A fierce man who succeeded in playing DOOM using television text broadcasting appeared
Speaking of
It's DOOM, But In Teletext | Hackaday
https://hackaday.com/2023/05/20/its-doom-but-in-teletext/#more-589746
It was lukneu who succeeded in playing DOOM using teletext. lukneu uses teletext to convert the data for rendering DOOM so that it can be sent by teletext, pipes the rendered data to an application that processes the teletext packet stream, and sends it to the television. We have developed a tool 'doom-teletext' that can decode and display teletext pages.
doom-teletext is published on GitHub.
GitHub - lukneu/doom-teletext: Play DOOM in teletext
https://github.com/lukneu/doom-teletext
Teletext is a technology for displaying graphics and characters on television. The data to be displayed is contained in the radio waves for television broadcasting and is hidden in invisible vertical blanking intervals . Text broadcasting was first broadcast in 1974, and even at the time of article creation, it was broadcast in several countries, mainly in Europe, and subtitled broadcasting etc. are also distributed in Japan using this technology. Although teletext cannot display some characters, it is possible to save information such as the color of the text of subsequent characters on the same line.
lukneu recommends reading the specs below for those who want to know more about Teletext.
Enhanced Teletext specification
(PDF file) https://www.etsi.org/deliver/etsi_i_ets/300700_300799/300706/01_60/ets_300706e01p.pdf
Teletext is not a technology for sending and receiving data, it is only capable of transmitting data, so it is not possible to make DOOM actually playable using teletext. However, there is no technical problem if you run DOOM on another terminal and output the game screen to the TV using teletext. doom-teletext is a tool to achieve this. There are various levels of text broadcasting, and it seems that high-level ones can reproduce high-resolution graphics, but low-level ones are used to enhance the feeling of text broadcasting. Lukneu wrote that he simply reproduced the DOOM screen.
You can check how you actually play DOOM with teletext with the following video.
DOOM in Teletext-YouTube
Hit the TV remote control.
Then the DOOM game screen was rendered based on the data sent by teletext. The game screen is completely represented by white blocks only, but red and light blue text are also used in other parts of the UI. Since the game screen is expressed only with white blocks, it is difficult to understand where the gun is and the structure of the stage in the still image, but when you see the moving video, the game screen moves slimy and the weapons and the positional relationship of the stage etc.
The word 'DOOM' on the game screen.
It is also possible to operate the game using the remote control. You can operate not only the setting screen but also the game screen with the remote control.
The actual game screen (right) and DOOM (left) reproduced by teletext are arranged as follows.
Comparing the scenes with large movements, you can see that the teletext version is drawn several frames later, but you can hardly feel the lag when watching the video.
In addition, lukneu runs DOOM on a Linux machine, creates data for teletext on this terminal, and sends it to Raspberry Pi. It seems that the data is converted to a composite video signal on the Raspberry Pi and output to the TV. In addition, if it is a higher spec Raspberry Pi, it seems that both execution of DOOM and video conversion can be executed on Raspberry Pi.
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