Conditioning Your PC

 My PC has held firm since 2016 and I've been happy that it's been able to run games well at high graphics but the fact that I can say that means that I've not thought about the demands that will be made of it by trying to process audio, all I've done is jump on my mainstay machine and install Reaper. Until now that's gone pretty well but when black friday came around I couldn't help myself but take advantage of some of the deals being offered over at the Waves store, one of my shiny new plugins however started to cause pops and crackles in the audio... what?!. Which has led us here, at the beginning of a journey to getting a machine that's fit for recording audio, running a DAW and even having a reasonable amount of VST plugins and instruments for long enough to put together a track and squeeze a mixdown from it.

First Steps

After googling things like "Crackling sound whilst running VST's" I came to the first thing to be aware of when running any of the standard audio interfaces:

Buffer Settings

 When you're recording and when you're mixing you have completely different requirements from your system and as such you can change your buffer size to accommodate your needs. Your buffer size is something that is generally dictated by your audio interface so you will be able to adjust this in the settings for that device, also most DAWs can access these settings from within their settings menus.

Your buffer is the amount of time allowed for your computer to process the audio of your interface so if you're recording you'll want as little latency as possible, meaning as low a buffer size as you can get away with before the audio starts degrading. Whilst mixing however a little latency won't make any difference so whacking that buffer size to max will give your PC all the time it needs to process the signal before presenting it to you.

Update your PC - Especially the BIOS

 This seems simple and obvious but really update everything on your PC that you can find, right from the BIOS to the operating system, the drivers and the applications. The reason that I pick out the BIOS specifically here is that it's easy to overlook and can have a direct impact on how memory and your processor are utilised, that being the case any update or improvement could hve as positive an impact on your system as a lot of the steps you'll take afterwards to get your PC dialed in.

LatencyMon

 So buffer settings were great to know about but weren't cutting it for me and this particularly processor heavy plugin (Reaper said it was conduming 10% of my CPU! maybe that's something that will be looked at later). More searching online found a tool named LatencyMon which has a free home use version, essentially this program will sit in the background running whilst you don't have your DAW open can will assess whether your PC is capable of running audio applications currently or not which was exactly what I needed. Note: Dispite the order that this atricle is laid out in, I hadn't actually updated my BIOS before running this test.

After running the application for a few minutes I was greeted with the above, apparently my PC isn't really suitable for running real-time audio tasks so there's going to be some tweaking needed.

Hard Pagefaults

Again, LatencyMon educates us about and helps us track hard pagefaults, which is essentially what happens when a memory address is provided which is not resident in physical memory, depending on the INT 14 handler if the page in which the address resides is known to windows but not resident windows will read from the pagefile which will take a lot of time. If the address can be read from the hard disk cache then the price will be limited. Essentially what we're looking to do with the hard pagefaults is find what's causing the majority of them and see if we need the process.

Here we simply head over to the Processes tab and sort by the number of hard pagefaults caused and hit them in order of impact.

