[utils] Add `join_nonempty`

24 files changed, 82 insertions, 131 deletions

diff --git a/yt_dlp/YoutubeDL.py b/yt_dlp/YoutubeDL.py
index 872bd5e11..0fbb3baa7 100644
--- a/yt_dlp/YoutubeDL.py
+++ b/yt_dlp/YoutubeDL.py
@@ -74,6 +74,7 @@ from .utils import (
     int_or_none,
     iri_to_uri,
     ISO3166Utils,
+    join_nonempty,
     LazyList,
     LINK_TEMPLATES,
     locked_file,
@@ -1169,7 +1170,7 @@ class YoutubeDL(object):
                 sub_ext = ''
                 if len(fn_groups) > 2:
                     sub_ext = fn_groups[-2]
-                filename = '.'.join(filter(None, [fn_groups[0][:trim_file_name], sub_ext, ext]))
+                filename = join_nonempty(fn_groups[0][:trim_file_name], sub_ext, ext, delim='.')
 
             return filename
         except ValueError as err:
@@ -3221,12 +3222,12 @@ class YoutubeDL(object):
                     format_field(f, 'acodec', default='unknown').replace('none', ''),
                     format_field(f, 'abr', f'%{abr_digits}dk'),
                     format_field(f, 'asr', '%5dHz'),
-                    ', '.join(filter(None, (
-                        self._format_screen('UNSUPPORTED', 'light red') if f.get('ext') in ('f4f', 'f4m') else '',
+                    join_nonempty(
+                        self._format_screen('UNSUPPORTED', 'light red') if f.get('ext') in ('f4f', 'f4m') else None,
                         format_field(f, 'language', '[%s]'),
                         format_field(f, 'format_note'),
                         format_field(f, 'container', ignore=(None, f.get('ext'))),
-                    ))),
+                        delim=', '),
                 ] for f in formats if f.get('preference') is None or f['preference'] >= -1000]
             header_line = self._list_format_headers(
                 'ID', 'EXT', 'RESOLUTION', 'FPS', 'HDR', delim, ' FILESIZE', '  TBR', 'PROTO',
diff --git a/yt_dlp/extractor/adobetv.py b/yt_dlp/extractor/adobetv.py
index 12b819206..3cfa1ff55 100644
--- a/yt_dlp/extractor/adobetv.py
+++ b/yt_dlp/extractor/adobetv.py
@@ -9,6 +9,7 @@ from ..utils import (
     float_or_none,
     int_or_none,
     ISO639Utils,
+    join_nonempty,
     OnDemandPagedList,
     parse_duration,
     str_or_none,
@@ -263,7 +264,7 @@ class AdobeTVVideoIE(AdobeTVBaseIE):
                 continue
             formats.append({
                 'filesize': int_or_none(source.get('kilobytes') or None, invscale=1000),
-                'format_id': '-'.join(filter(None, [source.get('format'), source.get('label')])),
+                'format_id': join_nonempty(source.get('format'), source.get('label')),
                 'height': int_or_none(source.get('height') or None),
                 'tbr': int_or_none(source.get('bitrate') or None),
                 'width': int_or_none(source.get('width') or None),
diff --git a/yt_dlp/extractor/animeondemand.py b/yt_dlp/extractor/animeondemand.py
index 54e097d2f..5694f7240 100644
--- a/yt_dlp/extractor/animeondemand.py
+++ b/yt_dlp/extractor/animeondemand.py
@@ -8,6 +8,7 @@ from ..utils import (
     determine_ext,
     extract_attributes,
     ExtractorError,
+    join_nonempty,
     url_or_none,
     urlencode_postdata,
     urljoin,
@@ -140,15 +141,8 @@ class AnimeOnDemandIE(InfoExtractor):
                     kind = self._search_regex(
                         r'videomaterialurl/\d+/([^/]+)/',
                         playlist_url, 'media kind', default=None)
-                    format_id_list = []
-                    if lang:
-                        format_id_list.append(lang)
-                    if kind:
-                        format_id_list.append(kind)
-                    if not format_id_list and num is not None:
-                        format_id_list.append(compat_str(num))
-                    format_id = '-'.join(format_id_list)
-                    format_note = ', '.join(filter(None, (kind, lang_note)))
+                    format_id = join_nonempty(lang, kind) if lang or kind else str(num)
+                    format_note = join_nonempty(kind, lang_note, delim=', ')
                     item_id_list = []
                     if format_id:
                         item_id_list.append(format_id)
@@ -195,12 +189,10 @@ class AnimeOnDemandIE(InfoExtractor):
                         if not file_:
                             continue
                         ext = determine_ext(file_)
-                        format_id_list = [lang, kind]
-                        if ext == 'm3u8':
-                            format_id_list.append('hls')
-                        elif source.get('type') == 'video/dash' or ext == 'mpd':
-                            format_id_list.append('dash')
-                        format_id = '-'.join(filter(None, format_id_list))
+                        format_id = join_nonempty(
+                            lang, kind,
+                            'hls' if ext == 'm3u8' else None,
+                            'dash' if source.get('type') == 'video/dash' or ext == 'mpd' else None)
                         if ext == 'm3u8':
                             file_formats = self._extract_m3u8_formats(
                                 file_, video_id, 'mp4',
diff --git a/yt_dlp/extractor/anvato.py b/yt_dlp/extractor/anvato.py
index d688e2c5b..0d444fc33 100644
--- a/yt_dlp/extractor/anvato.py
+++ b/yt_dlp/extractor/anvato.py
@@ -16,6 +16,7 @@ from ..utils import (
     determine_ext,
     intlist_to_bytes,
     int_or_none,
+    join_nonempty,
     strip_jsonp,
     unescapeHTML,
     unsmuggle_url,
@@ -303,13 +304,13 @@ class AnvatoIE(InfoExtractor):
             tbr = int_or_none(published_url.get('kbps'))
             a_format = {
                 'url': video_url,
-                'format_id': ('-'.join(filter(None, ['http', published_url.get('cdn_name')]))).lower(),
-                'tbr': tbr if tbr != 0 else None,
+                'format_id': join_nonempty('http', published_url.get('cdn_name')).lower(),
+                'tbr': tbr or None,
             }
 
