Extract comments only when needed #95 (Closes #94)

README.md

@@ -245,7 +245,7 @@ ## Video Selection:
                                      "OUTPUT TEMPLATE" for a list of available
                                      keys) to match if the key is present, !key
                                      to check if the key is not present,
-                                     key>NUMBER (like "comment_count > 12", also
+                                     key>NUMBER (like "view_count > 12", also
                                      works with >=, <, <=, !=, =) to compare
                                      against a number, key = 'LITERAL' (like
                                      "uploader = 'Mike Smith'", also works with
@@ -403,7 +403,9 @@ ## Filesystem Options:
     --no-write-playlist-metafiles    Do not write playlist metadata when using
                                      --write-info-json, --write-description etc.
     --get-comments                   Retrieve video comments to be placed in the
-                                     .info.json file
+                                     .info.json file. The comments are fetched
+                                     even without this option if the extraction
+                                     is known to be quick
     --load-info-json FILE            JSON file containing the video information
                                      (created with the "--write-info-json"
                                      option)
@@ -814,7 +816,7 @@ # OUTPUT TEMPLATE
  - `dislike_count` (numeric): Number of negative ratings of the video
  - `repost_count` (numeric): Number of reposts of the video
  - `average_rating` (numeric): Average rating give by users, the scale used depends on the webpage
- - `comment_count` (numeric): Number of comments on the video
+ - `comment_count` (numeric): Number of comments on the video (For some extractors, comments are only downloaded at the end, and so this field cannot be used)
  - `age_limit` (numeric): Age restriction for the video (years)
  - `is_live` (boolean): Whether this video is a live stream or a fixed-length video
  - `was_live` (boolean): Whether this video was originally a live stream

yt_dlp/YoutubeDL.py

@@ -2041,6 +2041,7 @@ def print_optional(field):
             self.to_stdout(formatSeconds(info_dict['duration']))
         print_mandatory('format')
         if self.params.get('forcejson', False):
+            self.post_extract(info_dict)
             self.to_stdout(json.dumps(info_dict))
 
     def process_info(self, info_dict):
@@ -2064,6 +2065,7 @@ def process_info(self, info_dict):
         if self._match_entry(info_dict, incomplete=False) is not None:
             return
 
+        self.post_extract(info_dict)
         self._num_downloads += 1
 
         info_dict = self.pre_process(info_dict)
@@ -2497,6 +2499,7 @@ def download(self, url_list):
                 raise
             else:
                 if self.params.get('dump_single_json', False):
+                    self.post_extract(res)
                     self.to_stdout(json.dumps(res))
 
         return self._download_retcode
@@ -2545,6 +2548,24 @@ def run_pp(self, pp, infodict, files_to_move={}):
                     del files_to_move[old_filename]
         return files_to_move, infodict
 
+    @staticmethod
+    def post_extract(info_dict):
+        def actual_post_extract(info_dict):
+            if info_dict.get('_type') in ('playlist', 'multi_video'):
+                for video_dict in info_dict.get('entries', {}):
+                    actual_post_extract(video_dict)
+                return
+
+            if '__post_extractor' not in info_dict:
+                return
+            post_extractor = info_dict['__post_extractor']
+            if post_extractor:
+                info_dict.update(post_extractor().items())
+            del info_dict['__post_extractor']
+            return
+
+        actual_post_extract(info_dict)
+
     def pre_process(self, ie_info):
         info = dict(ie_info)
         for pp in self._pps['beforedl']:

yt_dlp/extractor/bilibili.py

@@ -255,10 +255,6 @@ def _real_extract(self, url):
             info['uploader'] = self._html_search_meta(
                 'author', webpage, 'uploader', default=None)
 
-        comments = None
-        if self._downloader.params.get('getcomments', False):
-            comments = self._get_all_comment_pages(video_id)
-
         raw_danmaku = self._get_raw_danmaku(video_id, cid)
 
         raw_tags = self._get_tags(video_id)
@@ -266,11 +262,18 @@ def _real_extract(self, url):
 
         top_level_info = {
             'raw_danmaku': raw_danmaku,
-            'comments': comments,
-            'comment_count': len(comments) if comments is not None else None,
             'tags': tags,
             'raw_tags': raw_tags,
         }
+        if self._downloader.params.get('getcomments', False):
+            def get_comments():
+                comments = self._get_all_comment_pages(video_id)
+                return {
+                    'comments': comments,
+                    'comment_count': len(comments)
+                }
+
+            top_level_info['__post_extractor'] = get_comments
 
