At first glance, it resembles a hybrid between a video codec identifier, a hierarchical version number, and a set of parameters. While no public standard defines this exact string, we can reverse-engineer plausible interpretations by breaking it into segments.
may fail to play streams using this exact string if the "HEVC Video Extensions" are not installed or if the hardware doesn't meet the Level 5.1 requirements. Playback Errors hvc1.1.6.l153.b0