[twitch:stream] Prefer the 'source' format (fixes #4972)

youtube_dl/extractor/common.py

@@ -839,6 +839,7 @@ class InfoExtractor(object):
             note='Downloading m3u8 information',
             errnote='Failed to download m3u8 information')
         last_info = None
+        last_media= None
         kv_rex = re.compile(
             r'(?P<key>[a-zA-Z_-]+)=(?P<val>"[^"]+"|[^",]+)(?:,|$)')
         for line in m3u8_doc.splitlines():
@@ -849,6 +850,13 @@ class InfoExtractor(object):
                     if v.startswith('"'):
                         v = v[1:-1]
                     last_info[m.group('key')] = v
+            elif line.startswith('#EXT-X-MEDIA:'):
+                last_media = {}
+                for m in kv_rex.finditer(line):
+                    v = m.group('val')
+                    if v.startswith('"'):
+                        v = v[1:-1]
+                    last_media[m.group('key')] = v
             elif line.startswith('#') or not line.strip():
                 continue
             else:
@@ -877,6 +885,9 @@ class InfoExtractor(object):
                     width_str, height_str = resolution.split('x')
                     f['width'] = int(width_str)
                     f['height'] = int(height_str)
+                if last_media is not None:
+                    f['m3u8_media'] = last_media
+                    last_media = None
                 formats.append(f)
                 last_info = {}
         self._sort_formats(formats)

youtube_dl/extractor/twitch.py

@@ -348,6 +348,12 @@ class TwitchStreamIE(TwitchBaseIE):
             '%s/api/channel/hls/%s.m3u8?%s'
             % (self._USHER_BASE, channel_id, compat_urllib_parse.urlencode(query).encode('utf-8')),
             channel_id, 'mp4')
+        # prefer the 'source' stream, the others are limited to 30 fps
+        def _sort_source(f):
+            if f.get('m3u8_media') is not None and f['m3u8_media'].get('NAME') == 'Source':
+                return 1
+            return 0
+        formats = sorted(formats, key=_sort_source)
 
         view_count = stream.get('viewers')
         timestamp = parse_iso8601(stream.get('created_at'))