Apple iMovie HD Manuel d'utilisateur télécharger pdf (Page 14)

But if the mike is too close, stereo sepa-

ration is exaggerated—some sounds

come only from the left speaker, others

only from the right, and sounds in the

center are louder than they should be.

Move the mike too far away, and you get

a muddy-sounding recording with too

much room reverb.

When recording a live performance,

try to show up for rehearsals so that

you have time to experiment with differ

ent mike distances. If your camera has

a headphone jack, connect a good pair

of headphones—ones whose cups sur

round your ears and thus block out

external sounds. Record a test, play it

back, and listen.

For recording narrations, consider

assembling a makeshift sound booth

that will absorb room echo and block

computer and hard drive noise. Glue

some sound-absorbing acoustical foam

onto two sheets of plywood or foamcore.

(See www.soundsuckers.com for a wide

selection.) Position the two sheets in

front of you in a V shape, with the mike

at the narrow end. If you’re on a tight

budget, use blankets, pillows, carpet

remnants, or even a coat closet. The

idea is to surround yourself, and the

mike, with sound-absorbing material.

Another major microphone manufacturer,

Shure, has published some excellent

mike-placement tutorials. Download them

at www.shure.com/booklets.

Creating an Audio Bed

If you weren’t able to get good audio

when you originally shot your video, con

sider muting your video’s audio track and

just putting a music bed behind your

shots. Create a montage of shots, using

bookmarks and direct trimming to help

you time your edits to the music.

And ﬁnally, a related tip: If you’re shoot

ing scenes where the audio is mostly

ambient sound—the waves at the beach,

the din of a party—shoot a few minutes

of uninterrupted video, keeping the cam

era stationary. After importing the video,

delete the video track and keep the

audio. (In iMovie HD, drag the video clip

to the timeline, then choose Extract

Audio from the Advanced menu.) Now

you have an audio bed upon which you

can put a series of video shots. After you

add those shots, mute their audio. This

technique eliminates jarring sound

changes between shots.

A Field Guide to Mike Placement

Scenario Ideal Mike Position

Solo piano About a foot from the center of the

piano’s harp, pointed at the strings

(open the piano’s recital lid).

Wedding ceremony As close to the lovebirds as possible.

Many wedding videographers attach a

wireless lavaliere mike to the groom or

the ofﬁciator. (Bridal gowns tend to rustle

too much.) A mike hidden in a ﬂower

arrangement may also work.

Narrator 6 to 9 inches from the speaker’s mouth,

angled downward. To avoid plosive

problems, use a windscreen and position

the mike just off to the side, pointing at

the mouth. Alternative: a lavaliere mike.

Choral group 1 to 3 feet above and 2 to 4 feet in front

of the ﬁrst row of the choir.

Birthday party around a table On an extended ﬂoor stand, angled

downward. Alternative: on a tabletop desk

stand, pointing at the birthday kid.

Tips for Recording Better Sound

Upgrade Your Microphone

To get better sound, get a high-quality

external microphone and place it close to

your subject.

Before you buy an external mike, deter

mine whether your camcorder can accept

one. Some inexpensive camcorders don’t

provide a jack for an external mike;

others may require an adapter that con

nects to the bottom of the camera. Most

mid-range and all high-end camcorders

have external mike jacks. On most cam

eras, it’s a

⁄8-inch stereo minijack.

Clip-on. Microphones come in all sizes

and designs. Some are specialized—for

example, a lavaliere mike, which clips to

a lapel or shirt, is great for recording a

single voice, such as that of a teacher

(or TV host). But a lav mike is unsuitable

for recording a musical performance.

Shotgun approach. When you can’t get

the mike close to your subject but still

want to reduce extraneous noise, con

sider a shotgun mike. In a shotgun mike,

the microphone capsule is mounted

within a long barrel designed to reject

sound coming from the side of the mike.

Shotgun mikes are popular in TV news

and movie making. They’re sensitive

enough to be located out of the video

frame, and their highly directional sensi

tivity means they won’t pick up noise

from cameras and crew members.

A shotgun mike works best when mounted

on a boom, a long pole (often hand-held)

that allows the mike to point down at the

subject. When you see a video crew with

one person who appears to be holding a

ﬁshing pole with a long tube on the end of

it, you’re seeing a shotgun mike (and a

sound technician) in action.

Two in one. The most versatile mike

you can buy is a single-point stereo mike.

A stereo mike crams two microphone

capsules into a single package. Each

capsule is precisely positioned relative

to its companion, thus eliminating one of

the biggest challenges of stereo record

ing: getting accurate balance and sepa

ration between the left and right channels.

I use the AT822 from Audio-Technica

(www.audio-technica.com).

With high-quality extension cables, the

mike and camera can be up to about

25 feet apart. At greater distances, you

risk losing some high frequencies and

picking up hum and other electrical noise.

A balanced alternative. When you need

to run cables longer than 25 feet or

so—or when you want the best possible

quality and are prepared to pay for it—

consider a balanced mike. All of the

aforementioned mikes are available in

balanced and unbalanced versions.

A balanced mike is wired in a way that

reduces electrical noise and allows for

cable runs of up to 100 feet or so.

Balanced mikes cost more than unbal

anced ones, but professionals and

serious amateurs prefer balanced mikes

due to their resistance to electrical noise

and their support for longer cable runs.

A balanced mike typically uses an XLR

connector, and only high-end camcorders

have XLR jacks. But there is a way to

connect a balanced mike to an unbal

anced miniplug jack: the DXA-2 adaptor

from BeachTek (www.beachtek.com).

A compact metal box that attaches to

your camera’s tripod mount, the DXA-2

requires no external power supply

and has built-in knobs for adjusting

volume levels.

Placement is Everything

To do justice to any mike, position it

properly. For that school play or recital,

use a mike stand and position the mike

high, pointing down toward the stage at

about a 45-degree angle. If you can’t set

up your own mike stand, just try to get

the mike at least a few feet off the stage

and as close to center stage as possible.

How close should the mike be? That

depends on what you’re recording

(see the table at right). The closer the

mike is to a sound source, the less room

noise and reverberation it picks up.

spread M13

iMovie HD: Making Movies

Tips for Recording Better Sound

iMovie HD: Making Movies

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Apple iMovie HD Manuel d'utilisateur Page 14

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