Older devices (iPhone X and models before) do not have Apple Neural Engine onboard (or not accessible for developer). Without a dedicated Neural Engine for running Machine Learning algorithms, all the AI work must be done on CPU or GPU and require more power. Streaming also requires power for encoding and decoding video data. To reduce energy usage and avoid overheating, Event Detection is disabled when a live-stream session is active and is automatically enabled again when there is no live-stream session. While viewing a live-stream, you can manually trigger video recording on the viewer device.