Merge pull request #8766 from yan12125/dash-detect-ext

Detect file extensions of DASH formats from their codecs

diff --combined youtube_dl/extractor/common.py
index bfa9c82f6c42c9e126a7a30fde4391fcf49995c3,f337caf20e8d2b24692ac2c01903df8d9580f49b..3936772513a874b866346ee90803b9814f848cb1
--- 1/youtube_dl/extractor/common.py
--- 2/youtube_dl/extractor/common.py
+++ b/youtube_dl/extractor/common.py
@@@ -29,6 -29,7 +29,7 @@@ from ..utils import 
      age_restricted,
      bug_reports_message,
      clean_html,
+     codec2ext,
      compiled_regex_type,
      determine_ext,
      error_to_compat_str,
@@@ -105,7 -106,7 +106,7 @@@ class InfoExtractor(object)
                      * protocol   The protocol that will be used for the actual
                                   download, lower-case.
                                   "http", "https", "rtsp", "rtmp", "rtmpe",
 -                                 "m3u8", or "m3u8_native".
 +                                 "m3u8", "m3u8_native" or "http_dash_segments".
                      * preference Order number of this format. If this field is
                                   present and not None, the formats get sorted
                                   by this field, regardless of all other values.
@@@ -1471,6 -1472,7 +1472,7 @@@
                          f = {
                              'format_id': '%s-%s' % (mpd_id, representation_id) if mpd_id else representation_id,
                              'url': base_url,
+                             'ext': codec2ext(representation_attrib.get('codecs')),
                              'width': int_or_none(representation_attrib.get('width')),
                              'height': int_or_none(representation_attrib.get('height')),
                              'tbr': int_or_none(representation_attrib.get('bandwidth'), 1000),