitizer & scandoubler)

Post by nmalinoski »

Jademalo wrote:Bit of a weird question, but I'm curious - With the current hardware of the OSSC, would it be possible to make a firmware variant that had a forced locked output refresh rate regardless of input and accepting the tearing that comes with it?

I'm mostly thinking for games like RE2 on the N64 where the resolution changes constantly. If both 240p and 480i were set to the same output resolution (either 2x/passthrough or 4x/2x), then having a locked refresh should result in the OSSC not having to resync with the display on every change. (I think?)

I know this would be doable with a framebuffer, but my main interest is if it's doable without. Yes it may not be ideal quality wise with the tearing/stutter, but it should be lagless.
This has been brought up several times before, and, if I remember correctly, you won't be able to do it with the current OSSC. Part of the problem is that when sync drops, sync drops, and the HDMI devices in your chain will need to resync, even if the resulting scaled images are the same dimensions (they'll be at slightly different framerates as well).

Another part of the problem is that the current OSSC hardware lacks a full framebuffer, which would be needed (as well as coding of the requisite new firmware) for the kind of seamless transitions you're looking for.

I believe you can get seamless transitions now by using an HDMI-capable presentation scaler, like those from Extron and (I think) Kramer; but they'll be expensive, and they'll definitely add lag.
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Galdelico
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Galdelico »

nmalinoski wrote:Another part of the problem is that the current OSSC hardware lacks a full framebuffer, which would be needed (as well as coding of the requisite new firmware) for the kind of seamless transitions you're looking for.
Is that the reason why even the Framemeister can't handle resolution swaps properly? As in, the specific feature has never been coded into its firmware?
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bobrocks95
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Re: OSSC (DIY video digitizer & scandoubler)

Post by bobrocks95 »

"Quick Media Switching" in the HDMI 2.1 spec could *potentially* help speed up resolution changes. It's of course not available on anything yet, and may or may not require a true HDMI 2.1 transmitter chip (or the display implements it?)
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nmalinoski
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Re: OSSC (DIY video digitizer & scandoubler)

Post by nmalinoski »

Galdelico wrote:
nmalinoski wrote:Another part of the problem is that the current OSSC hardware lacks a full framebuffer, which would be needed (as well as coding of the requisite new firmware) for the kind of seamless transitions you're looking for.
Is that the reason why even the Framemeister can't handle resolution swaps properly? As in, the specific feature has never been coded into its firmware?
The only thing I can think of is that the Framemeister simply doesn't have anything in its firmware that lets it act like a presentation switcher. It would need to let you pick a specific resolution and framerate (1920x1080@60Hz, for example), and then continually output at that spec, regardless of input or lack thereof; and, in doing that kind of normalization, you run into other issues, like uneven scaling between 240p and 480i signals, and either dropped frames or screen tearing depending on vsync.
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

nmalinoski wrote:This has been brought up several times before, and, if I remember correctly, you won't be able to do it with the current OSSC. Part of the problem is that when sync drops, sync drops, and the HDMI devices in your chain will need to resync, even if the resulting scaled images are the same dimensions (they'll be at slightly different framerates as well).

Another part of the problem is that the current OSSC hardware lacks a full framebuffer, which would be needed (as well as coding of the requisite new firmware) for the kind of seamless transitions you're looking for.
I'm aware this is the issue, this is why I'm asking if it can be done with a firmware tweak to lock the output sync regardless of what's coming in. No framebuffer to fix issues, just lock it and hope for the best.
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marqs
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Re: OSSC (DIY video digitizer & scandoubler)

Post by marqs »

Jademalo wrote:
nmalinoski wrote:This has been brought up several times before, and, if I remember correctly, you won't be able to do it with the current OSSC. Part of the problem is that when sync drops, sync drops, and the HDMI devices in your chain will need to resync, even if the resulting scaled images are the same dimensions (they'll be at slightly different framerates as well).

