There are many techniques to creating proper surround sound projects, but you don't have to invest your mortgage on a full-blown sound system to achieve them.
As home theater equipment gets better and cheaper, more and more viewers expect their video soundtracks to jump from multiple speakers. The built-in TV speakers just won't cut it anymore. For the video producer, this presents a quandary: do you continue to create mono or stereo soundtracks at the risk of alienating viewers, or do you invest the extra time and money required to make the leap to surround sound? In the first of two articles, we'll look at planning your upcoming multi-channel audio/video project, surround recording techniques and how to do it in the most time and cost-effective way.
Like many video producers, my production partner and I have wanted to do a feature-length project for some time. Abandoning reason, we decided to write, direct, shoot and edit the entire thing ourselves. One problem: there was no money for the project, so we opted to do everything possible with equipment we already had on hand. After all, independent films shot on DV are far more common these days. Early in pre-production, I knew I wanted surround sound, but couldn't afford to buy any of the fancy toys the big boys use. The next few weeks included heavy research into surround recording equipment, techniques and options. As it turns out, there are several ways to create a multi-channel product with minimum investment. In fact, unless you just want to buy some gear, you can probably duplicate our results with equipment you already own.
How Many Channels?
Surround sound comes in several flavors. The most common type is 5.1 channel surround sound. The five main channels are: Left, Center, Right, Left Rear and Right Rear. The point-one designation refers to the subwoofer channel which typically contains the low frequency signals from all channels. If you've recently purchased or experienced a modern home theater, you're familiar with the setup. Pop in a current DVD release and you're in for an emersive audio experience.
In addition to the number of channels, there are a number of standards for encoding surround audio. First, and most common, is Dolby Digital; formerly called AC3. Dolby is a household name today with its brand stamped on everything from VHS tapes to digital television broadcasts. Dolby Digital is encoded, which means it digitally combines the entire 5.1 mix into one bitstream. Without this encoding, you would have to create and maintain as many as 6 discrete audio channels throughout your project. Dolby's older surround system — Pro Logic — was used on LaserDiscs and VHS tape before the advent of DVD. Another encoding system is DTS. Originally designed for theaters, DTS (Digital Theater Systems,) has made its way into home theater too, but is available on fewer titles. DTS encoding yields arguably better sound quality, but is rarely included in video editing or DVD authoring software, so we'll stay with Dolby Digital.
You Are There
The point of surround sound is to put the viewer in the middle of the action — as though they were standing at the camera position, hearing everything they see and more. While thoughts of jets flying by or bullets whizzing past your head are common, most surround content is environmental. Consider the makeup of a typical surround soundtrack. The center channel is almost always used for dialog — drawing the viewer's attention to the screen. The left and right channels contain audio information relevant to the action on the screen and, often, action just off the sides of the screen. Music is also spread across the left and right channels, much like a normal home stereo system. The rear or surround channels usually include background sounds, effects and possibly a little music. Imagine yourself in a restaurant. Independent of the discussion at your table, there are the sounds of dishes and silverware clanking, muffled conversations, laughter and maybe even some background music. At a sporting event, there is the action on the field, the sound of the stadium announcer along with cheers and jeers from the crowd. I could go on, but you get the idea. In the real world sounds come from all around us. To put our viewer in the scene, we need to create a convincing audio environment.
So how do we capture the sound of a location, or at least simulate it without expensive specialty microphones? We have two solutions — use inexpensive surround sound microphones or create simulated surround with just two microphones and some tweaking in post.
Sony and Reason Products both make inexpensive surround sound microphones suited to basic video production. Both capture surround audio and the Reason SSM even allows you to plug in a dialog mic for the center channel. While these two microphones should work fine for basic camcorder video, they sacrifice the ability to manipulate the audio in post-production by pre-encoding the surround information.
If you want more control during editing, consider using a pair of regular handheld microphones to produce simulated surround. This is a creative way to get an immersive audio experience, but it will take adding two separate audio recordings during your edit session along with careful left to right and front to rear panning. Simply face two mics opposing each other in a sort of extreme stereo configuration and place them in a location that most accurately depicts the environment, paying close attention to the sound around you. All you are doing here is recording the ambient sound around you, not necessarily your subject. If your scene includes someone speaking, you'll need to record this separately during another take with a single mic. You'll later add this take with the extreme stereo audio during editing. While this isn't, of course, capturing complete surround audio, it's capable of later being developed into very convincing simulated surround sound. Next month, I'll describe just how to do this by adding music, fx and dialog.
But what do you record with? Assuming you don't have access to a fancy multi-track audio recorder, there are a few other options. First, your camcorder is an excellent audio recorder. Using a few adapters, you can attach two microphones and go just about anywhere to gather your simulated surround information. Another option is a laptop computer. With a full battery and audio adapters in hand, it's another great portable multi-track audio recorder. For the ultimate in portability, consider a miniDisc recorder. For a couple hundred dollars, these little devices capture very high quality audio for hours on a single battery.
If you're serious about surround, it's time to inventory your available equipment. If you come up short, borrow what you can to do some experiments. For the next month your task is to plan and gather surround content using the techniques described in this article. Next month, we'll investigate ways to craft your recordings and other materials into a spacious surround track and put it on DVD.
Contributing Editor Hal Robertson is a digital media producer and technology consultant.
Sidebar: Do I Really Want To Do This?
As you read this article, you may be thinking multi-channel audio production is a lot of trouble, and you'd be right. It takes more planning, equipment and skill than your typical stereo soundtrack. Realistically, it's not necessary for every project but, properly executed, a surround mix can really wow the viewer. It shows you care about the finished product and the viewing experience. Ultimately, you have to decide who will see the video and under what circumstances. While surround production isn't necessary for an industrial training video, it's virtually required for projects that showcase your filmmaking skills.