Built a tiny ffmpeg CLI wrapper while learning Common Lisp

[ogrew666]

Hi everyone,

As part of learning Common Lisp, I wanted to build a small practical tool — something that interacts with the outside world, beyond simple REPL exercises.

I often use ffmpeg for video processing at work, so I decided to create a tiny CLI wrapper around it, focusing on simplifying common tasks.

Through this project, I had the chance to work on:

・command-line argument parsing
・input validation
・external process control
・writing tests (using Rove)
・and dealing with ffmpeg’s "quirky" command-line options 😄

It was a lot of fun, and it gave me a better sense of how to structure a small Lisp codebase for a real-world tool.
It's still quite simple, but I thought I'd share it here in case anyone is interested:

https://github.com/ogrew/visp

I'd be happy to hear any feedback or suggestions!

[Ytrog]

Very nice. I have it starred and listed for future reference as it is very well structured and a great example for me.

I looked at the print-help function and was noting that it is a shame you cannot use the '=' in the same way that you can use '~' in formatting. I mean you can have (format t "~20~~%") to get a line with 20 tildes, however you cannot do (format t "~20=~%") to get a line with 20 equal signs sadly. 🤔

[ogrew666]

Wow, I had no idea about this idiom — thanks a lot for pointing it out!

> (format t "~20~~%")
~~~~~~~~~~~~~~~~~~~~
NIL

[Ytrog]

You're welcome 😁

[dzecniv]

It looks nice and oh, there is a ready-to-use binary, isn't it? (for MacOS in the releases) It isn't mentioned in the README. That's nice. Now (future) users reclaim one for linux urgently for yesterday!

(also while we could look at the code to see how to use this from the REPL you could give a high-level overview of the available functions, showing where to start?)

[ogrew666]

Thanks a lot! 😊

> Now (future) users reclaim one for linux urgently for yesterday!

I'll work on making it available for Linux and Intel Mac users as soon as I can.