Another part of the problem is that the current OSSC hardware lacks a full framebuffer, which would be needed (as well as coding of the requisite new firmware) for the kind of seamless transitions you're looking for.
I'm aware this is the issue, this is why I'm asking if it can be done with a firmware tweak to lock the output sync regardless of what's coming in. No framebuffer to fix issues, just lock it and hope for the best.
The main issue is that you can't lock into hsync since its period is not guaranteed to remain stable during the transitions. Even if you could, line count discrepancies between the modes would mean that the output would switch between 524 and 525 lines which probably upsets several displays (that'd be easy to test with a custom fw, though). The only certain way to generate stable output would be using on-board oscillator and FPGA PLL to generate (unlocked) sync. In the primary mode the picture would roll very slow at best (dependiing on how close you can match the refresh rate), and on the other mode it'd roll tens of scanlines per second.
nmalinoski wrote:The only thing I can think of is that the Framemeister simply doesn't have anything in its firmware that lets it act like a presentation switcher. It would need to let you pick a specific resolution and framerate (1920x1080@60Hz, for example), and then continually output at that spec, regardless of input or lack thereof; and, in doing that kind of normalization, you run into other issues, like uneven scaling between 240p and 480i signals, and either dropped frames or screen tearing depending on vsync.
Isn't that exactly what Framemeister does when you disable framelock? That's why it's quite puzzling why it doesn't support seamless switching of input modes.
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

marqs wrote:The main issue is that you can't lock into hsync since its period is not guaranteed to remain stable during the transitions. Even if you could, line count discrepancies between the modes would mean that the output would switch between 524 and 525 lines which probably upsets several displays (that'd be easy to test with a custom fw, though). The only certain way to generate stable output would be using on-board oscillator and FPGA PLL to generate (unlocked) sync. In the primary mode the picture would roll very slow at best (dependiing on how close you can match the refresh rate), and on the other mode it'd roll tens of scanlines per second.
Alright, that's really interesting. Thanks for the answer!
Assuming the latter needs better hardware, would that still actually be a viable idea for true lagless output with switching resolutions? Or would the roll render it totally unusable. I'm not really able to visualise what the roll would look like, and I can't find any examples. I assumed it would just result in traditional screen tearing, which imo would possibly be a viable option to save that latency.
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airco
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Re: OSSC (DIY video digitizer & scandoubler)

Post by airco »

What do people use for HDMI audio extraction with the OSSC? I've tried two extraction boxes so far (ViewHD and Kanex Pro) and neither seems to work at 5x scale 1080p (the Kanex works on both 1200p modes). I could just route analog audio from the OSSC, but I'd rather use the same solution as my HDMI consoles for convenience and keep things digital to minimize ground loops (which I might be paranoid about). Desktop-sized solutions appreciated.
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

airco wrote:What do people use for HDMI audio extraction with the OSSC? I've tried two extraction boxes so far (ViewHD and Kanex Pro) and neither seems to work at 5x scale 1080p (the Kanex works on both 1200p modes). I could just route analog audio from the OSSC, but I'd rather use the same solution as my HDMI consoles for convenience and keep things digital to minimize ground loops (which I might be paranoid about). Desktop-sized solutions appreciated.
I've spent the last two weeks in a hole figuring this out, lol.

https://www.amazon.co.uk/gp/product/B01 ... UTF8&psc=1

This thing works for me. Every video mode seems to work, and I get both analogue and optical audio from it. I ended up having a bit of a nightmare trying to capture the optical audio, but that's a whole different ball game and should work absolutely fine if you're just plugging it into a receiver etc.

https://www.amazon.co.uk/gp/product/B01 ... UTF8&psc=1

This one also seemed to work fine - It's just a bog standard 1 in 1 out audio extractor.
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airco
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Re: OSSC (DIY video digitizer & scandoubler)

Post by airco »

Jademalo wrote:
airco wrote:What do people use for HDMI audio extraction with the OSSC? I've tried two extraction boxes so far (ViewHD and Kanex Pro) and neither seems to work at 5x scale 1080p (the Kanex works on both 1200p modes). I could just route analog audio from the OSSC, but I'd rather use the same solution as my HDMI consoles for convenience and keep things digital to minimize ground loops (which I might be paranoid about). Desktop-sized solutions appreciated.
I've spent the last two weeks in a hole figuring this out, lol.

https://www.amazon.co.uk/gp/product/B01 ... UTF8&psc=1

This thing works for me. Every video mode seems to work, and I get both analogue and optical audio from it. I ended up having a bit of a nightmare trying to capture the optical audio, but that's a whole different ball game and should work absolutely fine if you're just plugging it into a receiver etc.

https://www.amazon.co.uk/gp/product/B01 ... UTF8&psc=1

This one also seemed to work fine - It's just a bog standard 1 in 1 out audio extractor.
Thanks. Neither of those exact models seem to be available on US Amazon, but there's similar stuff from the same brands. I was hoping there would be some kind of higher end model that'd be a safer recommendation than the sea of Chinese knockoffs, but I guess I'll just buy a handful and see which, if any, work.

