Allocate, reallocate, or free an array through a pointer to a pointer.
If *ptr is NULL and nmemb > 0, allocate a new block. If nmemb is
zero, free the memory block pointed to by *ptr.
@param[in,out] ptr Pointer to a pointer to a memory block already
allocated with av_realloc(), or a pointer to NULL.
The pointer is updated on success, or freed on failure.
@paramin nmemb Number of elements
@paramin size Size of the single element
@return Zero on success, an AVERROR error code on failure
@warning Unlike av_malloc(), the allocated memory is not guaranteed to be
correctly aligned.
Allocate, reallocate, or free an array through a pointer to a pointer.
If *ptr is NULL and nmemb > 0, allocate a new block. If nmemb is zero, free the memory block pointed to by *ptr.
@param[in,out] ptr Pointer to a pointer to a memory block already allocated with av_realloc(), or a pointer to NULL. The pointer is updated on success, or freed on failure. @paramin nmemb Number of elements @paramin size Size of the single element
@return Zero on success, an AVERROR error code on failure
@warning Unlike av_malloc(), the allocated memory is not guaranteed to be correctly aligned.