fix: replace deprecated -vsync with -fps_mode for ffmpeg 7

extract.py

@@ -125,14 +125,15 @@ for INPUT_FILE in INPUT_FILES:
     # Only apply fps filter if probed fps differs from target (avoid needless re-timing)
     fps = probed.get(INPUT_FILE)
     needs_fps = not fps_matches(fps, TARGET_FPS_FLOAT)
-    video_codec = VIDEO_CODEC_BASE + (["-vf", f"fps={TARGET_FPS}:round=near", "-vsync", "cfr"] if needs_fps else [])
+    # fps filter alone forces CFR; use fps_mode cfr (vsync removed in ffmpeg >=7)
+    video_codec = VIDEO_CODEC_BASE + (["-vf", f"fps={TARGET_FPS}:round=near", "-fps_mode", "cfr"] if needs_fps else [])
     if fps is not None:
         print(f"[fps] {stem}: probed {fps:.3f} → {'convert to ' + TARGET_FPS if needs_fps else 'already ' + TARGET_FPS + ', keeping native timing'}")
     else:
         print(f"[fps] {stem}: unknown fps → forcing {TARGET_FPS} (safe fallback)")
         # ensure fallback forces target if we couldn't probe
         if not needs_fps:
-            video_codec = VIDEO_CODEC_BASE + ["-vf", f"fps={TARGET_FPS}:round=near", "-vsync", "cfr"]
+            video_codec = VIDEO_CODEC_BASE + ["-vf", f"fps={TARGET_FPS}:round=near", "-fps_mode", "cfr"]
 
     cmd_video = [
         "ffmpeg",