I saw your posts about trying to record optical audio and... yeah, I'll just record analog audio for now, I'm sure streaming compression will do worse things to the fidelity than anything my setup can do.
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

airco wrote:Thanks. Neither of those exact models seem to be available on US Amazon, but there's similar stuff from the same brands. I was hoping there would be some kind of higher end model that'd be a safer recommendation than the sea of Chinese knockoffs, but I guess I'll just buy a handful and see which, if any, work.

I saw your posts about trying to record optical audio and... yeah, I'll just record analog audio for now, I'm sure streaming compression will do worse things to the fidelity than anything my setup can do.
Brands are irrelevant, it's all just the same generic chinese stuff, even when you get to the more expensive ones. I had one that came with some cables, but the board inside was exactly the same. It's all based on the same chips, and it all works the same.

https://www.amazon.com/Optical-TOSLINK- ... B06VVTQY8D
https://www.amazon.com/AVENK-Splitter-E ... B01LZIKZBP

I'm actually genuinely surprised the ViewHD and Kanex ones didn't work. They're both just the same as the rest of the generic chinese ones, and I've not had any issues with them.

Haha, yeah it was a pain. The U24XL works a treat to capture though, if you can get one for ~$50 then I'd argue it's worth it. I don't think you've heard a ground loop like the one I have though, hooo boy is it bad.
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airco
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Re: OSSC (DIY video digitizer & scandoubler)

Post by airco »

Jademalo wrote:Brands are irrelevant, it's all just the same generic chinese stuff, even when you get to the more expensive ones. I had one that came with some cables, but the board inside was exactly the same. It's all based on the same chips, and it all works the same.

https://www.amazon.com/Optical-TOSLINK- ... B06VVTQY8D
https://www.amazon.com/AVENK-Splitter-E ... B01LZIKZBP

I'm actually genuinely surprised the ViewHD and Kanex ones didn't work. They're both just the same as the rest of the generic chinese ones, and I've not had any issues with them.
Okay, that's a little more disappointing. I don't have any leads as to why something like this would happen on my OSSC instead of others outside of DVI weirdness (I have an OSSC 1.5 connected via a simple DVI to HDMI cable), but DVI and HDMI should have the same functionality.
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

airco wrote:Okay, that's a little more disappointing. I don't have any leads as to why something like this would happen on my OSSC instead of others outside of DVI weirdness (I have an OSSC 1.5 connected via a simple DVI to HDMI cable), but DVI and HDMI should have the same functionality.
Hmm, that's my setup. DVI to HDMI into the extractor, then HDMI to DVI into my Vision E1S.
Which modes aren't working for you?

EDIT: Just checked again, 1920x1080 Line5x definitely works absolutely fine with my splitter, even on the SNES.
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Galdelico
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Galdelico »

nmalinoski wrote:The only thing I can think of is that the Framemeister simply doesn't have anything in its firmware that lets it act like a presentation switcher. It would need to let you pick a specific resolution and framerate (1920x1080@60Hz, for example), and then continually output at that spec, regardless of input or lack thereof; and, in doing that kind of normalization, you run into other issues, like uneven scaling between 240p and 480i signals, and either dropped frames or screen tearing depending on vsync.
I see, thanks for explaining. ^_-
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marqs
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Re: OSSC (DIY video digitizer & scandoubler)

Post by marqs »

Jademalo wrote:Assuming the latter needs better hardware, would that still actually be a viable idea for true lagless output with switching resolutions? Or would the roll render it totally unusable. I'm not really able to visualise what the roll would look like, and I can't find any examples. I assumed it would just result in traditional screen tearing, which imo would possibly be a viable option to save that latency.
I was talking about what would be possible with current HW. Sadly, rolling picture (consider screen moving up or down continuously) is not usable which was my point, so the first option would be the only practical one. I quickly generated a test fw that switches test pattern output from 525 to 524 lines when BTN1 is held down. As expected, neither of my desktop monitors could handle the switch without resync. The firmware (.jic format) is here for anyone to try.
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

marqs wrote:I was talking about what would be possible with current HW. Sadly, rolling picture (consider screen moving up or down continuously) is not usable which was my point, so the first option would be the only practical one. I quickly generated a test fw that switches test pattern output from 525 to 524 lines when BTN1 is held down. As expected, neither of my desktop monitors could handle the switch without resync. The firmware (.jic format) is here for anyone to try.
Aaah, alright. That's a shame.

