Progress is a strange thing. Sometimes you think you have moved forwards, but actually you have taken a step backwards. After using a 12-year old MacBook Pro as my Ableton Live and Max workhorse, I moved to a slightly more modern MacBook Pro that has USB C sockets, and only has a headphone output. I didn't think any more about the significance of that single audio output until I needed to do a screen recording of Ableton Live (which will be the subject of another blog post...).
On my 2008 MacBook Pro all I did was use a Y-shaped headphone sharing widget (from the days when two people could often be seen sharing a pair of earphones - each with one earphone) and connect a 3.5mm stereo jack (grey, on the left) into the headphone output and the line input. The headphone sharing widget was also connected to my amp so that you could hear the audio on the monitor speakers. This little bit of hardware magic allowed me to have Ableton Live running, start up QuickTime Player and select 'New Screen Recording...' and capture a video of the screen and the audio output of Ableton Live (or Max, or any other audio-emitting application... Quick, easy and simple - and all hardware!
But on my much newer MacBook Pro (with USB C sockets!) there wasn't any line input socket - just a headphone output. Okay, so all I needed to do was use my audio interface... Which is where things became slower, harder and more complex. Ah, the joys of unfamiliarity!
I have a Focusrite Scarlett 2i4 2nd Generation (the nearest current equivalent is the
2i2 3rd Generation), and it has served me very well - it just works. A simplified front panel is shown above, with functions shown underneath for reference. Most simple audio interfaces have similar layouts and functions. So I looked in the User Guide for 'Screen Recording' and didn't find anything. Searching on the Focusrite web-site didn't locate any relevant tutorial either, although there was a lot of help there - just not what I needed at this moment. So I Googled it, and, as usual, I found lots of YouTube videos and web-pages that were just nothing more than click-bait, suggesting that they would show me what to do, but not actually really delivering anything other than adverts that they could monetise. It may well be that amongst all of the eager 'Click me!' results there was some useful information on screen recording, but I didn't find it. It was at this point that I realised that I was going about it all wrong, and you are reading the result. I may even do a YouTube video that isn't just click-bait and contains actual real information at some stage...
Screen Recording should be easy
It seems like it should be easy. You just record what is happening on your computer's screen and the audio that it is producing. Unfortunately, recording the digital audio output of applications running on computers is not as straight-forward as you might hope. The Operating System audio input and output control panels only show devices that are connected to the external interfaces of the computer, not what is happening inside the computer. So you only see the built-in 'internal' microphone and speaker, and any audio interfaces - in this case, a Scarlett 2i4 connected via USB. Applications like DAWs or Screen Recorders do not appear in the audio control panels. If you delve deeper using the 'Audio MIDI Setup' utility program (in the 'Utilities' folder) then that gives more detail of the built-in microphone and speaker, plus audio interfaces connected to the computer via other interfaces (USB in this case, but older computers might have FireWire...), but nothing 'internal' at the application level is shown. There's no 'patch bay' or 'routing matrix' where you can set the connections between applications that have audio inputs and outputs.
There are a number of third party utilities that allow you to route digital audio 'internally' (inside the computer) from one application to another, and I have spent quite a lot of time trying to use them. It seems that a reliable and easy-to-use digital audio routing utility is not what I downloaded, several times, with several different operating systems, versions, fixes, forum visits, and lots of promises that each of them really was the solution. It is almost as if routing and making perfect digital copies of audio is deliberately made difficult... Hmmm...
Now I know that there are lots of these utilities out there, and I know that there are lots of YouTube videos, forum posts and tutorials on how to use them, but I just didn't manage to find one that worked. Maybe this is the Interweb that we deserve? Anyway, I went back to first principles.
