High CPU usage as XTC mode in Nuendo 2

erminardi · Post by **erminardi** » Sun Mar 06, 2005 6:46 am

Hi, I'm working with Nuendo 2.2 and luna2+pulsar2 in XTC mode, SFP 4.0.
PC, winXP pro sp1, Nuendo 2.2, project ASIO2 44.1KHZ 16 bit, PIII 1000, 512MB ram, 120GB HD.
When I set (all Creamware fx XTC) a compressor, an EQ, as insert in each of my 12 tracks + a couple of reverbs, choruses and delays as send, my CPU marks 50% 60% occupancy... It's strange because I think that the Creamware's DSP must working instead of the PC CPU!!!
Any suggestion? Any comment?
Thanks a lot

erminardi · Post by **erminardi** » Sun Mar 06, 2005 7:06 am

Ah, ok...
...so It's all right...

Thanks!

erminardi · Post by **erminardi** » Sun Mar 06, 2005 7:13 am

But I don't think that in Digidesign Protools TDM the PC CPU raise up as Creamware XTC...
Maybe a better integration with the proprietary multitrack.
My conclusion is that VST enviroment is better as native than DSP powered.

symbiote · Post by **symbiote** » Sun Mar 06, 2005 11:25 am

First off, I don't think Digidesign uses ASIO, but if their system is anywhere near low-latency, you'll get the exact same CPU usage. What happens with ASIO is, since the buffers are pretty short, they have to be serviced by the CPU pretty often. If you have a 128 samples delay, then each of your ASIO channels need to be emptied/refilled every 128 samples, or once every 3 milisecond. If you have alot of ASIO channels, that's alot of buffers to handle, so it's going to start taking a toll on your CPU usage. This is in addition to having to setup data transfers between memory and PCI cards, and rendering VSTi audio (and handling screeen redraws and servicing mouse interrupts and switching context etc etc etc.) XTC might be adding some more processing even to interface with the sequencer's VST mechanism.

This will happen with all ASIO cards, DSP on the card or not, so isn't really related to DSP. You'd take a similar performance hit running an all-native setup with an RME or MOTU or whatever card. Pretty sure ProTools will behave like this too.

erminardi · Post by **erminardi** » Mon Mar 07, 2005 4:06 am

Mmm, maybe I must consider a new PC like PIV 3.00 =)

erminardi · Post by **erminardi** » Mon Mar 07, 2005 4:06 pm

A little benchmark:

Pulsar II + Pentium III 1000 + 512MbRam + ASIO2 24bit 44100Hz + ULLI 7ms in Nuendo 2.2

14 full tracks (3 min each) with 1 compressor and 1 4PEQ (4 poles activated) as insert in each track

1 Masterverb (church)
1 multitap delay
1 Harmonic Chorus
1 Flanger
1 Pitch shifter (+6 semitones 1 voice)
all as send

result: CPU usage 30%, I can open native VSTs for other 40% 50% !!! =)
p.es. Amplitube, PSP stuff, waves, T-Racks stuff...

I use a second PC as external rack with all of my VSTi and 2 Luna II cards as ModularIII/Flexor 1.5 and more synthesis.

Not bad, I think...