Video stream is earlier than audio stream when converting rtmp to rtmp

Hello，I have used JavaCV from several months. Recentlly, I wanna to use it to transfer stream from one rtmp source A to another rtmp source B. but I find when I play B on Potplayer, Video stream is earlier than Audio stream in most scenarios. and the latency time is random. In rate case, Video Steam is sync with Audio Stream. The information I have: I use OBS to push a stream( from A local file ) to rtmp://A Init FFmpegFrameGrabber with rtmp://A and grabFrame(audio:true,video:true,processing:true,keyframe:false,data:false) Init FFmpegFrameRecorder with _rtmp://B and record(Frame) Play rtmp://B on Potplayer or VLC. The key code： ` try (FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(rtmpA);) { grabber.setOption("s_timeout", String.valueOf(10 * 1000_000)); grabber.setOption("rw_timeout", String.valueOf(10 * 1000_000)); grabber.start();

        try (FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(rtmpB, grabber.getImageWidth(), grabber.getImageHeight(), grabber.getAudioChannels())) {
            recorder.setVideoOption("crf", "18");

// recorder.setGopSize(2); recorder.setFrameRate(grabber.getVideoFrameRate()); recorder.setVideoCodec(AV_CODEC_ID_H264); recorder.setFormat("flv"); recorder.setMaxDelay(0); recorder.setInterleaved(true); recorder.setVideoOption("tune", "zerolatency"); recorder.setVideoOption("preset", "ultrafast"); recorder.setVideoOption("rtsp_transport", "tcp"); recorder.start(); Frame frame; while ((frame = grabber.grabFrame(true,true,true,false,false)) != null) { slideWindow.add(frame.clone()); } The method I have Tried: have tried many combinations of parameters。such as recorder.setTimestamp(grabber.getTimestamp)，recorder.setOption("vsync",xx). recorder.setFrameRate(a fixed number)but none of them worked. For the normal run of this basic function, I'm about to crash. Looking for your response.