This is a fork of the [ffmpeg](https://crates.io/crates/ffmpeg) crate by [meh.](https://github.com/meh/rust-ffmpeg), compatible with FFmpeg major version 4 (tested against 4.0.2). FFmpeg4 code is guarded by the `ffmpeg4` feature, enabled by the default. Disable `ffmpeg4` to compile against FFmpeg 3.4 (tested against 3.4.4). Earlier versions of FFmpeg are not officially supported. See my command line tool `metadata`'s [`Cargo.toml`](https://github.com/zmwangx/metadata/blob/master/Cargo.toml) for example usage when supporting both major versions of FFmpeg.