要实现Android多视频布局和编辑视频的功能，可以使用Android提供的MediaCodec和MediaMuxer等API。下面是一个示例代码，演示了如何将多个视频文件合并到一个视频上，并且设置视频的布局。

首先，在AndroidManifest.xml文件中添加以下权限：

然后，创建一个名为VideoEditor的类，并添加以下代码：

import android.media.MediaCodec;
import android.media.MediaExtractor;
import android.media.MediaFormat;
import android.media.MediaMuxer;
import android.util.Log;

import java.io.IOException;
import java.nio.ByteBuffer;

public class VideoEditor {
    private static final String TAG = "VideoEditor";

    public static void mergeVideos(String[] videoPaths, String outputPath, int outputWidth, int outputHeight) {
        try {
            MediaMuxer muxer = new MediaMuxer(outputPath, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);

            // 设置输出视频的尺寸和格式
            MediaFormat outputFormat = MediaFormat.createVideoFormat("video/avc", outputWidth, outputHeight);
            outputFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);
            outputFormat.setInteger(MediaFormat.KEY_BIT_RATE, 6000000);
            outputFormat.setInteger(MediaFormat.KEY_FRAME_RATE, 30);
            outputFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 1);

            // 添加视频轨道
            int videoTrackIndex = muxer.addTrack(outputFormat);
            muxer.start();

            // 逐个读取并写入视频文件
            for (String videoPath : videoPaths) {
                MediaExtractor extractor = new MediaExtractor();
                extractor.setDataSource(videoPath);

                int trackIndex = selectTrack(extractor, "video/");
                if (trackIndex >= 0) {
                    extractor.selectTrack(trackIndex);
                    MediaFormat format = extractor.getTrackFormat(trackIndex);

                    // 获取视频的宽高
                    int videoWidth = format.getInteger(MediaFormat.KEY_WIDTH);
                    int videoHeight = format.getInteger(MediaFormat.KEY_HEIGHT);

                    // 计算视频在输出视频中的位置和大小
                    int left = (outputWidth - videoWidth) / 2;
                    int top = (outputHeight - videoHeight) / 2;
                    int right = left + videoWidth;
                    int bottom = top + videoHeight;

                    // 创建解码器
                    MediaCodec decoder = MediaCodec.createDecoderByType("video/avc");
                    decoder.configure(format, null, null, 0);
                    decoder.start();

                    // 创建编码器
                    MediaCodec encoder = MediaCodec.createEncoderByType("video/avc");
                    encoder.configure(outputFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
                    encoder.start();

                    // 创建输入和输出缓冲区
                    ByteBuffer[] decoderInputBuffers = decoder.getInputBuffers();
                    ByteBuffer[] decoderOutputBuffers = decoder.getOutputBuffers();
                    ByteBuffer[] encoderInputBuffers = encoder.getInputBuffers();
                    ByteBuffer[] encoderOutputBuffers = encoder.getOutputBuffers();

                    // 循环解码并编码每一帧
                    boolean isEOS = false;
                    long presentationTimeUs = 0;
                    while (!isEOS) {
                        int inputIndex = decoder.dequeueInputBuffer(10000);
                        if (inputIndex >= 0) {
                            ByteBuffer inputBuffer = decoderInputBuffers[inputIndex];
                            int sampleSize = extractor.readSampleData(inputBuffer, 0);
                            if (sampleSize < 0) {
                                decoder.queueInputBuffer(inputIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
                                isEOS = true;
                            } else {
                                presentationTimeUs = extractor.getSampleTime();
                                decoder.queueInputBuffer(inputIndex, 0, sampleSize, presentationTimeUs, 0);
                                extractor.advance();
                            }
                        }

                        int outputIndex = decoder.dequeueOutputBuffer(info, 10000);
                        if (outputIndex >= 0) {
                            ByteBuffer outputBuffer = decoderOutputBuffers[outputIndex];
                            MediaFormat bufferFormat = decoder.getOutputFormat(outputIndex);

                            // 渲染输出的视频帧
                            renderVideoFrame(outputBuffer, bufferInfo.presentationTimeUs, left, top, right, bottom);

                            // 编码输出的视频帧
                            int inputBufferIndex = encoder.dequeueInputBuffer(10000);
                            if (inputBufferIndex >= 0) {
                                ByteBuffer inputBuffer = encoderInputBuffers[inputBufferIndex];
                                inputBuffer.clear