How To Fix That Glitchy Audio

Transcript:

Hello again! Dezz Asante here from the TechMuzeAcademy and today’s quick tip is in answer to a question that I read recently in the Gear Slutz Forum and I want to address it here today because its a question I get a lot. I’ll just read it straight off the forum.

He says,

“I have just started using Cubase version 6.5 on my Mac book 2.4 gigahertz I5 with 4 gigabytes of DDR3 ram.  I’m running my guitar straight into a 4-channel personas firebox and I’m having dramas when I record multiple tracks and my project is around 2 minutes long. My cpu is running at close to 90% , so when I’m up to that stage, my project playback becomes sketchy and recording becomes impossible. I’m recording at 44.1 kilohertz and I’m  not putting a million plugins on the tracks or anything, but I am using amplitude 3.0 on each track. Should my Mac handle Cubase better than this? I would have thought so.”

Yeah, this is a question that comes up a lot and basically there’s a simple solution for it. One thing to consider is that Amplitube 3  in particular and a lot of plug-ins like that are very, very cpu hungry and so they are going to eat up cycles like crazy and just a couple of instances of amplitude running simultaneously can really sort of drag down your system.

So, what I have done today is put up a little short session here. Just a little funky jam I threw together for the sake of this demonstration and I want play you what its… First of all, I’ll walk you through whats going on:

We got Superior Drummer on one track.  And I’ll pull that on the screen so you can see it. Superior  Drummer if you don’t have it is a fantastic little drum synthesizer, so I’ve got that taking care of the drums.  I’ve got Spectrasonics Trilian. We’ll pull that on the screen here, taking care of the bass guitar. So,these are two soft synths and I’ve got a version of Halion Sonic taking care of the organ part. So, we got 3 software instruments running and then on my rhythm guitar track I’ve got an instance of Amplitube 3 here, the plug-in in question. And,  I also got one on my lead guitar track as well.

Okay! So, we got two instances of Amplitube and we got 3 software instruments running. Really, we’ve got just these 5 tracks in the mix here.  I’ve got no plug-ins apart from the ones I just showed you running at all in this session. So, lets hit playback and have a listen to how this sounds.

Okay, obviously not very pleasant. And if you look down here at the cpu meter you can see that it is fluttering away and clipping at certain points as well.  In fact,  its a pretty much a constant peak on the cpu usage. So, I’ll stop that.

So,  how do we solve this problem? I mean my computer that I’m running this on right now is a quad core 2.66 gigahertz with 6 gigs of ram. So, you would anticipate that 5  tracks on your mix should be a breeze to handle.

Well, there’s a couple of things that you can do. The first thing to check for,  is to go into your hardware preferences in Cubase down in device setup and have a look at the I/O buffer size settings.  Now,  you can see the latency which is an indicator of how the input to output buffer is set.  If I hit the control panel here, I can see that my buffer size is 64 samples. Now, that’s a very small buffer size and that’s great for giving you a very low latency performance while you are recording your instruments. Its good to have the buffer as small as possible, but once you get some tracks on the screen,  you’re going to need to open that buffer up. Now, you see what happens right away, if I open this up to say 512 and I close that, my latency goes up to 12 milliseconds. But, on playback that’s not an issue.

So,  if I close out of that now and play this once again. And if we look at the cpu usage… we’ve got a nice clean playback and we got just a nice dance on the cpu meter, nice low down at the bottom and everything sounds great. A little clip there and if I go back in and set my buffer even larger say 1024 and hit okay, bring this back to the top, cpu is even lower now in usage and these tracks are playing just fine. Okay! So, thats the first thing to check.

If you found that your buffers are already open pretty wide, maybe you got quite a few tracks and plug-ins running and you are having some trouble still getting the playback to play smooth and clean, there are a couple other tricks that you can do. So, let me get back in and reduce my buffer size to simulate the problem. So I’ll bring this back down to say 128, latency goes down to 3 or under 4 milliseconds, cpu is dancing away again and we get the occasional clip and if I hit play. That glitchiness has crop  back up into our playback .

Okay! So,  what do you do if your I/O buffer is maxed out and you’re still getting this kind of performance. There’s a couple of little things that you can look at. In Cubase, if you are a Cubase user, Cubase has a very cool feature called Track Freeze. So,  if I freeze a track, essentially what its doing is exporting a mix of that track with the effects printed and then it disengages the plug-ins. And this all happens in the background, so everything on your screen will look the same,  but the plug-ins have been turned-off and an exported version of that track with the effect in it is replacing whats being played back. That’s a fantastic feature that Cubase has. I’m not sure which other does support that as well.

But if you don’t have a Cubase or you don’t have a Freeze Function, one thing that you can do is to manually export each track. So,  the way I would do it is I would go to my file export and again apologize for those of you who are not Cubase user you’ll have to dig around in your DAW to find out where this works but I’m going to export an audio mix now. Cubase also has a batch channel export which is a fantastic feature because I can do all of these tracks at once.

If you don’t have batch channel export, then what you’ll have to do is just solo each track and export them one at a time into your project audio folder and just import them back into the session. In Cubase, they made it real easy so I can actually go in and grab my instrument tracks and my audio channels and I’m going to save and bring them back in audio tracks and then export at the same bit depth that my project is at which is 32 bit.  And I’ll just call this, I don’t know, bounce.

Okay, for the sake of this demonstration I’m just going to choose a random place to save them. Here let me do this.  I’ll put them on the desktop so I can delete them later. I’ll make a new folder and I’m going to call it untitled folder. Sure, sounds good, and we’ll save into there and I’m going to hit export. So, this will take a moment or two and what its going to do is,  its going to print each of these tracks with the guitar tone, the Superior Drummer sounds is going to bring them all back into the session as audio files. Okay. So there it is now what I can do,  let me just get that out of the way for you,  is I can actually remove these tracks all together or I can turn off the plug-ins. The way I recommend you do it is, take your software instruments, disconnect them…which essentially turns them off in Cubase.

Okay, on these channels I’m going to turn off the plug-ins. Turn off the plug-ins there and then I’ll take all these tracks and I’ll put them in a new folder and we’ll call this folder backup.  Now,  I can close that folder out of the way, move it down to the bottom, shrink it up and make it inconspicuous and now what we’re… and by the way, the other thing I’d like to do before i do that is to mute them. So, I’ll grab my mute tool and I’ll just mute all those tracks at the event level. Okay! And when I hit play now….you can see that the cpu meter is way down low and the playback is nice and clean and smooth and everything sounds exactly as it did  prior to this export.

So, there’s a little quick tip that I hope you find useful and we’ll catch you on the next one.