Fix Smooth Streaming Client Manifest URLs

Partially revert track label support for Smooth Streaming
[4916daf]

trackName in server manifest and part of the client manifest StreamIndex URL should match. Also using arbitrary UTF-8 in language_name as part of the URL should be avoided

Source/Python/utils/mp4-dash.py

@@ -1119,11 +1119,7 @@ def OutputSmooth(options, audio_tracks, video_tracks):
 
     # process the audio tracks
     for audio_track in audio_tracks:
-        stream_name = audio_track.label
-        if stream_name == '':
-            stream_name = audio_track.language_name
-        if stream_name == '' or stream_name == 'Unknown':
-            stream_name = "audio_"+audio_track.language
+        stream_name = "audio_"+audio_track.language
         audio_url_pattern="QualityLevels({bitrate})/Fragments(%s={start time})" % (stream_name)
         stream_index = xml.SubElement(client_manifest,
                                       'StreamIndex',