OutputThread: unlock mutex for CloseFilter()

src/output/Internal.hxx

@@ -383,7 +383,12 @@ private:
 	void Reopen();
 
 	AudioFormat OpenFilter(AudioFormat &format, Error &error_r);
+
+	/**
+	 * Mutex must not be locked.
+	 */
 	void CloseFilter();
+
 	void ReopenFilter();
 
 	/**

src/output/OutputThread.cxx

@@ -174,7 +174,10 @@ AudioOutput::Open()
 		FormatError(error, "Failed to open \"%s\" [%s]",
 			    name, plugin.name);
 
+		mutex.unlock();
 		CloseFilter();
+		mutex.lock();
+
 		fail_timer.Update();
 		return;
 	}
@@ -184,7 +187,10 @@ AudioOutput::Open()
 		FormatError(error, "Failed to convert for \"%s\" [%s]",
 			    name, plugin.name);
 
+		mutex.unlock();
 		CloseFilter();
+		mutex.lock();
+
 		fail_timer.Update();
 		return;
 	}
@@ -233,7 +239,10 @@ AudioOutput::ReopenFilter()
 {
 	Error error;
 
+	mutex.unlock();
 	CloseFilter();
+	mutex.lock();
+
 	const AudioFormat filter_audio_format =
 		OpenFilter(in_audio_format, error);
 	if (!filter_audio_format.IsDefined() ||