Eve Spectrum Prototype Tester | Marat Tanalin

More about pixel-perfect (integer) scaling via HDMI

Additional empirical data collected when connecting via HDMI 1.x again:

  • When booting (loading) computer, the monitor menu displays “1280x1024@60Hz” as the current mode. But in fact, the resulting image looks like it’s first upscaled with blur to an intermediate resolution (probably exactly the 1280x1024 displayed in the monitor menu), then that already blurry image is finally upscaled with no blur with 2×2 square pixels.

    This is probably due to lack of EDID support for 720×400@70Hz, 640×400@70Hz, or 640×480@75Hz modes potentially used by non-UEFI BIOSes (“Award Modular BIOS v6.00PG” in my case) during boot. Black screen via DP during boot has probably the same root, while HDMI controller probably performs some transparent conversion of modes missing in EDID.

  • The interlaced 1080i mode is not scaled and is displayed as “1920x1078” in the monitor menu under Linux only. In Windows 10 and 7, and with the Panasonic GF5 photocamera as the video source, interlaced 1080i is displayed in the monitor menu as “1920x1080” and pixel-perfect scaling does work.

  • At resolutions 1440×900, 720×480, etc., the image is centered instead of scaling, only in the “Pixel perfect” scaling mode of the monitor. In the regular blurry “Maintain aspect ratio” scaling mode, the image is scaled at the same resolutions.

    So a possible reason of centering instead of scaling in the “Pixel perfect” mode is that specific scales (scaling ratios) in the “Pixel perfect” monitor mode are hard-coded into firmware instead of being calculated dynamically and are just wrongly set to 1.0 for corresponding resolutions.

  • The Windows-specific issue that makes it impossible to output 640×480 via HDMI to the monitor directly without prior forced GPU scaling to 800×600, happens in both Windows 10 and Windows 7.

I updated my first report about pixel-perfect (integer) scaling here accordingly, and added “NEW 2021-07-01” mark where reasonable.

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Pixel-perfect (integer) scaling —
testing with a non-computer video source:
Panasonic GF5 photocamera (1080i, 480p, 576p)

Tested Eve Spectrum with the Panasonic GF5 (2012, Micro 4/3, MiniHDMI) photocamera as the video source:

  • Works fine with no general issues compared with PC as the video source.

  • The photocamera supports three output modes:

    • 1920×1080i@60Hz (interlaced);
    • 720×480@60Hz (corresponds to the NTSC standard);
    • 720×576@50Hz (corresponds to the PAL standard).

    Just like with PC, pixel-perfect scaling:

    • does work in the 1080i mode (“1920x1080@60Hz” is displayed in the monitor menu);
    • does not work (centered instead) in 720×480@60Hz and 720×576@50Hz modes.
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DisplayPort-to-HDMI-2.0 adapter — no luck

Bought a DP-to-HDMI-2.0 adapter — Dell 492-BBXU officially capable of 4K@60Hz. Nothing changed.

  • Same 30 Hz as the maximum refresh rate at 4K.

  • Same black screen during boot.

  • The maximum refresh rate available at FHD is 120 Hz like via HDMI 1.x instead of 144 Hz available via direct DP connection.

The DP end is connected to the computer (which has a DP port capable of 4K@60Hz), the HDMI end is connected to the monitor (which has an HDMI 2.x port capable of 4K@60Hz too).

But at least there is now more clarity about a possible reason of 30 Hz issue

I’m starting to suspect there is something wrong in the way the monitor reports supported graphic modes to the video source.

If Eve Spectrum did not support the part of the DP standard that my graphics card GTX 650 Ti Boost uses for encoding/transmitting data via DP, this would unlikely apply to the DP-to-HDMI scenario given that in this case the monitor thinks it’s HDMI anyway and does not know (or does it somehow?) it’s converted from DP.

So the most probable reason of the 30 Hz limit at 4K is that the monitor reports (regardless of via HDMI or via DP) the list of supported graphic modes in a way that makes my GPU think that the monitor’s maximum refresh rate at 4K is 30 Hz.

E.g. 60 Hz and higher rates for 4K resolution are probably reported in a different way that older GPUs don’t understand regardless of whether via HDMI or via DP. So the issue is probably more fundamental than just a specific-interface-level (HDMI/DP) incompatibility.

