帮我写javacv代码基于ffmpeg将两个视频合成一个

好的，我可以帮你写这个JavaCV代码，可以基于FFmpeg合成两个视频。以下是JavaCV的示例代码：

import org.bytedeco.ffmpeg.global.avcodec;
import org.bytedeco.ffmpeg.global.avformat;
import org.bytedeco.ffmpeg.global.avutil;
import org.bytedeco.javacpp.*;
import org.bytedeco.javacv.*;

public class VideoMergeExample {
    public static void main(String[] args) {
        // 定义第一个视频文件
        String video1Path = "/path/to/video1.mp4";
        OpenCVFrameGrabber grabber1 = new OpenCVFrameGrabber(video1Path);
        try {
            grabber1.start();
        } catch (FrameGrabber.Exception e) {
            e.printStackTrace();
        }

        // 定义第二个视频文件
        String video2Path = "/path/to/video2.mp4";
        OpenCVFrameGrabber grabber2 = new OpenCVFrameGrabber(video2Path);
        try {
            grabber2.start();
        } catch (FrameGrabber.Exception e) {
            e.printStackTrace();
        }

        // 定义输出视频文件
        FFmpegFrameRecorder recorder = new FFmpegFrameRecorder("/path/to/output.mp4", grabber1.getImageWidth(), grabber1.getImageHeight(), grabber1.getAudioChannels());
        recorder.setFormat("mp4");
        recorder.setVideoCodec(avcodec.AV_CODEC_ID_H264);
        recorder.setFrameRate(grabber1.getFrameRate());
        recorder.setPixelFormat(avutil.AV_PIX_FMT_YUV420P); // 必须设置像素格式
        
        try {
            recorder.start();
        } catch (FrameRecorder.Exception e) {
            e.printStackTrace();
        }

        // 读取第一个视频并写入输出视频中
        Frame frame1 = null;
        try {
            while ((frame1 = grabber1.grab()) != null) {
                recorder.record(frame1);
            }
        } catch (FrameGrabber.Exception e) {
            e.printStackTrace();
        } catch (FrameRecorder.Exception e) {
            e.printStackTrace();
        }

        // 读取第二个视频并写入输出视频中
        Frame frame2 = null;
        try {
            while ((frame2 = grabber2.grab()) != null) {
                recorder.record(frame2);
            }
        } catch (FrameGrabber.Exception e) {
            e.printStackTrace();
        } catch (FrameRecorder.Exception e) {
            e.printStackTrace();
        }

        // 释放资源
        try {
            recorder.stop();
            grabber1.stop();
            grabber2.stop();
        } catch (FrameRecorder.Exception e) {
            e.printStackTrace();
        } catch (FrameGrabber.Exception e) {
            e.printStackTrace();
        }
    }
}

请注意替换视频路径和输出路径。如果有任何疑问，请随时与我联系。