Question
I'm using Tizen's low-level audio capabilities, and while most functionality works correctly, my application crashes when attempting to call Unprepare on an AudioPlayback instance. Here's the relevant code snippet:
playback.Prepare();
var finishedNormally = await tcs.Task;
Log.D("Unpreparing");
_audioPlaybacks[channel].Unprepare();
Log.D("Unprepared");
The crash occurs specifically during the Unprepare call, as shown in the error log:
E/PULSEAUDIO( 5535): thread-mainloop.c: pa_threaded_mainloop_stop(160) > Assertion '!in_worker(m)' failed at pulse/thread-mainloop.c:160, function pa_threaded_mainloop_stop(). Aborting.
I/DOTNET_LAUNCHER( 5535): onSigabrt called
Has anyone successfully used the Unprepare method in low-level audio operations without encountering this crash?
Answer
Problem Understanding
The crash occurs due to a thread synchronization issue in PulseAudio when attempting to unprepare an audio playback. The error suggests that the Unprepare operation is being called from an incorrect thread context.
Solution Methods
- Thread-Safe Unprepare Operation: The most effective solution is to execute the Unprepare call within a separate Task to ensure proper thread synchronization.
Code Examples
Here's the modified code that resolves the crash:
playback.Prepare();
if(DebugLog) Log.D("Prepared");
var finishedNormally = await tcs.Task;
if (DebugLog) Log.D($"TCS set .. finished normally {finishedNormally}");
var audioPlayback = _audioPlaybacks[channel];
await Task.Run(() => {
try {
Log.D("Unpreparing");
audioPlayback.Unprepare();
Log.D("Unprepared");
} catch (Exception ex) {
Log.E(ex);
}
});
_audioPlaybacks[channel] = null;
return finishedNormally;
Additional Tips
- Always handle exceptions when working with audio operations
- Consider adding debug logging to track the audio playback state
- Ensure proper cleanup of audio resources to prevent memory leaks
