[camera_android_x] implement CameraX RecordingStats and VideoRecordEvent APIs by Mairramer · Pull Request #13330 · flutter/packages

Mairramer · 2026-10-19T17:38:18Z

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…video recording

Mairramer · 2026-10-19T17:39:45Z

/gemini review

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Code Review

This pull request updates the Android CameraX implementation to resolve video recording discrepancies. It introduces Pigeon bindings for RecordingStats and VideoRecordEventStatus, and adds error-checking methods to VideoRecordEventFinalize. In AndroidCameraCameraX, startVideoCapturing now waits for the first frame to be recorded by monitoring status events, throwing a CameraException if finalization occurs prematurely. Additionally, stopVideoRecording now checks for finalization errors and throws a CameraException if any are found. Unit and integration tests have been updated to cover these new behaviors. There are no review comments to evaluate, and I have no feedback to provide.

gemini-code-assist

Code Review

This pull request addresses video recording duration discrepancies and short recording failures in the CameraX Android implementation. It introduces RecordingStats and VideoRecordEventStatus to wait for the first recorded frame before completing startVideoCapturing, and validates errors during finalization. Feedback suggests recreating the StreamQueue at the start of each recording session to prevent leftover finalize events from previous sessions from causing immediate failures, and defining error and hasError in VideoRecordEventFinalize as fields rather than asynchronous methods to avoid platform channel overhead.

gemini-code-assist · 2026-10-19T19:29:48Z

+abstract class VideoRecordEventFinalize extends VideoRecordEvent {
+  /// The error code of the finalization.
+  ///
+  /// See https://developer.android.com/reference/androidx/camera/video/VideoRecordEvent.Finalize#getError().
+  int getError();
+
+  /// Whether the recording finalized with an error.
+  ///
+  /// See https://developer.android.com/reference/androidx/camera/video/VideoRecordEvent.Finalize#hasError().
+  bool hasError();
+}


Since VideoRecordEventFinalize is an immutable event, its error and hasError properties are constant once the event is created. Instead of defining them as asynchronous methods (getError() and hasError()), which require asynchronous platform channel calls every time they are accessed, you can define them as fields (similar to how you did for RecordingStats). This avoids unnecessary asynchronous IPC overhead and allows synchronous access to these properties in Dart (e.g., event.hasError and event.error instead of await event.hasError() and await event.getError()).

abstract class VideoRecordEventFinalize extends VideoRecordEvent { /// The error code of the finalization. /// /// See https://developer.android.com/reference/androidx/camera/video/VideoRecordEvent.Finalize#getError(). late int error; /// Whether the recording finalized with an error. /// /// See https://developer.android.com/reference/androidx/camera/video/VideoRecordEvent.Finalize#hasError(). late bool hasError; }

Looks like there is an established pattern for doing this, so I'm pro. Is there some reason we can't do this here?

No issues with that. I'll make the change.

…e on start

camsim99

Overall this LGTM! This will be a great improvement for the plugin and its testing :)

One thing I'll point out is that ideally, we fix the issue of not knowing the video duration so we don't have to guess the delay in tests. flutter/flutter#101785 seems to cover that, which I'd be interested in prioritizing (bumped P3 --> P2). I'm ok with doing that here, though ideally, we plan for the smallest delay we can (left a comment about this re:350)

camsim99 · 2026-10-26T21:20:00Z

+abstract class VideoRecordEventFinalize extends VideoRecordEvent {
+  /// The error code of the finalization.
+  ///
+  /// See https://developer.android.com/reference/androidx/camera/video/VideoRecordEvent.Finalize#getError().
+  int getError();
+
+  /// Whether the recording finalized with an error.
+  ///
+  /// See https://developer.android.com/reference/androidx/camera/video/VideoRecordEvent.Finalize#hasError().
+  bool hasError();
+}


Looks like there is an established pattern for doing this, so I'm pro. Is there some reason we can't do this here?

camsim99 · 2026-10-26T21:23:07Z

-    expect(duration, lessThan(postStopTime));
+    expect(duration, greaterThan(1700));
+    final int delta = (duration - 2000).abs();
+    expect(delta, lessThan(350));


Why 350? Is this the lowest value you found experimentally?

Can you also leave a comment about the value you pick and link to flutter/flutter#101785?

Actually, 350 ms isn't the lowest value observed experimentally. I tested this on my S23 and measured intervals of around 100–200 ms. I chose 350 ms to leave some headroom for timer jitter and dropped frames, and avoid flakiness on CI.

I'll add a code comment to clarify this.

…properties synchronously via pigeon

Mairramer · 2026-10-26T23:16:19Z

Overall this LGTM! This will be a great improvement for the plugin and its testing :)

One thing I'll point out is that ideally, we fix the issue of not knowing the video duration so we don't have to guess the delay in tests. flutter/flutter#101785 seems to cover that, which I'd be interested in prioritizing (bumped P3 --> P2). I'm ok with doing that here, though ideally, we plan for the smallest delay we can (left a comment about this re:350)

I can take on flutter/flutter#101785 next. It'll be next in my queue, and I enjoy working on native code, so I'm happy to pick this one up.

… integration test

camsim99

Thanks for the quick updates :) and your interest in flutter/flutter#101785!!

feat: implement CameraX RecordingStats and VideoRecordEvent APIs for …

6e32dc6

…video recording

Mairramer added the CICD Run CI/CD label Oct 19, 2026

gemini-code-assist Bot reviewed Oct 19, 2026

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github-actions Bot added p: camera platform-android labels Oct 19, 2026

Mairramer changed the title ~~[WIP] implement CameraX RecordingStats and VideoRecordEvent APIs~~ [camera_android_x] implement CameraX RecordingStats and VideoRecordEvent APIs Oct 19, 2026

Merge branch 'main' into fix-camerax-video-recording-duration

72ec33f

Mairramer marked this pull request as ready for review October 19, 2026 19:27

gemini-code-assist Bot reviewed Oct 19, 2026

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fix: ignore leftover video recording events by recreating stream queu…

eba3888

…e on start

Mairramer requested a review from camsim99 October 20, 2026 11:51

Merge branch 'main' into fix-camerax-video-recording-duration

5efe1d0

camsim99 mentioned this pull request Oct 26, 2026

[camera_android_camerax] Expose recorded video duration from CameraX RecordingStats via camera_platform_interface flutter/flutter#195368

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camsim99 reviewed Oct 26, 2026

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refactor: update VideoRecordEventFinalize to pass error and hasError …

bfa519a

…properties synchronously via pigeon

fix: add tolerance for video duration check in camera_android_camerax…

4c2bced

… integration test

Mairramer requested a review from camsim99 October 26, 2026 23:19

chore: bump camera package version and update dependency constraints

29b7dc6

camsim99 approved these changes Oct 29, 2026

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camsim99 added the autosubmit Merge PR when tree becomes green via auto submit App label Oct 29, 2026

auto-submit Bot merged commit faab724 into flutter:main Oct 29, 2026
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Mairramer commented Oct 19, 2026 •

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