On the last few webcasts, SpaceX has shown video from both ground tracking cameras and the on-board camera side-by-side, and there's a noticable delay between the two, with the on-board camera being at least a couple of seconds behind the ground camera.
I'm not a signals processing engineer, but I suspect there may be two issues at play:
- Longer signal path - I'm assuming that the on-board signal is being bounced off of a satellite or routed through multiple receivers, as opposed to the ground cameras which are "right there", so to speak;
- Highly compressed signal - I'm also assuming that the video signal is highly compressed, which would add to the delay on each end.
Is that even in the ballpark? What else could account for the delay?