diff --git a/cht/stream/ffmpeg.py b/cht/stream/ffmpeg.py
index 566ecb4..4110cc5 100644
--- a/cht/stream/ffmpeg.py
+++ b/cht/stream/ffmpeg.py
@@ -103,7 +103,7 @@ def receive_record_relay_and_detect(stream_url, output_path, relay_url,
     scene_out = ffmpeg.output(
         scene_stream, "pipe:1",
         f="image2pipe", vcodec="mjpeg",
-        vsync="vfr", **{"q:v": "2"},
+        vsync="vfr", flush_packets=1, **{"q:v": "2"},
     )
 
     return ffmpeg.merge_outputs(file_out, relay_out, scene_out).global_args(*GLOBAL_ARGS)