mTXVideoJoiner = new TXVideoJoiner(mContext);  

// Set the video source list. A return value < 0 indicates invalid or unsupported formats in the input files.  
if (mTXVideoJoiner.setVideoPathList(videoSourceList) < 0) {  
    return;  
}  

// Set a listener to track concatenation progress and completion.  
mTXVideoJoiner.setVideoJoinerListener(new TXVideoJoinerListener() {  
    @Override  
    public void onJoinProgress(float progress) {}  

    @Override  
    public void onJoinComplete(TXJoinerResult result) {}  
});  

// Start concatenation. Specify the output resolution and path.  
// Note: If all input videos share the same format and resolution, concatenation is fast.  
// Otherwise, re-encoding is required, which slows the process.  
mTXVideoJoiner.joinVideo(TXVideoEditConstants.VIDEO_COMPRESSED_540P, mOutputPath);  

mTXVideoJoiner = new TXVideoJoiner(mContext);  

// Set the video source list.  
if (mTXVideoJoiner.setVideoPathList(videoSourceList) < 0) {  
    return;  
}  

// Set a listener for preview progress and completion.  
mTXVideoJoiner.setTXVideoPreviewListener(new TXVideoPreviewListener() {  
    @Override  
    public void onPreviewProgress(int time) {}  

    @Override  
    public void onPreviewFinished() {}  
});  

// Prepare the preview view.  
TXVideoEditConstants.TXPreviewParam param = new TXVideoEditConstants.TXPreviewParam();  
param.videoView = mVideoView;  
param.renderMode = TXVideoEditConstants.PREVIEW_RENDER_MODE_FILL_EDGE;  
mTXVideoJoiner.initWithPreview(param);  

// Start preview.  
mTXVideoJoiner.startPlay();  

mTXVideoJoiner = new TXVideoJoiner(mContext);  

// Set the video source list.  
if (mTXVideoJoiner.setVideoPathList(videoSourceList) < 0) {  
    return;  
}  

// Set a listener for split-screen merging progress and completion.  
mTXVideoJoiner.setVideoJoinerListener(new TXVideoJoinerListener() {  
    @Override  
    public void onJoinProgress(float progress) {}  

    @Override  
    public void onJoinComplete(TXJoinerResult result) {}  
});  

// Configure split-screen layout parameters.  
SplitScreenParam splitScreenParam = new SplitScreenParam();  
splitScreenParam.canvasWidth = 720;      // Canvas width during split-screen joining  
splitScreenParam.canvasHeight = 1280;    // Canvas height  
splitScreenParam.durationControlMode = DurationControlMode.ALIGNS_TO_LONGEST; // Duration matches the longest video  

// Define positions and sizes for each video on the canvas.  
TXAbsoluteRect rect1 = new TXAbsoluteRect();  
TXAbsoluteRect rect2 = new TXAbsoluteRect();  
splitScreenParam.rects.add(rect1);  
splitScreenParam.rects.add(rect2);  
mTXVideoJoiner.setSplitScreenList(splitScreenParam);  

// Set audio mixing weights for each video (e.g., video1: 100% volume, video2: 0%).  
List<Float> volumes = new LinkedList<>();  
volumes.add(1.0f);  
volumes.add(0.0f);  
mTXVideoJoiner.setVideoVolumes(volumes);  

// Start split-screen merging.  
// If input videos differ in format or resolution, re-encoding is required, which may slow the process.
mTXVideoJoiner.splitJoinVideo(TXVideoEditConstants.VIDEO_COMPRESSED_540P, mOutputPath);