             if media_format == 'm3u8' and tbr is not None:
                 a_format.update({
-                    'format_id': '-'.join(filter(None, ['hls', compat_str(tbr)])),
+                    'format_id': join_nonempty('hls', tbr),
                     'ext': 'mp4',
                 })
             elif media_format == 'm3u8-variant' or ext == 'm3u8':
diff --git a/yt_dlp/extractor/common.py b/yt_dlp/extractor/common.py
index ffecc4263..7500402fa 100644
--- a/yt_dlp/extractor/common.py
+++ b/yt_dlp/extractor/common.py
@@ -54,6 +54,7 @@ from ..utils import (
     GeoRestrictedError,
     GeoUtils,
     int_or_none,
+    join_nonempty,
     js_to_json,
     JSON_LD_RE,
     mimetype2ext,
@@ -1911,7 +1912,7 @@ class InfoExtractor(object):
             tbr = int_or_none(media_el.attrib.get('bitrate'))
             width = int_or_none(media_el.attrib.get('width'))
             height = int_or_none(media_el.attrib.get('height'))
-            format_id = '-'.join(filter(None, [f4m_id, compat_str(i if tbr is None else tbr)]))
+            format_id = join_nonempty(f4m_id, tbr or i)
             # If <bootstrapInfo> is present, the specified f4m is a
             # stream-level manifest, and only set-level manifests may refer to
             # external resources.  See section 11.4 and section 4 of F4M spec
@@ -1973,7 +1974,7 @@ class InfoExtractor(object):
 
     def _m3u8_meta_format(self, m3u8_url, ext=None, preference=None, quality=None, m3u8_id=None):
         return {
-            'format_id': '-'.join(filter(None, [m3u8_id, 'meta'])),
+            'format_id': join_nonempty(m3u8_id, 'meta'),
             'url': m3u8_url,
             'ext': ext,
             'protocol': 'm3u8',
@@ -2068,7 +2069,7 @@ class InfoExtractor(object):
 
