Viewport Margins for 360-Degree Immersive Video

360-degree video delivery is more and more widespread. New use cases are constantly emerging and make it a promising video technology for Extended Reality applications. Viewport Dependent Delivery (VDD) is an established technique used for saving network bit rate when transmitting omnidirectional video. One of the hardest challenges in VDD of 360-degree video is how to ensure that the video quality in the user’s viewport is always the highest possible, independent of the user’s head motion speed and span of motion. This paper introduces the concept of viewport margins. These can be understood as an extra high-quality spatial safety area around the user’s viewport. Viewport margins provide a better user experience for the receiver by reducing the Motion to High Quality Delay and the percentage of low-quality viewport seen by the user. We provide simulation results that show the advantage of using viewport margins for real-time low-delay VDD of 360-degree video.