You can have a zero latency limiter, but it does cone with a few gotchas.Well.. sorta.AFAIK actual zero latency limiting does not exist - physically impossible. You can have low latency or clippers tho.
One can think of a clipper with an instant attack and instant release. If you want zero latency, then your limiter has to have an instant attack (in the same sense as a clipper), but it can still have a longer release.
So in terms of the waveform, it essentially clips on one side, but it can still preserve the waveform on the other side after the strongest peak. The most important consequence in practice is that if the signal exceeds the threshold for more than just a single isolated peak, then this sort of limiter can still sometimes pass some of the waveform as long as there is a higher peak first to trigger the GR.
First thing is zero latency isn't actually true zero in digital audio land. There is always some kind of input buffer being applied. Thats because some operations wont work dealing with only one value at a time.
Gain does, you can in crease or decrease value without needing to know what the neighbouring values are. Frequencies, however is all about cycles per second so you need some value of time (multiple values) before you can work with it. Hence the need for a basic input buffer.
Sos we've already that very basic gain operations can be done instantly, the trouble is limiters aren't a simple increase or decrease in gain, that would only give us a basic volume control. So to make a limiter effectively you need to be able to compare a past value with a current value and add or subtract as a result. Fortunately, you can do that kind of thing because of the input buffer, so it doesn't have to add latency.
The trouble is it's limited in this simple state because what happens if there is a huge jump in values. It will either suddenly become over zealous and suck out those excess levels in Avery instant and non-musical way, or it will do a bit more averaging and ramp into these quick changes. It's more musical, but it can't react instantly.
Therefore it is possible to make a limiter without adding extra latency, but it can't act instantly to change, so you wouldn't be able to make a brickwall or ISP limiter. But you could make a soft clipper, or a basic limiter that may not be quick enough to catch some of those quick, excessive peaks.
But that's okay for live use really, its functional enough to do its job without adding extra latency, and you also really dont need it to so a brickwall thing, you can add one at later stage in production when you aren't recording.
Statistics: Posted by simon.a.billington — Sun May 05, 2024 8:41 am