This may be based on this technology from Qualcomm [1, 2]. The first article talks about privacy too.
A similar thing is mentioned in [3]: "In response to a question about the ethics of an always-on camera, Asghar noted that Qualcomm attempts to “make sure that the data that is there stays on the device.” Any images captured by the camera will be kept on the device itself. “As you know, these are capabilities that add to experiences…and [we want] to make sure that we have solutions that are abiding by all the privacy parameters and everything,” Asghar added."
[1] https://www.technologyreview.com/2017/03/29/243161/qualcomm-...
[2] https://rebootingcomputing.ieee.org/images/files/pdf/iccv-20...
[3] https://www.pcworld.com/article/556345/qualcomms-next-snapdr...