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you know a man is serious about integer scaling when the words ‘integer’ and ‘scaling’ make up a solid 10% of his introduction post :rofl:

i don’t have anything useful to add, i just wanted to say this is all really cool! :+1:

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Yeah, integer scaling is the main/only feature I’m interested in regarding Eve Spectrum, and the thing I investigate and track for years since purchased a 4K monitor in 2015, and the reason why I suggested myself and was then invited as a community tester of Eve Spectrum in the first place. Nice to see another one interested in the feature too. :handshake:

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HDMI ports #1 and #2: functionally different?

There is apparently a weird issue with HDMI port #2 of Eve Spectrum:

  • SNES Mini has a fixed output resolution of 1280×720 (HD). But when connected via HDMI port #2, it’s displayed as 720×480 instead — both in terms of image size and the current video mode displayed in the monitor menu/OSD. The issue does not reproduce when using HDMI port #1 — SNES Mini output is displayed properly as 1280×720.

  • In Ubuntu 18.10 (Linux), the maximum resolution available via HDMI port #2 is 960×540 at 60 Hz. In pixel-perfect mode, it was displayed centered without scaling. The issue does not reproduce when using HDMI port #1 — 3840×2160 is the maximum available resolution as expected.

Hopefully a firmware-level issue that could be fixed.

Somewhat good news is that 960×540 is not in the monitor’s EDID, yet it was displayed fine by the monitor. 960x540@60Hz was the current video mode explicitly displayed in the monitor menu/OSD. So it’s apparently technically possible for the monitor to display modes missing in EDID.

Sort of bad news is that 960×540 was displayed without scaling, so looks like specific integer scales for all supported resolutions are hard-coded instead of being calculated dynamically for any input resolution whatever it is.

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The snes mini will output 720x480 or 1280x720. Depends on the EDID; you can mess with this using an EDID minder e.g. TMDS-KITU – An Eco Friendly Installation Kit - ConnectPRO

Sounds like there are a few CEA/CVT timing compliance issues.

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Thanks. This might be a part of the issue that results in 30 Hz as the maximum refresh rate available with Eve Spectrum at 4K in my case.

As I previously suspected, the monitor probably reports the supported modes in some special not-quite-correct way, so the video-source device thinks the monitor is not capable of higher modes and sends the video signal at a fallback mode. HDMI port #2 probably just reveals this specifics in another, even more special way.

Btw, is there some official info (or at least some more detailed) about 720×480 as a legit SNES Mini output mode along with the usual 1280×720?

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Testing with a non-computer video source:
TV tuner D-Color DC1302HD ✔️

Originally, the third non-computer video source (besides SNES Mini and Panasonic GF5) I planned to test Eve Spectrum with was the hardware player Iconbit HD375W. Unfortunately, the player’s HDMI output apparently failed during the years when the player was unused: it now outputs nothing and the same also takes place with my Dell P2415Q 4K monitor, so this is surely not specific to Eve Spectrum.

As a replacement, I tested the TV tuner D-Color DC1302HD. The device has a built-in (though not quite great in terms of both usability and compatibility with real-world files) video-player and image-viewer functionality and supports multiple output modes:

  • 1920×1080p/i at 60/50 Hz;
  • 1280×720p/i at 60/50 Hz;
  • 720×480p/i at 60 Hz.
  • 720×576p/i at 50 Hz;

Based on testing results, all those modes work with Eve Spectrum correctly and consistently via both HDMI input ports of the monitor. This includes pixel-perfect scaling mode of Eve Spectrum that works correctly too.

The output mode of the TV tuner is explicitly selected manually via its menu. So there is probably no EDID-based video-mode auto­selection magic at all, and that might be the reason why the specifics of the Eve Spectrum’s HDMI port #2 (previously discovered with SNES Mini and Linux) did not reproduce with this video source.

Coincidentally, the TV tuner is based on hardware by the same MStar manufacturer as Eve Spectrum itself.

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thanks a lot for keeping up the testing and sharing it with us!

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That would be my guess, yeah. Every display in my house now has an EDID minder attached.

For example I have an old 1080p monitor which (mis)reports its maximum supported resolution as 1080p 30Hz when connected to a MacBook Pro. Added an EDID minder and BAM, a 1080p 60Hz option showed up on the MacBook Pro.

I also use this edid minder to force my iPad to output a 720p signal during streaming video playback to an old 720p only compatible plasma.

I currently force the snes into outputting 480p with this device (you wouldn’t want to use this mode with the EVE because it still renders internally at 720p even though it outputs 480p) TMDS-KITU – An Eco Friendly Installation Kit - ConnectPRO

I also use one of these EDID 101V - Integration Tools | Extron because without it the AMD Radeon drivers incorrectly report virtual super resolution ‘unavailable’ when connected to another of my older TV’s with a d-sub input.

