If you’ve read the pages of Videomaker
for a while–or maybe even if you haven’t–you probably have a
pretty good idea what video editing is. All you need are the right
tools and equipment, some know-how and a good set of eyeballs.
Pretty simple stuff, when you get right down to it.
But have you thought much about
what it takes to make a good-sounding video? As it turns
out, the requirements are basically the same. Good soundtracks
require that you have access to the right tools, have an audio-savvy
brain and a good set of ears. Thankfully, videographers at any
experience level and budget can get all three of these without
a huge investment in time or money.
What follows are a half-dozen basic
guidelines for effective audio editing. These are designed to
lay a foundation of knowledge that will serve you well on your
next video. Until then, listen up!
Guideline #1: Keep Your Goal in
When it comes to audio editing, videographers
will have different goals for the many different types of scenes
they’re working with. In one part of a video, you may be using
music or sound effects to enhance a certain mood. In another section,
adding sounds may be the key to helping the audience suspend their
disbelief of some on-screen illusion. Every audio goal is important,
and each requires a slightly different approach.
If your goal is to enhance a certain
mood with sound or music, subtlety is the key. The chirp of birds,
the crackle of a fire, the patter of a gentle rain and other such
mood sounds can add immensely to a scene if used with subtlety.
Keep in mind that these are background sounds and should
never compete with dialog or other sounds. Before recording, do
a test pass for each scene. Raise the level of the background
sounds until they start to become obvious, then back them down
Using background sounds to sell
an illusion also requires subtlety. If you want an audience to
believe your video’s hero is tottering on a window ledge atop
a 120-story building, a little wind and distant traffic noise
would come in handy. Push the level of these elements too far,
though, and your audience won’t buy it. They may even laugh.
But there are some sound effects
that usually don’t require much in the way of subtlety. Gunshots,
explosions, sirens and helicopters should be loud in the mix to
give them as much power as possible. If it’s realism you’re after,
choose your sound effects with care. Sounds that are too dramatic
for a given scene can come across as corny or overblown.
CD libraries are great sources of
sound effects and background ambiences. If you can’t afford to
buy these CDs, try recording your own effects. Your camcorder
is an able audio recorder, and you can use it as such to capture
effects. When it comes to cooking up your own sounds, the only
rule is that there are no rules. Creativity is the key to effective
Guideline #2: Continuity is King
Every place you shoot has its own
very distinct aural signature, made up largely of ambient noises
and reverberation (or the lack thereof). You may not notice this
acoustic signature consciously, but your brain learns much about
its environment from these subtle aural cues. Controlling and
"faking" this acoustic signature is the key to maintaining
aural continuity from one shot to the next.
Why do we need to worry about continuity
at all? Because scenes shot in two different locations will have
distinctly different ambiences. Cut two such scenes together,
and your viewers will notice the abrupt aural shift. The edit
may look fine, but the lack of continuity in the audio
will draw unwanted attention to the edit.
The best way to maintain aural continuity
involves a two-step process that starts on the shoot. Before you
leave a given location, let your camcorder record a few minutes
of "nat sound" when nothing noisy is happening. Nat
sound is the natural ambience of a room or outdoor location, and
it’s far from silent. The hum of an air conditioner, the babble
of voices in the next room, the distant roar of a freeway–all
of these contribute to the unique personality of that location.
By capturing some of this ambiance, you can apply it in post-production
to maintain continuity.
Mixing some of this ambiance into
your audio where appropriate will lend a consistency to the soundtrack.
Almost like aural "wallpaper," nat sound smoothes over
what would otherwise be bumpy, uneven audio. Because fidelity
and synchronization aren’t important in nat sound, you can dump
it down to a regular audiocassette for playback. Trickle a little
into your soundtrack, and the results are amazing.
Here’s an example of the use of
nat sound in preserving aural continuity. At a local diner, Paula
shot a dramatic scene that captured a heated discussion between
a man and woman. At one point, with the camera catching the man’s
reaction, the woman drops a bombshell–her mother is coming to
live with them. The actress delivered her line smoothly, and the
man’s reaction was perfect. Paula was happy with the take, and
began to tear down her equipment. As she rolled up her mike cables,
she let the camcorder record about five minutes of the natural
sound of the diner. Later, she would be very glad she did.