DAWs and Audio Interfaces
An audio interface is a handy combination of a few different utility functions all put together into one box. There are audio inputs, which can amplify microphones or guitars, as well as accept line inputs from synthesisers, drum machines, etc., and digitise and send that audio over a USB cable to a DAW running on the computer, where it can be recorded. There are audio outputs, so that the digital audio produced by the DAW can be sent over a USB cable to the audio interface, where it is converted back into analogue audio, and listened to on speakers or headphones. There's also monitor switching which lets you listen to the inputs before they are digitised, or the outputs of the DAW, or even mix the two. And there's all sorts of things borrowed from mixing desks: pads, phantom power, selection switches etc. But the basic functionality is: sockets for audio input to the DAW, and sockets for audio output from the DAW.
On my Focusrite Scarlett 2i4 audio interface, there are 2 input sockets, and 4 output sockets. Actually the inputs can be balanced (on XLR) on unbalanced (on quarter inch jacks), and there are two balanced outputs on quarter inch stereo jacks and four unbalanced outputs on RCA/Phono sockets, but that's just detail. As advertisers say: there are other audio interfaces, with different numbers of inputs and outputs.
I need diagrams - my mind thinks in pictures. The user guide for the Scarlett has words, and a few pictures - but nothing like the diagram above. Audio (microphone, guitar, synth, etc.) comes from the left hand side, gets converted to digital, goes through the USB cable and appears at the input of the DAW. Audio from the DAW goes through the USB cable, is converted back to analogue audio, and is then connected to speakers or headphones so it can be heard. Now you know too.
To configure an audio interface so that it replaces the default internal microphone and speakers, you need to set some preferences. There are several ways to do this, so I will cover them all - you will find that changes in one may well affect others. System Preferences (the gear icon) is the first place to visit. The Audio control panel has buttons for Input and Output:
Notice that the sound input shows only the internal microphone and the Scarlett 2i4 audio interface. I'm running Ableton Live and the Screen Recorder (QuickTime Player) on the computer at this point, and they do not appear in the list of sound inputs (they both have audio inputs and outputs!), so this reinforces the 'You can only control audio inputs and outputs that go outside the computer' viewpoint of the Operating System. On my old previous MacBook Pro then the input control panel had that very useful line input as well, and there was also a hidden digital optical output interface (S/PDIF / TOSLINK) hidden inside the 3.5mm output jack - a Mini-TOSLINK connector (different to the TOSLINK connector that you might find on a CD player's rear panel).
Inside Apple's 'Audio MIDI Setup' utility application, then you get more detail and more control:
Notice that the System Preferences Audio control panel calls the audio devices the 'internal microphone' and 'internal speakers', whereas in the Audio MIDI Setup utility they are the 'built-in microphone' and 'built-in output'. I would prefer it if there was a little more consistency in the naming conventions...
Inside a DAW, then there are much the same options, but presented in the UI style of the DAW. So, for Ableton Live you go to the Preferences control panel and select the 'Audio' tab:
The audio input selection has the Scarlett audio interface and the built-in microphone as the available audio input devices. (Note that the terminology used by Ableton reflects the Audio MIDI Setup naming convention...)
The audio output selection has the Scarlet audio interface and the built-in output as the available audio output devices, again using the Audio MIDI setup naming convention.
Most of the time, you will just confirm that the audio interface is chosen...
Screen Recording
Screen recording is very different to just using an audio interface with a DAW to record and playback audio. Screen recording puts two applications in that 'Computer' box in the middle of the diagram: the DAW and the Screen Recorder. I use Ableton Live as my DAW of choice for most purposes, but you can use your own DAW of preference. I use QuickTime Player (which can also record!) as the screen recorder because it came free with the computer, but you can use your own choice if you prefer. Note that although I did this on a Mac, the way that audio interfaces work is much the same on Macs and PCs, and other than you might require a driver to be installed on a PC, and you will need a screen recorder other than QuickTime Player, then you should be able to do screen recording as I describe below on a PC as well.
In all the diagrams that follow, I only show audio connections (both analogue and digital audio, as well as digital audio carried over a USB connection). The video connection between the screen of the computer (displaying the DAW!) and the Screen Recorder is not shown - but you know it is there really! Adding it to the diagrams just makes them way too complex!