I suspect a 4K EDID minder will solve your issues

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If 1080i works then 540p will also work because they have the same timings.

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I would be curious to know whether there are any differences in how the Spectrum handles DTV720x480 and VESA640x480.

852x480 compatibility would also be good to have so I can hook up my Extron DSC 301 HD scaler.

Thanks, interesting. Do I understand correctly that any resolution missing in EDID should work anyway as long as the refresh rate is the same and its total number of pixels (width multiplied by height) is equal to the total number of pixels at a resolution listed in EDID? But as far as I understand, 960×540 has a twice lower number of pixels compared with 1080i (effectively 1920×540). Or does only vertical resolution matter, not total number of pixels?

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Driving Eve Spectrum with MST DP output of Dell P2415Q

The Dell P2415Q 4K monitor I use since 2015 supports so called daisy-chaining: for this purpose, it’s equipped with not just a DisplayPort (DP) input for connecting a video source, but also with a DP output for connecting another monitor.

This was an interesting feature to investigate in combination with Eve Spectrum.

The tests were done with the latest Eve Spectrum’s firmware 102 rev. 875 (2021-07-12).

Summary

  • Only Dell P2415Q was visible to the system. Both monitors displayed the same image.
  • Computer boot was visible and stretched like it is always on Dell P2415Q alone.
  • 4K@60Hz was possible on Eve Spectrum with MST disabled in Dell P2415Q settings.
  • 640x480@75Hz worked on Eve Spectrum with pixel-perfect scaling, though EDID lacks the mode.

What is daisy-chaining?

Daisy-chaining is the feature the DisplayPort’s MST (Multi-Stream Transport) mode is intended for. It’s meant for connecting two monitors in a serial way, using just one DP output of the video source:

  1. the video source (computer) is connected to a DP input of a monitor called primary;
  2. another (secondary) monitor is connected to the DP output of the primary monitor.

Both monitors should be visible to the system and usable as separate displays just like if they were both connected directly to the computer.

Trying with MST disabled in Dell P2415Q settings (default)

So I connected my computer to Dell P2415Q’s DP input, and Eve Spectrum to Dell P2415Q’s DP output, using the DP 1.4 cable by Hama and DP 1.2 cable by VCOM correspondingly.

Only Dell P2415Q visible to system, same image on both

By default, the daisy-chaining/MST mode is disabled in Dell P2415Q settings: the “Display” → “MST” option is set to “Off”.

In this mode, the same image was output to both monitors. The only monitor visible to the system was Dell P2415Q, and available video modes (resolution + refresh rate) were limited to those of Dell P2415Q, so e.g. no HFR video modes like FHD@144Hz supported by Eve Spectrum were available.

4K@60Hz was possible on Eve Spectrum

Probably as a result of that Eve Spectrum and therefore its EDID (with its apparently not-quite-correctly reported data about supported video modes) were invisible to the system, Eve Spectrum finally displayed 4K at 60 Hz sent by Dell P2415Q, instead of just 30 Hz available previously when connecting my computer directly to Eve Spectrum.

In an attempt to use Dell P2415Q as a sort of DisplayPort “adapter” between my computer and Eve Spectrum, I tried to turn Dell P2415Q off with its “Power” button. But as a result, Eve Spectrum said “No signal” and switched to standby mode. Turning Dell P2415Q on again restored the image on it, but Eve Spectrum was still in standby mode. Turning Eve Spectrum off with its “Power” button, then on, did help — both monitors displayed the same image again.

Of course this is not an option for long-term use because:

  • both monitors have to be turned on at the same time and show the same image;

  • Spectrum-specific HFR modes like FHD@144Hz are not available;

  • and controlling Eve Spectrum’s brightness and other settings programmatically via DDC/CI is impossible (see below).

Computer boot is identical to Dell P2415Q alone

In terms of computer-boot visibility and scaling during boot, everything was identical to when Dell P2415Q is the only monitor connected to my computer:

  • Computer boot was visible on both monitors.

  • The video mode displayed as the current one in menus (OSD) of both monitors was 3840x2160@60Hz.

  • The image was stretched to entire screen and blurry on both monitors.

  • Pixel-perfect scaling feature of Eve Spectrum had no effect.