         if '#EXT-X-TARGETDURATION' in m3u8_doc:  # media playlist, return as is
             formats = [{
-                'format_id': '-'.join(map(str, filter(None, [m3u8_id, idx]))),
+                'format_id': join_nonempty(m3u8_id, idx),
                 'format_index': idx,
                 'url': m3u8_url,
                 'ext': ext,
@@ -2117,7 +2118,7 @@ class InfoExtractor(object):
             if media_url:
                 manifest_url = format_url(media_url)
                 formats.extend({
-                    'format_id': '-'.join(map(str, filter(None, (m3u8_id, group_id, name, idx)))),
+                    'format_id': join_nonempty(m3u8_id, group_id, name, idx),
                     'format_note': name,
                     'format_index': idx,
                     'url': manifest_url,
@@ -2174,9 +2175,9 @@ class InfoExtractor(object):
                     # format_id intact.
                     if not live:
                         stream_name = build_stream_name()
-                        format_id[1] = stream_name if stream_name else '%d' % (tbr if tbr else len(formats))
+                        format_id[1] = stream_name or '%d' % (tbr or len(formats))
                     f = {
-                        'format_id': '-'.join(map(str, filter(None, format_id))),
+                        'format_id': join_nonempty(*format_id),
                         'format_index': idx,
                         'url': manifest_url,
                         'manifest_url': m3u8_url,
@@ -2965,13 +2966,6 @@ class InfoExtractor(object):
                         })
                         fragment_ctx['time'] += fragment_ctx['duration']
 
-                format_id = []
-                if ism_id:
-                    format_id.append(ism_id)
-                if stream_name:
-                    format_id.append(stream_name)
-                format_id.append(compat_str(tbr))
-
                 if stream_type == 'text':
                     subtitles.setdefault(stream_language, []).append({
                         'ext': 'ismt',
@@ -2990,7 +2984,7 @@ class InfoExtractor(object):
                     })
                 elif stream_type in ('video', 'audio'):
                     formats.append({
-                        'format_id': '-'.join(format_id),
+                        'format_id': join_nonempty(ism_id, stream_name, tbr),
                         'url': ism_url,
                         'manifest_url': ism_url,
                         'ext': 'ismv' if stream_type == 'video' else 'isma',
diff --git a/yt_dlp/extractor/disney.py b/yt_dlp/extractor/disney.py
index f018cbe9d..0ad7b1f46 100644
--- a/yt_dlp/extractor/disney.py
+++ b/yt_dlp/extractor/disney.py
@@ -7,8 +7,8 @@ from .common import InfoExtractor
 from ..utils import (
     int_or_none,
     unified_strdate,
-    compat_str,
     determine_ext,
+    join_nonempty,
     update_url_query,
 )
 
