Can not turn off audio

[kevin406972552]

If audio mode is false.
fail log:
E/AndroidRuntime(18814): FATAL EXCEPTION: Thread-1373
E/AndroidRuntime(18814): Process: com.example.camera_with_rtmp_demo, PID: 18814
E/AndroidRuntime(18814): java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaCodec.start()' on a null object reference
E/AndroidRuntime(18814): at com.pedro.encoder.BaseEncoder.initCodec(BaseEncoder.java:56)
E/AndroidRuntime(18814): at com.pedro.encoder.BaseEncoder.start(BaseEncoder.java:44)
E/AndroidRuntime(18814): at com.whelksoft.camera_with_rtmp.RtmpCameraConnector.startEncoders(RtmpCameraConnector.kt:243)
E/AndroidRuntime(18814): at com.whelksoft.camera_with_rtmp.RtmpCameraConnector.onConnectionSuccessRtmp(RtmpCameraConnector.kt:492)
E/AndroidRuntime(18814): at net.ossrs.rtmp.SrsFlvMuxer$2.run(SrsFlvMuxer.java:290)
E/AndroidRuntime(18814): at java.lang.Thread.run(Thread.java:818)