g2g latency with dual lcd screen module? @realizator

[someperson]

tldr: are the common vr dual lcd screens any good for simple passthrough (~20ms glass2glass/~60fps/~1080p)/or can i use a non mobile oriented lcd at 60fps [no rotation fps loss]

so, I bought a stereopi to build a: ~20ms g2g stereo passthrough solution, literally just stereo camera input -> stereo capable hmd or similar, with 60fps, and preferably as high as possible resolution 1080p IF possible, usecase is basically a digital stereoscope at 5-15x magnification with maybe something like 15cm working distance (have read macro post) that has advantages in manueverability over normal stereo scopes

problems: 10ms 130$ setup runs at 30fps (probably bad for this?, afai can tell this was due to the rotation, so can I achieve 60fps with the correct rotation?), stereoninja project (digital microscope, stereopi->3d monitor over hdmi) gave up I think after they couldn't get under 100ms (even though it was hdmi monitor with 1ms delay?? I assume processing or fps issue?)

solutions?: dual lcd screens (one hdmi input, two lcd screen output) as seen in many diy OSVR goggles/HMD (see relativity etc..), Realizator mentioned these in some posts eg. 2020, If anyone is using them can you tell me if the g2g latency is noticeable (if measured under 20/30ms)? the price range is about 50 to 100 depending on what OSVR goggle guide reccomendation you look at

any advice/code etc.. is appreciated hope someone can give me the g2g latency of their system (looking at you realizator o-o), have made custom configs for this, can point me in the direction I need to go (just looking this stuff up is hard, my current queries are "stereo vr passthrough os solution", it's very niche especially trying to stay close to the price point of the "stereopi vr setup" at an ok resolution/framerat/latency

(here is an example of what I'm talking about btw (I know wrong specs for this, just one of the reccomandations from the osvr build guides https://de.aliexpress.com/item/32975198 ... pt=glo2deu)

[Realizator]

CM4 is able to output 60fps, but the issue is the stereoscopic mode capture framerate - it's hard to achieve 60fps at FHD. You can play with resolutions with your particular setup.

The single screen with album orientation is more preferable. The issue is that most dual screens have their own controller which splits the signal, and it adds some delay. The only way to check it is to measure the particular device.

Our main reason of playing with dual screen was the resolution not available on a single-screen displays.

[someperson]

thanks for the reply, what does your experience tell you might be the most realistic goal for ~20ms g2g? (single display resolution/framerate)

[Realizator]

In my experience, the "balance" is near HD resolution and the highest FPS achievable (you need to tune this on your setup). For 30 FPS you have 33ms between frames, for 60 it's 16ms.
With VGA, you'll have perfect timing, but 640x480 is too low a resolution for an immersive experience. It's acceptable for drone races, for example, where the delay is more important than the picture quality.