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Comment by ndegruchy | Hacker News Reader

So, this seems to just download chrome and run some sort of terminal emulator in it (then converts it to video). Do I have that right? Seems like massive overkill for something you could do with just ffmpeg and a terminal emulator...

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I've actually used ffmpeg + GNU screen to do something very similar in the past.

The benefit of using GNU screen is that the "tape" can be a shell script. I suppose if you don't like shell scripts that's not a benefit, but I do like them.

For example, instead of:

    Type "echo 'Welcome to VHS!'"
    # Pause for dramatic effect...
    Sleep 500ms
    Enter

With GNU screen, you would write:

    #!/bin/sh
    screen -d -m -S whatever -- bash
    screen -S whatever -X stuff "echo Welcome to screen" 
    sleep 0.5
    screen -S whatever -X stuff $'\n'

If you want to start interacting with the session, just do screen -r whatever

You can also read what is in the screen with -X hardcopy, then do something with the output, like verify the output is correct or adjust the input.

This is actually really cool. Thanks for sharing this!

Where/how does ffmpeg come in? How are you connecting screen output to ffmpeg input?

ffmpeg can capture an xterm as a source, it's called x11grab.

TIL! Thanks for sharing!

Edit: X11 as a source, not xterm. At least from what I can see.

I think that may just be copy-paste in the Dockerfile, as it doesn't seem to use chromium (nor chrome) anywhere else in the repo: https://sourcegraph.com/search?q=context:global+repo:%5Egith...

which for sure matches my mental model of using ttyd and ffmpeg -- what in the world would anyone need chromium for?

> what in the world would anyone need chromium for?

Perhaps rendering an xterm.js canvas? (I don't know, it's just a guess)

One of the dependencies is `rod`[0], which is a web scraping/automation library, and I believe requires a browser to work. I don't know what they're using it for though as I haven't looked at the code (and I'm not familiar with Go anyways). There's a feature of the library that finds and installs a browser, but they may just be preemptively including chromium in the dockerfile and assuming that non-docker users will already have a supported browser on their machine.

0: https://github.com/go-rod/rod

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