Bob Deinterlacing on a CRT

[SuperSpongo]

Hey guys,

Bob Deinterlacing is used for interlaced sources in various products such as the OSSC or the Retrotink 2X. I read that it is not recommended for certain flat screen panels because it causes severe image retention or burn-in. But I always thought that this would not be a problem on a CRT as it is somehow similar to displaying deinterlaced signals. Now I read that Bob Deinterlacing should not be used on a CRT either because it causes burn-in there as well. In my understanding, a CRT should not care about fast altering lines, right?

Could somebody confirm this and shed more light on it? I have a VGA only monitor that goes up to 800x600 and initially wanted to use it with the OSSC and Bob Deinterlacing. I don't think it will sync with the new 3x interlaced mode.

[headlesshobbs]

I couldn't get X3 mode to work with my LG, but for some reason the pc monitor accepted it. Now I think the issue with some panels is due to being IPS models or something and it's better to just let them deinterlace if the lag is good enough.

[SuperSpongo]

I think that most modern TVs will not accept a 1440i signal as it is most likely out of spec while PC monitors are more tolerant. CRTs are even more tolerant, but are capped in terms of dot clock frequency.
For example, my high end Sony F520 will accept any signal the OSSC throws at it, but my Sony PGM 2950E will most likely tap out at around 800x600.

[Gunstar]

Now I read that Bob Deinterlacing should not be used on a CRT either because it causes burn-in there as well. In my understanding, a CRT should not care about fast altering lines, right?

Interested in this as well since I use bob-deinterlacing on a PC CRT and haven't heard of this potential issue before or seen any burn-in in my admittedly small time playing interlaced games this way. Do you have a link to where you read that?

[SuperSpongo]

Yeah, it was in this reddit thread here:

https://www.reddit.com/r/crtgaming/comm ... i_flicker/

Do not use these modes with CRTs, Plasmas, or OLEDs, as these modes lead to faster-than-normal burn-in on those types of monitors.

...

You probably do not want to use the OSSC's bob deinterlacing modes with a CRT or any monitor that is susceptible to burn-in (such as a plasma or OLED), because bob deinterlacing can lead to burn-in on such monitors at a faster-than-normal rate.

Another user already said

Flicker is unrelated to burn in on CRTs, different deinterlace methods should make very little difference.

with the original poster answering

Huh, well now I'm confused. Why would the OSSC wiki and guide warn about burn-in from constant flicker in bob deinterlace modes? Is that only an issue with plasmas and oleds?

So I'd like to open up the question and hear different opinions.

[Fudoh]

The effect of "bob-burn in" on certain types of IPS LCD panels is rather new. I haven't found an explanation on why the effect is causing this behaviour on certain types of IPS panels. And that's the only setup the warning on the wiki applies to.

The flicker of horizontal lines (which happens with BOB deinterlacing) does not cause burn-in on CRTs (would be silly since interlaced content itself isn't so much different from what bob-deinterlacing would produce). It also does not cause burn-in on VA LCD panels, on OLEDs or on Plasma screens (Pioneer's early PDPs even internally apply bob-deinterlacing to 480i sources).

[SuperSpongo]

This is great info! Thanks Fudoh!

[thchardcore]

Sorry to pull this from the graveyard, but is this still the verdict regarding CRT use with bob-deinterlacing on the OSSC? Been playing Gradius IV more lately. Looks decent for how bad 480i is.

[Syntax]

I dont think burn in is the correct term here.

IPS suffer from image retention when the pixels are not given enough down time between switching on and off.

I've kept one of my monitors running on the wii source menu for over a day which resulted in tiles being present on any screen. They always clear up pretty fast and the screen shows no signs of permanent damage.

[SuperSpongo]

Are you using an OSSC or some other product that handles 480i with Bob Deinterlacing? If you're using the OSSC I'd recommend trying 3x laced mode if your monitor can handle it. I was very impressed.
If not, I'd say Bob Deinterlacing is fine for a CRT. I played a couple of hours of Mario Sunshine PAL (480i only) on a VGA display and there was no image retention.

[tongshadow]

Sorry to pull this from the graveyard, but is this still the verdict regarding CRT use with bob-deinterlacing on the OSSC? Been playing Gradius IV more lately. Looks decent for how bad 480i is.

It's miles better than on a flat panel, but still not even close to how a real SDTV CRT treats 480i. The reason why most people think "480i is bad" is because they havent seen a real SDTV in a long time.
On PVMs it seems to be a mixed bag, some say it's very flickery while others say it's ok.

[ChuChu Flamingo]

Its because PVMs and other pro grade monitors have higher tvl than consumer grade in general.

Since they use better phosphors and higher tvls the phosphor decay is dramatically less vs traditional consumer grade crts. What this means is on pro monitors 480i "appears" to flicker more since they have a lower decay rate. On the flipside it also means a sharper image.

At least this is what I've observed personally and read up on. For example 480i on my JVC d-series displays more flicker than say my Sony Wega or other consumer grade crts.

To hammer this point further I have a commodore 1702 monitor which displays beautifully but it is a tad soft due to being low tvl (especially vs modern consumer grade stuff). Flickering is pretty much nonexistent on 480i.

So yeah higher tvl=more noticeable 480i flicker.

Just thought I would share my opinion.

[fernan1234]

Preach my friends! 480i is a lost art, and bashing it sadly only comes from a place of poverty in memory or equipment.

I do think that some of the flicker issue on PVMs is exclusive to certain monitor models, not all high TVL monitors in general. In any case, even with more noticeable flicker, that super sharp interlaced picture will look almost 3D seen from the right distance.

Instead of wanting to get rid of it with deinterlacing, I want more lacing! Wish I could see what this mysterious "3x laced" OSSC mode looks like.

[BONKERS]

I've used bob on a CRT and never had an issue.

[thchardcore]

Are you using an OSSC or some other product that handles 480i with Bob Deinterlacing? If you're using the OSSC I'd recommend trying 3x laced mode if your monitor can handle it. I was very impressed.
If not, I'd say Bob Deinterlacing is fine for a CRT. I played a couple of hours of Mario Sunshine PAL (480i only) on a VGA display and there was no image retention.

I'm using an old 21 inch Sony PC CRT. OSSC is set to Bob-deinterlace and I am using the alternating scanline option. It actually looks pretty great. Gradius IV less so than Gradius V.