@@ -119,18 +119,13 @@ class DisneyIE(InfoExtractor):
                         continue
                     formats.append(f)
                 continue
-            format_id = []
-            if flavor_format:
-                format_id.append(flavor_format)
-            if tbr:
-                format_id.append(compat_str(tbr))
             ext = determine_ext(flavor_url)
             if flavor_format == 'applehttp' or ext == 'm3u8':
                 ext = 'mp4'
             width = int_or_none(flavor.get('width'))
             height = int_or_none(flavor.get('height'))
             formats.append({
-                'format_id': '-'.join(format_id),
+                'format_id': join_nonempty(flavor_format, tbr),
                 'url': flavor_url,
                 'width': width,
                 'height': height,
diff --git a/yt_dlp/extractor/dvtv.py b/yt_dlp/extractor/dvtv.py
index de7f6d670..08663cffb 100644
--- a/yt_dlp/extractor/dvtv.py
+++ b/yt_dlp/extractor/dvtv.py
@@ -8,6 +8,7 @@ from ..utils import (
     determine_ext,
     ExtractorError,
     int_or_none,
+    join_nonempty,
     js_to_json,
     mimetype2ext,
     try_get,
@@ -139,13 +140,9 @@ class DVTVIE(InfoExtractor):
                     label = video.get('label')
                     height = self._search_regex(
                         r'^(\d+)[pP]', label or '', 'height', default=None)
-                    format_id = ['http']
-                    for f in (ext, label):
-                        if f:
-                            format_id.append(f)
                     formats.append({
                         'url': video_url,
-                        'format_id': '-'.join(format_id),
+                        'format_id': join_nonempty('http', ext, label),
                         'height': int_or_none(height),
                     })
         self._sort_formats(formats)
diff --git a/yt_dlp/extractor/funimation.py b/yt_dlp/extractor/funimation.py
index 382cbe159..42711083e 100644
--- a/yt_dlp/extractor/funimation.py
+++ b/yt_dlp/extractor/funimation.py
@@ -10,6 +10,7 @@ from ..compat import compat_HTTPError
 from ..utils import (
     determine_ext,
     int_or_none,
+    join_nonempty,
     js_to_json,
     orderedSet,
     qualities,
@@ -288,10 +289,11 @@ class FunimationIE(FunimationBaseIE):
                     sub_type = sub_type if sub_type != 'FULL' else None
                     current_sub = {
                         'url': text_track['src'],
-                        'name': ' '.join(filter(None, (version, text_track.get('label'), sub_type)))
+                        'name': join_nonempty(version, text_track.get('label'), sub_type, delim=' ')
                     }
-                    lang = '_'.join(filter(None, (
-                        text_track.get('language', 'und'), version if version != 'Simulcast' else None, sub_type)))
+                    lang = join_nonempty(text_track.get('language', 'und'),
+                                         version if version != 'Simulcast' else None,
+                                         sub_type, delim='_')
                     if current_sub not in subtitles.get(lang, []):
                         subtitles.setdefault(lang, []).append(current_sub)
         return subtitles
diff --git a/yt_dlp/extractor/lego.py b/yt_dlp/extractor/lego.py
index b9d8b167c..901f43bcf 100644
--- a/yt_dlp/extractor/lego.py
+++ b/yt_dlp/extractor/lego.py
@@ -8,6 +8,7 @@ from ..compat import compat_HTTPError
 from ..utils import (
     ExtractorError,
     int_or_none,
+    join_nonempty,
     qualities,
 )
 
@@ -102,12 +103,8 @@ class LEGOIE(InfoExtractor):
                     m3u8_id=video_source_format, fatal=False))
             else:
                 video_source_quality = video_source.get('Quality')
-                format_id = []
-                for v in (video_source_format, video_source_quality):
-                    if v:
-                        format_id.append(v)
                 f = {
-                    'format_id': '-'.join(format_id),
+                    'format_id': join_nonempty(video_source_format, video_source_quality),
                     'quality': q(video_source_quality),
                     'url': video_source_url,
                 }
diff --git a/yt_dlp/extractor/mdr.py b/yt_dlp/extractor/mdr.py
index 0bdd62693..3ca174c2b 100644
--- a/yt_dlp/extractor/mdr.py
+++ b/yt_dlp/extractor/mdr.py
@@ -2,13 +2,11 @@
 from __future__ import unicode_literals
 
 from .common import InfoExtractor
-from ..compat import (
-    compat_str,
-    compat_urlparse,
-)
+from ..compat import compat_urlparse
 from ..utils import (
     determine_ext,
     int_or_none,
+    join_nonempty,
     parse_duration,
     parse_iso8601,
     url_or_none,
@@ -148,13 +146,9 @@ class MDRIE(InfoExtractor):
                     abr = int_or_none(xpath_text(asset, './bitrateAudio', 'abr'), 1000)
                     filesize = int_or_none(xpath_text(asset, './fileSize', 'file size'))
 
