diff --git a/mpp/mpp.cpp b/mpp/mpp.cpp
index 2cb96d88..1c4a719f 100644
--- a/mpp/mpp.cpp
+++ b/mpp/mpp.cpp
@@ -629,6 +629,8 @@ MPP_RET Mpp::put_frame(MppFrame frame)
     if (!mInitDone)
         return MPP_ERR_INIT;
 
+    mpp_dbg_pts("%p input frame pts %lld\n", this, mpp_frame_get_pts(frame));
+
     if (mInputTimeout == MPP_POLL_NON_BLOCK) {
         set_io_mode(MPP_IO_MODE_NORMAL);
         return put_frame_async(frame);
@@ -787,7 +789,7 @@ MPP_RET Mpp::get_packet(MppPacket *packet)
 
         mpp_buffer_sync_ro_partial_begin(buf, offset, impl->length);
 
-        mpp_dbg_pts("pts %lld\n", impl->pts);
+        mpp_dbg_pts("%p output packet pts %lld\n", this, impl->pts);
     }
 
     // dump output