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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Fri Feb 07, 2020 6:47 pm 


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But, at what cost?

As I've already stated, inserting blank frames (between frames) as a method of frame rate conversion/doubling effectively creates a significantly longer "vblank". To the eye, the "vblank" goes from microseconds to about eight milliseconds. Conservatively, the screen is "blank" over 400 times longer than it would be with a native 60Hz input.

You've also lost the rolling scan's advantages and the image will appear much more like LCD using BFI.
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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Fri Feb 07, 2020 10:37 pm 


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orange808 wrote:
But, at what cost?

As I've already stated, inserting blank frames (between frames) as a method of frame rate conversion/doubling effectively creates a significantly longer "vblank". To the eye, the "vblank" goes from microseconds to about eight milliseconds. Conservatively, the screen is "blank" over 400 times longer than it would be with a native 60Hz input.

You've also lost the rolling scan's advantages and the image will appear much more like LCD using BFI.

I agree with this. Either do basic frame doubling or motion interpolation, BFI on a CRT is silly


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Fri Feb 07, 2020 11:02 pm 


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maxtherabbit wrote:

I agree with this. Either do basic frame doubling or motion interpolation, BFI on a CRT is silly


I concluded the same in the original post. For CRT that is-- LCD is a different story. LCD could potentially benefit, but personally, Im not concerned about LCD. Others may be however, so if its trivial to add BFI mode to the new OSSC, I wouldnt argue against it.

As far as the flicker, vblank periods etc., its not nearly as cut and dry as orange is putting it above. Flicker is absolutely no worse than 60Hz, and neither is brightness. Im in the middle of a detailed response I'll add later.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Sat Feb 08, 2020 1:17 am 



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orange808 wrote:
But, at what cost?

As I've already stated, inserting blank frames (between frames) as a method of frame rate conversion/doubling effectively creates a significantly longer "vblank". To the eye, the "vblank" goes from microseconds to about eight milliseconds. Conservatively, the screen is "blank" over 400 times longer than it would be with a native 60Hz input.

You've also lost the rolling scan's advantages and the image will appear much more like LCD using BFI.

While this may be true. 120hz on a VGA CRT with 60hz content without BFI ends up looking much like 30hz on a 60hz display. Which is not great. And is why 480p+Adjustable Scanlines looks better to my eyes on a VGA CRT.

On an LCD 120hz+BFI has been used by a lot of people to get cleaner motion, which is why the option was put into RA in the first place. I don't know of any examples of people using that+A monitor's own 120hz strobe mode either. I"m curious to how that would look.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Sat Feb 08, 2020 5:38 pm 



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Kez wrote:
Are these CRTs able to accept Line3x from the OSSC? I feel like Line3x with 100% scanlines would probably also achieve the look you want.


I was wondering about this because in the OSSC Pro thread I saw some posts referencing the shortcomings of line2x 480p60 on a CRT PC monitor with OSSC scanlines (it looks unnatural because the CRT monitor has its own thin scanlines at 480p). Doesn’t playing at 960p or 1200p with 100% scanlines solve this issue?


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Sat Feb 08, 2020 6:19 pm 


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diamondtron wrote:
Kez wrote:
Are these CRTs able to accept Line3x from the OSSC? I feel like Line3x with 100% scanlines would probably also achieve the look you want.


I was wondering about this because in the OSSC Pro thread I saw some posts referencing the shortcomings of line2x 480p60 on a CRT PC monitor with OSSC scanlines (it looks unnatural because the CRT monitor has its own thin scanlines at 480p). Doesn’t playing at 960p or 1200p with 100% scanlines solve this issue?


No, but it looks better to my eyes.

---------

I do agree with Josh overall. PC CRTs get more hate than they deserve.

You still get clear motion, easy "centering" and overscan/underscan adjustment, no worries about the display's scaling and/or native resolution, no additional display processing lag, few worries about syncing to odd refresh rates, good compatiblity with tricky sync signals, and that distinct (although cooler than a consumer CRT) phosphor glow.

