Eli5- How do consumer drones (DJI, etc) broadcast the camera image to your phone from so far away? How come you can control a drone and view the feed like a mile away but I have trouble getting Wi-Fi reception on the other side of condo
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The answer is compression, codecs, and request time.
How do you stream a youtube video on your phone from miles away? It gets compressed. Same with a drone. You’re not really watching the video in its full glory on your phone. You’re watching what is basically a rough sketch of what the video actually looks like. Computers are really good at making those sketches, so it looks fine to you, but it is not what you would see on a nice 4k TV.
Compression can make videos really small, and the exact way the codec that does the compression works can be optimized for things like smoothly playing back a live feed, even when a couple frames get lost in transmission so it looks extra good in that one special use case.
Okay, sure, playback is possible – but YouTube always needs to buffer and sometimes cuts out, what’s stopping that from happening here? When you watch a YouTube video, you are requesting the video from a server, that basically keeps going back to a filing cabinet to get you the next few frames. But that server is handling many requests from many people for many different videos. If communication gets disrupted, the server in this three-step conversation might need you to remind it what you wanted, or it might need to find the right filing cabinet again – making interruptions much more noticeable.
With a drone, there are only two things talking: you and the drone. The drone is sending its video directly, so even if the transmission screws up, it’s not like either end needs to guess what it was supposed to be doing – the very next instant the drone will be back to sending video to you – and the drone probably uses a codec that helps gloss over this when it does happen.
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