DSP when project's not playing

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antic604

26 Mar 2018

I was under the impression that when using native devices and REs if there's no signal coming into them or out of them there should be no DSP processing. Even devices like Pulsar or Sychronous are linked to transport, so they shouldn't generate CV when no Play is pressed.

But when I'm opening the project and haven't even started playing it, there are 2 bars already.

Why?

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Loque
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Joined: 28 Dec 2015

26 Mar 2018

Good question. AFAIK they produce CPU usage due to LFOs always generate signals, so you can "hear" there signals (and their changes) while you play the keyboard. Would be nice if there were some room for optimizations, like disabling LFOs and stuff if you do not need them. But till now, every device you add which has a LFO, continuously consumes CPU, even if you dont need it. Even most (all?) devs do not provide a LFO-Off switch.

I am not sure, if there are other things that continiously consume CPU even if no audio is processed.
Reason12, Win10

antic604

26 Mar 2018

Well, even if that's the case (the LFOs are 'spinning') then I'd expect it to have minor impact, right? Instead, I'm seeing 3 bars when the project is just loaded vs. maximum 4 when it's at its fullest while playing. That's weird. In Bitwig 2, I've no DSP when it doesn't play and also along the playback there are very clear differences and variation in DSP levels depending on how complex is the arrangement at given moment. This is much less apparent in Reason.

Not complaining though. If it works, it works. Just thought it's a curious observation, contrary to my expectations at least.

WongoTheSane
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27 Mar 2018

I think some devices are always On no matter what, like reverbs for instance. Even if you're not playing anything through MIDI, you could have a microphone plugged in. The software could detect that there's no signal and send the info to the device, but while that's easy in software where you "know" who's sending what to who, it isn't in Reason because of its modular architecture (by that, I mean that some chains can be so long and complex that backtracking the signal chain in real time would be so expensive, CPU-wise, that it would defeat the purpose). Just my own interpretation, obviously.

antic604

27 Mar 2018

WongoTheSane wrote:
27 Mar 2018
I think some devices are always On no matter what, like reverbs for instance. Even if you're not playing anything through MIDI, you could have a microphone plugged in. The software could detect that there's no signal and send the info to the device, but while that's easy in software where you "know" who's sending what to who, it isn't in Reason because of its modular architecture (by that, I mean that some chains can be so long and complex that backtracking the signal chain in real time would be so expensive, CPU-wise, that it would defeat the purpose). Just my own interpretation, obviously.
Yes, that's probably it although it still doesn't explain 3 bars when not playing anything and max 4 when track is playing at full. If it was 1 vs. 4, I wouldn't mind or be surprised.

And as I said - Bitwig (or Live for that matter) - which isn't any less modular than Reason (and I'd argue it's even more flexible, with true audio-rate modulation) doesn't exhibit this.

When I have some time I'll try to find the culprit by the way of elimination :)

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Re8et
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27 Mar 2018

:idea: One way to think about it could be an edit mode that would totally disable audio engine, like a master button, but projects indipendent.
I can open two projects, in a live situations, and leave one on standby without harnessing cpu and then switch between the two.
Thoretically you could work the project, basically deafmode, but just in theory.

Bitwig works on macros, there's no graphical interface for connections, Reaktor is more similar to reason than Bitwig, and there are macros
and connections in edit mode between modules. I'm not aware of that possibility in Bitwig or Live without Max loaded. And Reaktor is very CPU intensive even when transport is not playing, but ther is a cpu limiter that disable audio when 99% threshold is hit and or you can manually disable it and enter so called deafmode.

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