IllegalStateException on mediarecorder.prepare - Android videostreaming over socket

I am trying to stream video over socket.

Here is the code snippet -

    serverSocket = new ServerSocket(serverPort);
    receiverSocket = new Socket();
    receiverSocket.connect(new InetSocketAddress(serverIP, serverPort));
  //  receiverSocket.setReceiveBufferSize(500000);
   receiverSocket.setSoTimeout(3000);
    senderSocket = serverSocket.accept();
   // senderSocket.setReceiveBufferSize(500000);
    ParcelFileDescriptor pfd = ParcelFileDescriptor.fromSocket(senderSocket);
    FileDescriptor fd = pfd.getFileDescriptor();
    mMediaRecorder.setOutputFile(fd);
  //  mMediaRecorder.setOutputFile(filePath);
    mMediaRecorder.setVideoEncodingBitRate(10000000);
    mMediaRecorder.setVideoFrameRate(30);
    mMediaRecorder.setVideoSize(mVideoSize.getWidth(), mVideoSize.getHeight());
    mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
    mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
    mMediaRecorder.setOrientationHint(orientation);
    mMediaRecorder.prepare();

However I get IllegalStateException on call to prepare().

java.lang.IllegalStateException
    at android.media.MediaRecorder._prepare(Native Method)
    at android.media.MediaRecorder.prepare(MediaRecorder.java:742)
    at com.example.i047468.videostreaming.VideoRecordingAsyncTask.setUpMediaRecorder(VideoRecordingAsyncTask.java:90)
    at com.example.i047468.videostreaming.VideoRecordingAsyncTask.doInBackground(VideoRecordingAsyncTask.java:52)

When I set the output file to "filePath" on sdcard all goes fine. So I guess it's not able to set the outputfile to socket fd and hence prepare fails.

How do I get this working? What is going wrong here? Exception stack is not revealing much.

Regards, Shailesh