codecVis: support DejaVu font on macOS

codec_visualizer/codecVis/__main__.py

@@ -7,9 +7,11 @@
 """
 
 import os
+import platform
 import sys
 import time
 import subprocess
+import shlex
 import shutil
 import glob
 import PIL
@@ -49,12 +51,17 @@ def get_codec(filename):
     return str(result.stdout.decode("utf-8")).rstrip("\n")
 
 def extract_frame(video_file, time_offset, output_file):
-    cmd = ["ffmpeg", "-y", "-ss", time.strftime('%H:%M:%S', time.gmtime(time_offset)) + ".00",
-           "-i", str(video_file), "-frames:v", "1", str(output_file)]
+    cmd = "ffmpeg -y -ss " + time.strftime('%H:%M:%S', time.gmtime(time_offset)) + ".00 -i " + str(video_file) + " -frames:v 1 " + str(output_file)
     devnull = open(os.devnull, 'w')
-    subprocess.call(cmd, stdout=devnull, stderr=devnull)
+    subprocess.call(shlex.split(cmd),stdout=devnull, stderr=devnull)
 
 def get_font_path():
+    if platform.system() == "Darwin":
+        # Assume DejaVu to be installed in the user library
+        path = "~/Library/Fonts/DejaVuSans-Bold.ttf"
+        return os.path.expanduser(path)
+
+    # Default platform: Linux
     path = "/usr/share/fonts"
     files = glob.glob(path + "/**/DejaVuSans-Bold.ttf", recursive = True)
     return files[0]