Android Camera - app passed NULL surface

Question

Whenever I run the cam_thread I get the error "app passed NULL surface". This code supposedly works on the HTC Incredible 1. I've reconfigured it slightly to run on a droid x. However I still get this error.

public class Android_Activity extends Activity 
{       
    Main_thread simulator;
    ToggleButton togglebutton;
    EditText ip_text;
    SensorManager sm = null;
    SurfaceView view;
    Sensors_thread the_sensors=null;
    String IP_address;
    Android_Activity the_app;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {       
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        view = new SurfaceView(this);       
        sm = (SensorManager) getSystemService(SENSOR_SERVICE);
        ip_text = (EditText) findViewById(R.id.IP_edit_txt);
        togglebutton = (ToggleButton) findViewById(R.id.CameraButton);
        togglebutton.setOnClickListener(new btn_listener());        
        the_app = this;
    }

    @Override
    protected void onResume() 
    {
        super.onResume();
    }

    protected void onStop()
    {
        super.onStop();
        simulator.stop_simu();
        this.finish();
    }

    private class btn_listener implements OnClickListener 
    {
        public void onClick(View v) 
        {       
            // Perform action on clicks
            if (togglebutton.isChecked()) 
            {
                IP_address = ip_text.getText().toString(); 

                simulator = new Main_thread(the_app, view, sm, IP_address);
                the_sensors = simulator.the_sensors;    
                sm.registerListener(the_sensors, 
                        SensorManager.SENSOR_ORIENTATION |SensorManager.SENSOR_ACCELEROMETER,
                        SensorManager.SENSOR_DELAY_UI);

                simulator.start();

                Toast.makeText(Android_Activity.this, "Start streaming" + IP_address, Toast.LENGTH_SHORT).show();
            } else 
            {
                simulator.stop_simu();
                sm.unregisterListener(the_sensors);
                Toast.makeText(Android_Activity.this, "Stop streaming", Toast.LENGTH_SHORT).show();
            }
        }
    }
}

Main Thread

package carl.IOIO_car;

import android.hardware.SensorManager;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class Main_thread extends Thread
{
    SurfaceView parent_context;
    SensorManager mSensorManager = null;
    Cam_thread the_cam;
    Sensors_thread the_sensors; 
    IOIO_Thread ioio_thread_;   
    String ip_address;
    Android_Activity the_app;

    public Main_thread(Android_Activity app, SurfaceView v, SensorManager m, String ip)
    {
        super();

        parent_context = v;     
        mSensorManager = m;
        ip_address = ip;
        the_app = app;
        Log.e("Debug Main", "IP is " + ip_address);
        the_cam = new Cam_thread(parent_context,ip_address);
        the_sensors = new Sensors_thread(mSensorManager,ip_address);
        ioio_thread_ = new IOIO_Thread(the_app, ip_address);
    }

    public void run() 
    {               
        //ioio_thread_.start(); 
        the_cam.start_thread();


    }

    public void stop_simu()
    {
        the_cam.stop_thread();
        the_sensors.stop_thread();
        //ioio_thread_.abort();
    }   
}

Cam_Thread

package carl.IOIO_car;

import java.io.ByteArrayOutputStream;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.List;

import android.graphics.Bitmap;
import android.hardware.Camera;
import android.hardware.Camera.PreviewCallback;
import android.util.Log;
import android.view.SurfaceView;

public class Cam_thread
{
    Camera mCamera;

    public static int HEADER_SIZE = 5;
    public static int DATAGRAM_MAX_SIZE = 1450 - HEADER_SIZE;   
    int frame_nb = 0;
    int size_packet_sent = 0;   
    InetAddress serverAddr;
    DatagramSocket socket;  

    Bitmap mBitmap;
    int[] mRGBData;
    int width_ima, height_ima;
    private static final String TAG = "IP_cam";

