Parsing timecodes of form MM:SS[.nnn] (#433)

* Updated timecode parsing

* Update docs for time command

docs/cli.rst

@@ -692,9 +692,9 @@ Options
 
 Set start/end/duration of input video.
 
-Values can be specified as frames (NNNN), seconds (NNNN.NNs), or timecode (HH:MM:SS.nnn). For example, to process only the first minute of a video:
+Values can be specified as frames (NNNN), seconds (NNNN.NNs), or timecode (HH:MM:SS.nnn or MM:SS.nnn). For example, to process only the first minute of a video:
 
-    ``scenedetect -i video.mp4 time --end 00:01:00``
+    ``scenedetect -i video.mp4 time --end 1:00``
 
     ``scenedetect -i video.mp4 time --duration 60s``
 

scenedetect/frame_timecode.py

@@ -283,11 +283,18 @@ def _parse_timecode_string(self, input: str) -> int:
             if timecode < 0:
                 raise ValueError("Timecode frame number must be positive.")
             return timecode
-        # Timecode in string format 'HH:MM:SS[.nnn]'
+        # Timecode in string format 'HH:MM:SS[.nnn]' or 'MM:SS[.nnn]'
         elif input.find(":") >= 0:
             values = input.split(":")
-            hrs, mins = int(values[0]), int(values[1])
-            secs = float(values[2]) if "." in values[2] else int(values[2])
+            # Case of 'HH:MM:SS[.nnn]'
+            if len(values) == 3:
+                hrs, mins = int(values[0]), int(values[1])
+                secs = float(values[2]) if "." in values[2] else int(values[2])
+            # Case of 'MM:SS[.nnn]'
+            elif len(values) == 2:
+                hrs = 0
+                mins = int(values[0])
+                secs = float(values[1]) if "." in values[1] else int(values[1])
             if not (hrs >= 0 and mins >= 0 and secs >= 0 and mins < 60 and secs < 60):
                 raise ValueError("Invalid timecode range (values outside allowed range).")
             secs += (hrs * 60 * 60) + (mins * 60)