Help with ASIO glitching

[nix]

Heya,
I have still been working on my old synth.
I want to ask for ideas what might be causing this-
the problem is- I can only run 4 instances before ASIO starts to glitch badly,
even with highest latency settings. Have tested on 2 systems
with different soundcards. CPU is reasonable, around 16% for the 4 instances combined

I have tried getting rid of-
Ruby green ticks
second midi2poly
fm links
modded envelope

I don't really know what's wrong, like I say CPU is fine, and a couple of instances run clean.
Any ideas?
It's a complexish wavetable synth

[CoreStylerz]

Wavetables may leads to great aliasing. You can may filter the oscillators in order to cutoff some frequencies.
Another thing i found gltichy in FS is the routing via bus. These glitches occurs for example when u change preset and the "effects" are recalculated.

[nix]

Thanks man 8D
It's not aliasing, I am talking about buffer underruns.
It could be to do with bussing though possibly,
but it still happens when controls are static-
will look at my mod sources and turn them all off to see if that helps.
It is for sure ASIO not coping with some element of my design.
The sound is like horrible chopping at max volume.
Here is the synth->
http://www.sendspace.com/pro/dl/sngp8h
It tends to chop the sound up at bar start,
when the note-ons happen
Would really appreciate it ne1 wants to have a look and build a small project.
Reaper is running it better than Orion here.
Cheers Stylerz

[Xtinct]

Don't think its the ASIO just loaded it into savihost and ran the cursor up the key board and every key clicked,
tried it with external keys and was better but still clicked on fast runs of overlapping notes
almost like the smooth retriggering of the envelopes was turned off.

[Nubeat7]

on my i5 it also starts to trouble with 4 instances, when it reaches around 70% of asio usage... which is normal in cubase

one instance needs about 15%

where are you reading the cpu usage? because there is a difference in cpu usage in task manager and asio usage in host which is also often called cpu..

i`m also wondering about that it uses 15% (read in host cpu) with just one osc with one voice and nothing else on, which seems pretty much, do you have selectors after all components like the effects and the osc`s, because with selectors behind set to off these parts shouldnt get processed they should also be after sequencers, envelopes... and everything where the audiostream passes through that things are just processed when set to "on"

[KG_is_back]

Does the glitching happens also on offline rendering or on realtime usage only? If it happens offline also, than it certainly has something to do with the algorithms.
About the reading of CPU. Task manager shows how much of the maximum possible number of cycles/s the process uses. The CPU meter inside the application (inside your daw or flowstone) shows how much % of reserved cycles the process uses (because windows reserves certain priority (max speed) to different processes).

However, some applications (including most plugins) can run only at single thread/core, so if you have quadcore CPU and the meter shows 25% it is likely the plugin actually uses its full potential cos' it can't use the rest 75% (rest 3 cores) - glitches happen even if CPU is showing 25% because that is the max for the plugin.

also daws behave very badly if you limit the max CPU in your notebook powering plan. Some time ago I had the CPU limited to 50% when running only on battery and all DAWs glitched like crazy taskmanager showed constant 50%CPU. That is very likely your case...

If the glitches happen on note starts, than it might mean that start of the notes contain very complex computations. Check stage(0) within the code modules.

[nix]

I have made progress,
and now can run 4 instances in Orion-
it was NuBeat's hint to look at selectors.
I thought I had done this pretty well,
but I found several junctures which needed a selector.

I'm not running on battery, I think my system is open to process
as quickly as it can.

Will push the project back into glitching and try a render, thanks KG 8D

I have never used my DAW and FS meters, I have always looked at task manager,
I realize now this is the wrong thing to do, thank you folks for this info.

I think the note start glitches were due to my porta method,
2 midi2poly were engaging in all instances, where 2 r only necessary for porta.

The envelopes are smooth here Xtinct, maybe something about them isn't playing nice on your system,
or you are experiencing the buffer underrun on note on.

Will keep going, and see if I can squeeze a few more instances in there.

Thanks so much for taking the time to help me crew 8D

[Tronic]

nix, I believe that you have it already check this,
but if you have not already done so you could see a parameter that is in power option preferences,
inherent to the CPU,
which sets the percentage of power that will have to be at minimum and at maximum load.
This parameter on some machines disturbs the processes audio
and you have many drop when the processor changes its power,
so set it to 100% for minimum and maximum.

Power_Option_for Audio_Best_Performance.JPG (45.42 KiB) Viewed 16097 times

and you can verify this by using this utility.
http://www.thesycon.de/deu/latency_check.shtml

[nix]

Cheers Tronic!
Have just checked that now,
looks like they were already set right,
but flicking it onto high performance has helped for sure.
Very handy hint.

So this problem is simply caused by my synth being too heavy.
Looks like I may be able to run 6 now though,
will pop back in with the figure later, when I know.
Will write this 5 part loop, and see if everything else is OK.

[KG_is_back]

In that case try to optimize the codes in assembly. Sometimes it might significantly speed up things (up to 30%)