Given that most people acquire a PC CRT for free (or pay pocket change), it's an outstanding value. You could spend 1,000s of pounds, euro, or dollars on a OLED and still struggle with all kinds of issues that a PC CRT will handle with ease.

PC CRTs are often small. They aren't widescreen. The scanlines are too smooth and they don't look right. They are heavy.

All true.

But, you get a lot of good stuff for very little money.

I admit I don't use a PC CRT often for line doubled 240p games, but it's not a bad solution.
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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Sat Feb 08, 2020 11:22 pm 



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orange808 wrote:
diamondtron wrote:
Kez wrote:
Are these CRTs able to accept Line3x from the OSSC? I feel like Line3x with 100% scanlines would probably also achieve the look you want.


I was wondering about this because in the OSSC Pro thread I saw some posts referencing the shortcomings of line2x 480p60 on a CRT PC monitor with OSSC scanlines (it looks unnatural because the CRT monitor has its own thin scanlines at 480p). Doesn’t playing at 960p or 1200p with 100% scanlines solve this issue?


No, but it looks better to my eyes.


What don’t you like about it? The CRT won’t have visible scanlines at 960p or 1200p, with OSSC 100% scanlines added I couldn’t tell much difference between it and stills of 240p.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Tue Feb 11, 2020 11:07 am 


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diamondtron wrote:

No, but it looks better to my eyes.


What don’t you like about it? The CRT won’t have visible scanlines at 960p or 1200p, with OSSC 100% scanlines added I couldn’t tell much difference between it and stills of 240p.[/quote]

I've always enjoyed the look of the fake scanlines on PC CRTs monitor with the OSSC but it just gets way too dark to enjoy properly. Are PVMs and BVMs this dark as well?


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Tue Feb 11, 2020 11:58 pm 


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Josh128 wrote:
Show me, please, in this thread, where I called frame doubling BFI. Where did I say, and I quote-

Xer Xian wrote:
"60Hz BFI for 240p content (or any content running at 60fps) does not need or benefit from frame doubling, it just requires a black frame inserted every other frame. No one calls that frame doubling.If you call for a frame doubling feature for use on CRTs while also saying that with BFI it will improve motion on flat panels as well, people (like me) could genuinely think that you want to have both at the same time and will tell you that that is dumb."

Go!

I wasn't referring to this thread, but rather to the OSSC Pro's thread, where you started the 240p120 debate. However, I went back and reread the relevant part of that thread, and it was actually someone else that talked about its supposed benefits on flat panels (specifically here). Apologies for that.

Quote:
Finally, to cite an outside source to show that RAs BFI does indeed eliminate motion blur on 60fps content on 120Hz capable LCDs, and also eliminates the stroboscopic illusion of running 60fps content at 120Hz
on CRTs, contrary to what you have claimed, here you go. And before you come back and say you havent claimed that, I'll quote you again:

Xer Xian wrote:
The double-image effect of repeated frames on a CRT cannot be alleviated with BFI.

I claimed that, and will also keep claiming that, since it is true under the standard definition of BFI. If you're replacing the repeated frames with black frames you're not simply inserting the latter, you're also substituting the former. Pedantic? Maybe - still much less irritating than your mansplaining.

Before I'm out of here for good, let me quote you for once, and thank you for proving the main point that I made in this thread - ie that 240p120 and 480p w/ 100% scanlines do not differ in terms of lines' thickness in any way other than - possibly - perceptually:

Josh128 wrote:
4.)240p120 w/ BFI vs 480p with Full Artificial Scanlines: So during the course of testing all these modes, I made an interesting observation-- 240p120 w/BFI and 480p with full artificial scanlines are virtually identical. In overall brightness, they appear to my eye as identical to each other. In terms of scanline thickness, again, identical. Per Fudohs comments in the OSSC Pro thread, and my own previous experiences with 480p modes, I was not expecting this, but I can not detect a noticeable difference.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 5:00 pm 


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Xer Xian wrote:
" The double-image effect of repeated frames on a CRT cannot be alleviated with BFI." I claimed that, and will also keep claiming that, since it is true under the standard definition of BFI. If you're replacing the repeated frames with black frames you're not simply inserting the latter, you're also substituting the former. Pedantic? Maybe - still much less irritating than your mansplaining.