-                    format_id = [media_type]
-                    if vbr or abr:
-                        format_id.append(compat_str(vbr or abr))
-
                     f = {
                         'url': video_url,
-                        'format_id': '-'.join(format_id),
+                        'format_id': join_nonempty(media_type, vbr or abr),
                         'filesize': filesize,
                         'abr': abr,
                         'vbr': vbr,
diff --git a/yt_dlp/extractor/mtv.py b/yt_dlp/extractor/mtv.py
index 141dd7deb..4812f11cc 100644
--- a/yt_dlp/extractor/mtv.py
+++ b/yt_dlp/extractor/mtv.py
@@ -15,6 +15,7 @@ from ..utils import (
     float_or_none,
     HEADRequest,
     int_or_none,
+    join_nonempty,
     RegexNotFoundError,
     sanitized_Request,
     strip_or_none,
@@ -99,9 +100,9 @@ class MTVServicesInfoExtractor(InfoExtractor):
                     formats.extend([{
                         'ext': 'flv' if rtmp_video_url.startswith('rtmp') else ext,
                         'url': rtmp_video_url,
-                        'format_id': '-'.join(filter(None, [
+                        'format_id': join_nonempty(
                             'rtmp' if rtmp_video_url.startswith('rtmp') else None,
-                            rendition.get('bitrate')])),
+                            rendition.get('bitrate')),
                         'width': int(rendition.get('width')),
                         'height': int(rendition.get('height')),
                     }])
diff --git a/yt_dlp/extractor/orf.py b/yt_dlp/extractor/orf.py
index 428ec97e4..e2b703880 100644
--- a/yt_dlp/extractor/orf.py
+++ b/yt_dlp/extractor/orf.py
@@ -11,6 +11,7 @@ from ..utils import (
     float_or_none,
     HEADRequest,
     int_or_none,
+    join_nonempty,
     orderedSet,
     remove_end,
     str_or_none,
@@ -82,12 +83,7 @@ class ORFTVthekIE(InfoExtractor):
                 src = url_or_none(fd.get('src'))
                 if not src:
                     continue
-                format_id_list = []
-                for key in ('delivery', 'quality', 'quality_string'):
-                    value = fd.get(key)
-                    if value:
-                        format_id_list.append(value)
-                format_id = '-'.join(format_id_list)
+                format_id = join_nonempty('delivery', 'quality', 'quality_string', from_dict=fd)
                 ext = determine_ext(src)
                 if ext == 'm3u8':
                     m3u8_formats = self._extract_m3u8_formats(
diff --git a/yt_dlp/extractor/piksel.py b/yt_dlp/extractor/piksel.py
index 5cc99a44e..84c3de2f0 100644
--- a/yt_dlp/extractor/piksel.py
+++ b/yt_dlp/extractor/piksel.py
@@ -4,11 +4,11 @@ from __future__ import unicode_literals
 import re
 
 from .common import InfoExtractor
-from ..compat import compat_str
 from ..utils import (
     dict_get,
     ExtractorError,
     int_or_none,
+    join_nonempty,
     parse_iso8601,
     try_get,
     unescapeHTML,
@@ -116,12 +116,8 @@ class PikselIE(InfoExtractor):
             elif asset_type == 'audio':
                 tbr = abr
 
-            format_id = ['http']
-            if tbr:
-                format_id.append(compat_str(tbr))
-
             formats.append({
-                'format_id': '-'.join(format_id),
+                'format_id': join_nonempty('http', tbr),
                 'url': unescapeHTML(http_url),
                 'vbr': vbr,
                 'abr': abr,
diff --git a/yt_dlp/extractor/srgssr.py b/yt_dlp/extractor/srgssr.py
index cbc1c47d2..f9919816d 100644
--- a/yt_dlp/extractor/srgssr.py
+++ b/yt_dlp/extractor/srgssr.py
@@ -7,6 +7,7 @@ from ..utils import (
     ExtractorError,
     float_or_none,
     int_or_none,
+    join_nonempty,
     parse_iso8601,
     qualities,
     try_get,
@@ -94,11 +95,7 @@ class SRGSSRIE(InfoExtractor):
                 continue
             protocol = source.get('protocol')
             quality = source.get('quality')
-            format_id = []
-            for e in (protocol, source.get('encoding'), quality):
-                if e:
-                    format_id.append(e)
-            format_id = '-'.join(format_id)
+            format_id = join_nonempty(protocol, source.get('encoding'), quality)
 
             if protocol in ('HDS', 'HLS'):
                 if source.get('tokenType') == 'AKAMAI':
diff --git a/yt_dlp/extractor/threeqsdn.py b/yt_dlp/extractor/threeqsdn.py
index bb7610352..e5c6a6de1 100644
--- a/yt_dlp/extractor/threeqsdn.py
+++ b/yt_dlp/extractor/threeqsdn.py
@@ -9,6 +9,7 @@ from ..utils import (
     ExtractorError,
     float_or_none,
     int_or_none,
+    join_nonempty,
     parse_iso8601,
 )
 
