+void *av_realloc(void *ptr, size_t size) av_alloc_size(2);
+
+/**
+ * Allocate or reallocate a block of memory.
+ * If *ptr is NULL and size > 0, allocate a new block. If
+ * size is zero, free the memory block pointed to by ptr.
+ * @param ptr Pointer to a pointer to a memory block already allocated
+ * with av_realloc(), or pointer to a pointer to NULL.
+ * The pointer is updated on success, or freed on failure.
+ * @param size Size in bytes for the memory block to be allocated or
+ * reallocated
+ * @return Zero on success, an AVERROR error code on failure.
+ * @warning Pointers originating from the av_malloc() family of functions must
+ * not be passed to av_reallocp(). The former can be implemented using
+ * memalign() (or other functions), and there is no guarantee that
+ * pointers from such functions can be passed to realloc() at all.
+ * The situation is undefined according to POSIX and may crash with
+ * some libc implementations.
+ */
+int av_reallocp(void *ptr, size_t size);
+
+/**
+ * Allocate or reallocate an array.
+ * If ptr is NULL and nmemb > 0, allocate a new block. If
+ * nmemb is zero, free the memory block pointed to by ptr.
+ * @param ptr Pointer to a memory block already allocated with
+ * av_realloc() or NULL.
+ * @param nmemb Number of elements
+ * @param size Size of the single element
+ * @return Pointer to a newly-reallocated block or NULL if the block
+ * cannot be reallocated or the function is used to free the memory block.
+ * @warning Pointers originating from the av_malloc() family of functions must
+ * not be passed to av_realloc(). The former can be implemented using
+ * memalign() (or other functions), and there is no guarantee that
+ * pointers from such functions can be passed to realloc() at all.
+ * The situation is undefined according to POSIX and may crash with
+ * some libc implementations.
+ */
+av_alloc_size(2, 3) void *av_realloc_array(void *ptr, size_t nmemb, size_t size);