feat(clipper/h264): add --h264-disable-reduce-stutter/--h264-drs flag…

… for opting in to a consistent framerate with duplicate frames when slowing down clips for potentially smoother merged video transitions

src/clipper/argparser.py

@@ -460,6 +460,19 @@ def getArgParser() -> argparse.ArgumentParser:
             ]
         ),
     )
+    parser.add_argument(
+        "--h264-disable-reduce-stutter",
+        "-h264-drs",
+        dest="h264DisableReduceStutter",
+        action="store_true",
+        help=" ".join(
+            [
+                "Disable reducing output clip sutter when using the h264 output video codec.",
+                "When disabled, output clips will all use the input video framerate and slowed down clips may have duplicate frames that cause some stuttering.",
+                "This may be useful when merging h264 videos however as in some cases keeping the same framerate results in smoother transitions between clips."
+            ]
+        ),
+    )
     parser.add_argument(
         "--auto-subs-lang",
         "-asl",

src/clipper/clip_maker.py

@@ -600,11 +600,14 @@ def getFfmpegVideoCodecH264(
     qmin: int,
 ) -> Tuple[str, str]:
     """Following recommendations from https://www.lighterra.com/papers/videoencodingh264"""
-    if mps["minterpFPS"] is not None:
-        fps_arg = f'-r {mps["minterpFPS"]}'
-    elif not mp["isVariableSpeed"]:
-        fps_arg = f'-r ({mps["r_frame_rate"]}*{mp["speed"]})'
-    else:
+    fps_arg = ""
+    if not mps["h264DisableReduceStutter"]:
+        if mps["minterpFPS"] is not None:
+            fps_arg = f'-r {mps["minterpFPS"]}'
+        elif not mp["isVariableSpeed"]:
+            fps_arg = f'-r ({mps["r_frame_rate"]}*{mp["speed"]})'
+
+    if mp["isVariableSpeed"]:
         fps_arg = "-fps_mode vfr"
 
     pixel_count = mps["width"] * mps["height"]