Question

我尝试从下面的链接测试一个关于屏幕记录的示例代码，我修改了一些代码来禁用录制音频。

http://www.truiton.com/2015/05/capture-record-android-screen-using-mediaprojection-apis/

我在Android Studio V1.3中测试代码，但是我收到以下错误，文件capture.mp4为空。

我不确定是否必须在真正的手机中测试代码？你可以帮帮我吗？谢谢！

错误信息

09-22 06:41:50.250    2167-2167/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: screencapture.truiton.com.myapplication, PID: 2167
    java.lang.RuntimeException: stop failed.
            at android.media.MediaRecorder.stop(Native Method)
            at screencapture.truiton.com.myapplication.MainActivity.onToggleScreenShare(MainActivity.java:93)
            at screencapture.truiton.com.myapplication.MainActivity$1.onClick(MainActivity.java:55)
            at android.view.View.performClick(View.java:4780)
            at android.widget.CompoundButton.performClick(CompoundButton.java:120)
            at android.view.View$PerformClick.run(View.java:19866)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5257)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

源代码

package screencapture.truiton.com.myapplication;

public class MainActivity extends Activity {

    private static final String TAG = "MainActivity";
    private static final int PERMISSION_CODE = 1;
    private int mScreenDensity;
    private MediaProjectionManager mProjectionManager;
    private static final int DISPLAY_WIDTH = 480;
    private static final int DISPLAY_HEIGHT = 640;
    private MediaProjection mMediaProjection;
    private VirtualDisplay mVirtualDisplay;
    private MediaProjectionCallback mMediaProjectionCallback;
    private ToggleButton mToggleButton;
    private MediaRecorder mMediaRecorder;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        DisplayMetrics metrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(metrics);
        mScreenDensity = metrics.densityDpi;

        mMediaRecorder = new MediaRecorder();
        initRecorder();
        prepareRecorder();

        mProjectionManager = (MediaProjectionManager) getSystemService
                (Context.MEDIA_PROJECTION_SERVICE);

        mToggleButton = (ToggleButton) findViewById(R.id.toggle);
        mToggleButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onToggleScreenShare(v);
            }
        });

        mMediaProjectionCallback = new MediaProjectionCallback();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mMediaProjection != null) {
            mMediaProjection.stop();
            mMediaProjection = null;
        }
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode != PERMISSION_CODE) {
            Log.e(TAG, "Unknown request code: " + requestCode);
            return;
        }
        if (resultCode != RESULT_OK) {
            Toast.makeText(this,
                    "Screen Cast Permission Denied", Toast.LENGTH_SHORT).show();
            mToggleButton.setChecked(false);
            return;
        }
        mMediaProjection = mProjectionManager.getMediaProjection(resultCode, data);
        mMediaProjection.registerCallback(mMediaProjectionCallback, null);
        mVirtualDisplay = createVirtualDisplay();
        mMediaRecorder.start();
    }

    public void onToggleScreenShare(View view) {
        if (((ToggleButton) view).isChecked()) {
            shareScreen();
        } else {
            mMediaRecorder.stop();
            mMediaRecorder.reset();
            Log.v(TAG, "Recording Stopped");
            stopScreenSharing();
            initRecorder();
            prepareRecorder();
        }
    }

    private void shareScreen() {
        if (mMediaProjection == null) {
            startActivityForResult(mProjectionManager.createScreenCaptureIntent(), PERMISSION_CODE);
            return;
        }
        mVirtualDisplay = createVirtualDisplay();
        mMediaRecorder.start();
    }

    private void stopScreenSharing() {
        if (mVirtualDisplay == null) {
            return;
        }
        mVirtualDisplay.release();
        //mMediaRecorder.release();
    }

    private VirtualDisplay createVirtualDisplay() {
        return mMediaProjection.createVirtualDisplay("MainActivity",
                DISPLAY_WIDTH, DISPLAY_HEIGHT, mScreenDensity,
                DisplayManager.VIRTUAL_DISPLAY_FLAG_AUTO_MIRROR,
                mMediaRecorder.getSurface(), null /*Callbacks*/, null /*Handler*/);
    }

    private class MediaProjectionCallback extends MediaProjection.Callback {
        @Override
        public void onStop() {
            if (mToggleButton.isChecked()) {
                mToggleButton.setChecked(false);
                mMediaRecorder.stop();
                mMediaRecorder.reset();
                Log.v(TAG, "Recording Stopped");
                initRecorder();
                prepareRecorder();
            }
            mMediaProjection = null;
            stopScreenSharing();
            Log.i(TAG, "MediaProjection Stopped");
        }
    }

    private void prepareRecorder() {
        try {
            mMediaRecorder.prepare();
        } catch (IllegalStateException e) {
            e.printStackTrace();
            finish();
        } catch (IOException e) {
            e.printStackTrace();
            finish();
        }
    }

    private void initRecorder() {

        //mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
        mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
        //mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

        mMediaRecorder.setVideoEncodingBitRate(512 * 1000);
        mMediaRecorder.setVideoFrameRate(30);
        mMediaRecorder.setVideoSize(DISPLAY_WIDTH, DISPLAY_HEIGHT);
        mMediaRecorder.setOutputFile(Environment.getExternalStorageDirectory() + "/capture.mp4");
    }
}

Answer 1

根据我的经验，Android模拟器允许从曲面读取（这是录制中唯一真正需要的东西）但由于框架Java代码中的错误/限制而无法编码视频（有时会截取屏幕截图）。主要有两个原因：

模拟器可能不会声明支持EGL_ANDROID_recordable扩展，这是MediaRecorder / MediaCodec所要求的。您可以通过执行以下命令来检查扩展支持：
```
adb shell dumpsys SurfaceFlinger | grep EGL_ANDROID_recordable
```
Android 6内置软件编码器支持的唯一颜色格式是YUV。来自仿真器GPU的视频缓冲区可能具有不同的格式。

请注意，上述限制并非专用于仿真器，也可能导致实际设备出现故障。您可以使用软件（在CPU上或通过GLES）进行格式转换，使用this answer中的方法大纲来解决这些问题，但无论如何，软件编码器的性能都会非常糟糕。

我可以在Android Studio中的模拟器中测试屏幕记录吗？

1 个答案: