Document improve: use .cargo/config.toml to set env

[vcup]

This way has serval benefits, for example.

• IDE syncing support
• support relative path than can be work everywhere
• repository embeded configuration

config.toml look like below.

[env]
FFMPEG_PKG_CONFIG_PATH = { value = "target/vcpkg/installed/x64-linux/lib/pkgconfig", relative = true }

useful links:
.cargo/config.toml
section detail
thread on stackoverflow

[ldm0]

Thanks for your information. I'll enhance the doc later.

[gezihuzi]

Currently, [env] in config.toml does not support specifying os and arch.

rust-lang/cargo#10273
rust-lang/cargo#10789

[vnghia]

You can use feature link_system_ffmpeg which will use pkg-config to find the ffmpeg https://github.com/CCExtractor/rusty_ffmpeg/blob/1c6a1f58355cdd22248f534f32b6bc143f8ffde4/build.rs#L409-L411 and set

[env]
PKG_CONFIG_PATH_x86_64-unknown-linux-gnu = { value = "target/vcpkg/installed/x64-linux-release/lib/pkgconfig", relative = true }

PKG_CONFIG_PATH_x86_64-apple-darwin = { value = "target/vcpkg/installed/x64-osx-release/lib/pkgconfig", relative = true }
PKG_CONFIG_PATH_aarch64-apple-darwin = { value = "target/vcpkg/installed/arm64-osx-release/lib/pkgconfig", relative = true }

On Windows, set

[env]
# Only Windows uses vcpkg linking.
VCPKG_ROOT = { value = "target/vcpkg", relative = true }
VCPKGRS_TRIPLET = { value = "x64-windows-static-release" }