You can see an example here: https://github.com/zmwangx/metadata/blob/883ed09f41fe16bb8b7878b137c896af29f2f3af/Cargo.toml
FFmpeg version detection: https://github.com/zmwangx/metadata/blob/883ed09f41fe16bb8b7878b137c896af29f2f3af/Makefile#L1-L26Yes (assuming you're compiling against FFmpeg 4.2).
You may also want to turn on some other features, e.g. `format` and `codec`, depending on what you actually use.You need to disable the `ffmpeg43` feature (default on) and enable the feature corresponding to your FFmpeg version, say `ffmpeg42` for 4.2.x. README has a table.