This project enables Raspberry Pi with Retropie to work with the native display modes for the emulated content. It manages things like scanline configuration (progressive or interlaced), refresh rate, and pixel aspect ratio.
The Raspberry Pi is an amazing device highly customizable.
Bundled with Raspberry Pi OS, the basis of the Retropie distribution, it has a tool called "vcgencmd" which allows customizing the video output settings in a detailed way. It's possible to set technical parameters, like sync pulse interval or pixel aspect ratio, it's allowing to represent the original behavior of the emulated content at the intended CRT faithful as possible.
Those scripts manage the "vcgemcmd" tool making the needed calculations and switching modes on the fly. Meaning that when you're browsing over the Emulationstation, the display settings will be optimized for that content, displaying at a standard resolution of 640x480i at 60Hz, or 640x576 at 50Hz, if the "aka PAL settings" was enabled. At the same time, managing to have the display outputting the proper settings for the target emulated platform.
But, how do I connect the Raspberry Pi to a CRT display using the HDMI output?
To manage that, it's needed to have two things.
A CRT display that is capable of managing the standard video modes with the proper inputs, like RGB or YPbPr, and a converter box from HDMI to the desired connection like an HDMI to YPbPr (component) or HDMI to RGB SCART.
Most television sets manufactured for the American market in the early 2000s tend to have the component YPbPr inputs. Important to say that I'm not talking about only North America, but the whole American continent. If we talk about the European market, the set from the same period tends to have the SCART input connection, allowing the same purpose, but changing the connection and the color space.
I tested with a cheap Chinese HDMI to YPbPr converter brought from Aliexpress. I believe that other converters, like HDMI to VGA or HDMI to SCART will also work as well. Be aware that if you want to use an HDMI to VGA adapter for outputting to a CRT VGA Display, the intended display must be capable of handling the 15Khz signal. Shortly, I can manage to add the 31Khz support. But currently, it's not supported.
The set of scripting is composed of two Python scripts. The "chvideo.py" and "consoledisp.py".
This script drives the "vcgencmd" for outputting the desired video mode accordingly with the desired specs, like horizontal resolution, scanline mode, and refresh rate. It does the calculation needed for the intended video settings.
This one has all the intended modes and manages the customizable settings for the target platform emulated. Driving the "chvideo" script.
Check for the Retroarch core's geometry specs and configure the chvideo.py to match the intended game (currently enabled only for arcades).
- A Raspberry Pi. Tested at the Raspberry Pi 3. As far as the "vcgemcmd" tool exists, it should work.
- Retropie installed.
- An HDMI to analog display signal converter. Make sure that it needs to be a simple converter without any video processing. Just search for "HDMI to YPbPr" or "HDMI to VGA" in any online Chinese store.
- Enable the SSH at raspi-config as described here.
- From the same network and any command-line tool like Terminal or CMD, copy and paste the commands below.
ssh pi@retropie 'bash <(curl -s https://raw.githubusercontent.com/cjuniorfox/retropie-crt/main/setup.sh)'
- Type the Raspberry's password if asked. The default password generally it's 'raspberry'.
- The automated tool will install all the files needed. Then finishes, a new option will be available from the Emulationstation's Retropie option menu called 'RETROPIE-CRT'.It isn't, will be needed to restart the Emulationstation.
- A new option will be available from the Emulationstation's Retropie option menu named 'RETROPIE-CRT'. To enable the CRT display settings, go to that option and enable the desired display mode between 625 50Hz (aka PAL), and 525 60Hz (aka NTSC) or switch back to HDMI mode choosing HDTV.
Important: Don't plug the Raspberry into the CRT display before applying the configuration unless you know your set can handle HDTV signals, with the risk of harming the set deflection circuitry if you do so.
At the first setup, keep the Raspberry connected to an HDTV-capable display over the HDMI and follow the steps below.
.Using the gamepad, navigate to the Retropie Menu, and then, choose the "RETROPIE-CRT" options menu.
Select the appropriate option for your needs. You have three options.
- SDTV - 525 60Hz aka NTSC (Americas/Japan) - It's the common option to play most of the systems as if you're emulating an American or Japanese set.
- SDTV - 625 50Hz aka PAL (Europe/Asia/Africa) - Enables the PAL mode, to run at 50 Hz sets.
- HDTV - Make the HDMI behave as normal for HDTV. Be aware this option does not uninstall the tool itself but just switches back the configuration of Raspberry's HDMI output.
Every arcade game has its own resolution. The first time you start an arcade game, the Retropie-CRT script addresses that by querying what the resolution is for the game before starting it.
The retrieved data is stored as rom_name-crt.json at the same path as the ROM itself.
Example:
I have the Sunset Riders in the /home/RetroPie/roms/mame folder as ssriders.zip. The resolution file is ssriders-crt.json.
In the aftermentioned example, Sunset Riders runs at 228 x 224 at 60 Hz resolution. So its JSON looks like this:
{
"width": 288,
"lines": 224,
"fps": "60.00",
"pal": false,
"overscan_left": 10,
"overscan_right": 10
}Some games start at some resolution, changing to a different one during gameplay. Because the script queries the game resolution during its initialization, some games end up running at the wrong resolution. To fix that, you can edit the json file by setting up the correct resolution for its game.
- Fixed configure.py installer script.
- Added custom resolutions for arcade games.
- Fixes some texting
- Added minimal support for users with composite video mode.