    SurfaceView parent_context;

    private boolean STOP_THREAD;
    String ip_address;

    public Cam_thread(SurfaceView context, String ip)
    {
        parent_context = context;

        ip_address = ip;
    }

    private void init()
    {
        try 
        {            
            serverAddr = InetAddress.getByName(ip_address);
            socket = new DatagramSocket();
            if (mCamera!=null){
                Log.e(TAG, "Nulling camera");
                mCamera.stopPreview();
                mCamera.setPreviewCallback(null);
                mCamera.release();
                mCamera=null;
        }
            if(mCamera == null){
            mCamera = Camera.open();        
            Log.e(TAG, "Setting up camera");
            Camera.Parameters parameters = mCamera.getParameters(); 
            //get a list of supported preview sizes and assign one
            List<Camera.Size> previewSizes = parameters.getSupportedPreviewSizes();
            Camera.Size previewSize = previewSizes.get(0);
            parameters.setPreviewSize(previewSize.width, previewSize.height);
            //Set Frame rate
            parameters.setPreviewFrameRate(30);
            //Set Scene
            List<String> modes = parameters.getSupportedSceneModes();
            parameters.setSceneMode(modes.get(0));
            //Set focus mode
            List<String> focus = parameters.getSupportedFocusModes();
            parameters.setFocusMode(focus.get(0));
            //Apply parameters to camera object
            mCamera.setParameters(parameters);
            //Provide a surface
            if(parent_context.getHolder()==null)
                Log.e(TAG, "Its a null holder");
            Log.e("Debug", "Before");
            mCamera.setPreviewDisplay(parent_context.getHolder());          
            Log.e("Debug", "After");
            //Sets a call when preview data is available
            mCamera.setPreviewCallback(new cam_PreviewCallback());  
            Log.e(TAG, "Camera configured");
            //Start the preview
            Log.e(TAG, "Starting preview");
            mCamera.startPreview();
            /*
            parameters.setPreviewSize(320, 240);
            parameters.setPreviewFrameRate(30);
            parameters.setSceneMode(Camera.Parameters.SCENE_MODE_SPORTS);
            parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
            parameters.setColorEffect(Camera.Parameters.EFFECT_NONE);
            mCamera.setParameters(parameters);
            mCamera.setPreviewDisplay(parent_context.getHolder());          
            mCamera.setPreviewCallback(new cam_PreviewCallback());           

            Log.e(TAG, "Starting preview");
            mCamera.startPreview();
            */
            }
        } 
        catch (Exception exception) 
        {

            Log.e(TAG, "Error: ", exception);
        }
    }

    public void start_thread()
    {
        Log.e("Cam", "Started the Cam thread");
        init();
    }

    public void stop_thread()
    {
        STOP_THREAD = true;
        if (mCamera!=null){
            mCamera.stopPreview();
            mCamera.release();
            mCamera=null;
        }
        socket.close();
    }

    public void send_data_UDP()
    {
        Log.e(TAG, "Started sending cam data");
        if(mBitmap != null)
        {
            int size_p=0,i;     
            ByteArrayOutputStream byteStream = new ByteArrayOutputStream(); 

            mBitmap.compress(Bitmap.CompressFormat.JPEG, 50, byteStream);   // !!!!!!!  change compression rate to change packets size

            byte data[] = byteStream.toByteArray();
            Log.e(TAG, "SIZE: " + data.length);

            int nb_packets = (int) Math.ceil(data.length / (float)DATAGRAM_MAX_SIZE);
            int size = DATAGRAM_MAX_SIZE;

            /* Loop through slices */
            for(i = 0; i < nb_packets; i++) 
            {           
                if(i >0 && i == nb_packets-1) size = data.length - i * DATAGRAM_MAX_SIZE;

                /* Set additional header */
                byte[] data2 = new byte[HEADER_SIZE + size];
                data2[0] = (byte)frame_nb;
                data2[1] = (byte)nb_packets;
                data2[2] = (byte)i;
                data2[3] = (byte)(size >> 8);
                data2[4] = (byte)size;

                /* Copy current slice to byte array */
                System.arraycopy(data, i * DATAGRAM_MAX_SIZE, data2, HEADER_SIZE, size);        

                try 
                {           
                    size_p = data2.length;
                    DatagramPacket packet = new DatagramPacket(data2, size_p, serverAddr, 9000);
                    socket.send(packet);
                    Log.e(TAG, "Sent a cam frame!");
                } catch (Exception e) { Log.e(TAG, "Error: ", e);}  
            }   
            frame_nb++;

            if(frame_nb == 128) frame_nb=0; 
        }
    }    


    /* function converting image to RGB format taken from project: ViewfinderEE368  
     * http://www.stanford.edu/class/ee368/Android/ViewfinderEE368/
     * 
     * Copyright (C) 2007 The Android Open Source Project
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at
     *
     *      http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    static public void decodeYUV420SP(int[] rgb, byte[] yuv420sp, int width, int height) 
    {
        final int frameSize = width * height;

