Outline

• Playing Video and Audio Android
• Quiz
• The camera on Android

Announcements

• Next Monday is Practice Final Day. (The Practice Final is up.)
• The Wednesday after that is Project Demo Day.
• You should bring lent-out on phones on Demo day. After demo-ing stuff, you need to return the phone.
• The neat ideas fair is this Tuesday, Dec. 7.
• I will try to check people's presentations before class. i.e., in the time frame 10-12.
• You should send me an e-mail to let me know you are presenting, so I try to check your presentation out.

Multimedia on Android

• The foundation of Android's multimedia platform is based on OpenCore from PacketVideo.
• We will begin looking at these libraries by looking at how to play an MP3 file.
• The steps to write such a program involve:
  1. Put the mp3 file in the res/raw directory of the project. You will have to create this folder.
  2. Create a new instance of MediaPlayer and reference your MP3 by calling MediaPlayer.create().
  3. Call the MediaPlayer method start().
• We will make a simple app with a single button which will cause an mp3 file with the radio broadcast of Orson Welles' War of the Worlds to play. (Public domain from the 1930s).

main.xml

• Here is the main.xml for our project (this is where we define the button):

  <?xml version="1.0" encoding="utf-8"?>
  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="vertical"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      >
  <TextView  
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" 
      android:text="Test Media Player"
      />
   <Button
      android:id="@+id/playwarworlds" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" 
      android:text="Play Orson Welles"
      />
  </LinearLayout>
  

AudioTestActivity.java

• Here is the source code of our activity:

  import android.view.View;
  import android.view.View.OnClickListener;
  import android.media.MediaPlayer;
  import android.media.MediaPlayer.*;
  
  public class AudioTestActivity extends Activity {
  
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.main);
          View button = findViewById(R.id.playwarworlds);
          button.setOnClickListener( new OnClickListener() {
              public void onClick(View v) 
              {
                  MediaPlayer player = MediaPlayer.create(AudioTestActivity.this, R.raw.warworlds);
                  player.start();
                  player.setOnCompletionListener(new OnCompletionListener() 
                  {
                      public void onCompletion(MediaPlayer m) 
                      {
                      }
                  });
              }
          });
      }
  }
  

• A MediaPlayer enters a prepare state before playing which gets the media ready to be played (might be remote).
• MediaPlayer also has pause(), resume() and stop() (returns to before prepare was called) methods which could be hooked up to buttons

Playing Video

• We next test out playing video in Android.
• To do this we will create a small app which will play the first copyrighted film ever (Fred Ott's sneeze).
• We will put a file fred_ott.mp4 on the sdcard of the emulator using the Emulator's File Explorer.
• Our app will then play this file.

main.xml

• Here is our main.xml file:

  <?xml version="1.0" encoding="utf-8"?>
  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="vertical"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      >
  <VideoView 
      android:id="@+id/video" 
      android:layout_width="320px" 
      android:layout_height="240px" 
  />
  <Button
      android:id="@+id/play"
      android:text="Play Fred Ott" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" 
      />
  </LinearLayout>
  

VideoTestActivity.java

• The activity is reasonably straightforward:

  package org.pollett;
  
  import android.app.Activity;
  import android.graphics.PixelFormat;
  import android.os.Bundle;
  import android.view.View;
  import android.widget.MediaController;
  import android.widget.VideoView;
  
  public class VideoTestActivity extends Activity 
  {
      @Override
      public void onCreate(Bundle savedInstanceState) 
      {
          super.onCreate(savedInstanceState);
          getWindow().setFormat(PixelFormat.TRANSLUCENT);
          setContentView(R.layout.main);
          video = (VideoView)findViewById(R.id.video);
          video.setVideoPath("/mnt/sdcard/fred_ott.mp4");
          mc = new MediaController(this);
          mc.setMediaPlayer(video);
          video.setMediaController(mc);
          video.requestFocus();
  
          View button = findViewById(R.id.play);
          button.setOnClickListener(new View.OnClickListener() 
          {
              public void onClick(View v)
              {
                  VideoTestActivity.this.mc.show();
              }
          }
          );
  
      }
      
      VideoView video;
      MediaController mc;
  }
  

Quiz

Android's Camera

• To use an Android phone's camera you make use of the Camera class.
• This class has a method takePicture(Camera.ShutterCallback shutter, Camera.PictureCallback raw, Camera.PictureCallback jpeg) which actually takes a picture
• Notice you provide three callbacks to the method to control how the picture is taken: the first has a method that is called when the shutter is opened, the second two have methods to get the reaw and jpeg data from the camera.
• Let's look at an app that takes a picture. To begin, we need to add the following lines to the AndroidManifest.xml file in order for anything to work:

  <uses-permission android:name="android.permission.CAMERA" />
  <uses-feature android:name="android.hardware.camera" />
  <uses-feature android:name="android.hardware.camera.autofocus" />
  

main.xml

• Our layout just has a SurfaceView in which the camera data will live:

  <?xml version="1.0" encoding="utf-8"?>
  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="vertical"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      >
  	<SurfaceView android:id="@+id/surface"
  		android:layout_weight="1" android:layout_width="fill_parent"
  		android:layout_height="fill_parent">
  	</SurfaceView>
  </LinearLayout>
  

• The Java Code for our app will consist of an extension of Activity, CameraTest, and a class implementing Camera.PictureCallback, called ImageCaptureCallback which we will use to save JPEG files.

