Data tracks support by ladvoc · Pull Request #586 · livekit/python-sdks

ladvoc · 2026-03-05T23:19:47Z

No description provided.

pblazej · 2026-03-16T10:46:53Z

Some things from talking to claude (maybe you find it useful):

SubscribeDataTrackError / PublishDataTrackError not exported
existing streams use aclose() (async), while DataTrackSubscription uses close() (sync); all of them can probably leverage https://www.geeksforgeeks.org/python/aenter-in-python/
no remote_data_track_unpublished event - just mirroring rust comment here
try_push should probably be push in python
remote_data_track_published should be data_track_published as other tracks
DataTrackFrame(payload=...) may validate the input type (what happens if you pass a string etc.)

livekit-rtc/livekit/rtc/data_track.py

livekit-rtc/livekit/rtc/participant.py

livekit-rtc/livekit/rtc/data_track.py

theomonnom · 2026-04-01T23:18:10Z

livekit-rtc/livekit/rtc/data_track.py

+    def _timestamp_now() -> int:
+        return int(time.time() * 1000)
+
+    def with_user_timestamp_now(self) -> DataTrackFrame:


Could it be static instead?

DataTrackFrame.now(payload=..)

I would probably stick with this since we may add additional timestamp fields in the future (e.g., a single frame could have both a capture and sensor timestamp).

I'm kind of wondering if this utility is needed at all then? It would be even more complicated if we have multiple timestamps. They don't really help much IMO

theomonnom · 2026-04-01T23:18:31Z

livekit-rtc/livekit/rtc/data_track.py

+            self._closed = True
+            FfiClient.instance.queue.unsubscribe(self._queue)
+
+    def close(self) -> None:


Let's make sure we have aclose (to be future proof)

livekit-rtc/livekit/rtc/data_track.py

theomonnom · 2026-04-02T18:07:26Z

examples/data_tracks/publisher.py

+            track.try_push(frame)
+        except rtc.PushFrameError as e:
+            logging.error("Failed to push frame: %s", e)


From an API perspective, I feel like it's kind of weird that "pushing" can fail? Since it looks like a queue?

V1 only supports lossy delivery, and queuing on the publisher side is minimal; this will error if attempting to push frames too fast (rather than queuing stale data).

Should this be named send?

There was a discussion about this back during the planning phase; originally it was going to be called "publish," but it was changed to "push" to disambiguate from publishing the track itself. The "try" prefix is to denote this is not guaranteed to succeed and to give us a path to introduce an async variant just called "push" to support reliable delivery in a future version.

livekit-rtc/livekit/rtc/data_track.py

theomonnom · 2026-04-02T18:08:43Z

livekit-rtc/livekit/rtc/data_track.py

+    def unpublish(self) -> None:
+        """Unpublishes the track."""
+        req = proto_ffi.FfiRequest()
+        req.local_data_track_unpublish.track_handle = self._ffi_handle.handle
+        FfiClient.instance.request(req)


Should this be async as well? Or maybe this shouldnt' even be here. But in LocalParticipant instead? for consistency

Based on how applications work with data tracks, we found it is more convenient to have here. This is the same API in the other SDKs. Also, currently not async in the Rust impl.

I see, tho isn't it better to be consistent with audio/video?

Even if the API is better, it introduces more cognitive load to have different APIs for similar purposes

livekit-rtc/livekit/rtc/data_track.py

…ython-client-implementation

livekit-rtc/livekit/rtc/data_track.py

livekit-rtc/livekit/rtc/participant.py

SFU used in CI testing doesn't currently have data tracks enabled. Tested locally and verified this case passes.

devin-ai-integration

Devin Review found 1 new potential issue.

View 14 additional findings in Devin Review.

devin-ai-integration · 2026-04-02T21:37:08Z

examples/data_tracks/publisher.py

+            frame = rtc.DataTrackFrame(payload=data, user_timestamp=int(time.time() * 1000))
+            track.try_push(frame)
+        except rtc.PushFrameError as e:
+            logging.error("Failed to push frame: %s", e)


🟡 Publisher example logs empty string for PushFrameError because exception doesn't pass message to super().init

PushFrameError.__init__ at livekit-rtc/livekit/rtc/data_track.py:42-43 stores the message as self.message but never calls super().__init__(message). When the publisher example formats the exception with %s, Python calls str(e) which returns str(self.args) — an empty tuple () renders as empty string. The log output will be "Failed to push frame: " with no actual error information. The subscriber example at examples/data_tracks/subscriber.py:27 correctly uses e.message, demonstrating the intended access pattern.

Suggested change

logging.error("Failed to push frame: %s", e)

logging.error("Failed to push frame: %s", e.message)

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ladvoc and others added 18 commits March 5, 2026 11:43

Pin submodule

c4e12dd

Update proto

61f4815

Add initial examples

159a198

Initial FFI implementation

1c603d5

Hide proto type

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Improve error reporting

0d4c5d2

More generic type signature for try_push

671777d

Data class for frame

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Data class for track info

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Frame convenience methods

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Doc strings

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generated protobuf

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Refine example

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Format

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Pin RTC

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End-to-end test for data tracks

19a592a

Patch proto generation script

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generated protobuf

b98deb3

1egoman reviewed Mar 19, 2026

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ladvoc added 3 commits March 19, 2026 16:21

Pin submodule

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Expose buffer size option

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ladvoc added 6 commits March 24, 2026 14:13

Rename event

9e6784e

Expose unpublished event

b54ac64

Pin submodule

38a5ebb

Generate proto

b75cb34

Add explicit request to receive next frame for subscription

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Format

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ladvoc added 6 commits March 31, 2026 12:22

Generate proto

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Use error message

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Use keyword args for data track options

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Pin submodule

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Generate proto

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Rename type

56c5f5f

theomonnom reviewed Apr 1, 2026

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theomonnom reviewed Apr 2, 2026

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Upgrade FFI to v0.12.52

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theomonnom reviewed Apr 2, 2026

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ladvoc added 5 commits April 2, 2026 11:11

Generate proto

7ef3f20

Add aclose method to data track stream

7365294

Remove del finalizer

789507a

Remove unnecessary utility

94e88e9

Add standalone read method

e5aa64b

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ladvoc added 2 commits April 2, 2026 11:38

Fix elapsed time calculation

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Merge remote-tracking branch 'origin/main' into jacobgelman/bot-242-p…

a37ce60

…ython-client-implementation

theomonnom reviewed Apr 2, 2026

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theomonnom approved these changes Apr 2, 2026

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ladvoc added 4 commits April 2, 2026 14:21

Remove user timestamp helper methods

991b0b1

Make unpublish async for future proofing

9e0d018

Format

aef4689

Disable data tracks tests in CI for now

886495f

SFU used in CI testing doesn't currently have data tracks enabled. Tested locally and verified this case passes.

devin-ai-integration bot reviewed Apr 2, 2026

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ladvoc merged commit 8064880 into main Apr 2, 2026
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ladvoc deleted the jacobgelman/bot-242-python-client-implementation branch April 2, 2026 22:02

	logging.error("Failed to push frame: %s", e)
	logging.error("Failed to push frame: %s", e.message)

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ladvoc commented Mar 5, 2026

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pblazej commented Mar 16, 2026 •

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