Add detailed description about GroupOfPicture

Change-Id: I96a447e59bdcf156ab6fbf9e766d867633ca47f3

diff --git a/vp9/simple_encode.h b/vp9/simple_encode.h
index 33f6138e7b03f5bd0f6dc8c2525a07a890d45a7c..704aa48829214a41e711751c15fed9eb4473361e 100644 (file)
--- a/vp9/simple_encode.h
+++ b/vp9/simple_encode.h
@@ -44,7 +44,18 @@ struct EncodeFrameResult {
 };
 
 struct GroupOfPicture {
+  // This list will be updated internally in StartEncode() and
+  // EncodeFrame()/EncodeFrameWithQuantizeIndex().
+  // In EncodeFrame()/EncodeFrameWithQuantizeIndex(), the update will only be
+  // triggered when the coded frame is the last one in the previous group of
+  // pictures.
   std::vector<EncodeFrameInfo> encode_frame_list;
+  // Indicates the index of the next coding frame in encode_frame_list.
+  // In other words, EncodeFrameInfo of the next coding frame can be
+  // obtained with encode_frame_list[encode_frame_index].
+  // Internally, encode_frame_index will be set to zero after the last frame of
+  // the group of pictures is coded. Otherwise, encode_frame_index will be
+  // increased after each EncodeFrame()/EncodeFrameWithQuantizeIndex() call.
   int encode_frame_index;
 };