CPU limit/sound cut-out - how often?
rudolphrapid
Beta Tester Posts: 129
I'm interested in how often you run into sound cut-out in your projects.
It seems to me easy to reach Deluge's CPU limit where several sounds get stopped playing back. I run into this issue regularily even though my songs are not so complicated, I think, and I usually keep 8 tracks unmuted at most. And I get disappearing sounds even if no analog delays and no time stretching is applied accross the whole project.
Last time I got sound cut-out in a 5-track section with a drum kit having 4 sounds, a bass synth, an arp synth, a pre-recorded audio track with some lo-fi effects on it and a kit with 6 pre-recorded audio clips (though three of them muted). In that last kit one of the sounds being triggered at the beginning of the loop usually gets cut-out when starting the song.
So how often do you have to deal with CPU limit? Do you usually play with sound priority?
Comments
Nice question. Yeah, it happens to me too. Does bother me too. Lately I tend to add stuff to a Song until I run into CPU problems. For me the biggest problem is that long samples get cut off and I might not hear it until I cannot backtrace anymore what caused a CPU hog. If it is always related to CPU. Could also be RAM or SD Card I/O bottleneck. Or bugs in some cases.
Guess we could send in Song+Samples to Rohan, I never did because I have a hard time to reproduce the problem, especially in "easy little" Songs. Hard to judge if I am on a "normal cpu usage" use case or if I am pushing the limits too hard and Rohan had to smile I am not thankful the Deluge keeps it together somehow
In complex, longer songs with 10-15+ instruments it happens a lot lately. Sound priority settings never worked for me. I never got it to work so it would ensure long samples to always play out and just limit polyphony for specific synths.
Some effects are likely to be CPU hogs, like excessive Unison or Analog Delay. Also large multisamples seem to take their toll. The only thing that seems to work for me consistently is bouncing Instruments to audio. And deleting the source from the Song. As far as I can tell, muted clips or kit rows still eat resources. For example if you have a muted kit row with a long sample you can unmute it anytime instantly, if the sample was completely offloaded it had to take some loading time. But that's only a guess.
A system monitor like this http://forums.synthstrom.com/discussion/comment/10760#Comment_10760 would help a lot to guess less and know more. I guess
ROTFL
It's tempting to say yes to a sort of visual feedback on system performance and alerting mechanism on system hog stuffs. However do we really benefit from a performance meter? I think users would constantly check the lights and worry about where and why it gets yellow or even red and check more and more if there is any sound cut-out. It would cause distraction from common workflow, I think.
Maybe it's still better just getting familiar with the unit's boundaries by experience and deal with it by senses
P.S.: Anyway I'm wondering how there's no public test mode on Deluge.
I've had some high track count projects on the Deluge and some feedback I got from Rohan included the following:
Valid point. A performance meter is a distraction.
Yeah. Thanks p_wats for the info, makes sense. Dont know if it helps in your case rudolphrapid, maybe kits loaded with plenty of muted sample rows?
That is a brilliant idea. It would help uncovering CPU issues Also, for bug hunting, beta releases could include a log writer, so any random malfunction gets recorded.
@amiga909 Yeah, being able to collect logs and dump files from SD card and send it to Rohan could be helpful in finding issues as well as in general support.
@p_wats Thanks for sharing this info.
I’m practicing to remove unused items from kits. However the first statement is a bit surprising to me.
My understanding is that all track types are based on the very same engine (analog synth) in the background: the audio clip is the analog synth with limited control and a single sample based oscillator while kit is a group of analog synths. So I don’t get why it puts more load on CPU having a kit with multiple synths with different arp and delay settings than having the same amount of synth tracks with same settings.
I look at kits as a group of instruments organized around a topic (like drum kit, sound effects, vocal chops, etc.) that are fully set up including play style, filters, effects, panning, etc., so all settings a single instrument (synth) can have on Deluge and that group can have a custom master effect section as well.
But if it’s the case what the purpose of kit is then?
But I may be easily wrong here, so feel free to correct me.
Is that info you got from Rohan?
I think the analog modeled delay itself eats more CPU than the digital version, if I recall, so take that for what it's worth.
I didn't mention the type of delay as your quoted statement neither did it. I wrote about items (instruments) in kits.
Anyway I know the analog delay eats more CPU than digital one. And in my opening post I emphasized that no analog delay had been used in the mentioned project producing sound cut-out.
I don't have info from Rohan but this is my understanding about Deluge. I may be wrong however
I did some more investigation and here are my findings. By synths (so when the oscillators are emulated VCOs) the mute is midi mute (so after unmuting the track the sound is generated by the next node start message only). If any of the oscillators is sample based there’s a constant pseudo playback in the background and by unmuting the track the sound is immediately generated by the actual position of the underlying sample. I used the word pseudo because maybe there’s no real streaming from the SD card while in muted but a continuous calculation of the actual sample position runs in the background.
