diff --git a/libavutil/mem.h b/libavutil/mem.h
index 04f2572001..86953531d5 100644
--- a/libavutil/mem.h
+++ b/libavutil/mem.h
@@ -33,26 +33,48 @@
 #endif
 
 /**
- * Memory allocation of size bytes with alignment suitable for all
- * memory accesses (including vectors if available on the
- * CPU). av_malloc(0) must return a non-NULL pointer.
+ * Allocate a block of \p size bytes with alignment suitable for all
+ * memory accesses (including vectors if available on the CPU).
+ * @param size Size in bytes for the memory block to be allocated.
+ * @return Pointer to the allocated block, NULL if it cannot allocate
+ * it.
+ * @see av_mallocz()
  */
 void *av_malloc(unsigned int size);
 
 /**
- * av_realloc semantics (same as glibc): If ptr is NULL and size > 0,
- * identical to malloc(size). If size is zero, it is identical to
- * free(ptr) and NULL is returned.
+ * Allocate or reallocate a block of memory.
+ * If \p ptr is NULL and \p size > 0, allocate a new block. If \p
+ * size is zero, free the memory block pointed by \p ptr.
+ * @param size Size in bytes for the memory block to be allocated or
+ * reallocated.
+ * @param ptr Pointer to a memory block already allocated with
+ * av_malloc(z)() or av_realloc() or NULL.
+ * @return Pointer to a newly reallocated block or NULL if it cannot
+ * reallocate or the function is used to free the memory block.
+ * @see av_fast_realloc()
  */
 void *av_realloc(void *ptr, unsigned int size);
 
 /**
- * Free memory which has been allocated with av_malloc(z)() or av_realloc().
+ * Free a memory block which has been allocated with av_malloc(z)() or
+ * av_realloc().
+ * @param ptr Pointer to the memory block which should be freed.
  * @note ptr = NULL is explicitly allowed.
  * @note It is recommended that you use av_freep() instead.
+ * @see av_freep()
  */
 void av_free(void *ptr);
 
+/**
+ * Allocate a block of \p size bytes with alignment suitable for all
+ * memory accesses (including vectors if available on the CPU) and
+ * set to zeroes all the bytes of the block.
+ * @param size Size in bytes for the memory block to be allocated.
+ * @return Pointer to the allocated block, NULL if it cannot allocate
+ * it.
+ * @see av_malloc()
+ */
 void *av_mallocz(unsigned int size);
 
 /**
@@ -64,8 +86,11 @@ void *av_mallocz(unsigned int size);
 char *av_strdup(const char *s);
 
 /**
- * Free memory and set the pointer to NULL.
- * @param ptr Pointer to the pointer which should be freed.
+ * Free a memory block which has been allocated with av_malloc(z)() or
+ * av_realloc() and set to NULL the pointer to it.
+ * @param ptr Pointer to the pointer to the memory block which should
+ * be freed.
+ * @see av_free()
  */
 void av_freep(void *ptr);