I don’t know how many Darers are Mac users, it’s sure not common to see them doing Twitch feeds. Part of the problem might be that it takes a lot of effort and fiddling to set it up properly. So for the benefit of everyone who’s interested in doing it, here’s what I’ve learned.
You’re going to need a few pieces of software, but the good news they’re all free or low-cost. Click on this post to see the instructions:
Screen Capture: CamTwist (free)
You can get it at camtwiststudio.com. It does a pretty decent job of capturing video content off the screen in real time, and it also can do some basic compositing. It’s not the most stable software, however, so I recommend running it at a low frame rate. Open CamTwist and double-click on Desktop, full screen, and if necessary select the screen you want to capture.
Audio Bus / Routing: Soundflower (free)
Download Soundflower from http://code.google.com/p/soundflower/ and install it. It comes with SoundflowerBed, a simple config application. Start it and route the 2ch bus to the speaker.
Open System Preferences and select the 2CH bus as your default audio output. This causes all apps to send their audio to Soundflower 2CH. Since you already routed 2CH to your speakers earlier, this should enable you to hear application sounds normally – they’re just routed through the Soundflower bus now. If you can’t hear anything, fiddle with the volume – including the input volume of the 2CH bus (which you can also find on the same settings window).
That’s the most basic audio setup imaginable, we’ll get to the good stuff later. All this enables you to do right now is stream your screen and all your audio output. We just need an app to take this data and send it to Twitch:
Streaming: Flash Media Live Encoder (free)
You can download the Media Live Encoder from Adobe. It’s a hassle though, so you might want to make sure to save your install image somewhere safe for later in case you need it again. Then open your Twitch account in a browser and download the streaming profile which they conveniently provide as a download. It’s an XML file, store it somewhere convenient. Start the Live Encoder, go to the File menu and load this XML file. It sets up the basics for streaming including your private streaming key, but you can still fiddle with the settings.
Select CamTwist as the video device, and Soundflower 2CH as the audio device.
If everything is set up correctly, you’re going to see a preview of your video stream showing your desktop, and the audio bars to the left of the preview should fluctuate when you play some music. Hit the “Start” button and see if you can stream to Twitch alright.
Congrats, you have completed a basic setup! But there’s more. You might want to also talk on your videos, and you might want to mix output levels of different apps a little. Sadly and incomprehensibly, OS X has no way of doing this on its own, so we need to download more software:
Microphone Routing: LineIn (free)
Download LineIn from https://www.rogueamoeba.com/freebies/ and install it. It allows you to route input from your microphone into the Soundflower bus. However, LineIn has a stunning limitation: it can only do one route at a time. This is bad because you don’t want to route your microphone input to your speakers (it’ll cause a nasty feedback screech), you only want to route it to the actual live stream. Luckily, you can trick LineIn to do this by duplicating the app. That’s it, just use “Duplicate” from the context menu and you’ll have 2 LineIn programs. Launch them both.
With the first instance, route your microphone to Soundflower 16CH. With the second, route Soundflower 2CH to 16CH:
Activate Pass Thru on both, you should now see the indicator bars lighting up when you make a sound in the room.
Go back to Adobe Media Live Encoder and choose 16CH as your audio device.
With this maneuver we have tricked both Soundflower and LineIn into doing something their developers didn’t have in mind, but it works beautifully: the 16CH bus is now strictly for our streaming, but the 2CH bus contains all non-microphone audio which we can directly listen to. To stop streaming the mic, just deactivate “Pass Thru” on the first LineIn instance until you need it again.
Mixing: SoundBunny ($10)
Per-application audio levels is again something OS X can’t do on its own, we’re going to need yet another app for that. Go download SoundBunny for Mac, it’s $9.99.
Now you get these nifty sliders that allow you to actually control sound levels individually.
And that concludes my Mac streaming guide. As you can see due to stunning limitations of the OS X audio system we need a lot of extra cruft to accomplish some basic mixing and routing, but these apps I showed here do an excellent job of it. The only downside is you need to have them all running, and it takes a few minutes from cold start until you’re all set up and ready to stream. Remember to save your settings, especially the Media Live Encoder ones, for the next time.
Webcam Window: CamTwist or VLC
One little extra thing I like to do is show a little webcam feed in the corner as well. You can do this with CamTwist, but it crashes my system when I try it. If that’s also a problem for you, use VLC. Click on “Open Capture Device” in the menu and you’ll be able to select your Mac’s camera as an input device. Use VLC’s settings to make the video window always-on-top and remove the window’s title bar. It should now be an unobtrusive little frame that you can place anywhere you want on your streaming desktop.
