updates

- added back the ability to use cookies.txt file (netscape format)
- updated error message for course subscription when failed to find classes
- remove requirement for shaka-packager in favor of ffmpeg (v5+)

utils.py

@@ -24,14 +24,14 @@ def extract_kid(mp4_file):
     if not os.path.exists(mp4_file):
         raise Exception("File does not exist")
     for box in boxes:
-        if box.header.box_type == 'moov':
+        if box.header.box_type == "moov":
             pssh_box = next(x for x in box.pssh if x.system_id == "edef8ba979d64acea3c827dcd51d21ed")
             hex = codecs.decode(pssh_box.payload, "hex")
 
             pssh = widevine_pssh_data_pb2.WidevinePsshData()
             pssh.ParseFromString(hex)
             content_id = base64.b16encode(pssh.content_id)
-            return content_id.decode("utf-8")
+            return content_id.decode("utf-8").lower()
 
     # No Moof or PSSH header found
-    return None
+    return None