fix some a/an typos

Signed-off-by: Lou Logan <lou@lrcd.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/libavutil/tree.h b/libavutil/tree.h
index e1aefaa9f6..9a9e11b92c 100644
--- a/libavutil/tree.h
+++ b/libavutil/tree.h
@@ -120,8 +120,8 @@ void av_tree_destroy(struct AVTreeNode *t);
 /**
  * Apply enu(opaque, &elem) to all the elements in the tree in a given range.
  *
- * @param cmp a comparison function that returns < 0 for a element below the
- *            range, > 0 for a element above the range and == 0 for a
+ * @param cmp a comparison function that returns < 0 for an element below the
+ *            range, > 0 for an element above the range and == 0 for an
  *            element inside the range
  *
  * @note The cmp function should use the same ordering used to construct the