How to use Mediaprojection library in android to capture screen and convert into mp4 file?

问题

Since android 5.0 they are providing mediaprojection library to capture screen content. but sample demo application provided by them is not clear. U can find sample app here. In that application they are projecting captured screen using virtualdisplay method

private void setUpVirtualDisplay() {
    Log.i(TAG, "Setting up a VirtualDisplay: " +
            mSurfaceView.getWidth() + "x" + mSurfaceView.getHeight() +
            " (" + mScreenDensity + ")");
    mVirtualDisplay = mMediaProjection.createVirtualDisplay("ScreenCapture",
            mSurfaceView.getWidth(), mSurfaceView.getHeight(), mScreenDensity,
            DisplayManager.VIRTUAL_DISPLAY_FLAG_AUTO_MIRROR,
            mSurface, null, null);
    mButtonToggle.setText(R.string.stop);
}

I want to convert captured screen into mp4 file for my screen recording application. Please help me to get through this.

回答1:

here is sample code refference from

public class MainActivity extends AppCompatActivity {

    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("/sdcard/capture.mp4");
    }
}

回答2:

You're passing the Surface from a SurfaceView into createVirtualDisplay(). Replace that with the Surface from a MediaRecorder.

回答3:

Look at this POST. There is a good explanation on how to use MediaProjection API to actually record the screen to an mp4 file on the external storage. This solution uses the MediaRecorder to store the video.

You can find another solution on the page of Matt Snider. There the MediaMuxer is used to store the video on to the external storage. But note that the output of the MediaMuxer is not streamable.

来源：https://stackoverflow.com/questions/29501618/how-to-use-mediaprojection-library-in-android-to-capture-screen-and-convert-into