Add Avisynth video encoding workflow

tools/filenames.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import re
-from datetime import datetime
+from datetime import datetime, timedelta
 from pathlib import Path
 
 
@@ -16,6 +16,18 @@ def format_filename_stem(dt: datetime) -> str:
     return naive_wall_time(dt).strftime("%Y%m%d_%H%M%S")
 
 
+def round_datetime_to_second(dt: datetime) -> datetime:
+    rounded = dt.replace(microsecond=0)
+    if dt.microsecond >= 500_000:
+        rounded += timedelta(seconds=1)
+    return rounded
+
+
+def format_rounded_filename_stem(dt: datetime) -> str:
+    rounded = round_datetime_to_second(dt)
+    return format_filename_stem(rounded)
+
+
 def normalized_extension(path: Path) -> str:
     return path.suffix.lower()