Supposedly you should be able to use an FFmpeg build (e.g. a dev build from [here](https://ffmpeg.zeranoe.com/builds/)) in `FFMPEG_DIR` and get `ffmpeg-sys` to compile, then everything else follows. That is to say, in theory the steps are:
1. Download an FFmpeg build with the dev libs;
2. Set `FFMPEG_DIR` env var to where it's located;
3. `cargo build`.
Realistically, I tried it once about two years ago, and couldn't get my final binary to actually link to libav*. I gave up because I'm not a Windows developer and have no idea of how the linker works on Windows and how to fix it, especially in a rustc setting.
Might be worth another try I guess? But unfortunately I cannot offer any Windows help if you can't get it to work. Might need to ask around on IRC if you're determined. In any case, let me how it goes.
> Some of the changes seem to do nothing but break the formatting
Oh, a little bit more on that: please don't make unnecessary changes like switching order of short and long options; this is my project so I'll switch back to my preference anyway, it'll just waste time for both of us.
The one unnecessary change I can get behind: I usually prefer qualified identifiers than bare imported identifiers (more readable without understanding context), meaning `pathlib.Path` not `Path`, but it seems I'm really using it a lot, and it's been a long time since `pathlib` was introduced in py34, so sure, let's just import `Path` alone.
Thanks for the PR. The changes are too substantial for an unannounced PR, so I can't promise when I'll have time to do the review. At a glance I can get behind some changes but not all, and everything being in a single commit makes reviewing and accepting some changes extremely hard. It looks like you squashed many commits? Please separate them if possible (otherwise I might find the task dreadful enough and just do a clean room reimplementation...). Also, all code should be formatted with [black](https://github.com/psf/black). Some of the changes seem to do nothing but break the formatting (e.g., changes to argparse code), it would be nice to format with black and drop those distractions.
If the requested changes (to make things easier for me) are too time consuming for you then unfortunately it might end up taking a long time for me to get back to you... (I'm certainly not saying you're obligated to change anything. In case this sounds passive aggressive, that's not my intention, I'm just setting reasonable expectations.) Fortunately it's not hard to use your own fork in any setting ([reference](https://pip.pypa.io/en/stable/reference/pip_install/#git) just in case you don't know how), so whatever you're trying to do shouldn't rely on my finding the time to review and merge the PR.