要将Android中的两个视频并排合并，可以使用Android的MediaCodec类和MediaMuxer类来实现。下面是一个使用这两个类的代码示例：

import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaCodecList;
import android.media.MediaFormat;
import android.media.MediaMuxer;
import android.os.Environment;

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

public class VideoMergeUtil {
    private static final String OUTPUT_VIDEO_MIME_TYPE = "video/avc";
    private static final String OUTPUT_VIDEO_FILE_NAME = "merged_video.mp4";
    private static final int OUTPUT_VIDEO_BIT_RATE = 2000000;
    private static final int OUTPUT_VIDEO_FRAME_RATE = 30;
    private static final int OUTPUT_VIDEO_IFRAME_INTERVAL = 5;

    public static void mergeVideos(String videoFilePath1, String videoFilePath2) {
        try {
            MediaExtractor extractor1 = new MediaExtractor();
            extractor1.setDataSource(videoFilePath1);

            MediaExtractor extractor2 = new MediaExtractor();
            extractor2.setDataSource(videoFilePath2);

            int videoTrackIndex1 = getMediaTrackIndex(extractor1, "video/");
            int videoTrackIndex2 = getMediaTrackIndex(extractor2, "video/");

            MediaFormat videoFormat1 = extractor1.getTrackFormat(videoTrackIndex1);
            MediaFormat videoFormat2 = extractor2.getTrackFormat(videoTrackIndex2);

            MediaCodec codec = MediaCodec.createDecoderByType(videoFormat1.getString(MediaFormat.KEY_MIME));

            MediaMuxer muxer = new MediaMuxer(Environment.getExternalStorageDirectory() + "/" + OUTPUT_VIDEO_FILE_NAME,
                    MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);

            int videoTrackIndex = muxer.addTrack(videoFormat1);

            muxer.start();

            ByteBuffer[] inputBuffers = codec.getInputBuffers();
            ByteBuffer[] outputBuffers = codec.getOutputBuffers();

            extractor1.selectTrack(videoTrackIndex1);
            extractor2.selectTrack(videoTrackIndex2);

            MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();

            while (true) {
                int inputBufferIndex = codec.dequeueInputBuffer(10000);

                if (inputBufferIndex >= 0) {
                    ByteBuffer inputBuffer = inputBuffers[inputBufferIndex];
                    int sampleSize = extractor1.readSampleData(inputBuffer, 0);

                    if (sampleSize < 0) {
                        codec.queueInputBuffer(inputBufferIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
                        break;
                    } else {
                        long presentationTimeUs = extractor1.getSampleTime();
                        codec.queueInputBuffer(inputBufferIndex, 0, sampleSize, presentationTimeUs, 0);
                        extractor1.advance();
                    }
                }

                int outputBufferIndex = codec.dequeueOutputBuffer(info, 10000);

                if (outputBufferIndex >= 0) {
                    ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];
                    muxer.writeSampleData(videoTrackIndex, outputBuffer, info);
                    codec.releaseOutputBuffer(outputBufferIndex, false);
                }

                if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
                    break;
                }
            }

            while (true) {
                int inputBufferIndex = codec.dequeueInputBuffer(10000);

                if (inputBufferIndex >= 0) {
                    ByteBuffer inputBuffer = inputBuffers[inputBufferIndex];
                    int sampleSize = extractor2.readSampleData(inputBuffer, 0);

                    if (sampleSize < 0) {
                        codec.queueInputBuffer(inputBufferIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
                        break;
                    } else {
                        long presentationTimeUs = extractor2.getSampleTime();
                        codec.queueInputBuffer(inputBufferIndex, 0, sampleSize, presentationTimeUs, 0);
                        extractor2.advance();
                    }
                }

                int outputBufferIndex = codec.dequeueOutputBuffer(info, 10000);

                if (outputBufferIndex >= 0) {
                    ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];
                    muxer.writeSampleData(videoTrackIndex, outputBuffer, info);
                    codec.releaseOutputBuffer(outputBufferIndex, false);
                }

                if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
                    break;
                }
            }

            muxer.stop();
            muxer.release();
            codec.stop();
            codec.release();
            extractor1.release();
            extractor2.release();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static int getMediaTrackIndex(MediaExtractor extractor, String mimeType) {
        int trackCount = extractor.getTrackCount();

        for (int i = 0;