我使用下面的代码录制了一个视频，它录制得很好，但是当它播放视频时，它播放的是颠倒的。

我尝试在 mrec.prepare(); 之前设置 mrec.setOrientationHint(180) 但它没有用。有什么提示吗？

import java.io.File;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import android.app.Activity;
import android.hardware.Camera;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.Window;

/**
 * @author SANA HASSAN
 */
public class CameraSurfaceView extends Activity {

    private Preview mPreview;
    private MediaRecorder mrec = new MediaRecorder();
    private int cameraId = 0;
    private Camera mCamera;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);

        mPreview = new Preview(this);
        setContentView(mPreview);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        menu.add(0, 0, 0, "Start");
        menu.add(0, 1, 0, "Stop");
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case 0:
                try {
                    startRecording();
                } 
                catch (Exception e) {
                    e.printStackTrace();
                    mrec.release();
                }
                break;

            case 1: 
                mrec.stop();
                mrec.release();
                mrec = null;
                break;

            default:
                break;
        }
        return super.onOptionsItemSelected(item);
    }

    protected void startRecording() throws IOException  {

        mrec = new MediaRecorder();
        mrec.setCamera(mCamera);
        mCamera.unlock();
        File directory = new File(Environment.getExternalStorageDirectory()+"/NICUVideos");
        directory.mkdirs();
        mrec.setAudioSource( MediaRecorder.AudioSource.MIC);
        mrec.setVideoSource(MediaRecorder.VideoSource.CAMERA);
        mrec.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        mrec.setOutputFile(Environment.getExternalStorageDirectory()+"/NICUVideos/"+System.currentTimeMillis()+".mp4"); 
        mrec.setPreviewDisplay(mPreview.getHolder().getSurface());
        mrec.setVideoSize(640, 480);

        Method[] methods = mrec.getClass().getMethods();
        for (Method method: methods){
            try{
                if(method.getName().equals("setAudioEncodingBitRate")){
                    method.invoke(mrec, 12200);
                }
                else if(method.getName().equals("setVideoEncodingBitRate")){
                    method.invoke(mrec, 800000);
                }
                else if(method.getName().equals("setAudioSamplingRate")){
                    method.invoke(mrec, 8000);
                }
                else if(method.getName().equals("setVideoFrameRate")){
                    method.invoke(mrec, 20);
                }
            }
            catch (IllegalArgumentException e) {
                e.printStackTrace();
            } 
            catch (IllegalAccessException e) {
                e.printStackTrace();
            } 
            catch (InvocationTargetException e) {
                e.printStackTrace();
            }
        }
        mrec.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        mrec.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
        mrec.setMaxDuration(60000); // 60 seconds
        mrec.setMaxFileSize(10000000); // Approximately 10 megabytes
        mrec.prepare();
        mrec.start();
    }

    protected void stopRecording() {
        mrec.stop();
        mrec.release();
        mCamera.release();
    }

    class Preview extends SurfaceView implements SurfaceHolder.Callback {
        SurfaceHolder mHolder;
        Activity activity;

        Preview(Activity activity) {
            super(activity);
            mHolder = getHolder();
            mHolder.addCallback(this);
            mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        }

        public void surfaceCreated(SurfaceHolder holder) {

            Camera.CameraInfo info=new Camera.CameraInfo();
            for (int i=0; i < Camera.getNumberOfCameras(); i++) {
                Camera.getCameraInfo(i, info);
                if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
                    mCamera=Camera.open(i);
                    cameraId = i;
                }
            }

            try {
               mCamera.setPreviewDisplay(holder);
            } catch (IOException exception) {
                mCamera.release();
                mCamera = null;
            }
        }

        public void surfaceDestroyed(SurfaceHolder holder) {
            mCamera.stopPreview();
            mCamera.release();
            mCamera = null;
        }

        public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
            setCameraDisplayOrientation(mCamera);
            mCamera.startPreview();
        }

        public void setCameraDisplayOrientation(Camera camera) {
            Camera.CameraInfo info = new Camera.CameraInfo();
            Camera.getCameraInfo(cameraId, info);

            int rotation = CameraSurfaceView.this.getWindowManager().getDefaultDisplay().getRotation();
            int degrees = 0;
            switch (rotation) {
                case Surface.ROTATION_0: degrees = 0; break;
                case Surface.ROTATION_90: degrees = 90; break;
                case Surface.ROTATION_180: degrees = 180; break;
                case Surface.ROTATION_270: degrees = 270; break;
            }

            int result;
            if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
                result = (info.orientation + degrees) % 360;
                result = (360 - result) % 360;  // compensate the mirror
            } else {  // back-facing
                result = (info.orientation - degrees + 360) % 360;
            }
            Log.d(Vars.TAG, "Result = "+result);
            camera.setDisplayOrientation(result);
        }
    }

}

最佳答案

此问题是由于 Android 仅通过设置一些元数据而不是实际旋转视频来处理旋转，然后一些播放软件忽略了该设置。

如 the docs 中所述:

Note that some video players may choose to ignore the compostion matrix in a video during playback.

您的选择是使用不同的播放软件来理解正在设置的元数据，或者在视频以正确的方向录制后重新编码。从您的描述中不清楚哪一个是您的情况下更好的解决方案。

关于Android 相机录制视频但播放颠倒，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/11426230/