How to record a screencast video for free on Mac OS X

It’s hard to find any detailed information on the web about how to record a screen video without buying expensive software. I found out how to do it, so here I’m going to explain what I did for the benefit of anyone else who’s trying to do the same.

I did this on Mac OS X 10.7 ‘Lion’, but I’ve been told it works on 10.6 ‘Snow Leopard’ too. The basic technique still works on 10.8 ‘Mountain Lion’, though sadly the trick for recording the application’s audio doesn’t work any more.

Taking a screen video is very easy, once you know where the feature is hidden. The QuickTime Player application has an option to record a screen video:

When you choose New Screen Recording from the menu, a small black window appears:

The little triangle reveals a menu that allows you to add an audio track from a microphone, and change a couple of other settings:

This works very nicely, and you can record a voiceover using an internal or external mic. The only trouble is the video doesn’t include the sounds made by the app itself. In some cases that probably doesn’t matter much, but it’s a real problem if you’re trying to demonstrate an app whose audio matters, like a game.

The next part does not work any more on 10.8. Sorry.

Fortunately there is a clever little app called Jack OS X that you can use to fix it.¹ So download and install Jack 0.89 or later.² Right now it’s still in beta, so you’ll have to look at the mailing list messages to find a link to the latest beta release. Make sure you have beta 20 or later. (Jack 0.89 should be released pretty soon, then this part will be easier.)

Open JackPilot. The first time you run it, the Preferences window will open. Make sure the option “Auto-Connect with physical ports” is ticked, and press Save. Then you’ll see a little window like this. Click Start.

Now open System Preferences >; Sound:

and change the sound output device to JackRouter.

Next open QuickTime Player and choose New Screen Recording from the File menu. Using the dropdown menu in the Screen Recording window, choose JackRouter as the microphone. Then open the app you want to record.

Go back to JackPilot, and click Routing. Select QuickTime Player in the middle column (the column labelled Receive Ports). In the left-hand “Send Ports” column, double-click on the name of the app you want to record. If you’re planning to record a live voiceover, double-click system as well. After you double-click these items, they’ll turn red, so it should look something like this:

Finally you can go to QuickTime Player and click the red button to start recording.

When you’ve finished recording your video, you should connect the QuickTime Player Send Port to the system Receive Port using JackRouter, or else you won’t hear the audio when you play it back.

If you have any trouble with this, post a comment below.

Footnotes:

1. Some blogs recommend using an app called SoundFlower for this. However, there are reports of SoundFlower causing serious problems on Lion (examples: one, two), as well as distorting the sound. The SoundFlower code has not been updated for more than a year, so these problems seem unlikely to be resolved soon. At the moment it does not look like a good choice for Lion users.

2. The released version of Jack didn’t quite work for me when I tried, so I emailed the project mailing list and Stéphane Letz fixed it the very same day. Open source development at its best.