Oooh, I'll give that a shot later when I get the chance, thanks for throwing that together!
MidOrFeed2015
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Re: OSSC (DIY video digitizer & scandoubler)

Post by MidOrFeed2015 »

mega Man x and x4 run at higher resolution on my OSSC than X legacy collection that recently came out. Let that SINK IN CAPCOM. they could not be bothered to even DO 4K on it!!
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bobrocks95
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Re: OSSC (DIY video digitizer & scandoubler)

Post by bobrocks95 »

MidOrFeed2015 wrote:mega Man x and x4 run at higher resolution on my OSSC than X legacy collection that recently came out. Let that SINK IN CAPCOM. they could not be bothered to even DO 4K on it!!
Looking at screenshots of the PC version they also are doing non-integer scaling with no filtering whatsoever, just like they did for classic Legacy Collection 2. The life bars in the first 3 games look awful.
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Konsolkongen
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Konsolkongen »

Agreed that shit should be illegal! :( Same goes for Windjammers on PS4 (which also has poor blurry scanlines), all the Psykio Shmups on Switch and every Inti Creates DS port too. I would much prefer black bars at the borders, and I refuse to believe that the people making these ports have ever seen a game running on a real CRT, as their “scanlines” more often than not are atrocious.
SavagePencil
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Re: OSSC (DIY video digitizer & scandoubler)

Post by SavagePencil »

Very silly question: if I feed a 601 signal into the OSSC, does it stay in that color space, or will it get changed to 709?

What should I tell my capture card to expect?
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Extrems
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Extrems »

It's converted to RGB and then your capture card may convert back to YCbCr. Whether it'll be Rec. 601 or 709 will depend on your capture card.
SavagePencil
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Re: OSSC (DIY video digitizer & scandoubler)

Post by SavagePencil »

Thank you. For the Datapath cards, will they convert?

What about the XCAPTURE-1?

Is there an easy way to tell?
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Extrems
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Extrems »

If you capture in RGB24/32 format, the Datapath VisionRGB won't. That's like the point of buying one, they're the cheapest cards around that can capture in RGB 4:4:4.
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

Quick note for if you're using a Vision with OBS - You need to set it to XRGB, Flip vertically, and 709.
I have no idea why this is actually the case, but OBS requires that to be set and if it's set to 609 the colour matrix is definitely doing the 709->601 conversion. Setting it to 709 with XRGB seems to not be subsampled though, colour bleed tests seem to be correct. The other modes are definitely subsampled though.
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

Hmm, this brought up something weird when I was testing it.

Using the GameCube component cables, it looks like when sampling square pixels there's a bit of bleed on the colours to the right.
Image

Does anyone else have a set of Gamecube component cables and a Vision E1S who can confirm that's normal? That screenshot was taken with the 240p test suite set to 480p and scaled assets, with 858/720 for square pixels. Sampling phase is defnitely correct too. I was under the impression that the GC Component cables were crazy sharp.

I honestly don't care at the end of the day and it's totally unnoticeable in practice, but I'm curious if that's just the video output or if there's something in my setup that isn't quite right.
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Fudoh
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Fudoh »

Cube internally renders at 4:2:2*, so there's always a SLIGHT color bleed with full resolution output (contrary to low-res output e.g. for GBA games, where proper processing can cover it).

(* this means that the horizontal color resolution is split into half and gets interpolated to full resolution during the D/A process.)
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

Fudoh wrote:Cube internally renders at 4:2:2*, so there's always a SLIGHT color bleed with full resolution output (contrary to low-res output e.g. for GBA games, where proper processing can cover it).
I'm well aware of the evil that is chroma subsampling at this point, lol. It was the bane of my existance with my old Extremecap U3 which internally resampled to 4:2:0, and did it badly. Interesting that it subsamples internally, but that clearly explains it. Also explains why the GBA output was throwing me off a bit!

Thanks!


Out of curiosity, are there any other analogue consoles that internally render at 4:2:2 or lower?
I know some of the 4k ones do it when using HDR or HDMI 1.4 stuff, but I didn't actually know there were any that did it before HD.
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Fudoh
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Fudoh »

If Cube does it, then the Wii might do it as well ? It's a bit hard to tell due to the sub-par image quality in general.
DC and PS2 are definitely 444. XBox was probably 444 as well, but has that internal rescaling bug which has some influence on the image quality.
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Jademalo
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Re: OSSC (DIY video digitizer & scandoubler)

Post by Jademalo »

Alright cool, thanks. I tried to check the Wii but yeah, the image quality isn't good enough to really tell.
I'd love to know why the Wii's output is so mediocre, lol.

Any extra info on the xbox internal rescaling bug? Never heard about that before
MidOrFeed2015
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Re: OSSC (DIY video digitizer & scandoubler)

Post by MidOrFeed2015 »

lol I was running melee 20XX (burnt) on my wii and the OSSC reported 119hz at 525i. maybe bad burn but that was a weird experience
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