Performance Differences between H.264 and H.265 Video Compression Standards in the Context of a Remote Tower Optical System

Abstract

Video compression is a crucial technology for efficient transmission of digital video, reducing the size of the relayed data stream while maintaining visual quality. This study examines the performance differences between H.264 and H.265 video compression standards in the context of a Remote Tower Optical System (RTOS), with a focus on detection range performance of an approaching aircraft during landing. While H.264 is widely adopted and well-established, H.265 offers improved compression efficiency and reduced bandwidth requirements, though its impact on operational visual clarity remains unclear. Recordings of 49 medium-sized aircraft landings at a German regional airport were analyzed, using the same high definition camera to generate two simultaneous video streams using H.264 and H.265 respectively. This ensured consistency in camera hardware, resolution, lighting, environmental conditions, and perspective. For each recording, the timing of the first objective pixel appearance was documented. The objective analysis revealed that H.264 demonstrated earlier pixel appearance in approximately 61% of cases, while H.265 either matched or outperformed H.264 in the remaining instances. Even though time differences were marginal, in the range of a couple of seconds, they were statistically significant. In a second step, a succeeding subjective evaluation aimed to assess the operational significance in terms of air traffic controllers' ability to detect H.264 vs. H.265 differences. Out of the pool of 49 landings, a subset of 12 video sample pairs was created, and evenly distributed into two groups of 6. In one group H.264 performed better and showed earlier pixel appearances whereas in the other group timings were identical or H.265 showed an earlier first pixel. 10 air traffic control officers assessed the detection range, and found no significant difference between the H.264 or H.265 coded videos. Given these findings, more modern state of the art codices like H.265 may help to improve compression efficiency and reduce bandwidth consumption without affecting the operational detection range performance.