Questions about latencies with Rack 2 VST in a DAW

VCV Rack
1

Hi there!

I am wondering how latencies in general and especially with the new Rack 2 VST are handled in a DAW… The audio module in Rack 2 shows a block size of 256 samples (5.3ms @48kHz) that can not be changed, but the plugin wrapper says “latency: none”, so I began to fear that every instance of Rack would add ~5ms of unreported latency. To test this I put 100 instances of Rack FX in a row, containing only an Audio-2 module patched to itself, but to my surprise I wasn’t noticing any additional latency when I was anticipating >500ms…

So… how does this work? And what should I pay attention to, to always get the lowest latency possible when using the VST in various ways? Can I assume it’s always latency free, with the exception of 1 sample for every cable?

PS: The 256 samples relate to my ASIO driver settings, I put it back to 64 samples now, which I usually try to run everything at… with 64 samples it’s only 1,3ms of (output-)latency, which together with input latency and processing buffer adds up to ~5ms roundtrip latency for the entire DAW, which is really good… if the latency doesn’t increase when using Rack VST I’m very happy with this.

PPS: My DAW is FL Studio.

2

don’t VSTs usually add zero latency? I don’t know how rack-vcv works, but why would it add any latency?

3

It depends on the VST, some add latency, some don’t. Effects that use oversampling usually add a bit, and some synths do add a bit as well, but usually very little. There are some extreme cases like mastering plugins with additional latencies of 50-90ms (probably mostly because of look-ahead).

But I don’t understand how it really works, I just hope Rack doesn’t add any, and so far it seems it doesn’t.

4

Yeah, there are very few vcv modules with latency like that. It might be k for a mastering limiter, but latency would be terrible for a modular synth.

5

I sometimes wonder how this works… like: why is it possible to run multiple VSTs in a chain without additional latency, but not possible to do oversampling without additional latency?

My fear was that Rack would add a bit because it might not be optimized for VST performance, but it seems it integrates into the buffer nicely and thus runs latency-free. I am very happy about this, because now running VSTs in the DAW gives me an advantage over running them inside standalone Rack (which always adds a bit of latency per VST) and I should be able to have a powerful low-latency-hybrid-setup.

It also makes me wonder: Would it be possible to run VSTs inside standalone Rack without latency by integrating them into Rack’s buffer?

6

I guess you must experience latency on the recorders / samplers, but I don’t think you will otherwise experience latency, you may run out of processor and experience hiccups but no latency

edited it is not a reply to @Squinky, is for thread in general , I pressed wrong button

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