Mansplaining, really?? Standard definition of BFI? Is this really the sword you want to fall on? Whether you are replacing repeated frames or inserting between original frames, its the same exact function. Absolutely ZERO difference between the two technically. Its still black frame insertion no matter what terminology you use. So rather than argue about semantics, or fuss about some odd scenario that I never brought up (like 60 or 120fps over 240Hz), just admit that BFI actually does eliminate the stroboscopic illusion of running 60fps source content at 120Hz refresh on a CRT. Because it does, and thats a fact. Arguing over its usefulness or lack thereof over line doubled 240p content displayed at 480p w/ full artificial scanlines is moot. Thats a different argument than claiming so matter-of-factly that "The double-image effect of repeated frames on a CRT cannot be alleviated with BFI.



Xer Xian wrote:
Before I'm out of here for good, let me quote you for once, and thank you for proving the main point that I made in this thread - ie that 240p120 and 480p w/ 100% scanlines do not differ in terms of lines' thickness in any way other than - possibly - perceptually:

Josh128 wrote:
4.)240p120 w/ BFI vs 480p with Full Artificial Scanlines: So during the course of testing all these modes, I made an interesting observation-- 240p120 w/BFI and 480p with full artificial scanlines are virtually identical. In overall brightness, they appear to my eye as identical to each other. In terms of scanline thickness, again, identical. Per Fudohs comments in the OSSC Pro thread, and my own previous experiences with 480p modes, I was not expecting this, but I can not detect a noticeable difference.


And?? I said this in the original post of this thread after making the observation and have never argued any differently for CRTs. However, you chose to leave out the part where I also concluded that the 240p120 w/ BFI mode would still be superior to line doubled 240p displayed at 480p w/ full scanlines for 120Hz capable LCDs. It eliminates blur vs the 480p60 mode and does not replace it with any double strobing illusion as you claimed. Many, many users with 120+Hz capable LCDs like the BFI option in Retroarch for precisely this reason.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 5:32 pm 


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Josh128 wrote:
So rather than argue about semantics, or fuss about some odd scenario that I never brought up (like 60 or 120fps over 240Hz), just admit that BFI actually does eliminate the stroboscopic illusion of running 60fps source content at 120Hz refresh on a CRT.

Admit? I stated that myself in the first message I posted on this thread:

Quote:
The double-image effect of repeated frames on a CRT cannot be alleviated with BFI. If you are no longer seeing the effect then RA must be running BFI at 60hz instead of 120hz (total frame rate being 120hz instead of 240hz) and substituting the repeated frame with a black frame, thus losing information (even if redundant).


You then kept quoting only the first period of the above and repeatedly explained to me what I had already written myself. That's mansplaining in my book.

Quote:
Josh128 wrote:
4.)240p120 w/ BFI vs 480p with Full Artificial Scanlines: So during the course of testing all these modes, I made an interesting observation-- 240p120 w/BFI and 480p with full artificial scanlines are virtually identical. In overall brightness, they appear to my eye as identical to each other. In terms of scanline thickness, again, identical. Per Fudohs comments in the OSSC Pro thread, and my own previous experiences with 480p modes, I was not expecting this, but I can not detect a noticeable difference.


And?? I said this in the original post of this thread after making the observation and have never argued any differently for CRTs.

Never? viewtopic.php?f=6&t=65892&p=1396815#p1396815

In the end, we both assumed something the other never meant to say or thought and we're still arguing over basically nothing. Isn't it about time to let this die here?


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 5:54 pm 


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Josh128 wrote:
Xer Xian wrote:
And?? I said this in the original post of this thread after making the observation and have never argued any differently for CRTs.

Never? viewtopic.php?f=6&t=65892&p=1396815#p1396815

In the end, we both assumed something the other never meant to say or thought and we're still arguing over basically nothing. Isn't it about time to let this die here?


Yes, never. That post is referring to 240p120 native, not with BFI. You can clearly see it was in reference to Fudohs response to your claim that 240p120 scanlines were no different or more natural looking than 480p60 w full artificial scanlines. This is not true-- its looks distinctly different.

