у код для функции видеозаписи с медиа-рекордером., Но он выдает Io Exception, Illegal State Exception, я много раз искал в google, но нет правильного объяснения этому, мой код

public class Simple extends Activity {
    /** Called when the activity is first created. */
    Button button,button2;
    MediaRecorder recorder;
    Camera camera;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        button=(Button) findViewById(R.id.button1);
        button2=(Button) findViewById(R.id.button2);

    camera=Camera.open();
    Camera.Parameters params = camera.getParameters();
    camera.setParameters(params);


    button.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub

            Toast.makeText(getBaseContext(), "Video Start", Toast.LENGTH_LONG).show();

            String mFileName = Environment.getExternalStorageDirectory().getAbsolutePath();
            mFileName += "/temp.3mp4";

            recorder=new MediaRecorder();


            recorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
            recorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
            recorder.setVideoFrameRate(10);
            recorder.setVideoSize(200, 300);
            recorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
            recorder.setMaxDuration(50000);
            recorder.setMaxFileSize(5000000);
            recorder.setOutputFile(mFileName);
            try {
                recorder.prepare();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Toast.makeText(getBaseContext(),e.toString(), Toast.LENGTH_LONG).show();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Toast.makeText(getBaseContext(),e.toString(), Toast.LENGTH_LONG).show();
            }
            }
    });

    button2.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Toast.makeText(getBaseContext(), "Video Stop", Toast.LENGTH_LONG).show();
            recorder.stop();
        }
    });

}

}