要从Android MediaCodec的解码输出缓冲区中获取位图，可以使用以下代码示例：

import android.graphics.Bitmap;
import android.media.Image;
import android.media.MediaCodec;
import android.media.MediaCodec.BufferInfo;
import android.media.MediaFormat;
import android.media.MediaExtractor;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

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

public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback {
    private static final String TAG = "MainActivity";
    private static final String VIDEO_PATH = Environment.getExternalStorageDirectory() + "/video.mp4";

    private SurfaceView mSurfaceView;
    private Surface mSurface;
    private MediaExtractor mExtractor;
    private MediaCodec mDecoder;
    private BufferInfo mBufferInfo;
    private ByteBuffer[] mInputBuffers;
    private ByteBuffer[] mOutputBuffers;
    private int mInputBufferIndex;
    private int mOutputBufferIndex;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mSurfaceView = findViewById(R.id.surface_view);
        mSurfaceView.getHolder().addCallback(this);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        releaseDecoder();
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        mSurface = holder.getSurface();
        initDecoder();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        releaseDecoder();
    }

    private void initDecoder() {
        try {
            mExtractor = new MediaExtractor();
            mExtractor.setDataSource(VIDEO_PATH);
            int trackIndex = selectTrack(mExtractor);
            if (trackIndex < 0) {
                Log.e(TAG, "No video track found in " + VIDEO_PATH);
                return;
            }
            mExtractor.selectTrack(trackIndex);

            MediaFormat format = mExtractor.getTrackFormat(trackIndex);
            String mime = format.getString(MediaFormat.KEY_MIME);
            mDecoder = MediaCodec.createDecoderByType(mime);
            mDecoder.configure(format, mSurface, null, 0);
            mDecoder.start();

            mBufferInfo = new BufferInfo();
            mInputBuffers = mDecoder.getInputBuffers();
            mOutputBuffers = mDecoder.getOutputBuffers();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private int selectTrack(MediaExtractor extractor) {
        int numTracks = extractor.getTrackCount();
        for (int i = 0; i < numTracks; i++) {
            MediaFormat format = extractor.getTrackFormat(i);
            String mime = format.getString(MediaFormat.KEY_MIME);
            if (mime.startsWith("video/")) {
                return i;
            }
        }
        return -1;
    }

    private void releaseDecoder() {
        if (mDecoder != null) {
            mDecoder.stop();
            mDecoder.release();
            mDecoder = null;
        }
        if (mExtractor != null) {
            mExtractor.release();
            mExtractor = null;
        }
    }

    private Bitmap getBitmapFromBuffer(ByteBuffer buffer, int width, int height) {
        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        buffer.rewind();
        bitmap.copyPixelsFromBuffer(buffer);
        return bitmap;
    }

    private void decodeFrame() {
        mInputBufferIndex = mDecoder.dequeueInputBuffer(-1);
        if (mInputBufferIndex >= 0) {
            ByteBuffer inputBuffer = mInputBuffers[mInputBufferIndex];
            int sampleSize = mExtractor.readSampleData(inputBuffer, 0);
            long presentationTimeUs = mExtractor.getSampleTime();
            mDecoder.queueInputBuffer(mInputBufferIndex, 0, sampleSize, presentationTimeUs, 0);
            mExtractor.advance();
        }

        mOutputBufferIndex = mDecoder.dequeueOutputBuffer(mBufferInfo, -1);
        if (mOutputBufferIndex >= 0) {
            if ((mBufferInfo.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
                mDecoder.releaseOutputBuffer(mOutputBufferIndex, false);
            } else {
                Image image = mDecoder.getOutputImage(mOutputBufferIndex);
                if (image != null) {
                    int width = image.getWidth();
                    int height = image.getHeight();
                    Image.Plane[] planes = image.getPlanes();
                    ByteBuffer buffer = planes[0].getBuffer();
                    Bitmap bitmap = getBitmapFromBuffer(buffer, width, height);
                    // 使用位图进行进一步处理