We love Raspberry Pi projects that involve TVs, and have covered several in the past that recreate authentic experiences including one project that broadcasts a UHF signal that any CRT close enough can tune into.
But this project, created by a maker known as Theloosearrow on Reddit, adds another missing piece to the puzzle by creating a closed captions effect for displaying subtitles. Using a Raspberry Pi and Arduino, this Raspberry Pi project overlays subtitles as closed captions while outputting video to a TV.
Theloosearrow explains that a Raspberry Pi is used to play video through its composite output. This is fed to an Arduino fitted with a Video Experimenter Shield, which has all sorts of fun tools to tinker with, but Theloosearrow is using it for its LM1881 video sync separator. With this module, it’s possible to include a custom close caption signal with the Raspberry Pi’s video output signal.
On the Pi, a custom Python script is used to both play videos and transmit SRT subtitle file data. It tells the Arduino when to play each line at a specific point in the video so everything synchronizes in real-time. The Arduino creates a closed caption signal using this subtitle data that the TV is able to natively display.