Ensure ffmpeg dependency is installed

- to ensure ffmpeg is installed for macos when reencoding video

src/processing/video_render.py

@@ -2,8 +2,12 @@
 import random
 import os
 import numpy as np
+import subprocess
+import sys
+
 # pass in homo matrix +  + 
 # implement video reencoding 
+
 class VideoRender:
     def __init__(self, homography):
         self._TRUE_PATH = os.path.join('data','true_map.png')
@@ -15,7 +19,24 @@ def reencode(self, input_path, output_path):
         """
         Re-encodes a MPEG4 video file to H.264 format. Overrides existing output videos if present.
         Deletes the unprocessed video when complete.
+        Ensures ffmpeg dependency is installed
         """
+
+        if sys.platform != 'darwin':
+            print("Designed to install dependency for macOS")
+        else:
+            try:
+                # check if it is installed already
+                subprocess.run(["brew", "list", "ffmpeg"], check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+            except:
+                # install dependency
+                print("Installing ffmpeg")
+                try:
+                    subprocess.run(["brew", "install", "ffmpeg"], check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+                except:
+                    print("Error installing ffmpeg")
+                    return
+
         reencode_command = f'ffmpeg -y -i {input_path} -vcodec libx264 -c:a copy {output_path}'
         os.system(reencode_command)
         # os.remove(input_path)