Synchronized Smartphone Video Recording System of Depth and RGB Image Frames with Sub-millisecond Precision

In this paper, we propose a recording system with high time synchronization (sync) precision which consists of heterogeneous sensors such as smartphone, depth camera, IMU, etc. Due to the general interest and mass adoption of smartphones, we include at least one of such devices into our system. This heterogeneous system requires a hybrid synchronization for the two different time authorities: smartphone and MCU, where we combine a hardware wired-based trigger sync with software sync. We evaluate our sync results on a custom and novel system mixing active infra-red depth with RGB camera. Our system achieves sub-millisecond precision of time sync. Moreover, our system exposes every RGB-depth image pair at the same time with this precision. We showcase a configuration in particular but the general principles behind our system could be replicated by other projects.