函数 av_malloc_array 

pub unsafe extern "C" fn av_malloc_array(
    nmemb: usize,
    size: usize,
) -> *mut c_void

Allocate a memory block for an array with av_malloc().

The allocated memory will have size size * nmemb bytes.

@param nmemb Number of element @param size Size of a single element @return Pointer to the allocated block, or NULL if the block cannot be allocated @see av_malloc()