        for (int j = 0, yp = 0; j < height; j++) {
            int uvp = frameSize + (j >> 1) * width, u = 0, v = 0;
            for (int i = 0; i < width; i++, yp++) {
                int y = (0xff & ((int) yuv420sp[yp])) - 16;
                if (y < 0) y = 0;
                if ((i & 1) == 0) {
                    v = (0xff & yuv420sp[uvp++]) - 128;
                    u = (0xff & yuv420sp[uvp++]) - 128;
                }

                int y1192 = 1192 * y;
                int r = (y1192 + 1634 * v);
                int g = (y1192 - 833 * v - 400 * u);
                int b = (y1192 + 2066 * u);

                if (r < 0) r = 0; else if (r > 262143) r = 262143;
                if (g < 0) g = 0; else if (g > 262143) g = 262143;
                if (b < 0) b = 0; else if (b > 262143) b = 262143;

                rgb[yp] = 0xff000000 | ((r << 6) & 0xff0000) | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);
            }
        }
    }

    // Preview callback used whenever new frame is available...send image via UDP !!!
    private class cam_PreviewCallback implements PreviewCallback 
    {
        @Override
        public void onPreviewFrame(byte[] data, Camera camera)
        {
            if(STOP_THREAD == true)
            {
                mCamera.setPreviewCallback(null);
                mCamera.stopPreview();
                mCamera.release();
                mCamera = null;
                return;
            }

            if (mBitmap == null)        //create Bitmap image first time
            {
                Camera.Parameters params = camera.getParameters();
                width_ima = params.getPreviewSize().width;
                height_ima = params.getPreviewSize().height;                      
                mBitmap = Bitmap.createBitmap(width_ima, height_ima, Bitmap.Config.RGB_565);
                mRGBData = new int[width_ima * height_ima];
            }

            decodeYUV420SP(mRGBData, data, width_ima, height_ima);
            mBitmap.setPixels(mRGBData, 0, width_ima, 0, 0, width_ima, height_ima);

            send_data_UDP();
        }
    }

}

Manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="carl.IOIO_car"
      android:versionCode="1"
      android:versionName="1.0">
          <uses-sdk android:minSdkVersion="8" />

    <application android:icon="@drawable/icon" android:debuggable="true" android:label="@string/app_name">
        <activity android:name="carl.IOIO_car.Android_Activity"
                android:label="@string/app_name"
                  android:theme="@android:style/Theme.NoTitleBar.Fullscreen"
                  android:screenOrientation="landscape">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.UPDATE_DEVICE_STATS"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE"></uses-permission>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-feature android:name="android.hardware.camera" />
    <uses-feature android:name="android.hardware.camera.autofocus" />
</manifest>

This original code was written by Dr. Oros. http://www.cogsci.uci.edu/~noros/android_car.html

Answer 1

05-22 11:27:24.977 16750-16750/com.egomez.facedetection I/CameraActivity﹕ Switching Camera 05-22 11:27:25.219 16750-16750/com.egomez.facedetection D/Camera﹕ app passed NULL surface

To get rid of that error I had to get holder of SurfaceView (on the scenario I was attempting to fix was Switching from front camera to back camera and viceversa).

    public void switchCamera(){
    Log.i(TAG, "Switching Camera");
    if (mCamera != null) {
        mCamera.stopPreview();
        mCamera.release();
        //mCamera = null;
    }

    //swap the id of the camera to be used
    if (camId == Camera.CameraInfo.CAMERA_FACING_BACK) {
        camId = Camera.CameraInfo.CAMERA_FACING_FRONT;
    }else {
        camId = Camera.CameraInfo.CAMERA_FACING_BACK;
    }
    try {
        mCamera = Camera.open(camId);
        //mCamera.setDisplayOrientation(90);
        //You must get the holder of SurfaceView!!!
        mCamera.setPreviewDisplay(mView.getHolder());
        //Then resume preview...
        mCamera.startPreview();
    }
    catch (Exception e) { e.printStackTrace(); }
}

Hope it helps for anyone running into similar issue.

Answer 2

Thats not true. Just set up a small delay with a Handler and it works fine on Nexus too.

Just had the problem myself with black Pictures on those devices but with 1sec of delay everything works fine