CameraTest.java

package org.pollett;

import java.text.SimpleDateFormat;
import java.util.Date;

import android.app.Activity;
import android.content.ContentValues;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore.MediaColumns;
import android.provider.MediaStore.Images.ImageColumns;
import android.provider.MediaStore.Images.Media;
import android.view.KeyEvent;
import android.view.MenuItem;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class CameraTest extends Activity implements SurfaceHolder.Callback {

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().setFormat(PixelFormat.TRANSLUCENT);
        setContentView(R.layout.main);
        
        /*
           the surface holder is used to manage what is actually displayed 
           on the surface 
         */
        surfaceView = (SurfaceView)findViewById(R.id.surface);
        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(this);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);            
    }

    /**
       Adds menu to view the photos that have already been taken.
     */
    public boolean onCreateOptionsMenu(android.view.Menu menu)
    {
        MenuItem item = menu.add(0, 0, 0, "View Photos?");
        item.setOnMenuItemClickListener(
            new MenuItem.OnMenuItemClickListener() {
                public boolean onMenuItemClick(MenuItem item) {
                    Intent intent = new Intent(Intent.ACTION_VIEW,
                            CameraTest.this.targetResource);
                    startActivity(intent);
                    return true;
                }
            }
        );
        return true;
    }

    /**
        Pushing the center button takes a picture,
        and sets up the callback for saving it.
     */
    public boolean onKeyDown(int keyCode, KeyEvent event)
    {
        ImageCaptureCallback camDemo = null;
        if(keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
            try {
                String filename= this.timeStampFormat.format(new Date());
                ContentValues values = new ContentValues();
                values.put(MediaColumns.TITLE, filename);
                values.put(ImageColumns.DESCRIPTION, "Image from emulator");
                Uri uri = getContentResolver().insert(
                        Media.EXTERNAL_CONTENT_URI, values);
                camDemo = new ImageCaptureCallback(
                        getContentResolver().openOutputStream(uri)
                        );
            } catch (Exception e) {
                
            }
        }
        if(keyCode == KeyEvent.KEYCODE_BACK) {
            return super.onKeyDown(keyCode, event);
        }
        if(keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
            this.camera.takePicture(this.mShutterCallback, 
                    this.mPictureCallbackRaw, camDemo);
            return true;
        }
        return false;
    }
  
    /**
       Start the camera after the surface is created
     */
    public void surfaceCreated(SurfaceHolder holder) {
                this.camera = Camera.open();
    }
    
    /**
       Actually, display the camera data in the surface
     */
    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        if(this.isPreviewRunning) {
            this.camera.stopPreview();
        }
        Camera.Parameters p = this.camera.getParameters();
        p.setPreviewSize(w, h);
        try {
            this.camera.setPreviewDisplay(holder);
            this.camera.startPreview();
            this.isPreviewRunning = true;
        } catch (Exception e) {
            
        }
    }


    /**
       Shut things down when surface goes away
     */
    public void surfaceDestroyed(SurfaceHolder holder) {
        this.camera.stopPreview();
        this.isPreviewRunning = false;
        this.camera.release();
    }

    //Handles raw data when picture taken
    Camera.PictureCallback mPictureCallbackRaw = new Camera.PictureCallback() {
        public void onPictureTaken(byte[] data, Camera c) {
            CameraTest.this.camera.startPreview();
        }
    };

    Camera.ShutterCallback mShutterCallback = new Camera.ShutterCallback() {
        public void onShutter() {
            //could be used to play a sound
        }
    };
   
    Camera camera;
    boolean isPreviewRunning = false;
    SimpleDateFormat timeStampFormat = new SimpleDateFormat("yyyyMMddHHmmssSS");
    SurfaceView surfaceView;
    SurfaceHolder surfaceHolder;
    Uri targetResource = Media.EXTERNAL_CONTENT_URI;
    
    
}

ImageCaptureCallback.java

package org.pollett;

import java.io.OutputStream;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;

public class ImageCaptureCallback implements PictureCallback {
    
    public ImageCaptureCallback(OutputStream fileoutputStream)
    {
        this.fileoutputStream = fileoutputStream;
    }
    
    public void onPictureTaken(byte[] data, Camera camera) {
        try {
            this.fileoutputStream.write(data);
            this.fileoutputStream.flush();
            this.fileoutputStream.close();
            
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
    OutputStream fileoutputStream;
}

Demo

• In the emulator when you run the app, it shows a moving test pattern:
  
• The picture gallery that you can get to using the menu looks like:
• In File Explorer you can actually see the jpeg files in a DCIM folder on the sdcard.