Does anyone really record analog audio on tape these days? Sure the pros are using DAT, but you might be surprised to find out how many different ways videographers gather audio for their productions. MiniDisc, camcorders, flash memory and even cassette tape are all real-world methods of collecting the audio bits needed for a video. Unfortunately, in addition to the original recording, each of these methods also require the additional step of capturing the audio into a computer for editing and placement in a video production.
What if you could eliminate this extra step and record the audio directly into the computer, saving time and maximizing quality? Well, you can and it’s not as hard as it might seem. In this article, we’ll explore the ins and outs of recording audio directly to your computer.
Listen To The Pros
Before we get into the hardware and software necessary for audio recording, let’s take a minute to consider what you’ll be recording and how it will be used in the finished video. One of the most common applications for audio recording is narration. Used in everything from travel videos to commercials, the voiceover is a staple of video productions and has its own set of rules. Listen closely to national advertising, how-to videos or documentaries. The narrator’s voice is usually very forward and intimate, with very little or no additional effects such as reverb or delay. While you don’t likely have a million-dollar studio to record your narration, you can use some of their techniques. By choosing a high-quality microphone and recording in the quietest, least reverberant room you can find, your recordings will sound much like their expensive counterparts. Walk-in closets, lined with sound-absorbent clothing, are perfect for recording voiceovers.
Another common application for audio recording is dialog replacement. Regardless of how carefully you recorded during the shoot, there are times when the dialog is muffled or masked by other sounds. Hollywood movies often replace virtually all the audio, including the dialog, in their projects, simply for control reasons. Television dramas are a little more realistic due to time constraints, replacing problem areas, but leaving much of the original audio recording intact. You can do this too with some planning and a little trial-and-error. Set up in a similar environment, even in the original location if possible, and use the same microphone and placement as the first recording to match the original sound. The professionals even miss this sometimes.
Two final common audio recording opportunities are music and sound effects. Have you ever seen a production where they used the exact same buyout music or sound effects you do? There’s nothing like an original recording to set your project apart from the rest. Music recording is tougher than sound effects, but the payoff is a completely unique production and a growing archive of original sounds you can use again.
Hardware On Hand
Let’s start with the computer. Video production is one of the most taxing things you can do on a computer. If you can edit video on your machine, you have more than enough horsepower to record and edit audio.
Most computers come with an average sound card that can adequately handle your audio duties. There are professional sound cards that are of course more expensive, but you might as well start with what you have to see if it’ll work for you. You’ll notice most sound cards use 1/8" jacks, the same as the ones as your camcorder. This means that you can use the same microphones, adapters and headphones you use during your video shoots.
The primary disadvantage of recording directly into a computer is noise. Fan noise is the primary culprit since it is always on when your computer is on. Some computers have multiple fans and can sound like a small airport during a recording session. One way to get around this limitation is the use of extension cables for the monitor, keyboard and mouse. Find a closet or another room adjacent to your preferred recording area, then purchase cables long enough to locate the tower, along with its noisy fans, in the other room. An alternative is to place the talent in the quiet room and use long microphone and headphone cables to attach to the computer.
Another very serious problem is that your computer is an excellent electronic noise generator. Radio frequencies and electromagnetic interference is spewing from your box at all times, which is often the source of odd hums and buzzes. With this in mind, keep your cables as far away from the other cables as possible and don’t run them parallel to your keyboard cable, for example.
An interesting solution to both noise problems is an external sound card, such as the Creative Extigy. External cards perform their digital work outside of the computer and then run a digital signal back to your machine via a USB cable. This has an added advantage in that you can use the Extigy with your desktop and laptop. Keep in mind, however, that we are still talking about consumer audio cards here. Audio professionals may find themselves seriously disappointed in the performance of consumer audio cards, internal or external.
Over the past few months, two major Windows-based audio programs have changed ownership – Adobe bought Syntrillium’s Cool Edit Pro and Sony Pictures Digital bought Sound Forge. The bean counters would call this consolidation. For you and me, it just means we have to learn some new names and carefully consider upgrades in the near future. Whether you choose the new Adobe Audition or Sony Pictures Digital’s Sound Forge, or some other product, there are some audio recording tricks you should know.
First, recording levels. With a separate mixer it’s simple to adjust microphone volume levels with the twist of a knob, but when you’re recording directly to a computer, you have to use the virtual mixer included with the operating system. In Windows (see Figure 1), look in the lower right-hand corner for a small speaker icon. Double-click it and you will see a mixer window with playback volume sliders for all your audio sources. Now click Options-Properties and you’ll see the additional choice of adjusting the recording levels for these sources. Depending on the sound card in your computer, you may also see level setting meters to guide your adjustments. If there are no meters, you can use the meters in your recording application. In Audition, right-click on the meters at the bottom of the screen and choose Monitor Record Levels. In Sound Forge, click the Record button and you’ll see a dialog box with level meters. Set your levels so the loudest sound just barely hits the peak and you’re ready to record. With digital audio, the levels should never hit the top: digital clipping is always bad.
Another audio recording anomaly is the setting of bit rate and sampling frequency. DV (and DVD) projects use 16-bit audio – either mono or stereo – at a sampling rate of 48,000Hz. By contrast, CD audio uses the same bit rate, but the sampling rate is 44,100Hz. While your video editing software may be able to compensate (up-sample or down-sample), you can eliminate any potential problems within your audio software. When starting a new project, set the bit and sampling rates to work on DV (and DVD) projects. While we’re on the topic of quality, for heaven’s sake, don’t use MP3 (or any kind of compressed audio) in your video productions. By the time you’ve output a project to DVD, the audio has been through three conversion processes, two of which were lossy compression. Save yourself the grief and use only the highest quality original materials.
Recording directly into a computer sounds like extra trouble, and it is sometimes. But the extra level of control and the higher quality of sound will go a long way toward creating a soundtrack you’ll be proud to play.
Sidebar: Professional Sound
You can record professional audio on your computer with a professional sound card. What do we mean by professional? First, and this should sound familiar, balanced XLR inputs and outputs would be nice. Multiple inputs are an indication you are looking at a pro card. You can look for 192kHz, 24-bit support and a huge signal to noise ratio is also important, something like 100dB, although all sound cards have numbers like this nowadays.
Sidebar: Video Software for Audio
Advanced editing applications are getting better at audio, led by Sony’s Vegas. Vegas allows you to record directly into an audio track as you watch your project preview. You can even set it up so that there is a pre-roll before the narration begins and then have the section loop back to automatically record a bunch of takes until your talent gets it right.