crf: "Constant Rate Factor" for x264 among other encoders. Think it like a output quality (higher = lower quality). I'd say 28 is way too high especially when you're using preset=veryfast (too bad quality). Since it's only 640-480, most of computers can handle fast or even medium in real-time. If not sure, I'd say just use default (by not giving anything).
pix_fmt: pixel format. 99% videos use this format, and it has best compatibility. FFMPEG will try to keep the original format when do transcoding, so in most of time you don't need to specify. However, in this very case, since the input is from a webcam, the chance it uses some weird format is high. And you don't want to keep that in your final result. So it's good to specify it out here.
My 2c: ChatGPT is great, but I recommend to read the comments it gives about each parameter, try to understand their purposes, and adjust accordingly if needed.
Also having a rough idea about how FFMPEG pipeline works (mainly the order of input, output and their associated switches in arguments) helps a lot.
Video process is a very complex thing and lots of time it relies on experience. Just be prepared sometimes your "typically works" command would break.
pix_fmt: pixel format. 99% videos use this format, and it has best compatibility. FFMPEG will try to keep the original format when do transcoding, so in most of time you don't need to specify. However, in this very case, since the input is from a webcam, the chance it uses some weird format is high. And you don't want to keep that in your final result. So it's good to specify it out here.
My 2c: ChatGPT is great, but I recommend to read the comments it gives about each parameter, try to understand their purposes, and adjust accordingly if needed.
Also having a rough idea about how FFMPEG pipeline works (mainly the order of input, output and their associated switches in arguments) helps a lot.
Video process is a very complex thing and lots of time it relies on experience. Just be prepared sometimes your "typically works" command would break.