public void EndCall()
{
if (_audioChannel != null)
{
_audioChannel.SampleReady -= AudioChannelSampleReady;
_audioChannel.Close();
_audioChannel = null;
}
_rtpManager.OnRemoteVideoSampleReady -= EncodedVideoSampleReceived;
_rtpManager.OnRemoteAudioSampleReady -= RemoteAudioSampleReceived;
_rtpManager.Close();
}