[ie/youtube] Add use_ad_playback_context extractor-arg (yt-dlp#15220)

Closes yt-dlp#15144
Authored by: WhatAmISupposedToPutHere

Author: WhatAmISupposedToPutHere

README.md

@@ -1871,6 +1871,7 @@ The following extractors use this feature:
 * `pot_trace`: Enable debug logging for PO Token fetching. Either `true` or `false` (default)
 * `fetch_pot`: Policy to use for fetching a PO Token from providers. One of `always` (always try fetch a PO Token regardless if the client requires one for the given context), `never` (never fetch a PO Token), or `auto` (default; only fetch a PO Token if the client requires one for the given context)
 * `jsc_trace`: Enable debug logging for JS Challenge fetching. Either `true` or `false` (default)
+* `use_ad_playback_context`: Skip preroll ads to eliminate the mandatory wait period before download. Do NOT use this when passing premium account cookies to yt-dlp, as it will result in a loss of premium formats. Only effective with the `web`, `web_safari`, `web_music` and `mweb` player clients. Either `true` or `false` (default)
 
 #### youtube-ejs
 * `jitless`: Run suported Javascript engines in JIT-less mode. Supported runtimes are `deno`, `node` and `bun`. Provides better security at the cost of performance/speed. Do note that `node` and `bun` are still considered unsecure. Either `true` or `false` (default)

yt_dlp/extractor/youtube/_base.py

@@ -104,6 +104,7 @@ class SubsPoTokenPolicy(BasePoTokenPolicy):
         },
         'INNERTUBE_CONTEXT_CLIENT_NAME': 1,
         'SUPPORTS_COOKIES': True,
+        'SUPPORTS_AD_PLAYBACK_CONTEXT': True,
         **WEB_PO_TOKEN_POLICIES,
     },
     # Safari UA returns pre-merged video+audio 144p/240p/360p/720p/1080p HLS formats
@@ -117,6 +118,7 @@ class SubsPoTokenPolicy(BasePoTokenPolicy):
         },
         'INNERTUBE_CONTEXT_CLIENT_NAME': 1,
         'SUPPORTS_COOKIES': True,
+        'SUPPORTS_AD_PLAYBACK_CONTEXT': True,
         **WEB_PO_TOKEN_POLICIES,
     },
     'web_embedded': {
@@ -157,6 +159,7 @@ class SubsPoTokenPolicy(BasePoTokenPolicy):
             ),
         },
         'SUPPORTS_COOKIES': True,
+        'SUPPORTS_AD_PLAYBACK_CONTEXT': True,
     },
     # This client now requires sign-in for every video
     'web_creator': {
@@ -313,6 +316,7 @@ class SubsPoTokenPolicy(BasePoTokenPolicy):
             ),
         },
         'SUPPORTS_COOKIES': True,
+        'SUPPORTS_AD_PLAYBACK_CONTEXT': True,
     },
     'tv': {
         'INNERTUBE_CONTEXT': {
@@ -412,6 +416,7 @@ def build_innertube_clients():
         ytcfg.setdefault('SUBS_PO_TOKEN_POLICY', SubsPoTokenPolicy())
         ytcfg.setdefault('REQUIRE_AUTH', False)
         ytcfg.setdefault('SUPPORTS_COOKIES', False)
+        ytcfg.setdefault('SUPPORTS_AD_PLAYBACK_CONTEXT', False)
         ytcfg.setdefault('PLAYER_PARAMS', None)
         ytcfg.setdefault('AUTHENTICATED_USER_AGENT', None)
         ytcfg['INNERTUBE_CONTEXT']['client'].setdefault('hl', 'en')

yt_dlp/extractor/youtube/_video.py

@@ -2629,16 +2629,23 @@ def _get_checkok_params():
         return {'contentCheckOk': True, 'racyCheckOk': True}
 
     @classmethod
-    def _generate_player_context(cls, sts=None):
+    def _generate_player_context(cls, sts=None, use_ad_playback_context=False):
         context = {
             'html5Preference': 'HTML5_PREF_WANTS',
         }
         if sts is not None:
             context['signatureTimestamp'] = sts
+
+        playback_context = {
+            'contentPlaybackContext': context,
+        }
+        if use_ad_playback_context:
+            playback_context['adPlaybackContext'] = {
+                'pyv': True,
+            }
+
         return {
-            'playbackContext': {
-                'contentPlaybackContext': context,
-            },
+            'playbackContext': playback_context,
             **cls._get_checkok_params(),
         }
 
@@ -2866,7 +2873,13 @@ def _extract_player_response(self, client, video_id, webpage_ytcfg, player_ytcfg
             yt_query['serviceIntegrityDimensions'] = {'poToken': po_token}
 
         sts = self._extract_signature_timestamp(video_id, player_url, webpage_ytcfg, fatal=False) if player_url else None
-        yt_query.update(self._generate_player_context(sts))
+
+        use_ad_playback_context = (
+            self._configuration_arg('use_ad_playback_context', ['false'])[0] != 'false'
+            and traverse_obj(INNERTUBE_CLIENTS, (client, 'SUPPORTS_AD_PLAYBACK_CONTEXT', {bool})))
+
+        yt_query.update(self._generate_player_context(sts, use_ad_playback_context))
+
         return self._extract_response(
             item_id=video_id, ep='player', query=yt_query,
             ytcfg=player_ytcfg, headers=headers, fatal=True,