diff --git a/doc/codecs.texi b/doc/codecs.texi
index 2afb09ce66..da048b155e 100644
--- a/doc/codecs.texi
+++ b/doc/codecs.texi
@@ -129,7 +129,7 @@ should be @code{1 / frame_rate} and timestamp increments should be
 identically 1.
 
 @item g @var{integer} (@emph{encoding,video})
-Set the group of picture size. Default value is 12.
+Set the group of picture (GOP) size. Default value is 12.
 
 @item ar @var{integer} (@emph{decoding/encoding,audio})
 Set audio sampling rate (in Hz).