The way they are now, Apple computers will not let you record your computer audio with any of their built in programs. Most programs that will let you record system audio can be pretty expensive. This is a problem for most people that need a cheap way to record system audio for whatever reason, such as screen recordings, or legally recording uncopyrighted audio. Fortunately, there is a way around this problem.
In this tutorial I will show you an ABSOLUTELY FREE way to record the system audio from your computer (not microphone) using Quicktime and a free program called Soundflower. This is useful for screen recordings that you need to capture your computer's audio with, or legally recording uncopyrighted audio. So let's take a look...
(I'm not as familiar with WIndows computers, but I believe there is another program called "Jack" that should do pretty much the same thing. But I'm not 100% sure.)
Step 1: System Preferences
The first thing you should do is open System Preferences, and go to Sound. Click on Input. You should see something like "Internal Microphone" and "Line-in". Now click on output. It should say something like "Internal Speakers" and maybe "Headphones" or something. And in the "Input" part. The input specifies where you want the computer to receive audio from when you do some sort of audio recording. The output specifies where you want your computer to play the audio through, or how you want to hear it.
If you notice, there's nothing in the input about receiving the computer audio, and nothing in the output about outputting the computer audio. But don't worry, we can fix that.
Step 2: Soundflower
The way we fix this problem of having no way to send the computer audio to Quicktime is with a free program called Soundflower. Soundflower is a Mac extension that allows programs to pass audio to other applications. It acts as an audio device, which allows programs to send or receive audio from it without any other support.
It can be downloaded from here.
Download and install this program by opening the .dmg file and following the on-screen instructions.
(If for some reason the download doesn't work, try downloading a different version, such as the beta version)
Once Soundflower is successfully installed, visit the Sound tab in your System Preferences again. Click on "Output." There should now be two more options there, "Soundflower (2ch)," and, "Soundflower (64ch)." This is the extension that you just installed. It shows up as an audio device to just to make everything even easier.
Make sure your in the "Output" section, and click on "Soundflower (2ch)." Now your computer is outputting all of it's audio through the Soundflower (2ch) extension. (The only downside is that you will not be able to hear audio through your speakers as long as this is selected.)
Now open Quicktime Player and click on File>New Screen Recording. Click the little arrow on the side of the Quicktime window. Under the microphone section, click on "Soundflower (2ch)."
If you would rather record ONLY audio and not the screen, click File>New Audio Recording, and do the same thing.
Now click the record button and record your computer's audio!
When you're done and you want to hear audio through your speakers again, go back to System Preferences>Sound>Output, and click on "Internal Speakers." Your audio will now play through your internal speakers again.
Have fun with this!