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 Post subject: Re: OSSC (DIY video digitizer & scandoubler)
PostPosted: Sat Apr 14, 2018 12:01 pm 


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Joined: 05 Nov 2013
Posts: 5825
Location: EU
RocketBelt wrote:
I suffered the bob deinterlace LG ips image retention issue again. I was messing with settings and did a firmaware update and didn't notice that my ossc had gone back to the default 480i/576i bob deinterlace setting. After only a short time (half an hour) on a game that has static elements on screen, these parts of the image were 'burned in' (also described as image retention or after-flicker) very clearly, and the set has been off all night but it is taking a long time for this effect to fade away this time. I've seen one other user reporting this issue in this thread, and this is potentially a very nasty issue for users of LG ips panels.

Marqs and bucko:

1. There should be at least a few lines on the ossc wiki warning about bob deinterlace causing image retention or after-flicker on LG ips.
2. At least consider making 480i/576i passthrough mode the default setting in future firmwares.

FYI it's not just LG-produced IPS panels, afaik AUO produced (misleadingly named 'AHVA') can be affected too.
The degree of sensitivity also seems to vary a lot, I've been using an LG IPS for several months (and it's definitely not my first, I've owned a number of IPS displays over the years)
And though I don't quite often play games that switch the OSSC to bob-deinterlacing mode so when it triggers it's only for short moments in menu screens, with that kind of usage I haven't noticed the slightest hint of persistence yet.
Some panels though show marks almost immediately, I've seen it, so the panel's model matters but as long as we don't know the cause it's impossible to track and prevent considering Manufacturers make many different ones they either renew or change almost every year without much notice.

But most importantly: it's not necessarily inherent to IPS only, some VA panels can show a degree of retention too, although it's more rare and they seem distinctively less prone than IPS in general.
Using bob-deinterlace mode on fixed items for many minutes or even hours straight it is likely that a number of VA display will suffer too. And don't take for granted that TN panels will never show any if exposed to that sharp strong flickering after a long exposure, all panel technologies have weaknesses that can be revealed by stress test.

Some material or process used in manufacturing LCDs must be responsible for this, and although the problem wasn't unknown in the past (like a decade ago and even further back), it seems that there's been a resurgence in recent years.
I don't recommend people to avoid IPS completely, that'd be ridiculous, only do if you know you will have use for the OSSC's bob-deinterlacing mode a lot. Otherwise you don't have much to worry about.
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 Post subject: Re: OSSC (DIY video digitizer & scandoubler)
PostPosted: Sat Apr 14, 2018 10:49 pm 


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Joined: 25 May 2014
Posts: 397
Xyga wrote:
FYI it's not just LG-produced IPS panels, afaik AUO produced (misleadingly named 'AHVA') can be affected too.

Samsungs "AD-PLS" can also sometimes show severe image retention.

Data point (or rather anecdote): During GCVideo development I had left the attract loop of Final Fantasy Crystal Chronicles running for an hour or so on a Samsung T27C370 and although the game shows a video in addition to its title screen, the monitor was showing a strong shadow of the game's logo for the next few hours.


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 Post subject: Re: OSSC (DIY video digitizer & scandoubler)
PostPosted: Sun Apr 15, 2018 12:48 am 



Joined: 18 Sep 2014
Posts: 97
It's a good anecdote but I'm not sure we're talking about the same effect. This isn't shadow, it's the outlines of static elements flickering on top of whatever is on the screen. My kids will leave a 4:3 dvd menu on screen all day with no ill effects, wheras static elements on a bob deinterlaced image can leave severe after-flicker in minutes which takes hours to clear.
This is why I'm suggesting passthrough mode should be the default setting for interlaced inputs.


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 Post subject: Re: OSSC (DIY video digitizer & scandoubler)
PostPosted: Sun Apr 15, 2018 6:47 am 


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Joined: 05 Nov 2013
Posts: 5825
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@Unseen: yup I forgot about PLS thanks to remind of these.

@RocketBelt: whatever we call the stuck afterimage, he's clearly talking about the same thing you do.

I think the reason the OSSC's bob-deinterlacing triggers this so easily is because it's so sharp and clean, it'll make a single/two row(s) of pixels rapidly flicker between very contrasted colors at the edge of some onscreen elements, and at high speed.
More blurry or flicker-filtered deinterlacing might have the flickering 'event' spread out over more rows and with toned down colors, which reduces or delays the likeliness of after-flicker persistence.

I too think the default deinterlacing of most displays is less risky even though it looks awful, maybe the default should be 'passthrough' and an explanatory/warning line added to the wiki indeed.
EDIT: or add a warning on the OSSC's display though I don't know how that would be possible considering the limited space.
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 Post subject: Re: OSSC (DIY video digitizer & scandoubler)
PostPosted: Sun Apr 15, 2018 11:29 am 


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Joined: 02 Oct 2010
Posts: 2928
Location: UK
Quote:
I too think the default deinterlacing of most displays is less risky even though it looks awful, maybe the default should be 'passthrough' and an explanatory/warning line added to the wiki indeed.


Warnings are already present in the quick start guide, I'll add the same text to the wiki too.
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OSSC Forums - http://www.videogameperfection.com/forums
Please check the XRGB Wiki before posting about the OSSC, XRGB Mini or XRGB3 - http://junkerhq.net/xrgb/index.php/Main_Page


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 Post subject: Re: OSSC (DIY video digitizer & scandoubler)
PostPosted: Mon Apr 16, 2018 1:47 am 


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Joined: 15 Sep 2014
Posts: 136
Are there any sources for populated boards of the audio boards for the OSSC? Maybe some overstock somewhere? I know VGP had these run out and priced them to move months ago but I didn't jump on it in time.

I know borti has an OSHPark of the board, but I wouldn't be able to populate the surface mount parts myself (plus the second part in his mouser cheatsheet doesn't seem to be in stock anymore)

Figured I would ask - thanks!


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 Post subject: Re: OSSC (DIY video digitizer & scandoubler)
PostPosted: Mon Apr 16, 2018 4:14 am 



Joined: 31 Dec 2016
Posts: 11
I have one of you want


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