plugins.twitch: add --twitch-supported-codecs

Add the temporary `--twitch-supported-codecs` plugin argument
for being able to set the client's video codec preference.

Set the default value to "h264" to ensure that no compatibility
issues arise on clients without AV1/HEVC decode capabilities.

src/streamlink/plugins/twitch.py

@@ -22,7 +22,7 @@
 from datetime import datetime, timedelta
 from json import dumps as json_dumps
 from random import random
-from typing import ClassVar, Mapping, Optional, Tuple, Type
+from typing import ClassVar, List, Mapping, Optional, Tuple, Type
 from urllib.parse import urlparse
 
 from requests.exceptions import HTTPError
@@ -203,19 +203,24 @@ def __init__(self, *args, disable_ads: bool = False, low_latency: bool = False,
 
 
 class UsherService:
-    def __init__(self, session):
+    def __init__(self, session: Streamlink, supported_codecs: Optional[List[str]] = None):
         self.session = session
+        self.supported_codecs = supported_codecs
 
     def _create_url(self, endpoint, **extra_params):
         url = f"https://usher.ttvnw.net{endpoint}"
         params = {
+            "platform": "web",
             "player": "twitchweb",
             "p": int(random() * 999999),
             "type": "any",
             "allow_source": "true",
             "allow_audio_only": "true",
             "allow_spectre": "false",
+            "playlist_include_framerate": "true",
         }
+        if self.supported_codecs:
+            params["supported_codecs"] = ",".join(self.supported_codecs)
         params.update(extra_params)
 
         req = self.session.http.prepare_new_request(url=url, params=params)
@@ -651,6 +656,23 @@ def decode_client_integrity_token(data: str, schema: Optional[validate.Schema] =
         Regular streams can cause buffering issues with this option enabled due to the reduced --hls-live-edge value.
     """,
 )
+@pluginargument(
+    "supported-codecs",
+    type="comma_list_filter",
+    type_kwargs={
+        "acceptable": ["h264", "h265", "av1"],
+        "unique": True,
+    },
+    default=["h264"],
+    help="""
+        A comma-separated list of codec names which signals Twitch the client's stream codec preference.
+        Which streams and which codecs are available depends on the specific channel and broadcast.
+
+        Default is "h264".
+
+        Supported codecs are "h264", "h265", "av1". Set to "h264,h265,av1" to enable all codecs.
+    """,
+)
 @pluginargument(
     "api-header",
     metavar="KEY=VALUE",
@@ -718,7 +740,10 @@ def __init__(self, *args, **kwargs):
             api_header=self.get_option("api-header"),
             access_token_param=self.get_option("access-token-param"),
         )
-        self.usher = UsherService(session=self.session)
+        self.usher = UsherService(
+            session=self.session,
+            supported_codecs=self.get_option("supported-codecs"),
+        )
 
         def method_factory(parent_method):
             def inner():

tests/plugins/test_twitch.py

@@ -460,6 +460,16 @@ def test_service(self, caplog: pytest.LogCaptureFixture, endpoint: str, expected
 
         assert [(r.name, r.levelname, r.message) for r in caplog.get_records(when="setup")] == logs
 
+    @pytest.mark.parametrize(("endpoint", "expected"), [
+        pytest.param({"options": {}}, None, id="unset"),
+        pytest.param({"options": {"supported_codecs": ["h264"]}}, "h264", id="h264"),
+        pytest.param({"options": {"supported_codecs": ["av1", "h264"]}}, "av1,h264", id="av1,h264"),
+        pytest.param({"options": {"supported_codecs": ["av1", "h264", "h265"]}}, "av1,h264,h265", id="av1,h264,h265"),
+    ], indirect=["endpoint"])
+    def test_supported_codecs(self, endpoint: str, expected: str):
+        qs = dict(parse_qsl(urlparse(endpoint).query))
+        assert qs.get("supported_codecs") == expected
+
 
 class TestTwitchAPIAccessToken:
     @pytest.fixture(autouse=True)