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Introduction | video | sound | lighting

Watching film is an audio and visual. But many times sound is given less importance than video. It is important to remember that sound is the second dimension that brings your production alive.

Good sound starts with a good microphone. The microphones on many DV video cameras are decent, but they come with a few inherent limitations. For one, the microphone is fixed to the camera so the microphone can only be where the camera is. This problem is magnified when the subject you are shooting is not close to the camera and there is a lot of external noises. Another problem that results is camera noise. When the audio level is low, the automatic gain control built into most DV video cameras will compensate. Doing so brings out sounds you never thought of: the sound of the tape drive, the automatic focus motor, the zoom motor, or even your own breath. If you want professional quality sound, you will have to buy an external mic

External Mics

There are many types of mics, but the two we will be concerned with are: lapel and shotgun microphones.

Lapel Mics
Lapel microphones are very small microphones that clip onto the inside of a persons' shirt. They are set up to only pick up sounds that are within a certain radius of the mic. This helps isolate the sound to make sure they only pick up your subject speaking, instead of a dog barking in the distance.

Shotgun Mics
Shotgun microphones look like a stick, and generally have higher overall quality. They are used by pointing the microphone at the subject you wish to record. Generally they are attached to a boom(a large stick) then hung over you subjects out of frame.

Most external mics require an external power source to power the mics. Some have a battery, but most require a powered "pre-amp" or "mixer" for the microphone to work.

You clip, you're dead

Clipping is when the sound exceeds a certain decibel level that either your microphone or sound recorder can handle. Clipping isn't really an issue when using the microphone that is built into most consumer level DV video cameras because the Automatic Gain Control adjusts the gain to compensate for low or high level noises. Examine the diagram and notice how a Normal Sound Wave stays curvy. Now compare that to the Sound Wave with Clipping. Notice how the clipped sound waves have square tops, it looks as if the top curves were cut off.

When sound is clipped, it has a very muffled scratchy sound that is not very fun to listen to. To avoid clipping you must adjust the gain control on your mixer. Careful not to adjust it too low or you will end up with no sound at all, but if you adjust it too high everything will sound scratchy and muffled because your sound is clipped. Also be weary of cheap external microphones. Many cheap microphones can't handle a very large decibel range, and can send a clipped signal to your mixer or sound recording device.

There is no way to fix a clipped sound. So it is always safer to adjust your mixer to record sound at a lower level and then amplify the sound in post production. But, if you adjust your mixer to record too low, when you amplify the sound in post production you may hear the low level electrical static sound mixed in with your source. Before you start your shoot, practice with the levels to find the balance that works best for you.

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Introduction | video | sound | lighting




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