+
+            # For fields playlist_index and autonumber convert all occurrences
+            # of %(field)s to %(field)0Nd for backward compatibility
+            field_size_compat_map = {
+                'playlist_index': len(str(template_dict['n_entries'])),
+                'autonumber': autonumber_size,
+            }
+            FIELD_SIZE_COMPAT_RE = r'(?<!%)%\((?P<field>autonumber|playlist_index)\)s'
+            mobj = re.search(FIELD_SIZE_COMPAT_RE, outtmpl)
+            if mobj:
+                outtmpl = re.sub(
+                    FIELD_SIZE_COMPAT_RE,
+                    r'%%(\1)0%dd' % field_size_compat_map[mobj.group('field')],
+                    outtmpl)
+
+            NUMERIC_FIELDS = set((
+                'width', 'height', 'tbr', 'abr', 'asr', 'vbr', 'fps', 'filesize', 'filesize_approx',
+                'timestamp', 'upload_year', 'upload_month', 'upload_day',
+                'duration', 'view_count', 'like_count', 'dislike_count', 'repost_count',
+                'average_rating', 'comment_count', 'age_limit',
+                'start_time', 'end_time',
+                'chapter_number', 'season_number', 'episode_number',
+                'track_number', 'disc_number', 'release_year',
+                'playlist_index',
+            ))
+
+            # Missing numeric fields used together with integer presentation types
+            # in format specification will break the argument substitution since
+            # string 'NA' is returned for missing fields. We will patch output
+            # template for missing fields to meet string presentation type.
+            for numeric_field in NUMERIC_FIELDS:
+                if numeric_field not in template_dict:
+                    # As of [1] format syntax is:
+                    #  %[mapping_key][conversion_flags][minimum_width][.precision][length_modifier]type
+                    # 1. https://docs.python.org/2/library/stdtypes.html#string-formatting
+                    FORMAT_RE = r'''(?x)
+                        (?<!%)
+                        %
+                        \({0}\)  # mapping key
+                        (?:[#0\-+ ]+)?  # conversion flags (optional)
+                        (?:\d+)?  # minimum field width (optional)
+                        (?:\.\d+)?  # precision (optional)
+                        [hlL]?  # length modifier (optional)
+                        [diouxXeEfFgGcrs%]  # conversion type
+                    '''
+                    outtmpl = re.sub(
+                        FORMAT_RE.format(numeric_field),
+                        r'%({0})s'.format(numeric_field), outtmpl)
+
+            filename = expand_path(outtmpl % template_dict)