check live chat replay existence

youtube_dl/YoutubeDL.py

@@ -1838,10 +1838,11 @@ class YoutubeDL(object):
                             return
                     else:
                         try:
-                            # TODO does this transfer session...?
-                            # TODO exceptions
                             dl(sub_filename, sub_info)
-                        except (ExtractorError, IOError, OSError, ValueError) as err:
+                        except (
+                            ExtractorError, IOError, OSError, ValueError,
+                            compat_urllib_error.URLError,
+                            compat_http_client.HTTPException, socket.error) as err:
                             self.report_warning('Unable to download subtitle for "%s": %s' %
                                                 (sub_lang, error_to_compat_str(err)))
                             continue

youtube_dl/extractor/youtube.py

@@ -1435,7 +1435,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             raise ExtractorError(
                 'Signature extraction failed: ' + tb, cause=e)
 
-    def _get_subtitles(self, video_id, webpage):
+    def _get_subtitles(self, video_id, webpage, is_live_content):
         try:
             subs_doc = self._download_xml(
                 'https://video.google.com/timedtext?hl=en&type=list&v=%s' % video_id,
@@ -1462,14 +1462,14 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                     'ext': ext,
                 })
             sub_lang_list[lang] = sub_formats
-        # TODO check that live chat replay actually exists
-        sub_lang_list['live_chat'] = [
-            {
-                'video_id': video_id,
-                'ext': 'json',
-                'protocol': 'youtube_live_chat_replay',
-            },
-        ]
+        if is_live_content:
+            sub_lang_list['live_chat'] = [
+                {
+                    'video_id': video_id,
+                    'ext': 'json',
+                    'protocol': 'youtube_live_chat_replay',
+                },
+            ]
         if not sub_lang_list:
             self._downloader.report_warning('video doesn\'t have subtitles')
             return {}
@@ -1493,6 +1493,14 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             return self._parse_json(
                 uppercase_escape(config), video_id, fatal=False)
 
+    def _get_yt_initial_data(self, video_id, webpage):
+        config = self._search_regex(
+            r'window\["ytInitialData"\]\s*=\s*(.*);',
+            webpage, 'ytInitialData', default=None)
+        if config:
+            return self._parse_json(
+                uppercase_escape(config), video_id, fatal=False)
+
     def _get_automatic_captions(self, video_id, webpage):
         """We need the webpage for getting the captions url, pass it as an
            argument to speed up the process."""
@@ -1993,6 +2001,16 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         if is_live is None:
             is_live = bool_or_none(video_details.get('isLive'))
 
+        has_live_chat_replay = False
+        is_live_content = bool_or_none(video_details.get('isLiveContent'))
+        if not is_live and is_live_content:
+            yt_initial_data = self._get_yt_initial_data(video_id, video_webpage)
+            try:
+                yt_initial_data['contents']['twoColumnWatchNextResults']['conversationBar']['liveChatRenderer']['continuations'][0]['reloadContinuationData']['continuation']
+                has_live_chat_replay = True
+            except (KeyError, IndexError):
+                pass
+
         # Check for "rental" videos
         if 'ypc_video_rental_bar_text' in video_info and 'author' not in video_info:
             raise ExtractorError('"rental" videos not supported. See https://github.com/ytdl-org/youtube-dl/issues/359 for more information.', expected=True)
@@ -2400,7 +2418,8 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             or try_get(video_info, lambda x: float_or_none(x['avg_rating'][0])))
 
         # subtitles
-        video_subtitles = self.extract_subtitles(video_id, video_webpage)
+        video_subtitles = self.extract_subtitles(
+            video_id, video_webpage, has_live_chat_replay)
         automatic_captions = self.extract_automatic_captions(video_id, video_webpage)
 
         video_duration = try_get(