Regarding the delay it’s definitely stopped until unmuting happens. So the mute is not a channel mute but it seems to halt sound generation on the channel.
These things seem to be valid for synth tracks as well as individual kit items.
In addition to this in my current song I got even more sound cut-out because of system overloading after turning on the looper to add 2-3 real-time chops.
So if real streaming happens by muted sample tracks it can be a reading bandwidth issue. But I doubt it as in this case those muted samples should be excluded first. I think the multiple sample position calculation puts heavy load on CPU (among other duties).
I tend to get the conclusion that a song file in Deluge is not good for a full song but for various song parts in order to lessen the complexity and track count in the projects.
the note cut problem: when do you get cuts exactly?
as far as I experience it, it happens with longer samples, around 10s and more. i don’t experience the note cut problem with Synths or short samples. it does not seem to be the problem the Deluge skips notes at all but long samples can get cut now and then. splitting long samples has solved some sample cut problems for me.
hard to guess whats going on in your song. is it a large song with many clips? loads of samples, synths?
thought about this too. but i like the arranger and on song load only reverb tail is not cut. i try to get better at avoiding hitting the limits of the Deluge.
It’s a good question how complex my song can be for Deluge. Would you mind to help me deciding it?
The song consists of 18 separate tracks (or instruments) so there’s 18 lines in arranger mode.
However as there are variations for some instruments grouped into sections (like drum variations or just instruments that come in later) there are 32 clips in song at all (35 if I add the audio clips created by looper by the end of the performance).
Looped clips are 8 or 16 bars length at 168 bpm so about 11 to 23 second length.
All kits contain samples and some of them are a bit longer. Delay applied on several kit items. In addition to this there are two kits for live audio so two or three kit items are there to process and pan line in (like slight shifts in pitch to make stereo chorus effect).
Almost the half of the instruments are synths however.
I usually keep 3-5 clips unmuted in the same time, max. is 8.
As I mentioned it earlier there’s neither analog delay nor time stretching in the project.
So what do you think? Is this info helpful for a sort of judgment?
“Would you mind to help me deciding it?”
Ultimately only Rohan could decide 
You help me to get ideas about my cpu problems too
18 presets/instruments, 35 clips is quite a lot.
I am hitting the sample cut problem in songs with about 15 instruments and 50+ clips (including white instances in arranger), no audio tracks.
“Looped clips are 8 or 16 bars length at 168 bpm so about 11 to 23 second length.”
Yeah, can confirm getting cuts in samples with 11s and more. How much of these are loaded in the song?
“Almost the half of the instruments are synths however.”
So thats about 8 synths. Yeah, thats about where I experienced upper limits too.
“I usually keep 3-5 clips unmuted in the same time, max. is 8.“
There could be potential. It can pay off to delete muted sample content.
Suggestions:
This kind of uncertainty around the limitation is a bit stressful
It's the point where Deluge's desing hits back a bit in my opinion. Synthstrom went opposite to most manufacturers who usually push hard limits on their devices. The Deluge just let the user exploit the hardware as he or she wants anytime. However while using those other intruments we know the limitation from he very start and we can usually play inside boundaries without worrying about putting too much on the hardware by Deluge there's the constant threat of the unknown limitations. On the other hand Deluge lets the user decide how to optimize things by each project individually which is a feature I still very like 
We just need to keep in mind that Deluge is not really a DAW running on a PC/Mac put in a nicely designed controller box 
@amiga909 Thanks for your tips! I'm working on further optimizing my current project and I already got some good results.
And here's a possible explanation from the manual on why the long samples are often cut out: "It will attempt to do this in the most subtle way possible, preferring to switch off voices which are “releasing”, and those which have been sounding for the longest time." I think Deluge should be a bit more clever to identify backing tracks and looped audio clips not to take them with high priority to stop.
On the other hand the manual priority setting worked pretty well for me in my projects where I experienced sound cut-out.
I'm having this same issue here but I'm only playing 6 clips at one time and the notes cutting out aren't long at all. Not even a bar and they get cut short over half the time. This thing can't be that CPU weak... right?
The other thing is that this only happens in arranger view. The notes play fine in both clip and song views.
SOLUTION: It's a priority thing which I only just found out was a "thing". ha. Setting the specific problem track to high priority solved my issue. Thread here: https://forums.synthstrom.com/discussion/3901/arranger-cutting-off-long-midi-notes#latest