  We present a HoloLens 2 server application for streaming device data via TCP
in real time. The server can stream data from the four grayscale cameras, depth
sensor, IMU, front RGB camera, microphone, head tracking, eye tracking, and
hand tracking. Each sent data frame has a timestamp and, optionally, the
instantaneous pose of the device in 3D space. The server allows downloading
device calibration data, such as camera intrinsics, and can be integrated into
Unity projects as a plugin, with support for basic upstream capabilities. To
achieve real time video streaming at full frame rate, we leverage the video
encoding capabilities of the HoloLens 2. Finally, we present a Python library
for receiving and decoding the data, which includes utilities that facilitate
passing the data to other libraries. The source code, Python demos, and
precompiled binaries are available at https://github.com/jdibenes/hl2ss.
