[extractor/common] Fix url meta field for unfragmented DASH formats (closes #20346)

youtube_dl/extractor/common.py

@@ -108,10 +108,13 @@ class InfoExtractor(object):
                                    for RTMP - RTMP URL,
                                    for HLS - URL of the M3U8 media playlist,
                                    for HDS - URL of the F4M manifest,
-                                   for DASH - URL of the MPD manifest or
-                                              base URL representing the media
-                                              if MPD manifest is parsed from
-                                              a string,
+                                   for DASH
+                                     - HTTP URL to plain file media (in case of
+                                       unfragmented media)
+                                     - URL of the MPD manifest or base URL
+                                       representing the media if MPD manifest
+                                       is parsed froma string (in case of
+                                       fragmented media)
                                    for MSS - URL of the ISM manifest.
                     * manifest_url
                                  The URL of the manifest file in case of
@@ -2137,8 +2140,6 @@ class InfoExtractor(object):
                         bandwidth = int_or_none(representation_attrib.get('bandwidth'))
                         f = {
                             'format_id': '%s-%s' % (mpd_id, representation_id) if mpd_id else representation_id,
-                            # NB: mpd_url may be empty when MPD manifest is parsed from a string
-                            'url': mpd_url or base_url,
                             'manifest_url': mpd_url,
                             'ext': mimetype2ext(mime_type),
                             'width': int_or_none(representation_attrib.get('width')),
@@ -2277,10 +2278,14 @@ class InfoExtractor(object):
                                     fragment['duration'] = segment_duration
                                 fragments.append(fragment)
                             representation_ms_info['fragments'] = fragments
-                        # NB: MPD manifest may contain direct URLs to unfragmented media.
-                        # No fragments key is present in this case.
+                        # If there is a fragments key available then we correctly recognized fragmented media.
+                        # Otherwise we will assume unfragmented media with direct access. Technically, such
+                        # assumption is not necessarily correct since we may simply have no support for
+                        # some forms of fragmented media renditions yet, but for now we'll use this fallback.
                         if 'fragments' in representation_ms_info:
                             f.update({
+                                # NB: mpd_url may be empty when MPD manifest is parsed from a string
+                                'url': mpd_url or base_url,
                                 'fragment_base_url': base_url,
                                 'fragments': [],
                                 'protocol': 'http_dash_segments',
@@ -2291,6 +2296,10 @@ class InfoExtractor(object):
                                     f['url'] = initialization_url
                                 f['fragments'].append({location_key(initialization_url): initialization_url})
                             f['fragments'].extend(representation_ms_info['fragments'])
+                        else:
+                            # Assuming direct URL to unfragmented media.
+                            f['url'] = base_url
+
                         # According to [1, 5.3.5.2, Table 7, page 35] @id of Representation
                         # is not necessarily unique within a Period thus formats with
                         # the same `format_id` are quite possible. There are numerous examples