Look, Im tired of arguing too. I dont get enjoyment out of it, but you made several claims that were not accurate and unless I missed it, still have not admitted that. In the meanwhile you have been trying to say I have made claims that I didnt, just like above, which was not about 240p60 w/ BFI. The only bold claim I made, and it was in the OSSC Pro thread, was that I did not see any double strobing illusions when I first looked at it (240p60 native). After being questioned about it, I re-checked and was indeed able to see the effect and quickly admitted I was wrong about it. I freely admit to being 100% wrong about it. Personally, I still find the effect to be hardly noticeable, but I was definitely wrong about it not being present at all.

Its not about "me" being right or wrong, its about the info presented here as being accurate or inaccurate. If I am proved wrong I have no problems in admitting it.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 6:17 pm 


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Josh128 wrote:
Look, Im tired of arguing too. I dont get enjoyment out of it, but you made several claims that were not accurate and unless I missed it, still have not admitted that.

Its not about "me" being right or wrong, its about the info presented here as being accurate or inaccurate. If I am proved wrong I have no problems in admitting it.

Same here - see my apologies above when I erroneously attributed to you something said by someone else. And my concession about 240p120 possibly having thinner-looking blanklines due to perceptual reasons - not to the lack of additional 480p scanlines like you or others stated (otherwise that would show up w/ BFI as well).

No other things left for me to admit, though.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 8:48 pm 


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people who unironically use the word mansplaining don't have an opinion


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 9:50 pm 


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Who cares about opinions, give me the facts instead


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 10:09 pm 


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I think this thread demonstrates why there is no good reason to play 240p games on a PC CRT. 15kHz TV's are still plentiful, and many of them have component, which makes them easy to hook up to a PC and RGB consoles with a RGB>YPbPr converter.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 10:11 pm 


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But then again there's no reason not to have implemented on the OSSC Pro. I mean why not? If it serves its purpose on a handful of users' setups and is technically easy to implement (which it is), then I'd always appreciate the option - even if I might never use it myself.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 10:16 pm 


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Xer Xian wrote:
Its not about "me" being right or wrong, its about the info presented here as being accurate or inaccurate. If I am proved wrong I have no problems in admitting it.

Same here - see my apologies above when I erroneously attributed to you something said by someone else. And my concession about 240p120 possibly having thinner-looking blanklines due to perceptual reasons - not to the lack of additional 480p scanlines like you or others stated (otherwise that would show up w/ BFI as well).

No other things left for me to admit, though.[/quote]

Quote:
If you feed 240p120 to a modern display and activate 120hz BFI you will substitute one kind of vision artifact (image persistence) with another (double-image effect).


So you still believe that RA's BFI on a 120Hz display will cause a double image effect then?


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 10:21 pm 


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Fudoh wrote:
But then again there's no reason not to have implemented on the OSSC Pro. I mean why not? If it serves its purpose on a handful of users' setups and is technically easy to implement (which it is), then I'd always appreciate the option - even if I might never use it myself.


Oh yeah, especially for the 120hz OLEDs we have now. I'm not sure if their native BFI mode has lag, so maybe external BFI from an OSSC might be faster, hard to say.

But for PC CRT's, keep those for Dreamcast, PS2, and newer stuff. Grab a secondary 13" or 20" 15kHz TV for 240p consoles, if space is a concern.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 10:21 pm 


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BazookaBen wrote:
I think this thread demonstrates why there is no good reason to play 240p games on a PC CRT. 15kHz TV's are still plentiful, and many of them have component, which makes them easy to hook up to a PC and RGB consoles with a RGB>YPbPr converter.


I think it proves the opposite. Games at 240p120 native on a PC CRT are beautiful, stunning even, IMO. Top of the line BVM quality image. Dont know if you saw that among all the fuss, but the brightness is way above what is possible at 480p60 line doubled. Scanlines are also thinner, apparently due to the increased brightness of the image lines, and look more authentic because of it. So you can get the image of a $1000+ BVM on a CRT that most people can't give away fast enough. The concern over double-strobing is WAY overblown. Its no worse than the blurring of game content on a 60Hz LCD. I'd say they are directly equivalent in terms of noticability.

