feat: add stream-copy exports

core/paths.py

@@ -25,14 +25,17 @@ def _log(*args) -> None:
 
 
 def build_export_path(folder: str, basename: str, counter: int,
-                      sub: int | None = None, tag: str | None = None) -> str:
+                      sub: int | None = None, tag: str | None = None,
+                      extension: str = ".mp4") -> str:
     """Build clip output path.  *folder* should be the vid folder (e.g. .../mp4/vid_001)."""
     name = f"{basename}_{counter:03d}"
     if tag is not None:
         name = f"{name}_{tag}"
     if sub is not None:
         name = f"{name}_{sub}"
-    return os.path.join(folder, name + ".mp4")
+    if extension and not extension.startswith("."):
+        extension = "." + extension
+    return os.path.join(folder, name + extension)
 
 
 def build_sequence_dir(folder: str, basename: str, counter: int,