@@ -119,24 +120,16 @@ class ThreeQSDNIE(InfoExtractor):
                     src = s.get('src')
                     if not (src and self._is_valid_url(src, video_id)):
                         continue
-                    width = None
-                    format_id = ['http']
                     ext = determine_ext(src)
-                    if ext:
-                        format_id.append(ext)
                     height = int_or_none(s.get('height'))
-                    if height:
-                        format_id.append('%dp' % height)
-                        if aspect:
-                            width = int(height * aspect)
                     formats.append({
                         'ext': ext,
-                        'format_id': '-'.join(format_id),
+                        'format_id': join_nonempty('http', ext, height and '%dp' % height),
                         'height': height,
                         'source_preference': 0,
                         'url': src,
                         'vcodec': 'none' if height == 0 else None,
-                        'width': width,
+                        'width': int(height * aspect) if height and aspect else None,
                     })
         # It seems like this would be correctly handled by default
         # However, unless someone can confirm this, the old
diff --git a/yt_dlp/extractor/tiktok.py b/yt_dlp/extractor/tiktok.py
index 859951637..8ec28f053 100644
--- a/yt_dlp/extractor/tiktok.py
+++ b/yt_dlp/extractor/tiktok.py
@@ -12,6 +12,7 @@ from ..compat import compat_urllib_parse_unquote
 from ..utils import (
     ExtractorError,
     int_or_none,
+    join_nonempty,
     str_or_none,
     traverse_obj,
     try_get,
@@ -107,8 +108,8 @@ class TikTokBaseIE(InfoExtractor):
                 'acodec': 'aac',
                 'source_preference': -2 if 'aweme/v1' in url else -1,  # Downloads from API might get blocked
                 **add_meta, **parsed_meta,
-                'format_note': ' '.join(filter(None, (
-                    add_meta.get('format_note'), '(API)' if 'aweme/v1' in url else '')))
+                'format_note': join_nonempty(
+                    add_meta.get('format_note'), '(API)' if 'aweme/v1' in url else None, delim=' ')
             } for url in addr.get('url_list') or []]
 
         # Hack: Add direct video links first to prioritize them when removing duplicate formats
diff --git a/yt_dlp/extractor/tonline.py b/yt_dlp/extractor/tonline.py
index cc11eae2a..9b6a40db5 100644
--- a/yt_dlp/extractor/tonline.py
+++ b/yt_dlp/extractor/tonline.py
@@ -2,7 +2,7 @@
 from __future__ import unicode_literals
 
 from .common import InfoExtractor
-from ..utils import int_or_none
+from ..utils import int_or_none, join_nonempty
 
 
 class TOnlineIE(InfoExtractor):
@@ -30,13 +30,8 @@ class TOnlineIE(InfoExtractor):
             asset_source = asset.get('source') or asset.get('source2')
             if not asset_source:
                 continue
-            formats_id = []
-            for field_key in ('type', 'profile'):
-                field_value = asset.get(field_key)
-                if field_value:
-                    formats_id.append(field_value)
             formats.append({
-                'format_id': '-'.join(formats_id),
+                'format_id': join_nonempty('type', 'profile', from_dict=asset),
                 'url': asset_source,
             })
 
