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F.A.Q

Here are some Frequently Asked Questions that people often have:

Does it work on PC?

No, it doesn't, and probably never will. RePlay is developed with many features relying on ARM architecture and Raspberry Pi devices.

Does it work on other devices like Orange Pi?

No, it doesn't, and never will. Other devices completely lack support for Linux OpenGL ES and/or KMS/DRM video mode (no X), among other things.

What is the advantage over other RPi distros like Lakka, RetroPie, or RecalBox?

Since the system is entirely focused on a single device family with a limited list of supported systems, I can maximize the hardware's power and introduce many unique features. It's also worth noting that the system is extremely fast and user-friendly, with each system core thoroughly tested and pre-configured. This ensures the best experience right out of the box.

Why RePlayOS instead of a new RGB-Pi OS 5?

The primary aim of RePlayOS is to offer a system that is fast and easy to start with. It demonstrates that emulation can achieve high quality when properly configured, allowing everyone to enjoy optimal gaming conditions from the start, without requiring technical emulation skills to fine-tune everything.

In all versions of RGB-Pi OS (0, 1, 2, 4), we were limited by the two frontends used (mine for the user interface, and RetroArch for gaming). This limitation prevented certain functionalities, such as in-game menu rotation, a fully adaptable interface across various resolutions and devices, customization based on my design preferences, and more.

RePlay's frontend is not just a simple launcher; it is a complete libretro-based frontend similar to the one utilized in RetroArch/Lakka.

Numerous features are exclusively achievable by using a custom libretro-based frontend, which cannot be accomplished using a stand-alone launcher paired with RetroArch. These include dual-screen support, minimal input lag (comparable to or even less than that of the original hardware) without utilizing runahead, complete control over various system options and configurations, core speed and performance enhancements, improvements in DynaRes engine for instant timing changes in CRT TVs, special functionalities like the coin-op time feature, and many others.

RePlay is compatible with both LCD and CRT monitors, including RGB-Pi 2 hardware.

What about input lag?

By default, the system operates in an ultra-low-latency mode, achieving a remarkable 0 frames of input lag without techniques like runahead, providing full compatibility across all emulated systems.

Also, please note that some system cores provide their own custom runahead functionality. When combined with this feature, input lag could be significantly less than that experienced on the real hardware.

Does connecting a joystick to USB 2.0 instead of USB 3.0 affect input lag?

Usually, there is no noticeable difference. USB 2.0 already supports polling every 1 ms (1000 Hz) for compatible controllers. Most joysticks use the same polling rate on either port, so USB 3.0’s higher bandwidth does not make them respond faster.

Does enabling scanlines in RePlay affect input lag?

Display and analog filters process the current frame without buffering an extra frame. They add GPU work, so input lag can increase if rendering misses its presentation deadline. Cost depends on the filter, native game resolution and output size; high-resolution LCD masks and analog filter reconstruction are more demanding than simple scanlines or Dither Blending. See Filter Performance.

Is it OpenSource?

The OS operates under a dual-license model: while most components are free and open-source, the frontend remains proprietary. For more details, please refer to the licensing information on the download page.

Can you add feature X to RePlay?

The answer is likely to be no, as I'm trying to keep the system easy and small from both user and developer perspectives.

Is RePlayOS available?

Yes. Public RePlayOS releases are available from the Downloads page. See the Changelog for version details.

Is it compatible with the old RGB-Pi (GPIO) or other similar devices?

Partially. Limited support for DPI (GPIO) video has been introduced recently with certain limitations: - Requires some simple manual configuration that can be done directly from RePlay UI - It only works in Raspberry Pi 5/500 models - The RGB color mode is limited to 18 bits (can cause visible color banding on 24/32 bits content) - There is not audio support, so an additional USB audio DAC is required. - JAMMA and RGB-Pi+ devices will work only for video output, both audio and joystick controllers are not supported.

RGB-Pi 2 is an available HDMI-to-SCART option designed for RePlayOS. Other CRT devices may work, but support varies by output type and the limitations listed above.

The new RGB-Pi 2 is an HDMI-to-SCART solution that uses 24-bit processing for both audio and video, features different sync combiners, and includes an additional audio jack.

The current RePlayOS v2 image supports Raspberry Pi Zero 2, 3, 4 and 5 models for CRT TVs using progressive and interlaced video modes. Check the requirements before using an older Zero 2 image.

UPDATE: Although interlaced support has been reintroduced in the Pi5 through the RP1 chip, its image quality and stability still fall significantly short compared to our new solution.

Will it support image scraping?

No, it won't. The main goal of the system is to be super fast, easy, and easy to setup. Scraping does not comply with this goal. In addition, it is not even feasible from a technical point of view since the UI layout makes not possible to fit images on either LCD or CRT screens.

Can I use other cores?

The answer is no. All the cores included in RePlay have been selected and pre-configured based on a balance between the best performance and emulation quality across different supported models of Raspberry Pi. That being said, depending on each Raspberry Pi model, some systems may be activated or deactivated, and it's possible that cores within the same system may also be changed. All the cores have been tested for years and come with optimal default configurations based on performance, emulation quality, fidelity, bugs, screen type, and more.

What is libretro?

The Libretro API is a lightweight C-based Application Programming Interface (API) that exposes generic audio, video, and input callbacks.

There are two sides to Libretro development:

  • frontends are programs that provide a user interface and all the implementation-specific details to run libretro-compatible cores.
  • cores are programs built as a single library file (such as a game, emulator, or media player) that use the libretro API so that can be executed by libretro frontends.

Developers of cores don’t have to worry about writing different video drivers for Direct3D, OpenGL or worrying about catering to all possible input APIs, sound APIs, gamepads, etc.

RePlayOS uses a custom libretro frontend specifically tailored to Raspberry devices. It is programmed in C and uses the following libraries:

  • DRM, EGL, and OpenGL ES 3.X for video
  • SDL3 for audio and input devices

Can I use CRT shaders on my LCD?

Yes. On Raspberry Pi 4 and newer, VIDEO > DISPLAY FILTER offers four scanline strengths and CRT TV, which combines scanlines with a fine phosphor mask. Integer scaling is not required. These are lightweight approximations of screen texture; they do not reproduce a real CRT's contrast or motion characteristics.

LCD Grid Dark/Light, LCD RGB, LCD BGR and LCD DMG presets are also available. A separate Analog Filter option provides RGB, S-Video, Composite and Dither Blending, which can be combined with a display preset. See Video Configuration for descriptions and screenshots.

Can I play movies?

Yes, RePlayOS includes its own Alpha Player multimedia core for playing all kinds of audio and video files. Since it is a software-based core, it requires a fairly powerful CPU, so it is recommended to use a Raspberry Pi 5 if you plan to play movies.