Returns the format description of the samples in a
- iOS 4.0+
- macOS 10.7+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 6.0+
- Core Media
The format description of the samples in the
NULL if there is an error.
On return, the caller does not own the returned
format, and must retain it explicitly if the caller needs to maintain a reference to it.