Add Avisynth video encoding workflow

tools/timezones.py

@@ -0,0 +1,36 @@
+from __future__ import annotations
+
+import re
+from datetime import datetime, timedelta, timezone
+
+
+TZ_RE = re.compile(r"^(?P<sign>[+-])(?P<h>\d{2})(?::?(?P<m>\d{2}))?$")
+
+
+def local_timezone() -> timezone:
+    offset = datetime.now().astimezone().utcoffset()
+    if offset is None:
+        return timezone.utc
+    return timezone(offset)
+
+
+def parse_timezone_offset(value: str) -> timezone:
+    match = TZ_RE.match(value.strip())
+    if not match:
+        raise ValueError("timezone must look like +09:00 or -05:30")
+    sign = 1 if match.group("sign") == "+" else -1
+    hours = int(match.group("h"))
+    minutes = int(match.group("m") or "0")
+    if minutes not in {0, 15, 30, 45}:
+        raise ValueError("timezone minutes must be 00, 15, 30, or 45")
+    return timezone(sign * timedelta(hours=hours, minutes=minutes))
+
+
+def timezone_to_string(tz: timezone) -> str:
+    offset = tz.utcoffset(None)
+    if offset is None:
+        return "+00:00"
+    total_minutes = int(offset.total_seconds() // 60)
+    sign = "+" if total_minutes >= 0 else "-"
+    total_minutes = abs(total_minutes)
+    return f"{sign}{total_minutes // 60:02d}:{total_minutes % 60:02d}"