Given that during computer boot, Dell P2415Q, when connected to computer as the only monitor, always displays 3840x2160@60Hz as the current video mode in its menu/OSD, I suspect it performs some implicit internal conversion of unsupported video modes such as 720×400@70Hz (apparently used during computer boot on computers with non-UEFI BIOS) to 4K@60Hz. So Eve Spectrum apparently received the same video signal already prescaled to 4K by Dell P2415Q, therefore further scaling was impossible.

Attempt to turn daisy-chaining/MST on

Enabling daisy-chaining/MST in the Dell P2415Q menu with it set to be primary (“Display” → “MST” → “Primary”), resulted in that both monitors switched to standby mode. I was forced to blindly turn my computer off via a sequence of Win+D (to minimize all windows), Alt+F4 (to show the Windows’ shutdown window), and Enter (to shut the computer down). After turning my computer on again, the computer self-restarted multiple times in several seconds after boot start, cyclically.

After several iterations, including turning off the power of the computer and both monitors, Dell P2415Q said there is no signal and suggested to try switching to “Secondary” as the value of its “MST” option. (Later I read in the Dell P2415Q manual that there is a way to manually force displaying this option. That’s called RTFM. :slightly_smiling_face:) I accepted and computer was finally able to boot. As a result of switching Dell P2415Q to the “Secondary” value, both monitors displayed the same image again just like in case of the default “Off”, but now with 30 Hz as the refresh rate of both monitors.

In case of DP 1.2 and Dell P2415Q, 30 Hz is the expected refresh rate due to the limited DP 1.2 bandwidth. But if daisy-chaining worked, both monitors should have been visible and usable as separate displays by the computer, while in fact the only display available to the system was Dell P2415Q.

So looks like Eve Spectrum 4K monitor does not support operating as a secondary monitor in multi-display configurations based on daisy-chaining/MST. According to the Dell P2415Q manual (PDF, 6.7 MB), daisy-chaining is not tied to the specific monitor model and should work with any DP-1.2-capable monitor.

No way to control brightness etc. via DDC/CI

Because Eve Spectrum was not visible to the system as a separate display, and the only visible one was Dell P2415Q, it was not possible to control brightness and other settings of Eve Spectrum programmatically via DDC/CI e.g. with the ClickMonitorDDC utility.

So the only way to change brightness of Eve Spectrum according to the usecase was using the monitor menu/OSD with its physical joystick: e.g. during regular desktop work (web surfing, file management, programming, etc.), enough brightness is 0 (zero) (at constrast of 25 due to the current impossibility to set it below 25 programmatically), while watching movies needs a brightness of 30 or higher.

Eve Spectrum worked fine in unsupported 640x480@75Hz

Dell P2415Q supports 640x480@75Hz video mode which Eve Spectrum’s EDID lacks. But with the daisy-chaining/MST serial connection, the mode was displayed fine on Eve Spectrum too:

  • The mode was indicated correctly in the Eve Spectrum menu.
  • Pixel-perfect (integer) scaling did work fine.

This is probably another confirmation that Eve Spectrum is capable of displaying modes missing in its EDID, along with 960×540 under Linux via HDMI port #2, and 1920×1078 (1080i under Linux) via HDMI port #1.

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I can confirm that Eve Spectrum can support custom resolutions and refresh rates missing from EDID.

Large Vertical Totals (Quick Frame Transport, aka 60Hz modes that transmit in 1/144sec over the cable), such as Vertical Total ~3500, is supported by the Eve Spectrum for 1080p signals.

MT, you should test Quick Frame Transport for lag-reduced 1080p/60 integer scaling.

I have some custom numbers for you to enter in ToastyX or NVIDIA Custom Resolution, if you would like to test lag-reduced 1080p modes, more than 50% less lag for screen bottom edge, since it’s a 60Hz refresh cycle transmitted over the cable in 1/144sec, and painted onto the panel in 1/144sec, so your eyes sees the low-Hz refresh cycle sooner.

I’ve often created odd refresh rates like 65.3Hz and 128Hz on Spectrum and it works fine, provided you derive from a working higher-Hz mode and edit the Hz downwards without modifying other numbers in Custom Resolution Utility.

There are some ambiguities like scaling behaviors (already known in this thread), but the modes will display.

I have confirmed Eve Spectrum supports Quick Frame Transport, but sometimes I have to create it in both ToastyX and NVIDIA, for it to work ‘properly’ (because of the need to override NVIDIA scaling behaviors)

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Flicker-free — no detectable PWM

Tested my prototype for pulse-width modulation (PWM) using the TFT Central’s technique. The technique is based on taking a photo with a regular photocamera while moving it. This allows to turn PWM as a temporal effect into a spatial one.

