diff --git a/src/zm_packet.h b/src/zm_packet.h
index ea609429f..6b567bc4e 100644
--- a/src/zm_packet.h
+++ b/src/zm_packet.h
@@ -49,6 +49,7 @@ class ZMPacket {
     AVMediaType codec_type;
     int image_index;
     int codec_imgsize;
+    int64_t   pts;                // pts in the packet can be in another time base. This MUST be in AV_TIME_BASE_Q
 
   public:
     AVPacket *av_packet() { return &packet; }