OSX: Audio lags/sometimes stuttering at CPU ~52%


I think there is some problem with the stability of the audio process. I use the 64bit version on a quad core 2,5 with 8ms. If the CPU reaches about 45%++, sometimes, sporadically, the audio stutters one time, or lags a bit. Maybe it’s dependent on the gui drawings, I don’t know. This does absolutely not happen in Cubase or Logic. The audio output is rock solid on these DAWs. Maybe you could improve something on the stability of the audio process?

I also notice lags in the gui drawing, that a independent from the audio lags it seems. The gui freezes then for maybe half a second, randomly. Nothing extra ordinary is happening at the point where the freezes happens.

Could this something to do with the 32bit audio bridge? This bridge is also extremely slow when restoring presets as I reported here, too. Maybe this is the problem, that the bridge consumes a lot of cpu that is not shown in the cpu meter… I should take a look on OSX activity monitor, too.

Does this happen with all your songs, or maybe one specific? Maybe it is a part of a track with lots of shit happening? A certain vst(i) that is automated?

As Djeroek said we’ll need a bit more info.

Lots of things come into play here: temporary CPU spikes of internal and plugin FX and instruments (CPU meter shows average usage only), memory swapping, plugin bridging, and so on. This is also very very hard to compare among DAWS, different projects, because of this complexity.

If you have a concrete example we can have a look at this here in detail to see if we can improve things in this very special scenario.

It happens on all song projects, no matter what setup is in. Memory usage is usually very low in my projects, since I don’t use much samples. I never haven seen this in Renoise 2.8 32 bit. I will do further tests, but one points seems to be obvious at least to me: If I recall a A/B preset to a bridged plugin, there is usually a huge lag (resulting sometimes in a beachball or a complete DAW lock). If the parameter flow to 32 bit plugins is such slow, I would guess, that realtime controlling would be also very slow…

Yes, bridged plugin are definitely causing more overhead than unbridged ones. If you rely on many 32bit plugins, then running the 32bit version of Renoise probably works better for you?
Does using the 32bit version without plugin bridges change something regarding the CPU usage and “stuttering”?

Taktik, I compared the same song to 32 bit Renoise. I noticed the following:

  • In 32 bit there are only sometimes little audio glitches (3ms-8ms), an I cannot recognize a pattern here. A visual/gui glitch is not visible. I can go down to 3ms and it still feels quite stable.

  • In 64 bit mode 3 ms is almost impossible, and maybe at 8ms I would say it’s almost stable, but there are also random glitches, more and much monger than in 32bit. It seems that a lot of glitches happen if a bridged plugin is playing. The glitches in 64 bit will also strongly affect the gui.

  • On both versions I have a big glitch if I save the song… Shouldn’t be the audio process so stable, that it cannot be interrupted from subsidiary processes?

Could you optimize the 32 bit bridge so it cannot block the DAW? E.g. there is a beachball/gui freeze if I recall an A/B preset? Is this the same freeze (in shorter variant) that causes the gui/audio glitches in 64 bit?

BTW. I don’t use the plugin sandbox option.


If you save to disk then plugin parameters and instrument samples have to be read out and written along to disk. Which means that if you do that while the song is playing, plugin parameters that are read out may perhaps be changed at the same time by automation. Reading and writing a parameter at the same time is pretty much impossible so this will produce artifacts if such clash occurs. You really expect too much if you desire to have your audio played back glitch-free in this situation and there is no other DAW developer that would be able to warrant you such expectation.

Next to that:Audio glitches solely occur on the cause of poor buffering and processing power of an audiocard. The less buffering and less processing the audiochip can do itself, the more latency you need so that the system cpu can do the preprocessing for that audiocard (because that is actually what the latency is good for or frankly a cause of).
If you get glitches with 3msecs in both 32-bit and 64-bit mode and you specially get more with 64-bit mode, this is a signal of a buffering/processing limitation of your audio hardware.

Hey vV, ok I understand. I doesn’t matter for me if the song crackles while saving :)/> I just quoted this, because I thought it’s the same problem.

But I would expect that the obvious lag in the 32 bit bridge can be reduced or improved. I don’t think this is an limitation of my audio hardware, since it’s all the time 24 bit always there. I mentioned 3ms only to show, what is Renoise capable of by using my hardware. Of course 8ms is cool, too, and enough for me. Since 3ms runs “almost” stable in 32bit, and there are kind of random mini glitches, I believe also this could be improved. Of course this is not why I started this topic, it’s the lagging in 64 bit mode.

I think there is some kind of situation where the 32 bit host will block Renoise, because communication is not working or something.

Same problem here. When it reaches about 50% of ‘cpu usage’ it is stuttering, you can hear that horrible crackling sound. Unacceptable. The thing is that it was all right in R2.8x and now it is not.
Windows 7, 64bit, I7, 16gb

UPDATE: Just checked in R2.8x and apparently it is stuttering too.

Luke, do you use 64bit?

Win7 64bit + Renoise 3.0b6 64bit.
UPDATE: Just checked in R2.8x 64bit ver and apparently it is stuttering too.

I have experienced that different drivers (DirectSound/ASIO) can perform quite differently.

Which audio driver have you got selected in the Renoise prefs - is it the same in 2.8 and 3.0?
Have you tried switching to a different driver, or to increase the latency?

BTW I tried this on a Core i7 Snow Leopard system, too: The same result. From ~50% on there will be recurring audio slowdowns with stuttering. And very often this happens when a 32-bit-bridged plugin comes in, but only on the beginning. And it seems to be quite independent from chosen latency!

Hi taktik and others, this song is a perfect example for the slow downs I am talking about: If I go to position 25 and loop it, I hear horrible crackles altohugh the cpu is around 41%.
Much more crackles are audible in the Edit and the Mix tabs. They almost will disappear if I switch to Sampler. Also even with 16ms latency and 33% cpu and still have sometimes little crackles. So still the gui can destabilize audio and also audio is not stable. Also tried different fps settings, no change. This time also 32bit vs. 64 bit no changes.

Diabling/enabling scopes makes no difference, too.

EDIT: If I disable the convolver in the “rev” send channel, the crackles will disappear in edit view. But why it does also disappear if I switch to Sampler?

With vsti’s in this song or without?

Without most plugins since I did not install them. I can remove all tracks except bass and reverb send, the crackle still is there.

Ok, because on my system everything is fine. i7 on windows 7 64bit (cpu usage ~20%). Seems to be a mac specific problem?

macbook pro, core i5, r3b6, tried via internal audio and external (20ms buffer/48khz) - NO ISSUES AT ALL.

p.s. Also I’m running this on the external "27 inch screen.

p.s.s. Why you are using that FLAC sample compression??? I see no reason for using flac samples at all.


when switching convolver to mono mode - no issues, back in stereo mode - crackle issues again.


Ok, I’ve tried 88khz at 10ms latency on external audio card, looped 25th pattern and here are the nasty crackles comes in @ 45-50% cpu load. Also clicked different tabs, crackles gets much worse. But the issue can be solved turning off the convolver dsp. Turn off that convreverb on send - no issues, turn on - there are CRACKLES.

So i guess its a convolver issue.

Hey atarix, it’s no my song. FLAC doesn’t stress the CPU at all while playing since it’s decompressed on load.

So I conclude you have also crackles if going down to 10ms latency? Can you test if the crackles go almost away if you switch to sampler tab?