Now I agree that 240p120 w/BFI on CRT is moot. It looks identical in brightness, flicker, and scanline detail to 480p60 w/ artificial scanlines.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 10:27 pm 


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Josh128 wrote:
I think it proves the opposite. Games at 240p120 native on a PC CRT are beautiful,


That's because you're ignoring the double strobe effect. I think being able to see the pixel art clear in motion is pretty important, and easily solved by getting a normal standard definition TV for free on craigslist.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 10:34 pm 


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BazookaBen wrote:
Josh128 wrote:
I think it proves the opposite. Games at 240p120 native on a PC CRT are beautiful,


That's because you're ignoring the double strobe effect. I think being able to see the pixel art clear in motion is pretty important, and easily solved by getting a normal standard definition TV for free on craigslist.


I'm not ignoring it, though. Its just not a very pronounced effect, and the positives of the large increase in brightness and better looking scanlines outweigh the negative of the double-strobe effect, and by quite a long shot, IMO. Seriously, I have a 27" FD Trinitron Wega sitting in the same room and it looks great-- but I think the 31KHz CRT in 240p120p mode trounces it in image quality in every way possible except for the double strobe effect and size, of course.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 10:37 pm 


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A PC CRT pairs up with MiSTer very well. Probably the best display you could use if you want to use all the cores on a single display.

Also, you guys are starting to repeat yourselves.
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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 10:46 pm 


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Josh128 wrote:
Quote:
If you feed 240p120 to a modern display and activate 120hz BFI you will substitute one kind of vision artifact (image persistence) with another (double-image effect).


So you still believe that RA's BFI on a 120Hz display will cause a double image effect then?

I wasn't referring to RA's BFI, but rather to standard '120hz BFI', which, along with 120fps content (or frame-doubled 60fps) would require a display capable of 240hz (unless, I guess, it can refresh the two halves of the screen independently, like the previous gen of LG OLEDs were supposed to do till they scrapped the feature - which is apparently to be implemented on the 2020 models). Indeed, we're going in circles now. I hope we're now on the same page at least.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Wed Feb 12, 2020 11:00 pm 


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Shelcoof wrote:
I've always enjoyed the look of the fake scanlines on PC CRTs monitor with the OSSC but it just gets way too dark to enjoy properly. Are PVMs and BVMs this dark as well?


Do you use the Tendak, by any chance? If so, get the Portta one. Costs the same, brighter, and especially if it is plugged in! I keep spreading the word on here but it's mostly fallen on deaf ears.
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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Thu Feb 13, 2020 6:09 am 


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kitty666cats wrote:
Shelcoof wrote:
I've always enjoyed the look of the fake scanlines on PC CRTs monitor with the OSSC but it just gets way too dark to enjoy properly. Are PVMs and BVMs this dark as well?


Do you use the Tendak, by any chance? If so, get the Portta one. Costs the same, brighter, and especially if it is plugged in! I keep spreading the word on here but it's mostly fallen on deaf ears.


I have both Portta and Tendak and I wouldn't necessarily agree it is brighter more like its not as dark. It doesn't crush blacks as much if you know what I'm saying. I find if I plug it in there is more noise and jitter so I leave it unplugged and I don't see a difference in brightness at all when plugged in either.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Thu Feb 13, 2020 11:37 am 


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True 240p is brighter on a BVM than 480p + 100% scanlines. It all comes down to how the electron gun is moving. At 15khz (240p), the gun is moving slower than at 31khz (480p).

At 240p, the gun is drawing a scanline every frame and it takes around 1/240th (-h blank) of a frame to move from right to left.

At 480p + scanlines, in the same period the gun draws two scanlines.. the actual image and then a "blank" line. It is spending half as long actually lighting up phosphors, so the image is darker.

240p120 addresses this issue by just drawing the line twice, thus it is still 31khz but it is spending most of its time lighting up phosphors. So it's brighter, but the trade-off for this is the "double image" effect as every line is being drawn twice.