• CompatTelRunner.exe
  • This is a windows telemetry service, it can be the cause of all sorts of problems and generally get in the way on startup etc.. in the best of situations it will scan your computer and call home to microsoft with the information so that they can improve their software, in the worst it's a little snich which hogs system resources for no tangible benefit to you personally - so for recording purposes I've killed it. Here's how, I used the Task Scheduler method.
• AsusGameFirstService.exe
  • This seems to be part of the ASUS suite of sevices, I'm not entirely sure what its' for but I'm happy that if I need to run any Asus software it will kick off any services I need so if you hit Win + R then you open the run dialog, enter into that "msconfig" and hit enter. Then I went over to Services and disabled this service from starting up when the machine does.
• Chrome.exe
  • This one speaks for itself, don't run chrome whilst recording and if you do keep the tabs to a minumum.
• Mmc.exe
  • This is another windows process that wa likely open from my having the task manager running so should be ignored, I've only left it here so that I don't research it again (it handles snap-ins for windows, things like monitor graphs etc..).
• BDServiceHost.exe
  • This is my instance of BitDefender, which is a great antivirus but probably doesn't need to be running whilst I'm recording. It is also said that some wifi drivers can cause audio issues so were the wifi to be turned off then both chrome and BitDefender could be disabled. Whilst this may seem extreme given how useful it is to have the internet available on the computer you're using, it wouldn't be difficult to create another longin on the machine that was designated for recording and didn't have these things enabled... food for thought.
• Microsoft.photos.exe
  • This is part of microsoft photos (not an application I use very often) and has been reported to cause latency issues as it is responsible for scanning folders and files for thumbnails. I saw a lot of discussion on microsoft forums about it but the answer that seems to make most people happy was to uninstall it through powershell so that's exactly what I did:
    • Hit the windows key and start typing "powershell", when it comes up right click on it and select "Run as administrator" to run it. Copy and paste the following command to uninstall photos:
      • Get-AppxPackage *photo* | Remove-AppxPackage
• Video.ui.exe
  • This relates to the xbox live app and affiliated services, personally I use a playstation more than not and if I want xbox related information I can alway log in, it's not a priority for this PC. As for the photos app I found that Powershell can be used to get rid of these components.
  • Xbox app
    • Get-AppxPackage *xboxapp* | Remove-AppxPackage
  • Console Companion
    • Get-AppxPackage *Microsoft.XboxApp* | Remove-AppxPackage
  • Xbox smart glass
    • Get-AppxPackage *XboxOneSmartGlass* | Remove-AppxPackage
  • Xbox Game Bar
    • Get-AppxPackage *Microsoft.XboxGamingOverlay* | Remove-AppxPackage
  • Xbox Speech Window
    • Get-AppxPackage *Microsoft.XboxSpeechToTextOverlay* | Remove-AppxPackage

DPCs and ISRs  (Deferred Procedure Calls and Interrups Service Routines)

Looking at the about page fort LatencyMon teaches us about a few different causes of audio dropouts and gives us a way of chasing them down. Essentially DPCs and ISRs are high priority processes which a PC will execute in a way that is difficult to schedule or account for, all really that can be hpoed for here is for your processes to run and exit quickly so that your audio processing isn't impacted. 

To take a look at how our system is impacted head over to the Drivers tab, order by ISR or DPC count and start going through things

ISR's

• Wdf01000.sys  (high ISR)
  • This is my top for ISR count and of course it's a required Windows driver so there's not a huge amount that can be done.. I've read about people resorting to reinstalling windows to get the latency caused by this down but I did find a thread here that gave the following as s slight fix, restart after applying:
    • Power Plan Settings > Advanced > USB settings > USB selective suspend settings > Plugged in: Disabled
    • Power Plan Settings > Advanced > PCI Express > Link State Power Management > Plugged in: Off
• HDAudBus.sys  (high ISR)
  • I've not found definitive proof one way or the other as to whether I can turn this off or not. It relates to the Realtek High Definition Audio drivers which are the lowest audio drivers I have as it was preinstalled with windows. Whilst I do have other audio drivers most things I've read seem to say that removing this one can cause issues so I've not disabled it but I did find a fix to a potential issue here. The fix proposed was:
    • Open Regedit and find and set the following in the key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\PCI""YOUR HD AUDIO PARENT""\DeviceParameters\Interrupt Management\MessageSignaled\InterruptProperties\ "MSISupported" Change to "0x00000001" or "1"
    • YOUR HD AUDIO PARENT can be found in Device Manager\Sound, Video and game controllers\hdaudio, realtek and other\Properties\Details\Parent
• Dxgkrnl.sys  (high DPC)
  • This lists itself as being a "DirectX Graphics Kernel" which is pretty ambiguous to me, I did find something potentially related here though which relates to NVidia drivers (which are what I have)
    • go to the NVidia Control Panel > Manage 3D Settings > Power Management Mode and change the value to "prefer maximum performance"