diff --git a/yt_dlp/extractor/ustream.py b/yt_dlp/extractor/ustream.py
index 8b758795f..4a7a8f879 100644
--- a/yt_dlp/extractor/ustream.py
+++ b/yt_dlp/extractor/ustream.py
@@ -13,6 +13,7 @@ from ..utils import (
     ExtractorError,
     int_or_none,
     float_or_none,
+    join_nonempty,
     mimetype2ext,
     str_or_none,
 )
@@ -139,8 +140,8 @@ class UstreamIE(InfoExtractor):
             content_type = stream['contentType']
             kind = content_type.split('/')[0]
             f = {
-                'format_id': '-'.join(filter(None, [
-                    'dash', kind, str_or_none(stream.get('bitrate'))])),
+                'format_id': join_nonempty(
+                    'dash', kind, str_or_none(stream.get('bitrate'))),
                 'protocol': 'http_dash_segments',
                 # TODO: generate a MPD doc for external players?
                 'url': encode_data_uri(b'<MPD/>', 'text/xml'),
diff --git a/yt_dlp/extractor/vrv.py b/yt_dlp/extractor/vrv.py
index 419602148..7bc55f333 100644
--- a/yt_dlp/extractor/vrv.py
+++ b/yt_dlp/extractor/vrv.py
@@ -19,6 +19,7 @@ from ..utils import (
     ExtractorError,
     float_or_none,
     int_or_none,
+    join_nonempty,
     traverse_obj,
 )
 
@@ -141,14 +142,10 @@ class VRVIE(VRVBaseIE):
     def _extract_vrv_formats(self, url, video_id, stream_format, audio_lang, hardsub_lang):
         if not url or stream_format not in ('hls', 'dash', 'adaptive_hls'):
             return []
-        stream_id_list = []
-        if audio_lang:
-            stream_id_list.append('audio-%s' % audio_lang)
-        if hardsub_lang:
-            stream_id_list.append('hardsub-%s' % hardsub_lang)
-        format_id = stream_format
-        if stream_id_list:
-            format_id += '-' + '-'.join(stream_id_list)
+        format_id = join_nonempty(
+            stream_format,
+            audio_lang and 'audio-%s' % audio_lang,
+            hardsub_lang and 'hardsub-%s' % hardsub_lang)
         if 'hls' in stream_format:
             adaptive_formats = self._extract_m3u8_formats(
                 url, video_id, 'mp4', m3u8_id=format_id,
diff --git a/yt_dlp/extractor/webcaster.py b/yt_dlp/extractor/webcaster.py
index e4b65f54f..a858e992c 100644
--- a/yt_dlp/extractor/webcaster.py
+++ b/yt_dlp/extractor/webcaster.py
@@ -6,6 +6,7 @@ import re
 from .common import InfoExtractor
 from ..utils import (
     determine_ext,
+    join_nonempty,
     xpath_text,
 )
 
@@ -34,12 +35,9 @@ class WebcasterIE(InfoExtractor):
 
         title = xpath_text(video, './/event_name', 'event name', fatal=True)
 