If you take 240p120 and then replace every other frame with a black image, what you end up with (and what Xer Xian is saying) is effectively 480p60+scanlines with BFI. On an LCD this effect improves perception of motion, but on a CRT adding the BFI reduces brightness as once again the gun is spending half its time not lighting anything up.. and CRTs have great motion anyway so it is not really helpful.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Thu Feb 13, 2020 12:08 pm 


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Kez wrote:
If you take 240p120 and then replace every other frame with a black image, what you end up with (and what Xer Xian is saying) is effectively 480p60+scanlines with BFI. On an LCD this effect improves perception of motion, but on a CRT adding the BFI reduces brightness as once again the gun is spending half its time not lighting anything up.. and CRTs have great motion anyway so it is not really helpful.


Although its accomplished differently, but the luminance appears to be identical. Contrary to what some claimed, flicker is no worse on the BFI mode, either. Below is what I said in the OP.

Josh128 wrote:
After comparing 240p120 BFI and line doubled 480p with full scanlines on CRT, it would be tempting to say that a 240p120 BFI mode would not be worth the trouble to implement as its indistinguishable from line doubled 480p w/ full scanlines, BUT-- I believe that the 240p120 BFI mode would be merited on 120Hz LCDs, where it would not only alleviate the double strobing illusion, but also greatly reduce blurring that is prevalent on 60Hz content on LCD screens.


Its interesting to watch a single electron gun scan (taken with high shutter speed) of 240p120 vs 480p60 w/scanlines. The trailing phosphors on the 120Hz are lit for a much longer length above the scan on the 120Hz because the beam is moving twice as fast. The phosphors excite faster than they decay and this is clearly visible on the faster scan.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Thu Feb 13, 2020 12:45 pm 


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Yeah I was really just summarising everything and answering Shelcoof's question about BVMs.

Josh128 wrote:
Although its accomplished differently, but the luminance appears to be identical. Contrary to what some claimed, flicker is no worse on the BFI mode, either. Below is what I said in the OP..


Yes, I meant brightness vs 240p120 is reduced when substituting black frames. I agree with what you said in the OP, and I don't think anyone is debating the usefulness of BFI on LCDs. Only on an LCD it wouldn't be 240p120 BFI.. it would be 1080p60 w/ BFI or something similar.. and that may create bandwidth issues even for the Pro?

I may be getting something mixed up in my head here but aren't 240p120 and 480p60 both 31khz signals? i.e. the gun is moving at the same speed. 240p120 just draws the frame twice whereas 480p + scanlines draws every other line blank.


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 Post subject: Re: 31KHz CRT: 240p120 vs. 240p120 w/BFI vs. 480p60 w/ Scanl
PostPosted: Thu Feb 13, 2020 1:11 pm 


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Kez wrote:
Yeah I was really just summarising everything and answering Shelcoof's question about BVMs.


I don't think anyone is debating the usefulness of BFI on LCDs. Only on an LCD it wouldn't be 240p120 BFI.. it would be 1080p60 w/ BFI or something similar.. and that may create bandwidth issues even for the Pro?

I may be getting something mixed up in my head here but aren't 240p120 and 480p60 both 31khz signals? i.e. the gun is moving at the same speed. 240p120 just draws the frame twice whereas 480p + scanlines draws every other line blank.


From what I read, the 240p120 w/BFI is supposed to work on 120Hz LCDs and people already use it with RA, but I cant confirm personally if its 240p or some higher resolution at 120Hz, but it can not be a 60Hz signal for BFI regardless of the resolution. It must be double the source frame rate of 60Hz. And yes, 240p120 and 480p60 are both ~31KHz signals. When I say the beam is moving faster, Im talking about the vertical scan of the entire screen. If you are talking about the actual horizontal lines scanned in a 1 second period, they are the same, but for 480p +scanlines, half of the beam scans are with the R,G,B guns at 0.

It would be great if someone here with a 120Hz or higher LCD could do some testing and report back.


Last edited by Josh128 on Thu Feb 13, 2020 4:46 pm, edited 2 times in total.

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