Add --flat-playlist option (Closes #4003)

youtube_dl/YoutubeDL.py

@@ -165,6 +165,8 @@ class YoutubeDL(object):
                        'auto' for elaborate guessing
     encoding:          Use this encoding instead of the system-specified.
     extract_flat:      Do not resolve URLs, return the immediate result.
+                       Pass in 'in_playlist' to only show this behavior for
+                       playlist items.
 
     The following parameters are not used by YoutubeDL itself, they are used by
     the FileDownloader:
@@ -568,8 +570,13 @@ def process_ie_result(self, ie_result, download=True, extra_info={}):
 
         result_type = ie_result.get('_type', 'video')
 
-        if self.params.get('extract_flat', False):
-            if result_type in ('url', 'url_transparent'):
+        if result_type in ('url', 'url_transparent'):
+            extract_flat = self.params.get('extract_flat', False)
+            if ((extract_flat == 'in_playlist' and 'playlist' in extra_info) or
+                    extract_flat is True):
+                self.add_extra_info(ie_result, extra_info)
+                if self.params.get('forcejson', False):
+                    self.to_stdout(json.dumps(ie_result))
                 return ie_result
 
         if result_type == 'video':

youtube_dl/__init__.py

@@ -367,6 +367,7 @@ def _real_main(argv=None):
         'youtube_include_dash_manifest': opts.youtube_include_dash_manifest,
         'encoding': opts.encoding,
         'exec_cmd': opts.exec_cmd,
+        'extract_flat': opts.extract_flat,
     }
 
     with YoutubeDL(ydl_opts) as ydl:

youtube_dl/options.py

@@ -159,6 +159,11 @@ def _hide_login_info(opts):
         '--ignore-config',
         action='store_true',
         help='Do not read configuration files. When given in the global configuration file /etc/youtube-dl.conf: do not read the user configuration in ~/.config/youtube-dl.conf (%APPDATA%/youtube-dl/config.txt on Windows)')
+    general.add_option(
+        '--flat-playlist',
+        action='store_const', dest='extract_flat', const='in_playlist',
+        default=False,
+        help='Do not extract the videos of a playlist, only list them.')
 
     selection = optparse.OptionGroup(parser, 'Video Selection')
     selection.add_option(