[utils] Extract known extensions for reuse

youtube_dl/utils.py

@@ -70,6 +70,21 @@
     'January', 'February', 'March', 'April', 'May', 'June',
     'July', 'August', 'September', 'October', 'November', 'December']
 
+KNOWN_EXTENSIONS = (
+    'mp4', 'm4a', 'm4p', 'm4b', 'm4r', 'm4v', 'aac',
+    'flv', 'f4v', 'f4a', 'f4b',
+    'webm', 'ogg', 'ogv', 'oga', 'ogx', 'spx', 'opus',
+    'mkv', 'mka', 'mk3d',
+    'avi', 'divx',
+    'mov',
+    'asf', 'wmv', 'wma',
+    '3gp', '3g2',
+    'mp3',
+    'flac',
+    'ape',
+    'wav',
+    'f4f', 'f4m', 'm3u8', 'smil')
+
 
 def preferredencoding():
     """Get preferred encoding.
@@ -942,20 +957,8 @@ def determine_ext(url, default_ext='unknown_video'):
     guess = url.partition('?')[0].rpartition('.')[2]
     if re.match(r'^[A-Za-z0-9]+$', guess):
         return guess
-    elif guess.rstrip('/') in (
-            'mp4', 'm4a', 'm4p', 'm4b', 'm4r', 'm4v', 'aac',
-            'flv', 'f4v', 'f4a', 'f4b',
-            'webm', 'ogg', 'ogv', 'oga', 'ogx', 'spx', 'opus',
-            'mkv', 'mka', 'mk3d',
-            'avi', 'divx',
-            'mov',
-            'asf', 'wmv', 'wma',
-            '3gp', '3g2',
-            'mp3',
-            'flac',
-            'ape',
-            'wav',
-            'f4f', 'f4m', 'm3u8', 'smil'):
+    # Try extract ext from URLs like http://example.com/foo/bar.mp4/?download
+    elif guess.rstrip('/') in KNOWN_EXTENSIONS:
         return guess.rstrip('/')
     else:
         return default_ext