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Mixing Audio for
Digital Video Part 1 of a 4 part series | |
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Douglas
Spotted Eagle Sundance Media Group Stockton, Utah, USA |
| Article Focus: Grammy-winning producer Douglas Spotted Eagle answers questions about mixing audio for video, with particular focus on DV editing. The article covers the physical environment, software and hardware tools, mixing techniques, and mastering audio for video. |
Video editors have long ignored audio for a variety of reasons, the most of which is that there have always been post-houses to deal with audio. The non-linear desktop editor rarely has access to these top-end post production houses, so what are the physical requirements, knowledge, and skills needed for the at-the-office or in-the-home editor? Let's start with the physical requirements. Obviously, the computer is the first and usually the last consideration. Little thought is often given to the mixing/listening environment, and this is mistake number one. The professional quality mix requires a professional quality environment, regardless of how this is achieved. Having a set of computer speakers in an office or converted bedroom won't cut it under any circumstances, so let's get that concept out of the way to start with. Not even GOOD computer speakers will suffice for the pro-sumer. Mixes need to be checked through high quality speakers so that regardless of the final viewing/listening environment, the mix sounds good. Having 2 sets of speakers is always good.
Most
of the monitors available for desktop production are powered; a few
aren't. Powered monitors offer many advantages, the biggest of which is
fewer cables, amplification matched to speaker specifications, and less
noise due to no speaker cables to absorb electrical interference. Make
sure the speaker monitor is shielded to keep interference from your
computer or external viewing monitor.
To get
the audio from the computer to the speakers, you'll also need a
converter/quality sound card. The MAudio Delta Series are
most excellent, as is their Quattro and Omni cards. These are even
more important when it comes to recording, because these cards don't
have noise and garbage generally associated with the lower end sound
cards found in most computers. Equal to the MAudio tools are the Echo Audio tools,
such as the Layla, Mona, Mia, and Gina. There are other cards available
from a variety of manufacturers as well, however the MAudio and Echo
Audio tools are industry standards. The Creative Labs Audigy
series is also a fine choice of sound card on the lower end of the
spectrum.
While not necessary, a small mixer is always valuable to have around for monitoring, easy inputting of cassette decks, Minidisk players, voice over mics, immediate control of output from computer, etc. The MAudio Mixim10 is a great choice, as is the Samson Mixpad. You'll find the Mixim 10's in our rooms. For those desiring more input channels, Mackie boards are commonly found, relatively inexpensive, and readily available both new and used. Desktop mixers generally have better preamps than those found in inexpensive or even standard sound cards, and so provide for a cleaner recording of voiceovers, instruments, etc. If a mixer is not employed, it's a good idea to have a preamp of some kind for voice overs and instrument/sound FX recording. Having a front panel mount plate for OHCI input, volume control, headphone output is also very handy to have, and can be obtained for less than 30.00 in most computer stores.
Cabling is equally important here. Cheap cables use thin
wires/thin shields, and will ultimately introduce noise/buzz/hum into
your system that wasn't there before. The interior of a computer
case is already quite noisy with lots of electrical interference moving
about. Keep that noise from coming into your system with quality cable.
This doesn't mean you need Monster cable (although it's one of the
better hyped brands) but Canare, Mogami, or other high end cable is
great, low cost, and well worth the effort to find
it.
Care must be taken to eliminate room bounce/reflections. This is critical in order to hear what is truly happening with the mix. Bass will be muddy/boomy, high end sibilance may be artificially enhanced by painted walls, glass windows, and even the desktop environment itself. There are many ways to treat this problem. First, understand that carpet on the walls does very little to prevent reflections. It will block some extreme high end frequencies from flying around, but that's about it. Bass, mids, and high frequencies will not be affected by this mythological means of making a studio look "cool." Products from manufacturers such as Auralex and Sonex are available in small quantities for very little cost, and huge benefits. Auralex even has an online university to help determine your needs. There are few high dollar studios in existence that don't use these products to reduce/eliminate room 'flutter' and reflection. Generally, for most home and corporate studio environments, having acoustic treatment directly behind the monitors, directly behind the listening environment, and potentially to the sides of the listener's ear will take care of all but the worst of problems. Some folks will tell you that egg crate foam that is used for mattresses will work well for this. DON'T USE IT! This type of foam breaks down quickly, creates dust and small particles of foam that will get into your keyboard, computer, and listening area. It's also not fire safe should you be a commercial room and will invalidate your insurance. Use quality foam or treatment materials from a qualified manufacturer. It costs less than you'd think. And it's available in many colors. Visit Auralex University for more information on how best to suit your mix environment.
Be sure your monitor speakers are at
least 6" from the wall, and equi-distant from each other, and from the
listening position. Monitors that are 4 feet apart should be
approximately 4 feet away from the listeners ear. Monitoring at optimum
levels, this distance will provide for a 'sweet spot' where the aural
picture is perfect, or near perfect. If possible, mount/stand speakers
on separate stands, rather than having them rest on a computer
workstation table. (Do not wall mount them unless you have a concrete
wall.) This will help de-couple them from the table, cleaning up bass
and keeping the mid range tight. If at all possible, get the
monitors at ear height.
That about covers of the physical dynamics of the room/mixing area. In Part Two of this series, we'll examine software and hardware tools that make for a smoother, easier mix.
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