Intel Haswell graphics can output true 240p on Windows 7

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Nintendo Maniac 64
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Intel Haswell graphics can output true 240p on Windows 7

Post by Nintendo Maniac 64 » Thu Mar 12, 2015 6:16 pm

If you aren't aware, modern AMD and Nvidia GPUs are not capable of outputting a true native 240p signal, especially on modern Windows OSes. I initially though this was also the case for Intel graphics as well, but it turns out it's only partially the case.

Simply put, Intel Haswell graphics seem to have a minimum horizontal resolution of 376 pixels via its custom resolution functionality.

This means the likes of 320x240 are not possible, but that does mean 400x240 is fully possible, which was used in games like Doom. Even the custom resolution of 376x240 can be usable if you're OK with some underscan and/or can crop off the left and right sides a bit via your monitor's own picture-adjustment settings.


One thing though is that, at least on Windows, it doesn't seem to expose any really-low resolutions unless you run at 640x480, and even then any programs may not list them. Therefore, it's easiest to use a program like Reso.exe which does see those very low resolutions, and lets you make a shortcut to the program in question while launching at whatever resolution you've set (and then going back to your desktop resolution when you exit said program).


I don't have any photos just of Cen64 running with that native 240p just yet, but hopefully I'll upload at least one later today.
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Mizox
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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by Mizox » Fri Mar 13, 2015 12:27 am

do you know if this works with sandybridge or ivybridge as well? or is it just haswell?

also, my concern is whether or not a modern monitor can even recognize a signal with such low hsync, most state a minimum of ~30khz on their spec sheets

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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by Nintendo Maniac 64 » Fri Mar 13, 2015 12:31 am

Mizox wrote:do you know if this works with sandybridge or ivybridge as well? or is it just haswell?
Unfortunately I do not have access to systems running either. I did just have access to a laptop with Sandy Bridge just last week, but I didn't discover the 240p thing until last night.
Mizox wrote:also, my concern is whether or not a modern monitor can even recognize a signal with such low hsync, most state a minimum of ~30khz on their spec sheets
Well in my experience the only reason you'd be interested in a native 240p signal is if you're trying to use a CRT. Am I incorrect in this, and is there a reason to actually use 240p on non-CRT displays?
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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by MarathonMan » Fri Mar 13, 2015 8:34 am

What's wrong with pixel doubling techniques? Instead of 1 pixel, you plot 4.

Source image (240p) becomes:

Code: Select all

12
34
Output image (480p) is:

Code: Select all

1122
1122
3344
3344
Output image (720p) is:

Code: Select all

11112222
11112222
11112222
11112222
33334444
33334444
33334444
33334444
etc.

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Nintendo Maniac 64
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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by Nintendo Maniac 64 » Fri Mar 13, 2015 2:25 pm

Nothing wrong with it on modern flat-screen displays, but on CRTs it allows for actual physical scanlines.

And this is coming from someone that typically dislikes simulated scanlines (they seem to typically be too large).


EDIT: There's also the whole CRT phosphor pixel achitecture thing which would need something like a 4k 120hz OLED display to be able to really start getting close to correctly simulating.
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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by Mizox » Thu Mar 26, 2015 6:34 pm

Nintendo Maniac 64 wrote:
Mizox wrote:do you know if this works with sandybridge or ivybridge as well? or is it just haswell?
Unfortunately I do not have access to systems running either. I did just have access to a laptop with Sandy Bridge just last week, but I didn't discover the 240p thing until last night.
Mizox wrote:also, my concern is whether or not a modern monitor can even recognize a signal with such low hsync, most state a minimum of ~30khz on their spec sheets
Well in my experience the only reason you'd be interested in a native 240p signal is if you're trying to use a CRT. Am I incorrect in this, and is there a reason to actually use 240p on non-CRT displays?
I was referring to CRTs as well actually, I have a number of CRT monitors and all of them seem to have an operating range of 480p60 to 1200p75, none of them will accept 15khz...

unless you're talking about using a CRT television (which I also have a few of), in which case, how would one go about converting the RGBHV output to S-video or YPbPr component? all of the adapters/converters I've seen for sale take the overly convoluted (and image-destroying) route of feeding it into a scaler and then outputting a digitally resampled signal, which completely defeats the purpose of the whole exercise, looks like shit, and adds a shitload of latency.

