berarr

cht/stream/ffmpeg.py

@@ -40,15 +40,22 @@ def receive_and_record(stream_url, output_path):
 
 
 def receive_record_and_relay(stream_url, output_path, relay_url):
-    """Receive TCP stream, write to MKV, and relay to UDP loopback for live display.
+    """Receive TCP stream, write to fragmented MP4, and relay to UDP loopback.
 
-    Uses ffmpeg tee via merge_outputs: one ffmpeg process handles both outputs
-    from the same decoded input, keeping them in sync with identical timestamps.
+    Fragmented MP4 (frag_keyframe+empty_moov) avoids MKV tail corruption:
+    each keyframe boundary closes a self-contained fragment, so the file is
+    always valid up to the last complete fragment (~1 keyframe interval ≈ 2s).
+    This allows the scene detector to use a 2s safety margin instead of 6s.
+
+    Uses ffmpeg tee via merge_outputs: one process, identical timestamps.
     """
     stream = ffmpeg.input(stream_url, fflags="nobuffer", flags="low_delay")
     file_out = ffmpeg.output(
         stream, str(output_path),
-        c="copy", f="matroska", flush_packets=1,
+        c="copy", f="mp4",
+        movflags="frag_keyframe+empty_moov+default_base_moof",
+        flush_packets=1,
+        **{"bsf:a": "aac_adtstoasc"},
     )
     relay_out = ffmpeg.output(
         stream, relay_url,