You can use the Multimedia API to create a custom class that extends javax.microedition.media.protocol.DataSource to customize how data is read from your application to the BlackBerry® device media player. DataSource provides a SourceStream implementation which uses SourceStream.read() to transfer data.

1. Import the required classes and interfaces.

   import java.lang.Thread;
   import java.io.InputStream;
   import java.io.OutputStream;
   import javax.microedition.media.protocol.DataSource;
   import javax.microedition.media.protocol.SourceStream;
   import javax.microedition.io.ContentConnection;
   import javax.microedition.io.file.FileConnection;
   import net.rim.device.api.io.SharedInputStream;

2. Create a custom class that extends the abstract javax.microedition.media.protocol.DataSource class.

   public final class LimitedRateStreamingSource extends DataSource {

3. Declare instance fields that you will need for your DataSource implementation. The following fields were taken from the sample bufferedplaybackdemo project.

   /** The stream connection over which media content is passed */
   private ContentConnection _contentConnection;
   
   /** An input stream shared between several readers */
   private SharedInputStream _readAhead;
   
   /** A stream to the buffered resource */
   private LimitedRateSourceStream _feedToPlayer;
   
   /** The MIME type of the remote media file */
   private String _forcedContentType;
   
   /** The thread which retrieves the remote media file */
   private ConnectionThread _loaderThread;
   
   /** The local save file into which the remote file is written */
   private FileConnection _saveFile;
   
   /** A stream for the local save file */
   private OutputStream _saveStream;

4. Create a constructor for your custom class.

   LimitedRateStreamingSource(String locator) {
       super(locator);
   }
   

5. Implement javax.microedition.media.protocol.DataSource.connect(). This method is used to open a connection to the source described by the locator and initiate communication. Please refer to the the sample bufferedplaybackdemo project for additional details.

   public void connect() throws IOException {

6. Implement javax.microedition.media.protocol.DataSource.disconnect(). This method is used to close the connection to the source described by the locator and free resources used to maintain the connection. Please refer to the the sample bufferedplaybackdemo project for additional details.

   public void disconnect() {

7. Implement javax.microedition.media.protocol.DataSource.getContentType(). This method is used to retrieve a String that describes the content-type of the media that the source is providing. Please refer to the the sample bufferedplaybackdemo project for additional details.

   public String getContentType() {
       return _feedToPlayer.getContentDescriptor().getContentType();
   }

8. Implement javax.microedition.media.protocol.DataSource.getStreams(). This method is used to retrieve a collection of streams that this source manages. Please refer to the the sample bufferedplaybackdemo project for additional details.

   public SourceStream[] getStreams() {
       return new SourceStream[] { _feedToPlayer };
   }

9. Implement javax.microedition.media.protocol.DataSource.start(). This method is used to initiate data-transfer and must be called before data is available for reading. Please refer to the the sample bufferedplaybackdemo project for additional details.

   public void start() throws IOException {
       if (_saveStream != null) {
           _loaderThread = new ConnectionThread();
           _loaderThread.start();
       }
   }

10. Implement javax.microedition.media.protocol.DataSource.stop(). This method is used to stop the data-transfer. Please refer to the the sample bufferedplaybackdemo project for additional details.

    public void stop() throws IOException {
        // Set the boolean flag to stop the thread
        _stop = true;
    }

11. Create an class that implements javax.microedition.media.protocol.SourceStream. In this example, an inner class is used to provide a stream to the buffered media resource. Please refer to the the sample bufferedplaybackdemo project for additional details.

    private final class LimitedRateSourceStream implements SourceStream {

12. Implement getSeekType() to return if media is seekable or not during playback.

    public int getSeekType() {
        return SEEKABLE_TO_START;
    }

13. Within this inner class, implement javax.microedition.media.protocol.SourceStream.read(). This method is used to reads data from the input stream into an array of bytes. Please refer to the the sample bufferedplaybackdemo project for additional details.

    public int read(byte[] bytes, int off, int len) throws IOException {

14. Within this inner class, you may also want to implement seek(), tell(), and close(). Please refer to the the sample bufferedplaybackdemo project for additional details.
15. Close off the inner class and create another inner class that extends java.lang.Thread. Use this when creating a thread to download the remote file and write it to the local file. Please refer to the the sample bufferedplaybackdemo project for additional details.

    private final class ConnectionThread extends Thread {