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.
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.