System Sound Capture not working on new iMac Pro.

Hi there, 

I am using Wirecast 13.1.0 which is a beta version I think. 

I have a new iMac Pro 3,2 GHz 8 core, 32 Gb DDR4, Radeon Pro Vega 56 8 Gb. 

I am using Mac OS Catalinia 10.15.2

I am having problem capturing system audio when recording my videos. I have had this problem in all previous version too. Sometimes working and sometimes not working. But right now I cannot make it work. I have read a previous thread on this but wasn't able to solve my problem with that information. 

I have the checkbox Capture System Audio checked in the Screen Capture Properties. 

I have the TelestreamAudio.kext and I have not upgraded Mac OS since I installed this version as you can see in the attached picture. There you can also see what other .kext files are in the system. 

Would deeply appreciate your help. 


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  • The .kext extension won't work on computers with T2 chip such as the iMac Pro. If you use a USB monitoring device it will bypass the T2 chip (which is both a security and sound chip) you'll be able to capture system sound again. Eventually, no .kext extension will work at all in future macOS updates. These are Apple hardware and OS changes. Apple introduced the T2 starting with the iMac Pro in late 2017 so this has long been the case and continues as they move other Macs to the T2 chip. We have an FAQ on this.

  • Michael Oddane said:
    I have read a previous thread on this but wasn't able to solve my problem with that information. 

     I'm not sure what you've tried but we've posted that a solution is to use USB audio out. It absolutely works. We do this on our T2 Macs.

  • CraigS Thanks Craig for your answer,

    How do I use USB audio out? Could you give me more details? What kind of device do I need to buy? 

  • Michael Oddane Any USB audio out device. There are some very inexpensive ones on Amazon (although I can't recommend any one specifically). I use Behringer U-Phoria UMC22

  • CraigS I have this one. But I am not sure how I can use it to record the system audio with Wirecast. Please explain. 

  • When I attach the Scarlett Solo to the computer I can choose it as a source for sound capture with Wirecast. But I don't understand how this can help me to capture the system sound like for instance if I want to show a clip from YouTube in my video and I want to record the sound from that YouTube video. Or play some music in the background from Spotify while recording a video. 

  • Michael Oddane Can I use the Black Magic Atem Mini. 

    Right now I am using an 2,5 mm audio out cable in the earphone outlet on the iMacPro. From there I attach the other end of the cord to the Mic IN on the Atem Mini. But this becomes analogue and I get a lot of problems controlling the sound. There is a lot of distortion unless I get everything 100% OK. 

    I am using this setup to record skypesessions into Wirecast using Screencapture. I should use Rendevouz but the line gets cut all the time so it doesn't work properly. 

  • Michael Oddane If you monitor through USB,  the .kext extension works because audio is no longer going through the T2 chip.

  • CraigS I am sorry Craig. Please tell me in detail how to make this happen. 

    I have the machine on the picture above. I plug it in and can choose it in the Wirecast as sound recording. But there is no sound coming into the machine. How do I make it work? 

  • Michael Oddane You're overthinking this. Simply monitor computer audio on USB and you can capture system sound as you used to in Wirecast. Nothing more than that. 

  • CraigS I'm sorry to keep persisting. Perhaps my English is not good enough over here in Sweden. But what do you mean by monitoring?

    I have the device hooked up to the computer. I find it in Wirecast and choose it as a source for sound. But that doesn't do it. If I connect the device and then chose it in preferences in my Mac so the "sound out" goes through this device still nothing happens. 

    If I just have it attached and choose to capture the system sound as normal in Wirecast still nothing happens. 

    Please walk me through the steps how to connect this device and what I need to do in my Mac and/or Wirecast to use it to record system audio. 

    Thanks in advance, 

  • @Michael Oddane  Just monitor out of USB on your Mac.

  • CraigS 

    I have done that. I have chosen the Scarlet Solo USB as the sound out. And I have tried both choosing the Scarlett Solo USB Audio as the sound source in Wirecast and I have tried making System Sound Capture with the Scarlett Solo USB as the sound out divice. It does not work. Do I need to connect something more that just the USB cable to the iMac Pro? Do I need to put a 2,5mm Audiocord from the earphone port on the computer not the Scarlett Solo USB? 

    Is the Device not the correct one? 

    I would deeply appreciate if you could elaborate a few lines on how this is suppose to work. 

    Thanks in advance. 

  • Michael Oddane You need only to send it out of USB for monitoring. It certainly should work as I've been doing this on the iMac Pro as an early adopter.

    Once you set USB out for monitoring I have no problem capturing audio from YouTube videos, videos playing in QuickTime, screen capturing Skype audio (although not necessary with NDI). Others at Telestream have tested this and many users are doing likewise which is why we have the FAQ on it. It really works. There's nothing special that need be done other than that. Even using the cheap USB to headphone (under 10$) audio devices on Amazon work. 

    I put my headphones into my Behringer (USB device) to monitor. Nothing more complex than that.

    Perhaps your Scarlett is using a driver and not the system USB device.

  • Michael Oddane 
    ScreenCapture with Capture System Audio works like it normally does in past versions of Wirecast on other Macs as long as you monitor USB.

  • I have tried exactly what you say. I have chosen the Scarlet Solo in the Sound Out for my Mac. Then I try to do the System Sound Capture as before in Wirecast. But as you can see when I go to preferences for the System Sound Capture there are no options to choose Capture Sound. The checkbox is not there. Also I tried to Chose the Scarlett Solo as the source for sound but same thing there is not an option to capture sound. 

    Do you know why the option is not there? 

  • When I use normal Screen Capture the options are there and I can choose Capture sound but still nothing happens. 

    It is also interesting that when I choose The Scarlett Solo for monitoring Audio there are no option to control sound in the Mac. The soundbar/controller is not highlighted. . 

    It says: "the chosen device lacks option to control volume". Translated from Swedish. 

  • Michael Oddane Please test with a new document and only use Screen Capture and capture a webpage with a YouTube video playing.

    The issue may be with your Scarlett and accessing USB. The solution we recommend most certainly works so the issue is likely with your setup.
    If the Scarlett is using something other that the System USB Driver that might be the issue.

  • CraigS Thanks Craig, 

    Can I see somewhere in the Mac if the Scarlett is using the USB driver? 

  • Michael Oddane Do you have Focusrite Control installed? The Scarlett shouldn't need a driver but the software might be a factor.

  • CraigS No software, I just plugged it in and it worked. 

    This is how it looks in the system report. 

  • Michael Oddane Remove all other USB devices for testing. They may be blocking monitoring. Remove devices under Audio. That may be diverting the audio.

    Please follow previous instructions with a new simple document.

    This is what I have under Audio.

  • CraigS CraigS Thanks Craig, I'll test this tomorrow and get back to you with the results. 

  • Michael Oddane  - I would recommend Dante VIA - but the most recent version is not compatible with Catalina as far as I know. You should contact Audinate, and ask them via presales when that will be available. I will tell you it works beautiful on Mojave on my 2019 MacBook Pro, which also has a T2 chip.


  • We're putting together an FAQ on this.
    Dante Via is one solution. It has multiple parts
    And more here.

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