java nio 底层sdk 缓冲区溢出，不定期出现。kit生命周期正常

[zcwfeng]

java.lang.NullPointerException: Attempt to invoke virtual method 'int java.nio.ByteBuffer.limit()' on a null object reference
at com.ksyun.media.rtc.kit.RtcWrapper.sendAudio(RtcWrapper.java:88)
at com.ksyun.media.rtc.kit.RTCIO$RTCAudioSinkPin.onFrameAvailable(RTCIO.java:78)
at com.ksyun.media.rtc.kit.RTCIO$RTCAudioSinkPin.onFrameAvailable(RTCIO.java:66)
at com.ksyun.media.streamer.framework.SrcPin.onFrameAvailable(SrcPin.java:44)
at com.ksyun.media.streamer.filter.audio.b.a(AudioBufSrcPin.java:20)
at com.ksyun.media.streamer.filter.audio.b.onFrameAvailable(AudioBufSrcPin.java:16)
at com.ksyun.media.streamer.framework.PinAdapter$1.onFrameAvailable(PinAdapter.java:20)
at com.ksyun.media.streamer.framework.SrcPin.onFrameAvailable(SrcPin.java:44)
at com.ksyun.media.streamer.filter.audio.b.a(AudioBufSrcPin.java:20)
at com.ksyun.media.streamer.filter.audio.b.onFrameAvailable(AudioBufSrcPin.java:16)
at com.ksyun.media.streamer.framework.PinAdapter$1.onFrameAvailable(PinAdapter.java:20)
at com.ksyun.media.streamer.framework.SrcPin.onFrameAvailable(SrcPin.java:44)
at com.ksyun.media.streamer.filter.audio.b.a(AudioBufSrcPin.java:20)
at com.ksyun.media.streamer.filter.audio.b.onFrameAvailable(AudioBufSrcPin.java:16)
at com.ksyun.media.streamer.capture.AudioCapture$a.run(AudioCapture.java:345)