Function av_buffer_is_writable

pub unsafe extern "C" fn av_buffer_is_writable(
    buf: *const AVBufferRef,
) -> c_int

@return 1 if the caller may write to the data referred to by buf (which is true if and only if buf is the only reference to the underlying AVBuffer). Return 0 otherwise. A positive answer is valid until av_buffer_ref() is called on buf.