Cargo Features

alac = { version = "0.5.0", default-features = false, features = ["mp4", "caf"] }
default = mp4

The mp4 feature is set by default whenever alac is added without default-features = false somewhere in the dependency tree.

mp4 default = mp4parse

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features.

caf implicit feature
mp4parse mp4

Enables mp4parse ^0.10.0