diff --git a/libav/avformat.h b/libav/avformat.h
index 0f04e71989..e17c7a514b 100644
--- a/libav/avformat.h
+++ b/libav/avformat.h
@@ -15,6 +15,7 @@ typedef struct AVPacket {
     int size;
     int stream_index;
     int flags;
+    int duration;       
 #define PKT_FLAG_KEY   0x0001
 #define PKT_FLAG_DROPPED_FRAME   0x0002
 } AVPacket;