computer hardware – Is there a GoPro developer API for wireless streaming of telemetry data to the camera?

I have a microprocessor (arduino-like ESP32) project that is collecting a bunch of real-time telemetry in flight, and I need to be able to sync that data with GoPro video after the fact. My half-assed brainstorms thus far are unrealistic;

  • Have the telemetry device(s) in view of the camera, and have them blink an LED to communicate sync information. The LED would be examined in video processing and used to establish a match of timestamps. For example, once per minute, the current time could be “blinked” to the camera. The problems are numerous: the LEDs could be too bright in a dark scene, or not visible at all in direct sunlight. It may not be practical for the telemetry device to be in view of the camera.
  • Do the sync by audio. This is a terrible, awful idea, but I include it for completeness. The telemetry device would have to beep audibly, and be heard over any other audio in the environment.
  • Have the user do some equivalent of a movie set’s “clapper” at the beginning of recording, showing the device to the camera. You’d sync up the visual event with the input on the telemetry data track, and you’d have a start point. Unfortunately, unless the camera’s clock was perfectly in sync with the telemetry device, the telemetry and video would drift out of sync.
  • I would consider using a remote microphone (if they exist for GoPro) and replacing the actual mic with my microprocessor. I could make whatever tones I needed, any time I wanted, and use that audio to sync the telemetry from the processor with the video (eliminating that entire audio track from the final video.) Potentially, I could communicate the entire data stream to the camera via audio. However, I would need a stereo microphone arrangement for this to work. One channel for data and the other for audio from the scene.

The best bet would be for me to be able to send data directly to the camera from the microprocessor, where the camera would record that as an auxiliary data stream in the mp4. Since every packet of a media container’s data streams contains an explicit timestamp within the chronology of the media, I’d be done.

So what I’m looking for is whether GoPro offer such access to their cameras for people developing accessories. Their developer website is glitchy at the moment and contains dead links, so I’m guessing I’m SOL?