Audio Advice

Hal Robertson
October 2003

Many video producers are satisfied to concentrate their post-production efforts on the visual side of the project at hand, leaving the audio chips to fall where they may. That's too bad. High quality audio processing software is plentiful and often bundled free in all but the simplest of video editing packages. So, rather than ignore this important part of your upcoming video project, take a few minutes to familiarize yourself with some of the most common and powerful ways to spice up a video soundtrack.

For those who capture their video through FireWire, the process is a snap. Simply plug in and click the record button. But analog capture is still a way of life for multitudes of video producers. If you fit in the latter category, take heart - there are measures you can take to ensure clean audio during your video capture sessions. First, make sure you have a good, solid audio connection between your video playback device and the audio input on your computer. Some video capture cards have their own audio sections, while others require that you use the sound card in your computer. While most of these connections are standard today, there are a few special cards that require a custom pigtail or other unique connector. Just make sure it's seated properly - especially if you capture video intermittently. Second, keep your audio cables as far away from other devices as possible. Power supplies, video monitors and even the computer itself can create various hums and buzzes. If you must locate your audio cables near these menaces, run the audio wires perpendicular rather than parallel to the noisemakers. That will help to minimize the interference.

Once the audio is inside your computer and on the timeline, it's time to normalize. When normalizing, your software analyzes the overall volume and brings the volume up without clipping. Adobe Premiere calls this Audio Gain or Smart Gain - your software of choice may use another name, but the process is the same. Why normalize? The main reason is to get all your clips playing as close to full volume as possible. This helps them compete with the other audio elements in your project. Another benefit to normalizing is the effect it has on separate takes of the same scene, ensuring they all play at roughly the same level, regardless of how they were recorded.

Filters are all around us. Air filters, coffee filters, oil filters, and don't forget audio filters. That's right, there is a way to remove some of the undesirable elements in your audio too. Audio filters come in three basic types - low pass, high pass and band pass - each does just what its name implies. Low pass filters allow the lower frequencies through and block higher frequencies at a point you specify. This is handy for minimizing hiss and other high frequency noises. High pass filters work in much the same way, only allowing the higher frequencies through while blocking the lower ones. This type of filter is handy for eliminating boomy sounds like wind and background noise along with certain types of hum. Band pass filters work in the middle of the audio spectrum, allowing only those frequencies within a specific range to pass through. Each of these filters is a useful addition to your audio toolbox. Experiment with them on your next project.

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