added Single Peer Connection support to Rust #888

xianshijing-lk · 2026-02-11T05:21:42Z

after setting the LIVEKIT_URL, LIVEKIT_API_KEY, LIVEKIT_API_SECRET to staging endpoint, you will see things like

run tests:
cargo test -p livekit --features "__lk-e2e-test,native-tls" -- --nocapture

[INFO audio_test] Testing with 48000Hz, 1ch. -> 48000Hz, 1ch.
[INFO livekit_api::signal_client::signal_stream] connecting to wss://xianstaging-hixkk74p.staging.livekit.cloud/rtc/v1?sdk=rust&protocol=16&auto_subscribe=1&adaptive_stream=0&version=0.7.30&join_request=EhsKFQgIEgYwLjcuMzAYECIFbWFjb3NgARICCAE%3D
[INFO livekit_api::signal_client::signal_stream] connecting to wss://xianstaging-hixkk74p.staging.livekit.cloud/rtc/v1?sdk=rust&protocol=16&auto_subscribe=1&adaptive_stream=0&version=0.7.30&join_request=EhsKFQgIEgYwLjcuMzAYECIFbWFjb3NgARICCAE%3D
[INFO livekit_api::signal_client] [CONNECT] SUCCESS: v1 path connection successful, single_pc_mode=true
[ERROR livekit_api::signal_client] [CONNECT] ====== CONNECTION ESTABLISHED ======

ladvoc · 2026-02-11T05:46:15Z

livekit/src/room/mod.rs

@@ -1059,6 +1066,35 @@ impl RoomSession {
            track_id = stream_id.into();


nitpick: This could be moved into the else block below.

ladvoc · 2026-02-11T05:51:20Z

livekit/src/room/mod.rs

+                return;
+            }
+            // In dual PC mode: answer is local, offer is remote
+            (remote_desc.unwrap(), Some(local_desc.unwrap()))


question: Is it possible for sync state to be requested at a time when the subscriber PC lacks a local or remote description? If yes or it is unclear, we should avoid unwrapping here, and instead log a warning.

Good point, I actually don't know if it is possible, but I think it is dangerous to do unwrap() here, let me address it.

livekit/src/room/mod.rs

ladvoc · 2026-02-11T05:55:51Z

livekit-api/src/signal_client/mod.rs

+    };
+
+    // Create ClientInfo
+    let client_info = proto::ClientInfo {


nitpick: Spreading ..Default::default() would be cleaner here:

let client_info = proto::ClientInfo { sdk: proto::client_info::Sdk::Rust as i32, version: options.sdk_options.sdk_version.clone().unwrap_or_default(), protocol: PROTOCOL_VERSION as i32, os: std::env::consts::OS.to_string(), client_protocol: 1, // Indicates support for RPC compression ..Default::default() };

Same for the other protobuf types below where we set an empty string or Option::None.

ladvoc

It looking good so far! Before merging, I think it's important to test various reconnect scenarios, as this change could potentially break them.

lukasIO · 2026-02-11T15:10:59Z

livekit-api/src/signal_client/mod.rs

+                    return Err(err);
+                }
+
+                // If using v1 path and it failed, always try fallback to v0 path.


on the browser websocket implementation we unfortunately don't get a 404 for this error case back, but arguably we don't want to retry with v0 path if the connection error is anything other than "v1 path isn't available".

Would be good to try and see what kind of error we get here if the server doesn't support it and only initiate the fallback in that case

when you are running a livekit dev server at your localhost, it will fail.

