CameraX: NullPointerException when trying to record video

I have a simple video recording app set up like this:

VideoCaptureConfig videoCaptureConfig = new VideoCaptureConfig.Builder()
        .setLensFacing(CameraX.LensFacing.BACK)
        .setTargetAspectRatio(new Rational(16, 9))
        .setTargetRotation(viewFinder.getDisplay().getRotation())
        .build();
videoCapture = new VideoCapture(videoCaptureConfig);

CameraX.bindToLifecycle(this, preview, videoCapture);

…

 videoCapture.startRecording(file, new VideoCapture.OnVideoSavedListener() { ... });

which leads to the following NullPointerException:

    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.AudioRecord.startRecording()' on a null object reference
        at androidx.camera.core.VideoCapture.startRecording(VideoCapture.java:262)
        at androidx.camera.core.VideoCapture.startRecording(VideoCapture.java:236)
        at de.twometer.stream.cam.CameraActivity.lambda$onCreate$1$CameraActivity(CameraActivity.java:77)
        at de.twometer.stream.cam.-$$Lambda$CameraActivity$MvEAnqH_74mMgbMAcSbB_pNoJ3k.onClick(Unknown Source:4)
        at android.view.View.performClick(View.java:7352)
        at android.view.View.performClickInternal(View.java:7318)
        at android.view.View.access$3200(View.java:846)
        at android.view.View$PerformClick.run(View.java:27807)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7037)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:965)

I am using CameraX version 1.0.0-alpha04

[Twometer]

Nevermind, I am just stupid and forgot to request audio permission.

[temcguir]

androidx.camera.video.VideoCapture should not require the audio permission unless you call PendingRecording.withAudioEnabled().

Please see this guide on how to use the new VideoCapture API.