The digital audio output of the DAW needs to be sent to the input of the Screen Recorder (QuickTime Player, using 'New Screen Recording...') and it would be nice if it also went to the audio interface over the USB cable so that it can be heard. This is where those utility applications come in - they allow you to route the digital audio output of the DAW to the Screen Recorder and to the audio interface. If you try to do this with some Screen Recorders then they just show you the audio inputs and outputs that are available externally to the computer - which in this case would be the Scarlett 2i4 audio interface. So the 'internal' 'DAW output' digital audio may not appear on the list of audio sources for the Screen Recorder.
Here's the Screen Recording window that QuickTime Player pops up when you select 'New screen Recording...' from the File menu. The slider at the bottom is the audio output volume control, and notice that it does not allow you to choose which audio device it sends audio to - it uses the device set in one of the previous control panels. But remember that this control is only used when QuickTime Player is playing a video file that you have recorded - note that there is no output from the Screen Recorder inside the 'Computer' box on the diagram that shows how things are connected together when a screen recording is happening:
The red spot button in the middle is the 'Record' button, and the little down arrow gives a drop-down menu that allows you to select the audio input source:
As with all of the previous control panels, this one is set to the Scarlett audio interface over USB - which, as you can see from the diagram of the inside of the 'Computer' box, is completely wrong. The input of the Screen Recorder should be the audio output of the DAW! (Which isn't an option...) The utility routing applications that I mentioned would be used here to do the internal routing of the digital audio instead of this selector. I'm not going to show any of the utility routing applications here to keep things simple.
Of course, you might want to do more than just hear the output of the DAW in the screen recording. A spoken commentary is a popular way of explaining what is happening, and so the audio inputs of the audio interface can be used to send that microphone output to the screen recorder, where it can be mixed with the output of the DAW. One way to do this might be like this:
The required utility application that routes the audio, mixes and sends the DAW output is now more complex, and a lot of these utility functions could probably be done by the Screen Recorder - although QuickTime Player only allows you to choose one audio input to record at once, so you would need to have an external mixer and mix the microphone output with the DAW input, and then send that back to the Screen Recorder. It turns out that this is a much simpler way to achieve the same result as the complex utility routing application:
In this configuration, an external mixer is used to mix together the audio output of the DAW with the commentary from the microphone. Levels and panning can be adjusted by the mixer, and the setup of the DAW and Screen Recorder software is easy and requires no complex utility application - the DAW output is sent to the audio interface, as usual, whilst the Screen Recorder just records the output of the mixer via the audio interface. The DAW output can be monitored by the audio interface, which may mean that you need to select the source of the monitoring - on my Scarlett 2i4, there's a rotary control that lets you choose between monitoring the inputs or the outputs. I set it to monitor the outputs so that I hear the DAW audio, and not the microphone. (I hate hearing my own voice)
In terms of software configuration, the DAW output is sent to the audio interface (Scarlett 2i4 in my case: this is set in Ableton Live Preferences), whilst the Screen Recorder input is set to be from the audio interface (the Scarlett 2i4 in my case: this is set in QuickTime Player (the little drop-down menu next to the red record button):
So by not using a complex routing utility application to interconnect audio applications inside the computer, we have a simple solution that we can control using native control panels.
Here's a diagram showing how the mixer connects everything together. The microphone is probably going to be panned in the centre, and is on channel 1 of this example mixer. Channels 3 and 4 are used for the DAW left and right outputs (from the unbalanced outputs of the audio interface). The left and right outputs of the mixer go to the inputs of the audio interface.
The downside of this approach is that the Screen Recorder is not getting the direct digital output of the DAW - instead it gets the DAW audio converted to analogue audio, then mixed with the microphone, and then redigitised. So the audio will not have been digital from beginning to end, but the gain in simplicity is considerable.
Note that the mixer on the input of the audio interface can be very simple - it could even be passive .(A microphone that requires phantom power is going to need either a mixer that can provide the power, or one of those phantom power boxes if you want to use a passive mixer)
Here's a screen recording about to happen. Ableton Live is running (literally) and the QuickTime Player is waiting for the red 'Record' button to be pressed to start the screen recording (which records the video of the screen and the audio - since everything so far has only talked about the audio, then it seems like a good point to mention that the whole point of this type of screen recording is to capture the video and the audio outputs of the DAW!)