Upon reviewing the footage, Paula
discovered that a loud cough from just off-camera ruined the actress’
key line. There was no time for a re-shoot at the diner, so Paula
had the actress come to her house to record the line again. Paula
miked the actress with the same lavalier mike, being careful to
position it in roughly the same spot. After three tries, Paula
got a keeper take.
Dubbed straight into the scene,
the new line would sound awful. The background bustle of the diner
would disappear for the duration of the edit, replaced by the
stuffy quietness of a living room. To make the edit invisible,
Paula adds in some of the nat sound of the diner from an audiocassette.
After two or three tries, Paula gets the nat sound level set to
match the other shots. The result is a seamless edit, with no
change in background ambiance. The scene is saved.
Guideline #3: Set Record Levels
Every electronic circuit–be it camcorder
record head, audio mixer input or home theater amplifier–has
a signal level it performs best at. Feed a circuit a signal that’s
much lower than optimum, and unwanted noise begins to threaten
the integrity of the signal. Give the circuit too strong a signal,
and abrasive, harsh overload distortion is the result.
Every place you can control
signal levels, you should. If your record VCR has automatic or
manual record levels, use the latter and set levels yourself.
No automatic circuit can do a consistently good job setting levels;
with practice, you can.
The main goal in setting proper
signal levels for recording or dubbing is always the same: keep
levels as high as possible without distortion. Peaks (occasional
loud sounds) have a greater effect on where we set levels than
do "average" sounds. Watching your meters closely for
a minute or two should give you a good idea how severe any signal
peaks are. Are you recording the consistent rush of a waterfall,
or the drone of an uninspired narrator? If so, peaks will be relatively
mild and you can set your average levels quite high. Program audio
with occasional loud sounds will require you to set your average
level much lower to keep peaks from distorting.
Most level meters show optimum signal
level at "0dB." Meter readings below optimum fall into
negative numbers (-12dB, for example), while higher values go
positive (e.g., +3dB). Analog circuits rarely distort if signals
push a little beyond 0dB–most have "headroom" to accommodate
the occasional signal peak. Digital systems, on the other hand,
usually distort severely the instant a signal passes 0dB.
Here are some guidelines for setting
input levels on various types of audio post-production equipment:
- Digital audio recorder (Hi8
PCM, DV, nonlinear editing system)
Think of the 0dB level as a "brick wall" that will destroy
your audio signal if you push into it. Set levels so peaks hit
at about -2dB or -3dB.
- VHS-family linear track
Though this is an analog audio format, its relatively poor performance
gives it very little headroom. Don’t let peaks push past about
- 8mm-family AFM audio The
AFM track has a generous (read forgiving) amount
of headroom. On most systems, peaks will stay clean upwards of
- VHS and S-VHS hi-fi
Thanks to an audio compression system, hi-fi audio has headroom
galore. I’ve seen average levels running at +10dB, with
peaks considerably higher than that. With most hi-fi VCRs, you
can light all the red LEDs and still not have distortion. To be
safe, though, keep peaks below +10dB.
- Analog signal processor (i.e.
compressor, EQ) Most analog
processors have good headroom, handling peaks of +10dB with ease.
In general, though, try to keep average levels around 0dB with
peaks around +6dB.
- Digital signal processor (i.e.
reverb, delay unit) Like
a digital recorder, most digital processors clip severely above
0dB. You can feed conservative levels to these processors and
still enjoy excellent sound quality. Keep peaks between -3dB and
Guideline #4: Use Audio Processors
As a videographer, you probably have
a grasp on the ins and outs of color correctors, special effects
generators and other video toys. But did you know that there are
countless audio processors available, each as useful to
good videography as any video processor? Knowing how to apply
these processors in post-production can make a huge difference
in the quality of your soundtracks.
Here’s a quick run-down of the most
common audio processors, and how they can help the sound of your
All sounds cover a certain range of frequencies. When a sound
is lacking (or is too strong) in one frequency area, it doesn’t
sound quite right. Improper miking usually results in such out-of-balance
sounds, and an EQ can go a long way towards fixing the problem.