The error that I get is :
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc?sdk=rust&protocol=16&auto_subscribe=1&adaptive_stream=0&version=0.7.30&reconnect=1&sid=PA_8z9tP8yTwhtr
[INFO peer_connection_signaling_test::signaling_tests] [V1 (Single PC)] Reconnecting after node failure...
[ERROR livekit::rtc_engine] resuming connection failed: signal failure: ws failure: Connection closed normally
[ERROR livekit::rtc_engine] restarting connection... attempt: 1
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc/v1?join_request=EhkKEwgIEgYwLjcuMzAYECIFbWFjb3MSAggB
[WARN livekit_api::signal_client] signal connection failed on v1 path: WsError(Http(Response { status: 404, version: HTTP/1.1, headers: {"content-type": "text/plain; charset=utf-8", "vary": "Origin", "x-content-type-options": "nosniff", "date": "Wed, 11 Feb 2026 21:38:09 GMT", "content-length": "19"}, body: Some([52, 48, 52, 32, 112, 97, 103, 101, 32, 110, 111, 116, 32, 102, 111, 117, 110, 100, 10]) }))
[WARN livekit_api::signal_client] v1 path failed, falling back to v0 path
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc?sdk=rust&protocol=16&auto_subscribe=1&adaptive_stream=0&version=0.7.30
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc/v1?join_request=EhkKEwgIEgYwLjcuMzAYECIFbWFjb3MSAggB
[WARN livekit_api::signal_client] signal connection failed on v1 path: WsError(Http(Response { status: 404, version: HTTP/1.1, headers: {"content-type": "text/plain; charset=utf-8", "vary": "Origin", "x-content-type-options": "nosniff", "date": "Wed, 11 Feb 2026 21:38:09 GMT", "content-length": "19"}, body: Some([52, 48, 52, 32, 112, 97, 103, 101, 32, 110, 111, 116, 32, 102, 111, 117, 110, 100, 10]) }))
[WARN livekit_api::signal_client] v1 path failed, falling back to v0 path
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc?sdk=rust&protocol=16&auto_subscribe=1&adaptive_stream=0&version=0.7.30
[INFO peer_connection_signaling_test::signaling_tests] [V1 (Single PC)] Connected! Room: "test_SinglePC_64069a7c-c66a-46ca-b3db-7d73a81051b8"

[WARN livekit_api::signal_client] signal connection failed on v1 path: WsError(Http(Response { status: 404, version: HTTP/1.1, headers: {"content-type": "text/plain; charset=utf-8", "vary": "Origin", "x-content-type-options": "nosniff", "date": "Wed, 11 Feb 2026 21:38:09 GMT", "content-length": "19"}, body: Some([52, 48, 52, 32, 112, 97, 103, 101, 32, 110, 111, 116, 32, 102, 111, 117, 110, 100, 10]) }))

the WsError here has a 404 status, which is great insight. It tells us that the endpoint for v1 doesn't exist.
This also means the fallback to v0 should only be applied if the error status is a 404.

…n) signaling, add tests

…back to V0

xianshijing-lk

I addressed all the comments, please take another look

xianshijing-lk · 2026-02-11T21:40:39Z

livekit-api/src/signal_client/mod.rs

+                    return Err(err);
+                }
+
+                // If using v1 path and it failed, always try fallback to v0 path.


when you are running a livekit dev server at your localhost, it will fail.

