ISP-In-A-Box: The $500 Mac mini (Building a Streaming Audio Server, Part II)

Today, we want to finish building our streaming audio server by picking up where we left off in Part I. We’ll assume that you already have chosen your favorite player or smartphone and that you’ve opted out of buying Apple’s just-announced Victrola (click inset) or Sony’s latest marvel, the NetJuke. Did we forget to say it … April Fool’s. So we’ll be putting in place your own server using a Mac mini to send your tunes to your streaming audio player, whatever it may be. As we mentioned last week, streaming music is a processor and bandwidth intensive operation because your Mac not only has to decode a compressed music file stored on your local disk and broadcast it to the streaming server, but the streaming server also has to recompress it and manage the audio streams for each player that connects to your streaming server. Put another way, you probably don’t want to be transmitting a 192K audio stream in stereo if you only have a broadband Internet connection with limited upload bandwidth.

So the best place to begin the design of your streaming audio server is with a pencil and some math fundamentals. The bottom line is that a streaming audio server can only stream as much data as your Internet upload connection will support. How do you figure this out? Well, first you need to know how much upload bandwidth your Internet connection supports. Don’t take your ISP’s word for it. Instead, visit a site such as DSL Reports and run a Speed Test. The MegaPath Networks site usually works well. We don’t care so much about download performance for this project. What we’re interested in is the upload number. Let’s assume your upload number is 256 kbps. To determine the maximum bitrate that your server can support, divide the number of simultaneous streams you wish to support by the upload bandwidth of your connection. For example, the maximum bitrate your 256 kbps connection could support with two streams is 128 kbps. For 8 simultaneous streams, the supported bitrate would be 32 kbps. What happens if you do the math wrong or cheat? Your server crashes and burns. It’s that simple. Actually, the burning part is hyperbole, but you can almost count on a crash.

Another factor to consider in planning the bitrate for your streaming server is the player hardware and download bandwidth of your target audience. We’re going to assume that you are the target audience for your stream to keep things on the up and up. You did read our first installment, didn’t you? So, if you only will be supporting one stream (to you) and you plan to listen to your music on your cellphone, then a bit rate of 24 kbps in mono is probably about right unless you want the audio stream at the receiving end to die and restart regularly. If, on the other hand, you plan to play the stream from your home server at your beach house 500 miles away using an AudioTron with a three megabit cable modem connection to the Internet, then a 128 kbps stream in stereo may be more appropriate to improve the quality of the music at the receiving end. Just keep in mind that the higher the stream rate, the more processing power is required to pump out the stream. And, to broadcast in stereo, means multiplying everything by two.

Choosing A Streaming Server. Assuming you’ve solved the bandwidth requirements, step two is actually choosing a Streaming Audio Server. As we mentioned in the first part of this article, this is complicated a bit by the fact that you also need a Broadcast Server in the Shoutcast environment. If you only want a system which can send a single song on demand or a system which will play a predefined playlist, then Nullsoft’s Shoutcast DNAS server for the Mac is a perfect fit, and you can download it here. Be sure to carefully read the installation and configuration instructions which are included on Nullsoft’s web site. For the broadcaster component on Mac OS X, you can download the Shoutcast DSP Plugin for Mac OS X here. Be sure to review the configuration settings before you install the software and keep in mind that the Mac broadcast module cannot stream input from a sound card, only a playlist.

Other Broadcast Options. Let’s assume that your only reason for doing any of this is to impress your friends by playing some unique content on your cellphone "live." Nothing quite beats the iMan’s talk-radio broadcast if this is your goal. And there are a couple of approaches on the Mac platform. The first is to install the Shoutcast DNAS server on your Mac as outlined above and use the Windows platform for the broadcasting module. In this scenario, you download WinAmp 2 for Windows XP from here and then download the Shoutcast DSP Plugin for WinAmp 2.0 from here. You obviously have to have a Mac and a spare Windows XP machine and a radio with a line out jack to make this work. The only trick to successfully connecting all the pieces is making sure the passwords for the streaming server on the Mac and the WinAmp broadcaster module match. And, of course, make sure that the Shoutcast port isn’t blocked by a firewall on either your Mac or the Windows XP machine. If this sounds like a configuration nightmare, trust me. It is!

The Smarter Alternative. Unless you just spent your last nickel for lunch today, there is a far simpler way to bring up a streaming audio server on the Mac platform, but it’ll cost you $40. The product is Rogue Amoeba’s Nicecast. You can try it for free, and it’s fully functional for the first 20 minutes of every broadcast. Then the quality of the audio stream starts to deteriorate. If we’re still talking about listening to the iMan, 20 minutes is probably more than enough in one sitting anyway. In short, you can make absolutely certain that Nicecast meets your needs before you spend a dime. Complete installation and setup takes about two minutes, and Nicecast provides both the streaming server component which is Shoutcast-compatible and the broadcaster component. And any content you can play or hear on your Mac can be streamed with Nicecast. This includes iTunes as well as input from a microphone, a mixer, any radio with a line out jack, or even EyeTV. On the Mac mini, you’ll need a USB input device for most of these options. Griffin’s iMic is the best value. Finally Nicecast includes 40 professional plug-in’s including a terrific equalizer to improve the quality of your stream.

To get started, download and install the software. Run the application by double-clicking the Nicecast icon in your Applications folder. Click on the Source button and pick your input source. Click on the Input button and name your streaming station. You can include a genre and web site address if desired. Click on the Quality button and choose the quality of your audio stream. Nicecast will make an educated guess based upon the speed of your Internet connection, but you can change it in one click by selecting one of the predefined stream types. Click the Share button, and Nicecast will provide you the web link to use in your player. Make certain that Port 8000 is open on your Mac firewall and that Port 8000 on your hardware-based firewall is mapped to the internal IP address of your Mac streaming server. Now click the Start Broadcast button, and you’re in business. It really doesn’t get much easier than that which explains why Nicecast has won just about every software award worth winning including MacWorld’s Editor’s Choice in December, 2004. And, if you do ever need help, Nicecast’s first-rate documentation is as close as the Help button in the application. Finally, if you’re thinking this whole project sounds pretty silly, then take a few minutes and read this article which explains better than I why, a year from now, this project and the Mac mini may not look so silly after all. See you next week for FTP servers.