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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by Nintendo Maniac 64 » Thu Mar 26, 2015 8:34 pm

Mizox wrote: I was referring to CRTs as well actually, I have a number of CRT monitors and all of them seem to have an operating range of 480p60 to 1200p75, none of them will accept 15khz...
It's my understanding that the 15khz 240p commonly seen on the likes of SCART is of a different video signal compared to 240p over VGA.
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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by iwasaperson » Sun Mar 29, 2015 6:49 pm

Nintendo Maniac 64 wrote:If you aren't aware, modern AMD and Nvidia GPUs are not capable of outputting a true native 240p signal, especially on modern Windows OSes. I initially though this was also the case for Intel graphics as well, but it turns out it's only partially the case.

Simply put, Intel Haswell graphics seem to have a minimum horizontal resolution of 376 pixels via its custom resolution functionality.

This means the likes of 320x240 are not possible, but that does mean 400x240 is fully possible, which was used in games like Doom. Even the custom resolution of 376x240 can be usable if you're OK with some underscan and/or can crop off the left and right sides a bit via your monitor's own picture-adjustment settings.


One thing though is that, at least on Windows, it doesn't seem to expose any really-low resolutions unless you run at 640x480, and even then any programs may not list them. Therefore, it's easiest to use a program like Reso.exe which does see those very low resolutions, and lets you make a shortcut to the program in question while launching at whatever resolution you've set (and then going back to your desktop resolution when you exit said program).


I don't have any photos just of Cen64 running with that native 240p just yet, but hopefully I'll upload at least one later today.
320x240 works fine in Windows Catalyst using CRU (Custom Resolution Utility) and in Linux using any of the open source drivers and xrandr.

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Nintendo Maniac 64
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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by Nintendo Maniac 64 » Sun Mar 29, 2015 10:09 pm

iwasaperson wrote:320x240 works fine in Windows Catalyst using CRU (Custom Resolution Utility)
This did not work on my AMD E-350 APU back when I tried it 4-9 months ago.
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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by iwasaperson » Sun Mar 29, 2015 10:44 pm

Nintendo Maniac 64 wrote:
iwasaperson wrote:320x240 works fine in Windows Catalyst using CRU (Custom Resolution Utility)
This did not work on my AMD E-350 APU back when I tried it 4-9 months ago.
Works for me in Windows 8.1.

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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by Nintendo Maniac 64 » Sun Mar 29, 2015 10:46 pm

iwasaperson wrote:Works for me in Windows 8.1.
Well I was on Windows 7...

Also, are you getting a native 240p output rather than a scaled or window-boxed one?
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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by iwasaperson » Sun Mar 29, 2015 11:17 pm

Nintendo Maniac 64 wrote:
iwasaperson wrote:Works for me in Windows 8.1.
Well I was on Windows 7...

Also, are you getting a native 240p output rather than a scaled or window-boxed one?
Native on my CRT (I have to run at 120 Hz though).

Try 3840x240 and see if that works for you. Horizontal resolution matters little if you're using an emulator like RetroArch, where the UI is completely scaleable. If you use RetroArch and you're running at 120 Hz, make sure you turn on Black Frame Insertion. If you're monitor is 15 KHz compatible, just run at 60 Hz.

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Re: Intel Haswell graphics can output true 240p on Windows 7

Post by Nintendo Maniac 64 » Sun Mar 29, 2015 11:24 pm

iwasaperson wrote:Native on my CRT (I have to run at 120 Hz though).
Ah, that's something I never actually thought of - I'm running 162hz on the Intel GPU but I don't think I ever thought to try a high refresh rate - perhaps I'll do that.
iwasaperson wrote:Try 3840x240
Can't, my CRT won't accept any horizontal resolution over 2056.
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