-        def make_id(parts, separator):
-            return separator.join(filter(None, parts))
-
         formats = []
         for format_id in (None, 'noise'):
-            track_tag = make_id(('track', format_id), '_')
+            track_tag = join_nonempty('track', format_id, delim='_')
             for track in video.findall('.//iphone/%s' % track_tag):
                 track_url = track.text
                 if not track_url:
@@ -48,7 +46,7 @@ class WebcasterIE(InfoExtractor):
                     m3u8_formats = self._extract_m3u8_formats(
                         track_url, video_id, 'mp4',
                         entry_protocol='m3u8_native',
-                        m3u8_id=make_id(('hls', format_id), '-'), fatal=False)
+                        m3u8_id=join_nonempty('hls', format_id, delim='-'), fatal=False)
                     for f in m3u8_formats:
                         f.update({
                             'source_preference': 0 if format_id == 'noise' else 1,
diff --git a/yt_dlp/extractor/youtube.py b/yt_dlp/extractor/youtube.py
index 28bb2fbdf..11dba5598 100644
--- a/yt_dlp/extractor/youtube.py
+++ b/yt_dlp/extractor/youtube.py
@@ -39,6 +39,7 @@ from ..utils import (
     int_or_none,
     intlist_to_bytes,
     is_html,
+    join_nonempty,
     mimetype2ext,
     network_exceptions,
     orderedSet,
@@ -2507,11 +2508,11 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                 'asr': int_or_none(fmt.get('audioSampleRate')),
                 'filesize': int_or_none(fmt.get('contentLength')),
                 'format_id': itag,
-                'format_note': ', '.join(filter(None, (
+                'format_note': join_nonempty(
                     '%s%s' % (audio_track.get('displayName') or '',
                               ' (default)' if audio_track.get('audioIsDefault') else ''),
                     fmt.get('qualityLabel') or quality.replace('audio_quality_', ''),
-                    throttled and 'THROTTLED'))),
+                    throttled and 'THROTTLED', delim=', '),
                 'source_preference': -10 if throttled else -1,
                 'fps': int_or_none(fmt.get('fps')) or None,
                 'height': height,
diff --git a/yt_dlp/extractor/zattoo.py b/yt_dlp/extractor/zattoo.py
index a13d12436..98d15604d 100644
--- a/yt_dlp/extractor/zattoo.py
+++ b/yt_dlp/extractor/zattoo.py
@@ -12,6 +12,7 @@ from ..compat import (
 from ..utils import (
     ExtractorError,
     int_or_none,
+    join_nonempty,
     try_get,
     url_or_none,
     urlencode_postdata,
@@ -156,15 +157,9 @@ class ZattooPlatformBaseIE(InfoExtractor):
                 watch_url = url_or_none(watch.get('url'))
                 if not watch_url:
                     continue
-                format_id_list = [stream_type]
-                maxrate = watch.get('maxrate')
-                if maxrate:
-                    format_id_list.append(compat_str(maxrate))
                 audio_channel = watch.get('audio_channel')
-                if audio_channel:
-                    format_id_list.append(compat_str(audio_channel))
                 preference = 1 if audio_channel == 'A' else None
-                format_id = '-'.join(format_id_list)
+                format_id = join_nonempty(stream_type, watch.get('maxrate'), audio_channel)
                 if stream_type in ('dash', 'dash_widevine', 'dash_playready'):
                     this_formats = self._extract_mpd_formats(
                         watch_url, video_id, mpd_id=format_id, fatal=False)
diff --git a/yt_dlp/extractor/zdf.py b/yt_dlp/extractor/zdf.py
index 8c279c5ab..df236c050 100644
--- a/yt_dlp/extractor/zdf.py
+++ b/yt_dlp/extractor/zdf.py
@@ -9,12 +9,12 @@ from ..utils import (
     determine_ext,
     float_or_none,
     int_or_none,
+    join_nonempty,
     merge_dicts,
     NO_DEFAULT,
     orderedSet,
     parse_codecs,
     qualities,
-    str_or_none,
     try_get,
     unified_timestamp,
     update_url_query,
@@ -70,11 +70,11 @@ class ZDFBaseIE(InfoExtractor):
                     f = {'vcodec': data[0], 'acodec': data[1]}
             f.update({
                 'url': format_url,
-                'format_id': '-'.join(filter(str_or_none, ('http', meta.get('type'), meta.get('quality')))),
+                'format_id': join_nonempty('http', meta.get('type'), meta.get('quality')),
             })
             new_formats = [f]
         formats.extend(merge_dicts(f, {
-            'format_note': ', '.join(filter(None, (meta.get('quality'), meta.get('class')))),
+            'format_note': join_nonempty('quality', 'class', from_dict=meta, delim=', '),
             'language': meta.get('language'),
             'language_preference': 10 if meta.get('class') == 'main' else -10 if meta.get('class') == 'ad' else -1,
             'quality': qualities(self._QUALITIES)(meta.get('quality')),
diff --git a/yt_dlp/utils.py b/yt_dlp/utils.py
index 17f34a853..75b4ed61b 100644
--- a/yt_dlp/utils.py
+++ b/yt_dlp/utils.py
@@ -6570,3 +6570,9 @@ def remove_terminal_sequences(string):
 
 def number_of_digits(number):
     return len('%d' % number)
+
+
+def join_nonempty(*values, delim='-', from_dict=None):
+    if from_dict is not None:
+        values = operator.itemgetter(values)(from_dict)
+    return delim.join(map(str, filter(None, values)))