         '''
         # Requires https://github.com/m13253/danmaku2ass which is licenced under GPL3

yt_dlp/extractor/common.py

@@ -294,6 +294,14 @@ class InfoExtractor(object):
                     players on other sites. Can be True (=always allowed),
                     False (=never allowed), None (=unknown), or a string
                     specifying the criteria for embedability (Eg: 'whitelist').
+    __post_extractor: A function to be called just before the metadata is
+                    written to either disk, logger or console. The function
+                    must return a dict which will be added to the info_dict.
+                    This is usefull for additional information that is
+                    time-consuming to extract. Note that the fields thus
+                    extracted will not be available to output template and
+                    match_filter. So, only "comments" and "comment_count" are
+                    currently allowed to be extracted via this method.
 
     The following fields should only be used when the video belongs to some logical
     chapter or section:

yt_dlp/extractor/youtube.py

@@ -2012,9 +2012,10 @@ def chapter_time(mmlir):
 
         # Get comments
         # TODO: Refactor and move to seperate function
-        if get_comments:
+        def extract_comments():
             expected_video_comment_count = 0
             video_comments = []
+            comment_xsrf = xsrf_token
 
             def find_value(html, key, num_chars=2, separator='"'):
                 pos_begin = html.find(key) + len(key) + num_chars
@@ -2083,7 +2084,7 @@ def get_continuation(continuation, session_token, replies=False):
             self.to_screen('Downloading comments')
             while continuations:
                 continuation = continuations.pop()
-                comment_response = get_continuation(continuation, xsrf_token)
+                comment_response = get_continuation(continuation, comment_xsrf)
                 if not comment_response:
                     continue
                 if list(search_dict(comment_response, 'externalErrorMessage')):
@@ -2094,7 +2095,7 @@ def get_continuation(continuation, session_token, replies=False):
                     continue
                 # not sure if this actually helps
                 if 'xsrf_token' in comment_response:
-                    xsrf_token = comment_response['xsrf_token']
+                    comment_xsrf = comment_response['xsrf_token']
 
                 item_section = comment_response['response']['continuationContents']['itemSectionContinuation']
                 if first_continuation:
@@ -2123,7 +2124,7 @@ def get_continuation(continuation, session_token, replies=False):
                     while reply_continuations:
                         time.sleep(1)
                         continuation = reply_continuations.pop()
-                        replies_data = get_continuation(continuation, xsrf_token, True)
+                        replies_data = get_continuation(continuation, comment_xsrf, True)
                         if not replies_data or 'continuationContents' not in replies_data[1]['response']:
                             continue
 
@@ -2152,10 +2153,13 @@ def get_continuation(continuation, session_token, replies=False):
                 time.sleep(1)
 
             self.to_screen('Total comments downloaded: %d of ~%d' % (len(video_comments), expected_video_comment_count))
-            info.update({
+            return {
                 'comments': video_comments,
                 'comment_count': expected_video_comment_count
-            })
+            }
+
+        if get_comments:
+            info['__post_extractor'] = extract_comments
 
         self.mark_watched(video_id, player_response)
 

yt_dlp/options.py

@@ -347,7 +347,7 @@ def _dict_from_multiple_values_options_callback(
             'Specify any key (see "OUTPUT TEMPLATE" for a list of available keys) to '
             'match if the key is present, '
             '!key to check if the key is not present, '
-            'key>NUMBER (like "comment_count > 12", also works with '
+            'key>NUMBER (like "view_count > 12", also works with '
             '>=, <, <=, !=, =) to compare against a number, '
             'key = \'LITERAL\' (like "uploader = \'Mike Smith\'", also works with !=) '
             'to match against a string literal '
@@ -985,7 +985,9 @@ def _dict_from_multiple_values_options_callback(
     filesystem.add_option(
         '--get-comments',
         action='store_true', dest='getcomments', default=False,
-        help='Retrieve video comments to be placed in the .info.json file')
+        help=(
+            'Retrieve video comments to be placed in the .info.json file. '
+            'The comments are fetched even without this option if the extraction is known to be quick'))
     filesystem.add_option(
         '--load-info-json', '--load-info',
         dest='load_info_filename', metavar='FILE',