An EQ lets you boost or cut specific
frequency ranges. If a mike sounds dull and muddy, removing some
low-mids can clean up the sound. If a speaker sat too far from
his mike, an EQ can bring up the bass to restore the missing warmth.
Most audio mixers have simple EQ built-in, which is adequate for
many needs. When you need more control, however, a stand-alone
EQ is the best solution.
Instead of altering frequency balance like an EQ, a compressor/limiter
affects the level of a signal. Compression involves reducing the
volume of loud sounds, while bringing up the level of quiet sounds.
This makes your audio much more consistent in level, and gives
it a louder, more "in-your-face" quality. TV ads often
use extreme compression, making them sound much louder than the
show they’re interrupting. Limiting performs more severe processing
than compression, but only on the loudest peaks. Limiting is less
noticeable to the ear, and is useful for keeping loud sounds from
distorting during recording.
Most "dynamics processors"
will perform compression or limiting (some do both at the same
time), and most are stereo units. Investing a few hundred dollars
in a compressor/limiter–and learning to use it properly–will
go a long way toward improving the quality of your soundtrack.
- Reverb/delay unit
This type of digital processor adds the most deliberate "effect"
to your sound by creating something that wasn’t originally part
of the audio. Reverb processors simulate the smooth decay of sound
you hear in a room; delay processors create a repetitive "Hello…
hello… hello…" echo effect.
Reverb and delay effects can be
useful in creating a disorienting, unreal sound. This type of
effect could really enhance a dream sequence or similar scene.
Don’t go overboard with this type of processing–a little bit
tends to go a long way.
Artificial reverb can be an aid
in maintaining continuity, as you can add the sound of a given
room onto an otherwise "dry" recording. Note that it’s
quite hard to simulate a natural space exactly, and no reverb
processor will add in the other noises that give a location its
unique character. In most cases, you’re still better off recording
some natural sound on the shoot.
Guideline #5: Stay in Sync
Synchronization of sound and video
quickly becomes an issue when editing. The important thing is
to make a distinction between those audio elements that must stay
in absolute sync with the video and those that can run "wild."
Unless you have an audio recorder that will chase time code (assuming
you have a time-code system), your best bet is to keep synchronized
elements on videotape. The audio won’t slip out of sync or wiggle
around in pitch if it stays securely on tape.
Elements that don’t require sync
can come from any number of different playback sources during
an edit. You can route CD players, cassette decks, MiniDisc players,
VCRs and computers into an audio mixer to blend sounds on the
fly. To get things in rough sync, look for a specific on-screen
action to cue you where to start your audio sources. ("If
I start the CD just as the car door slams, the music fades out
at the perfect time.") Because most audio sources play back
at a reliable speed, you’ll get consistent results until your
edit is complete. In the off chance you’ll need to re-edit a scene,
make a written note of where you started each audio element.
Audio elements that require sync
- Any on-screen dialogue (mouth
- Sharp sounds that coincide with
Audio elements that don’t require
- Off-camera dialogue.
- Talent talking at a great distance
(wide shot), or with mouth not visible.
- Background music.
- Background ambience (natural sound).
- Sustained sound effect (earthquake
Some videographers mix their non-synced
elements together onto one tape, often called an audio "submaster"
or "submix." This is more convenient than trying to
start numerous different audio sources at the same time, but it
does have one disadvantage–you can’t adjust the relative level
of sounds once you mix them together.
Guideline #6: Know Your Gear
Our last guideline is almost obvious
in its simplicity, but many folks overlook it. In simple terms,
know your equipment inside and out. Know the capabilities of your
audio mixer. Know which tracks will and won’t dub on your VCR.
Have a good grasp on the signals levels that your various equipment
The better you know your equipment,
the more smoothly each edit session will go. More importantly,
your finished product will look and sound much better. Learning
all about your equipment may require reading the manuals (gasp!),
but you’ll never regret the time you spent exploring your gear.
Remember: you can never know too
much about your equipment.