The error that I get is :
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc?sdk=rust&protocol=16&auto_subscribe=1&adaptive_stream=0&version=0.7.30&reconnect=1&sid=PA_8z9tP8yTwhtr
[INFO peer_connection_signaling_test::signaling_tests] [V1 (Single PC)] Reconnecting after node failure...
[ERROR livekit::rtc_engine] resuming connection failed: signal failure: ws failure: Connection closed normally
[ERROR livekit::rtc_engine] restarting connection... attempt: 1
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc/v1?join_request=EhkKEwgIEgYwLjcuMzAYECIFbWFjb3MSAggB
[WARN livekit_api::signal_client] signal connection failed on v1 path: WsError(Http(Response { status: 404, version: HTTP/1.1, headers: {"content-type": "text/plain; charset=utf-8", "vary": "Origin", "x-content-type-options": "nosniff", "date": "Wed, 11 Feb 2026 21:38:09 GMT", "content-length": "19"}, body: Some([52, 48, 52, 32, 112, 97, 103, 101, 32, 110, 111, 116, 32, 102, 111, 117, 110, 100, 10]) }))
[WARN livekit_api::signal_client] v1 path failed, falling back to v0 path
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc?sdk=rust&protocol=16&auto_subscribe=1&adaptive_stream=0&version=0.7.30
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc/v1?join_request=EhkKEwgIEgYwLjcuMzAYECIFbWFjb3MSAggB
[WARN livekit_api::signal_client] signal connection failed on v1 path: WsError(Http(Response { status: 404, version: HTTP/1.1, headers: {"content-type": "text/plain; charset=utf-8", "vary": "Origin", "x-content-type-options": "nosniff", "date": "Wed, 11 Feb 2026 21:38:09 GMT", "content-length": "19"}, body: Some([52, 48, 52, 32, 112, 97, 103, 101, 32, 110, 111, 116, 32, 102, 111, 117, 110, 100, 10]) }))
[WARN livekit_api::signal_client] v1 path failed, falling back to v0 path
[INFO livekit_api::signal_client::signal_stream] connecting to ws://localhost:7880/rtc?sdk=rust&protocol=16&auto_subscribe=1&adaptive_stream=0&version=0.7.30
[INFO peer_connection_signaling_test::signaling_tests] [V1 (Single PC)] Connected! Room: "test_SinglePC_64069a7c-c66a-46ca-b3db-7d73a81051b8"

xianshijing-lk · 2026-02-11T21:43:56Z

livekit-api/src/signal_client/mod.rs

+    };
+
+    // Create ClientInfo
+    let client_info = proto::ClientInfo {


xianshijing-lk · 2026-02-11T21:45:09Z

livekit/src/room/mod.rs

@@ -1059,6 +1066,35 @@ impl RoomSession {
            track_id = stream_id.into();


xianshijing-lk · 2026-02-11T21:48:08Z

livekit/src/room/mod.rs

+                return;
+            }
+            // In dual PC mode: answer is local, offer is remote
+            (remote_desc.unwrap(), Some(local_desc.unwrap()))


Good point, I actually don't know if it is possible, but I think it is dangerous to do unwrap() here, let me address it.

boks1971 · 2026-02-12T05:28:03Z

livekit/src/rtc_engine/rtc_session.rs

-                        mid_to_track_id: Default::default(),
-                    }))
-                    .await;
+                if self.single_pc_mode {


This path should be unnecessary. There should not be an offer on publisher PC from server. In single PC mode, client always offers and server answers.

added Single Peer Connection support to Rust

2f81100

xianshijing-lk requested review from ladvoc, lukasIO and theomonnom February 11, 2026 05:21

ladvoc reviewed Feb 11, 2026

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livekit/src/room/mod.rs Outdated Show resolved Hide resolved

ladvoc reviewed Feb 11, 2026

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lukasIO reviewed Feb 11, 2026

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xianshijing-lk added 2 commits February 11, 2026 13:35

fix the code to make it work for both v0 and v1 (single peerconnectio…

430fe51

…n) signaling, add tests

fix the README and make the tests run with localhost, as it will fall…

a13c540

…back to V0

xianshijing-lk force-pushed the sxian/CLT-2547/add_single_pc_to_rust branch from 69d4597 to a13c540 Compare February 11, 2026 21:50

xianshijing-lk and others added 2 commits February 11, 2026 13:50

cargo fmt

f41ef29

generated protobuf

20a520d

xianshijing-lk commented Feb 11, 2026

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xianshijing-lk mentioned this pull request Feb 12, 2026

adding single peer connection support livekit/client-sdk-cpp#57

Open

boks1971 reviewed Feb 12, 2026

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lukasIO mentioned this pull request Feb 12, 2026

Update FFI and remove napi livekit/node-sdks#599

Open

		@@ -1059,6 +1066,35 @@ impl RoomSession {
		track_id = stream_id.into();

added Single Peer Connection support to Rust #888

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added Single Peer Connection support to Rust #888

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ladvoc Feb 11, 2026 •

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