Synchronization of Cameras Using Wireless Beacons

A method for generating timing data representing timing of a video capture relative to a master timing, the method comprising:

• receiving, by a radio circuit of a station camera, a wireless beacon signal from an access point device, the wireless beacon signal including a timestamp generated from a timer of the access point device;
• synchronizing a local timer of the radio circuit to the timestamp received from the access point camera;
• determining an offset between the synchronized local timer of the radio circuit and a local timer of an image processing circuit;
• and
• storing metadata in association with the captured video representing the offset between the synchronized local timer of the radio circuit and the local time of the image processing circuit.

A non-transitory computer-readable medium storing instructions for generating timing data representing timing of a video capture relative to a master timing, the instructions when executed by a processor cause the processor to perform steps including:

• receiving, by a radio circuit of a station camera, a wireless beacon signal from an access point device, the wireless beacon signal including a current beacon timestamp generated from a timer of the access point device;
• synchronizing a radio circuit timer of the radio circuit to the current beacon timestamp received from the access point;
• sending a timing query request from an image processor of the station camera to the radio circuit of the station camera;
• responsive to the timing query request, capturing by the radio circuit a radio circuit current radio circuit timestamp representing a current value of the radio circuit timer and outputting an interrupt signal to image processor;
• responsive to the image processor receiving the interrupt signal, capturing by the image processor, a current image processor timestamp representing a current value of an image processor timer, the image processor timer operating from a separate oscillator than the radio circuit timer;
• reading, by the image processor, the current radio circuit timestamp captured by the radio circuit;
• calculating, by the image processor, one or more timing metrics representing a time deviation between the radio circuit timer and the image processor timer based on at least the current radio circuit timestamp and the current image processor timestamp;
• storing the one or more timing metrics as metadata in association with one or more video frames captured concurrently with the radio circuit timestamp and the image processor timestamp.

A camera device, comprising:

• a radio integrated circuit comprising:
• a radio circuit timer including a first oscillator and a first digital counter to count a number of oscillations of the first oscillator;
• radio circuit logic to receive a wireless beacon signal from an access point device, the wireless beacon signal including a current beacon timestamp generated from a timer of the access point device, to synchronize the radio circuit timer to the current beacon timestamp received from the access point, and to capture a radio circuit current radio circuit timestamp representing a current value of the radio circuit timer and output an interrupt signal on an external pin responsive to receiving a timing query request;
• an image processor circuit comprising:
• an image processor timer including a second oscillator and a second digital counter to count a number of oscillations of the second oscillator;
• a processor;
• and
• a non-transitory computer-readable medium storing instructions that when executed by the processor cause the processor to perform steps including:
• sending the timing query request to the radio circuit logic of the radio integrated circuit;
• responsive to receiving the interrupt signal from the radio circuit logic via an external pin of the image processor circuit, capturing, a current image processor timestamp representing a current value of the image processor timer;
• reading the current radio circuit timestamp captured by the radio circuit;
• calculating one or more timing metrics representing a time deviation between the radio circuit timer and the image processor timer based on at least the current radio circuit timestamp and the current image processor timestamp;
• storing the one or more timing metrics as metadata in association with one or more video frames captured concurrently with the radio circuit timestamp and the image processor timestamp.