PWM is not detectable on Eve Spectrum — there were no visible separate lines on resulting photos. Tested at 0/0, 50/50 and 100/100 levels of brightness and contrast. The photos were taken with Panasonic GF5 photocamera.

So Eve Spectrum 4K monitor is flicker-free.

Strobing as a user-controlled feature

At the same time, the monitor has so called strobing (“Performance” → “Backlight strobing”) as a user-controlled feature. Strobing is basically PWM synchronized with refresh rate, disabled by default and used for improving perceived clarity of moving objects. With strobing enabled, flickering is of course inevitable.

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Pixel-perfect (integer) scaling via HDMI port #2
under Ubuntu 21.04 with firmware 102 rev. 894

Retested Eve Spectrum prototype with the latest firmware 102 rev. 894, under Ubuntu 21.04 (Linux) I recently installed from scratch instead of Ubuntu 18.10. The nVidia-driver version is 470.57.02.

  • The maximum resolution and refresh rate are still limited compared with HDMI port #1, but now the maximum resolution is 1600×900 instead of the previous 960×540. Not sure what exactly affected this: Ubuntu version, nVidia-driver version, or firmware version. High-refresh rates (120+ Hz) are not available.

  • All resolutions available via Ubuntu GUI are displayed correctly in the monitor menu/OSD, even though its EDID lacks most of them. Another confirmation the monitor is capable of operating in arbitrary video modes not predefined in its EDID.

  • Almost all available resolutions are not scaled in pixel-perfect mode and displayed centered-unscaled instead. The only scaled resolutions are those that the monitor EDID has: 1280×720, 1024×768, 800×600, 640×480 (640×480 is not available via GUI, but available via xrandr). Another confirmation the scales (scaling ratios) are unfortunately precalculated and hard-coded in the monitor firmware instead of being calculated dynamically regardless of what the input resolution is and whether the monitor EDID contains it.

  • The full list of video modes available in Ubuntu 21.04 with Eve Spectrum connected via HDMI port #2:

    • 1600×900 at 59.83 Hz;
    • 1400×900 at 59.88 Hz;
    • 1368×768 at 59.85/59.88 Hz;
    • 1360×768 at 59.80/59.96 Hz;
    • 1280×800 at 59.81/59.91 Hz;
    • 1280×720 at 59.74/59.86 Hz;
    • 1152×864 at 60 Hz;
    • 1024×768 at 60 Hz;
    • 1024×576 at 59.82/59.90 Hz;
    • 960×540 at 59.63/59.82 Hz;
    • 800×600 at 56.25/60.32/72.19 Hz;
    • 640×480 at 59.94 Hz (via xrandr).
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Hi Marat, I just received my Spectrum 4k (ES07D03) and was wondering if integer scaling works with DP 1.4. I have updated to the latest firmware available (104) and am running the monitor with Adaptive-Sync ON. Below are the nVidia settings I’m using - not sure if there’s anything in the OSD that needs to be enabled as well. The reason I ask is I am trying to run games at 2560x1440 and am noticing considerable blurring around the text. Any help is greatly appreciated!

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Hi, Ben. Congrats on receiving your Spectrum.

The maximum resolution integer scaling works at with a 4K (3840×2160) display is Full HD (1920×1080):

3840/1920 = 2160/1080 = 2.0 → 2×2 pixels.

At QHD (2560×1440), you should get either a blurry image stretched to the entire screen or an unscaled centered image with black bars around the image:

  • You get a stretched blurry image in the mode called “Aspect ratio” in the nVidia control panel and “Maintain aspect ratio” in the Eve Spectrum menu/OSD.

  • You get a centered unscaled image in the mode called “No scaling” in the nVidia CP and “Pixel perfect” or “1:1” in the Eve Spectrum menu/OSD.

As I described in this thread, there are some quirks regarding GPU scaling forcedly and/or silently applied in some situations. This might be your case.

To be sure scaling is performed by the monitor and not by the GPU, make sure the logical resolution you use is displayed as the current video mode in the monitor menu. For example, “2560x1440@60Hz” should be displayed in the top-right corner of the Spectrum menu if it is the mode you selected via Windows display settings, GPU control panel, or in-game settings.

Also I would select the “No scaling” mode in the nVidia control panel even if the “Display” is selected in the “Perform scaling on” dropdown.

For what it’s worth, your GPU is apparently capable of integer (pre)scaling (the fourth option on your screenshot), so it’s important to clearly differentiate between scaling by the monitor and scaling via the GPU.

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