Getting to Know Icecast
Half the battle of setting up a new server or program is knowing what is required before the actual execution. This applies to most tasks, whether you are renovating a room in your home or when tackling a job at work. Knowing what items or tools are required is essential before jumping in and attempting to complete a chore. This chapter explains the basic tools or libraries needed by icecast in order to stream over the network. Once those tools are installed, the rest happens easily and the task is more enjoyable.
Hardware Requirements
Icecast does not require much in the way of hardware since it does not perform any actually encoding of the audio data. A Linux machine with as little as an i486 processor and 32 megabytes of RAM can manage an encoded live audio stream or distribute static music files over a network. The most minimal recommended configuration today, however, would be a 400 MHz Pentium II machine with a minimum of 64 megabytes of RAM. However, as this configuration is quite outdated as well as hard to find in most situations now, most any machine of reasonable speed should work.
Users of other distributions may find Linux operable on less (or more), but icecast may not be so forgiving. A general rule of thumb is, the faster the computer, the better. Slower machines may end up dropping packets, resulting in choppy audio or a rebuffering of the audio stream. You should also have a supported NIC or network interface card. Use a 10/100/1000 NIC to optimize available bandwidth.
Choose a well-known and trusted audio card. This should also be an audio card supported by most Linux distributions as this card also determines the quality of the encoding as well as the viability of your audio feed. The SoundBlaster series sound cards from Creative Labs are highly recommended by most Linux professionals. Although, I have had success in the past using an Ensoniq card on one machine, and an embedded sound card on an Intel motherboard on another machine. Nearly all sound cards are supported by the popular Linux flavors and, in turn, work well with icecast. Other than those few items, make certain your card is supported by your Linux distribution of choice. Most Linux releases provide some sort of utility to test the card and configure the sound system. Otherwise, many GUI interfaces provide a sound system configuration tool. This is true of both KDE and Gnome.
 | There have been, in the past, minor issues with PCI audio cards co-existing on motherboards containing embedded sound cards. Either disable the integrated sound card in the motherboard BIOS or use it in place of an extra sound card. |
While preparing a machine for an icecast install, make certain some fairly good speakers are connected to test the sound. I made the mistake of first placing my rack-mounted icecast server in the server room and then hooking up the speakers there. Not good. The cooling equipment in a server room can prove a distraction. Take the time to test the machine, your configuration files, and sound quality in the quiet of your office or home.
Also, consider investing in a set of sound-dampening headsets. This allows you to test the raw audio output without the distraction of external noises. Bose makes a fine pair of headphones, but for those unwilling to shell out over $300.00 for a headset, there are alternative derivative brands. You will not only be able to assess the audio quality of your sound card but will not disturb co-workers or family members.
After making certain the correct hardware is installed and properly configured, test your sound card. A couple of the cards I have used in test icecast servers are "SoundBlaster Live!" using the "emu10k1" module and an Ensoniq card using the "es1371" module. Check your /etc/modules.conf file for any information about the audio module used by the Linux distribution of your choice. The card types are displayed when you run the sndconfig command as root from the command line in run level 3 or the system-config-soundcard utility with Red Hat Enterprise Linux and Fedora Core versions in run level 5. With SUSE distributions, use the YaST tool (now open sourced) and configure the sound card under Hardware, Sound. Other distributions may have alternative sound card setup routines. Begin feeding sound to the sound card if you are first attempting to stream live audio. My audio input feed is a stereo cable from a radio control room that connects to the blue or input port of the sound card. This feeds the raw audio data to the icecast server program. Your hardware setup, color coding, and soundcard configuration may vary.