The Interface to Software
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—and in many cases, it's more important. Let's break down the interfaces you will need in order to get sound and MIDI into your machine.
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 Express, USB, and FireWire audio interfaces.
Peripheral component interconnect express or PCI Express (PCI-E) is a standard card that sits inside a desktop computer and adds audio functionality. PCI-E cards can range from simple one-input/one-output configurations to extensive audio options with many inputs and outputs. The cards with more extensive inputs and outputs usually plug into a box called a breakout box via a special cable. Unfortunately, laptops can't use PCI-E cards without an expensive expansion chassis. For desktop computers, PCI-E is a great option and there is a nice variety of these interfaces for every budget.
Universal serial bus (USB) is a way to connect peripherals such as mice and joysticks to computers. One of the greatest benefits of USB is that it is compatible with desktop and laptop computers. USB is simply a kind of hardware port on computers that allows users to attach devices to the computer using a USB cable. USB is a standard found on all computers. USB devices simply plug into the computer; no work inside the machine is involved. This makes it possible for you to have a portable recording studio.
USB interfaces are reasonably priced. However, due to the way USB pushes data back and forth to the computer, don't expect a ton of inputs and outputs. USB is great for small setups and portable solutions. USB 2.0 is a newer form of USB that uses the same standard interface but transfers data at a much higher rate. Make sure your computer has a USB 2.0 port to take advantage of the greater speed it offers.
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 in directly 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 the standard for most audio interfaces 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 number of inputs you need is contingent on the number of microphones/audio sources you wish to record simultaneously.
Not all computers are equipped with FireWire ports, however, so it is important to know if your machine is equipped if you plan to buy a FireWire interface. Expansion cards for both desktop and laptop computers can give your computer FireWire capabilities. FireWire interfaces, connectors, and expansion cards are available in two speeds, FireWire 400 and FireWire 800. FireWire 800 allows you to transfer twice the information per second as FireWire 400. Look for FireWire S1600 and S3200 to enter the market in the coming year. Expect to see audio interfaces, external hard drives, and other peripherals taking advantage of these new FireWire standards in the coming years.
The Curse of Latency
Computer systems are great, but there is one catch: latency. When your guitar is 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 only with 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 getting better—that's the good news.
Computers are getting faster and can do all the conversions more quickly than they used to. 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, however; 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 have three options: you need a hardware reverb processor, you must sacrifice the reverb, or you must deal with the latency.