fix: Android recorderController.stop() never completes#486
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rubenvde wants to merge 2 commits into
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Prevent encoder hang and ensure proper cleanup when stopping recordings. Add queueEosBuffer helper and proactively queue EOS in signalToStop if an input buffer is available, run MediaCodec callback on the handler, move completionCallback to finally, call release() after sending results or on error, and post result.success on the main looper for thread-safety.
Post the EOS check to the handler thread so EOS queuing runs on the same thread as onInputBufferAvailable, preventing race conditions when an input buffer is already available. Add an early return if the encoder is stopped. Move handlerThread.quitSafely() into the finally block and remove join() to avoid deadlocking when stopEncoder is invoked from callbacks; ensure completionCallback is invoked before quitting the thread.
Contributor
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Same issue! |
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This does not work for me it actually crashes the app when I call stop(). |
sherief4
approved these changes
Apr 18, 2026
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Description
Fixes a hang where
await recorderController.stop()on Android never completes, especially for recordings >30 seconds. This was introduced in the 2.0.x rewrite that replacedMediaRecorderwithAudioRecord+MediaCodec.Root causes fixed:
Deadlock in
stopEncoder()—stopEncoder()is called fromonOutputBufferAvailableon the handler thread, but it calledhandlerThread.join(), waiting for itself to finish. Removed thejoin()anduse
quitSafely()only.Race condition in
signalToStop()— EOS buffer queuing now runs on the handler thread viahandler.post {}, avoiding races withonInputBufferAvailablethat caused "MediaCodec discarded an unknownbuffer" errors.
release()called before async completion — For the non-WAV path,release()was called synchronously aftersignalToStop(), before the completion callback fired. Movedrelease()into the completioncallback.
result.success()called from wrong thread —sendRecordingResult()now posts to the main looper, since Flutter'sMethodChannel.Resultmust be called on the platform thread.completionCallbackswallowed on error — MovedcompletionCallback?.invoke()to afinallyblock instopEncoder()so the Flutter result is always resolved.Missing handler in
setCallback()—mediaCodec.setCallback()now passes thehandlerso callbacks run on the intendedHandlerThread.Checklist
fix:,feat:,docs:etc).docsand added dartdoc comments with///.examplesordocs.There's no test infrastructure in the project and the bug is a native Android threading issue that's difficult to unit test from Dart
Breaking Change?
Related Issues
#470