A quick tip: When you have the DAW full-screen, then the screen recorder window (QuickTime Player in this case) is going to be covered up. To get it back on top, you just go to the Dock at the bottom of the screen and click on the QuickTime Player icon. (There's an equivalent way to do this in Windows...)
One thing that does need to be mentioned is that the Screen Recorder output should not be connected to the audio interface - if you do this, then a feedback loop can sometimes be created. So when making a screen recording in QuickTime Player, the output slider is always left at zero:
There is a way to simplify things even more, and this is when no microphone commentary is used. Taking the original 'headphone sharing; approach, this can be implemented by using two cables to connect the output of the audio interface to the input - very much like the mixer setup above.
The DAW and Screen Recorder have been moved around to make the diagram simpler, and if we continue with the simplification, by splitting the computer and the audio interface into two separate parts, then we get this extreme clarification:
The digital output from the DAW goes through the USB cable to the audio interface, where it is converted to analogue audio, then this is input into the audio interface input section, is digitised, goes along the USB cable, and ends up being recorded by the Screen Recorder. So only two quarter inch Jack to RCA/Phono cables are required:
This shows the back of my 2i4 audio interface, but the two outputs on the rear panel are just the two main unbalanced outputs, and so any 2in, 2 out audio interface will have these outputs.
This really is the headphone adapter all over again, but translated so that it works with the audio interface - and the monitor function of the audio interface allows the output of the DAW to be heard on speakers or headphones by monitoring the input.
Simpler still
If you don't need stereo, then you could have only one analogue cable from the output to the input of the audio interface, and use the other input for the microphone! This will give you DAW audio in one channel, and the microphone in the other channel. Extreme and minimalistic - and useful in emergencies.
Later...
My mind just won't let go of some things, and this was one of those. It turns out that the 3rd generation Scarlett interfaces with more input sources (and less front panel controls you control them from your computer over the USB cable) - the 4i4, 8i6 and upwards in inputs and outputs, have anew feature called 'Loopback' which allows you to get at the internal audio signals that are needed to do screen recording. I'm going to acquire one of these interfaces at some stage (this isn't YouTube, where people who make videos seem to get loads of gear - I buy everything you see here myself!) and see if this makes screen recording easier. My suspicion is that there will need to be quite a lot of changes to the audio routing so that the DAW is recorded by QuickTime in Screen Recorder mode (or whatever other recorder you use.) Anyway, watch this space.
One other thing that I'm now aware of is that you can make a screen recording directly in macOS Mojave with just a keyboard shortcut: Shift+Command+5 (a bit like Shift+Command+3 which takes a picture of the screen...) But audio doesn't seem to be selectable, so I need to look a bit deeper. As always, watch this blog...
Links
I mentioned my Focusrite Scarlett 2i4 2nd Generation audio interface because that is what I used for these experiments - but the nearest current equivalent is the
2i2 3rd Generation which is a 2 in, 2 out audio interface that will work fine for screen recording. It also only has two unbalanced outputs, so it is easier to get the connections correct! Full marks to Focusrite for making an audio interface that works perfectly for an unusual use case!
There are many mixers that can do the 'simple' mixer role - even a passive mixer. Here are some to research further:
Maker Hart Loop Mixer
Behringer MX400
Bastl Dude (monophonic...)
Rakit Rackimix 5 Channel Mixer
If you find my writing helpful, informative or entertaining, then please consider visiting this link:
The two numbers in orange between the frequency and amplitude grids are NOT related to the horizontal indexing of the 64 oscillators - this space was just a convenient place to put the 'Span' limits of the vertical frequency axis (anywhere else gets in the way of other UI elements). The left number is the lowest frequency set by the frequency grid and the 'Span' rotary control. The right hand number is the highest frequency set by the frequency grid and the 'Span' vertical control. It all makes sense once you are used to the way the grids and the span control work!
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