Android :: Video Recording / Source And Encoder Giving Error

When I add video source and video encoder, it gives error in recoreder.prepare() (prepare failed) while the same code is working only for audio. I am not finding what I am doing wrong.

setContentView(R.layout.camera);
preview=(SurfaceView)findViewById(R.id.surface);
previewHolder=preview.getHolder(); previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
recorder = new MediaRecorder();
String url = "/sdcard/dcim/test.3gp";
camera = Camera.open();
Camera.Parameters parameters = camera.getParameters();
parameters.setPreviewSize(352, 288);
parameters.set("orientation", "portrait");
camera.setParameters(parameters);
recorder.setAudioSource(MediaRecorder.AudioSource.MIC); recorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setOutputFile(url);
recorder.setVideoFrameRate(15);
recorder.setVideoSize(480, 320);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB); recorder.setVideoEncoder(MediaRecorder.VideoEncoder.H263);
recorder.prepare(); recorder.start(); Thread.sleep(100000);
recorder.stop(); recorder.release();
} catch (Exception e) { e.getMessage(); }