diff --git a/libavcodec/pixdesc.h b/libavcodec/pixdesc.h
index fff4e3d27d..28695e6674 100644
--- a/libavcodec/pixdesc.h
+++ b/libavcodec/pixdesc.h
@@ -25,8 +25,18 @@
 
 typedef struct AVComponentDescriptor{
     uint16_t plane        :2;            ///< which of the 4 planes contains the component
-    uint16_t step_minus1  :3;            ///< number of bytes between 2 horizontally consecutive pixels minus 1
-    uint16_t offset_plus1 :3;            ///< number of bytes before the component of the first pixel plus 1
+
+    /**
+     * Number of elements between 2 horizontally consecutive pixels minus 1.
+     * Elements are bits for bitstream formats, bytes otherwise.
+     */
+    uint16_t step_minus1  :3;
+
+    /**
+     * Number of elements before the component of the first pixel plus 1.
+     * Elements are bits for bitstream formats, bytes otherwise.
+     */
+    uint16_t offset_plus1 :3;
     uint16_t shift        :3;            ///< number of least significant bits that must be shifted away to get the value
     uint16_t depth_minus1 :4;            ///< number of bits in the component minus 1
 }AVComponentDescriptor;