If every millisecond counts, then existing solutions of low cost digital video cameras and existing video compressors do not qualify, unless running at insane framerates like 240 FPS.
Frame rate isn't necessarily related to latency. 30FPS, or even 24FPS, is a sufficient frame rate as long as the end-to-end latency is low enough.
A few more thoughts:
* Analog video is fine, from the perspective of the pilots. There's no inherent advantage to going digital, or even to higher resolutions. They're happy with 480 lines. Sure more is better, but I promise they'll give up resolution to get low latency and reliability (no dropouts).
* Next to latency, dirtbag @%$##$%ing other pilots plugging in their quads in the pits on the same FREAKING channel as someone in an active heat is the next biggest problem. Despite rules and penalties, this happens ALL THE TIME even at international competitions. Happened to my son during his very first qualifying heat in Shenzhen, in fact... he was doing great and then suddenly he's
looking at some guy's shoes in the pit area. His quad crashed into a gate and he was taken out of that qualifier, and due to the scheduling they didn't offer reflies at this event, so his total practice time on the track before the actual races was reduced due to some other jerk's stupidity. (We tracked down who it was using recorded video and got him disqualified, but that didn't help TeamUSA.)
This problem is almost always some pilot believing "It won't matter for just a quick second". They drop their transmitter power to "pit mode" (generally a couple of mW, whereas most racing is at 25mW these days), remove their transmitting antenna (never mind the SWR mismatch), etc. and "plug in for just a quick test". But at these speeds it only takes a moment of zero visibility to crash into something, and since they've dropped to 25mW to reduce inter-pilot interference the receivers are that much more sensitive and can pick up one of these "quick tests" in the nearby pits sufficient to corrupt or entirely override video coming from a quad that's hundreds of yards away on the other side of the track. Yes, we use directional antennas (some really good ones, in fact) but it's amazing how often the offending &!#$&%&!'er must be in one of the side lobes of the pattern and gets picked up just fine.
THIS is the reason we are considering going to digital video. Not because we need better resolution, but because we need to be able to reject interference from other people on the same analog frequency. The uplinks resolved this a few years ago by going digital and using a token-based system where you "pair" a given transmitter (remote control) to the aircraft's receiver. This system works quite well and they can have dozens of pilots flying "line of sight" (not FPV) in real time without incident. But those are relatively low bandwidth comms compared to (even low-res analog) video.
We've thought about doing some sort of cellphone-like TDMA system, but up in the 5.x GHz ISM band where FPV video lives, so that we can successfully accommodate "plug-ins" like I described. It will take some sort of system like that to fix this, because you literally don't know and can't prevent when some stupid, idiotic, self-serving jerk will plug in during a race and take out a pilot by generating an analog signal or a data stream right on top of what the pilot SHOULD be receiving.
* Another issue, though less important than solving the above, is dropouts. FPV pilots scan eBay for truly analog mini-monitors that display snow instead of a blue screen when no signal is being received. All FPV goggles are analog too. Why? Because signal strength varies all over the place during a race. The antennas are constantly changing orientation to each other, the distances (and thus propagation loss) change wildly, etc. Digital video has the incredibly annoying "feature" of simply turning off when the signal strength goes below some threshold. But analog does not suffer from that... your image quality may degrade, you may lose color (due to loss of color burst on each line) and fall back to B&W for a moment, but the key is
graceful degradation rather than brick-wall failure. Once a digital video system "loses sync" it can take several seconds to resume operation. That's an eternity. Imagine driving on the freeway inside a curving tunnel at 80 MPH and someone covers your eyes... seconds feel like years, even a couple of seconds can spell disaster. Far better to gracefully degrade like analog video, from loss of clarity to loss of color to higher S/N ratio (snow) because the human brain and vision system are quite good at interpolating in a noisy environment. But they can't interpolate from a blue screen!
For this reason, my son and I have been toying with employing DSP correlation in a multichannel diversity receiver. There are serious volume, mass, and power limitations on the aircraft themselves, but the ground stations are basically unlimited so doing lots of processing on the ground is totally feasible. (Correlation will not address the issue of bat-freaking braindead idiots transmitting on the same channel so that problem would still have to be addressed.)
* Whatever the front end, the output signal would be best as baseband NTSC. The entire industry is tooled up to support that, and the race operators (MultiGP, FAI, etc.) will resist anything that isn't plug compatible. Why do they care? Because they have live judges dedicated to each pilot position, plus they record all video streams, in case someone files a protest. All that infrastructure is NTSC. If a pilot arrives and he cannot provide an NTSC signal to show his FPV, at best he will lose any protests (for lack of evidence) and at worst he will be prohibited from racing.