create video file

RecordActivity.java

videoFile = new File(Environment.getExternalStorageDirectory().getPath() + "/Recorder/video.mp4");

		if (!videoFile.exists()) {
			try {
				videoFile.createNewFile();
				Log.i(LOG_TAG, "create videoFile success");
			} catch (Exception e) {
				Log.e(LOG_TAG, "create videoFile failed");
			}
		} else {
			Log.i(LOG_TAG, "videoFile exited already");
		}

		ffmpeg_link = videoFile.getAbsolutePath();