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Surprise Release: RT5X Firmware 4.0 “CRT Sim Edition”

  • Writer: Retro Tink
    Retro Tink
  • 13 minutes ago
  • 2 min read

Surprise! We’ve just dropped RT5X Firmware Version 4.0: the “CRT Sim Edition.” Original Post on X


A significant portion of the RT4K’s advanced processing pipeline has been backported to the RT5X.


This brings true HDR10 output, energy-normalizing scanlines, full RGB shadow masks, and brand-new “Quasi-4K” resolutions to the RT5X. The goal is to give RT5X users access to as many of the latest CRT processing effects as the RT4K, and take advantage of modern 4K TV resolutions and HDR.




Technical Details


The RT5X now runs the same 12-bit-per-channel (12bpc) RGB 4:4:4 linear light pipeline as the RT4K, allowing us to bring many of the 4K's advanced CRT and HDR effects:

  • Real Rec. 2020 HDR10 output instead of the old “injection” method.

  • CRT effects are now brighter and fully color-correct.

  • The scanline engine gains energy normalization (the same feature we added to the RT4K late last year). Variable-width scanlines no longer crush blacks or distort the gamma curve.

We’ve also added “Quasi-4K” output modes (3840×960, 2880×1200 and 2880x1080) for compatible displays. These native horizontal 4K resolutions preserve the full detail of RGB masks while letting your TV handle smooth vertical scanline interpolation.


While these modes are "experimental" and overclock the RT5X, if your TV is compatible, the mask effects can come shockingly close to an RT4K Pro/CE in some cases.


Quick Start Guide


After updating to FW 4.0:

  1. Set your output resolution to the best one supported by your TV/Display. Ideally if your TV is 4K capable, 3840x960 or 2880x1200 will work.

  2. Check out the new presets — they automatically turn on HDR, RGB masks, and scanlines.

  3. Feel free to adjust to your liking (and also check out the Color Correction menu too).

  4. If your TV is NOT HDR compatible go the the HDMI Settings Menu and turn off HDR.



Don't forget to calibrate the gain in the ADC-II menu to get the best possible output!


Limitations (Please Read)


There's some bad news. The RT5X underwent a few redesigns in 2021 as a result of the component shortage. The good news is that the vast majority of units in the field can use all features. However please note:

  • Rev. A units (launch / very early 2021 models) may be unstable above 1080p until we finish reworking the Gen Lock code.

  • Rev. B units (sold before mid-2022) have degraded shadow mask quality.

  • Rev. C units (mid-2022 and newer) have full RGB 4:4:4 shadow mask support and no limitations.


The current firmware also uses generic sampling and does not include MADI or inverse telecine (those features were removed to fit everything into the RT5X’s smaller FPGA). MADI may be added back later once we optimize it further for the limited memory on the 5X. For 480i-heavy users who rely on edge-interpolated MADI, the older 3.xx firmware branch may still be a better fit for now.


Why a Separate Branch?


Version 4.0 is a branch, not a full replacement for the existing firmware. We noticed a lot of you wanted a simple “just replace my CRT” experience, so this release brings the RT5X’s output much closer to what modern HDR 4K TVs are capable of. We really hope you enjoy this update and continue to get years of enjoyment out of your RT5X!

 
 
 
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