Interpret raw values as they are

Before this commit, a negative number was resulting
in a bad value. -10 was being replaced with _10, raising
undesired exceptions.

m3u8/model.py

@@ -1071,7 +1071,6 @@ def find_key(keydata, keylist):
 def denormalize_attribute(attribute):
     return attribute.replace('_', '-').upper()
 
-
 def quoted(string):
     return '"%s"' % string
 

m3u8/parser.py

@@ -320,7 +320,7 @@ def _parse_simple_parameter_raw_value(line, cast_to=str, normalize=False):
     param, value = line.split(':', 1)
     param = normalize_attribute(param.replace('#EXT-X-', ''))
     if normalize:
-        value = normalize_attribute(value)
+        value = value.strip().lower()
     return param, cast_to(value)
 
 

tests/playlists.py

@@ -919,4 +919,13 @@
 #EXT-X-VERSION:4
 '''
 
+PLAYLIST_WITH_NEGATIVE_MEDIA_SEQUENCE = '''
+#EXTM3U
+#EXT-X-TARGETDURATION:5220
+#EXT-X-MEDIA-SEQUENCE:-2680
+#EXTINF:5220,
+http://media.example.com/entire.ts
+#EXT-X-ENDLIST
+'''
+
 del abspath, dirname, join

tests/test_parser.py

@@ -414,3 +414,8 @@ def test_low_latency_playlist():
     assert data['rendition_reports'][0]['uri'] == "../1M/waitForMSN.php"
     assert data['rendition_reports'][0]['last_msn'] == 273
     assert data['rendition_reports'][0]['last_part'] == 3
+
+
+def test_negative_media_sequence():
+    data = m3u8.parse(playlists.PLAYLIST_WITH_NEGATIVE_MEDIA_SEQUENCE)
+    assert data['media_sequence'] == -2680