Yeah, there's a difference between linear phase (which you can achieve with a causal filter, i.e. one that is running in real-time) and constant-phase, which re

Yeah, there's a difference between linear phase (which you can achieve with a causal filter, i.e. one that is running in real-time) and constant-phase, which requires that you have more or less the whole signal before you filter it (you can approximate it to the extent you're willing to add more latency).