You can use digital zoom in both live video and archive view modes.

You can zoom in the video image by stretching it with two fingers.

If it is not a PTZ camera, you can also zoom in by double-tapping the screen. Video will be zoomed in to x3 size.

You cannot make the video smaller than its original size. You can zoom in up to x5 size.

When you zoom in the video, you can select the part of the frame that you want to view by moving your finger outside the video viewing area.