Disable the sound of the record button

[sdroider]

I want to turn off the sound of pressing the record button. When you press the button, the sound "beep" occurs. How to turn off this sound?
If in the class CameraService.java remove mMediaRecorder.setAudioSource (MediaRecorder.AudioSource.MIC) then an error occurs!

FATAL EXCEPTION: main
Process: example.chatea.servicecamera, PID: 15568 java.lang.RuntimeException: Unable to start service example.chatea.servicecamera.CameraService@e8912c4 with null: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.Intent.getIntExtra(java.lang.String, int)' on a null object reference
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3057)
at android.app.ActivityThread.access$2200(ActivityThread.java:165)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1467)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:150)
at android.app.ActivityThread.main(ActivityThread.java:5546)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:684)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.Intent.getIntExtra(java.lang.String, int)' on a null object reference
at example.chatea.servicecamera.CameraService.onStartCommand(CameraService.java:89)
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3040)
at android.app.ActivityThread.access$2200(ActivityThread.java:165)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1467)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:150)
at android.app.ActivityThread.main(ActivityThread.java:5546)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:684)