[ffmpeg-restream] monotonic seq (PR #64)

ffmpeg_relay.py

@@ -64,6 +64,7 @@ class FfmpegRelay:
         self.started_at = time.time()
         self.failures = 0
         self.restarting = False
+        self.last_served_seq = -1
         self.resolved = _resolve_redirect(url, self._headers_dict())
         self._ensure_dir()
 
@@ -167,12 +168,26 @@ class FfmpegRelay:
                 self.restarting = False
 
     def playlist_text(self):
-        """Return current playlist content (empty string if relay warming up)."""
+        """Return current playlist content (empty string if relay warming up).
+        MEDIA-SEQUENCE is served monotonically non-decreasing across restarts:
+        if ffmpeg restarted and reset sequence to 0, we bump it to
+        last_served_seq+1 so hls.js never sees a backward jump (which causes
+        a discontinuity error -> brief giât at exactly the restart moments)."""
         try:
             with open(self.playlist, "r", encoding="utf-8") as f:
-                return f.read()
+                text = f.read()
         except Exception:
             return ""
+        m = re.search(r"#EXT-X-MEDIA-SEQUENCE:(\d+)", text)
+        if m:
+            seq = int(m.group(1))
+            if seq < self.last_served_seq:
+                seq = self.last_served_seq
+            # keep serving a forward-moving sequence
+            self.last_served_seq = max(self.last_served_seq, seq)
+            text = text.replace("#EXT-X-MEDIA-SEQUENCE:%d" % int(m.group(1)),
+                                "#EXT-X-MEDIA-SEQUENCE:%d" % self.last_served_seq, 1)
+        return text
 
     def segment(self, name):
         """Return (bytes, status) for a local segment file."""