Audio

See Audio and Video, the MediaPlayer state diagram, and the list of approved formats.

Audio in ApiDemos/Media/MediaPlayer

1. mediaplayer_1.xml creates four buttons.
2. strings.xml has the captions for the four buttons:
   1. Play Video from Local File
   2. Play Streaming Video
   3. Play Audio from Local File
   4. Play Audio from Resources
3. MediaPlayerDemo.java displays the four buttons. When a button is pressed, it uses an Intent object to go hunting for an Activity of class MediaPlayerDemo_Audio.
4. MediaPlayerDemo_Audio.java creates a MediaPlayer object and starts it.

An MP3 file

Go here and download the sound file China-sound--Lo-Fi-Preview-.mp3. Right-click on the res folder in the Eclipse Package Explorer, select New → Folder, and create a subfolder named raw. Rename the file china.mp3 (no uppercase or dashes) and drag it into raw.
Select how files should be imported into the project:
• Copy files
OK

Center the ToggleButton

In main.xml, change the LinearLayout to a RelativeLayout. Then give the ToggleButton the following attribute.

android:layout_centerInParent="true"

Source code in Audio.zip

1. AudioActivity.java
2. main.xml
3. strings.xml
4. china.mp3
5. AndroidManifest.xml

Things to try

1. Read the sound file from the web instead of from the res/raw directory. In the onClick method of the OnClickListener, change

   						mediaPlayer = MediaPlayer.create(AudioActivity.this, R.raw.china);	//calls prepare
   						if (mediaPlayer == null) {
   							Toast.makeText(AudioActivity.this, "couldn't create MediaPayer", Toast.LENGTH_LONG).show();
   							return;
   						}
   

   to

   						mediaPlayer = new MediaPlayer();
   						if (mediaPlayer == null) {
   							Toast.makeText(AudioActivity.this, "mediaPlayer is null", Toast.LENGTH_LONG).show();
   							return;
   						}
   
   						try {
   							mediaPlayer.setDataSource(
   								"http://oit2.scps.nyu.edu/~meretzkm/INFO1-CE9236/src/button/chinese.mp3"
   							);
   
   						}
   
   						catch (Exception e) {
   							Toast.makeText(AudioActivity.this, e.toString(), Toast.LENGTH_LONG).show();
   							return;
   						}
   
   						try {
   							mediaPlayer.prepare();
   						}
   
   						catch (Exception e) {
   							Toast.makeText(AudioActivity.this, e.toString(), Toast.LENGTH_LONG).show();
   							return;
   						}
   

   Surprisingly, it is not necessary to add the following element to the manifest element in AndroidManifest.xml.

   <uses-permission android:name="android.permission.INTERNET"/>
   

   If downloading the sound file causes an annoying delay after the button is pressed, download the sound file when the Activity is created.


2. setDataSource worked with a .mp3 file but threw an exception with a .mid file. Why? The .mid file worked when I put it in the res/raw directory.


3. Read the sound file from the phone’s file system. The file will not be part of the app. Place the sound file on your desktop, and then copy it into the /data directory of the file system of the Android Emulator with the following commands in the Mac Terminal or the Windows command prompt cmd.exe.

   cd Desktop
   adb shell ls -l /data
   

   adb push myfile.mp3 /data
   100 KB/s (219596 bytes in 2.128s)
   

   adb shell ls -l /data
   -rw-rw-rw- root     root       219596 2011-06-28 15:50 myfile.mp3
   

   Change the call to setDataSource to the following. It has a triple slash.

   							mediaPlayer.setDataSource("file:///data/myfile.mp3");
   



4. Display our current position in the audiofile.


5. Another audio demo: ApiDemos/Media/AudioFx.