Hello, I finished a one third octave filterbank audio plugin for some specific simulation which currently works for mono and stereo input signals. I calculated linear phase perfect reconstruction FIR filter coefficients for 26 third octave bands. That means I need 26 parallel convolutions for each channel of the input audio bus. In order to do that, I import the filter coefficients and assign them to an array of 26 ProcessorChains.
I know that this naturally takes a lot of CPU power (I need up to approx. 10000 filter coefficients per third octave band), so it might seem unrealistic to try what I’m actually trying to do next: I want to use the plugin also for multichannel input signals (for realtime processing of ambisonics or WFS audio signals). I found some behaviour of my plugin which I don’t understand: Let’s say, I have a 8 channel input signal. When I treat this signal as 4 independent stereo signals and extend my ProcessorChain to size [26][4], the plugin is not usable (any DAW crashes). When I do the same with 4 input channels (ProcessorChain array of size [26][2]), the plugin works fine. But on the other hand it is possible to use 8 instances of my original plugin without any problem, given that the CPU is powerfull enough. So, before blindly trying out different ways, maybe someone can explain to me what’s happening here. Do I have to use multiple threads? Should I use ProcessorDuplicators instead of only ProcessorChains? Since I don’t have a background in computer science, it is a bit hard for me to understand what’s going on here.
Are you actually initializing all your ProcessorChains? Maybe your code is still only initializing them for stereo use? (Or whatever the “2” or “4” in your 2D array represents.) Have you run the plugin under the debugger to see where the crash is exactly coming from?
Excessive CPU use rarely causes a crash by itself, you will just get stuttery and corrupted audio usually. (Your exact mileage with that will of course vary, it can be possible just too much CPU use would crash the host, but I wouldn’t be investigating that possibility myself first.)