Computers are highly adaptable machines. They can handle almost anything you throw at them…that is, if you can get your information into the machine. In the case of music, you need a special interface to get sound and/or MIDI into the computer. In addition to the software component, the interface is just as important, in many cases more important. Let's break down the interfaces that you will need in order to get sound and MIDI into your machine.
MIDI
Of all the interfaces, the MIDI interface is the simplest for the computer. MIDI format consists of simple data that can easily be streamed to a computer. You can get a simple MIDI interface inexpensively, and many companies make interfaces to work with every make and model of computer. The MIDI format is often included with the PCI, USB, and Firewire interfaces.
PCI
PCI (peripheral component interconnect) is a standard card that sits inside a desktop computer and adds audio functionality. PCI cards can range from simple one-input/one-output configurations to extensive audio options with many inputs and outputs. The more extensive inputs and outputs usually plug into a box called a breakout box that is connected to the PCI card via a special cable. Unfortunately, laptops can't use PCI cards without expensive modifications or expansion chassis. For desktop computers, PCI is a great way to go and there is a nice variety of these interfaces for every budget.
USB
USB (universal serial bus) is a relatively new way to connect peripherals such as mice and joysticks to computers. It was only a matter of time before audio interfaces started to appear using USB. One of the greatest benefits of USB is that it is compatible with desktop
Firewire
Firewire or IEEE1394, as it's also known, is a high-speed interface that, like USB, no longer requires a card inside a computer. Firewire is another hardware port on the computer that allows devices to plug directly into the computer using a Firewire cable. Firewire was originally conceived for digital video cameras to transfer large amounts of video data to a computer at high speeds. As an audio interface, Firewire is very popular because it can handle a large data flow and many simultaneous inputs and outputs. It's also ideal for laptop computers that need a powerful audio interface. Firewire is fast becoming the preferred audio interface offered today.
No matter what interface you choose, make sure it offers the connectivity you need. Look especially hard at the number of microphone inputs your interface allows.
The Curse of Latency
Computer systems are really great…but there is one catch:
When you are plugged into an amplifier, you expect the sound to come out immediately after you play, right? You would expect the same from a recording system: You plug in and hear the signal in real time. But this is not necessarily the case with a computer. Computers deal with only digital information, so they have to convert your audio (analog) signal to digital. The computer then has to store it somewhere and retrieve it to send it back out. Then it must convert the digital signal to audio again. The problem is that the process takes some time, on the order of a few milliseconds. One millisecond won't feel like much, but approach ten or more and it starts to feel lethargic. This has been a problem from day one, but it's only getting better — that's the good news.
Computers are getting faster and can do all the conversions quicker. Interface manufacturers have also smartened up and added features that give low or no latency monitoring, which cuts down greatly or eliminates latency. There is usually a catch with low-latency modes; you usually lose the effects from the computer. So if you're recording a vocal part and you want to monitor the signal with reverb, you need a hardware reverb processor, you must sacrifice the reverb, or you must deal with the latency.
Don't be too worried about latency. Latency times have decreased significantly over the past few years, so now it's just a minor annoyance. At the speed technology moves, latency should be a nonissue soon.
