digital audio video_chap3_jul2009

8/8/2019 Digital Audio Video_Chap3_Jul2009

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IMD20503 Digital Audio and Video

Sound Edi t ingEditing Interface

Sound effects


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Object ives

Students should be able to:

Know the editing interface of most sound editing

application.

Utilize the effects and processes available in the

software.


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In t roduc t ion

There are a lot of software packages that you can use to

create audio assets.

Find out which one is the best to suits your requirementsand stick with it.

Most of the software packages can perform similar

functions.

There are many other add-ons and plug-ins that can be

applied. Recording, editing and adding effects and processes to

audio files are the most common tasks that can be done

with an audio software.


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Dest ruc t ive and Nondest ruc t ive

Edi t ing

There are 2 types of altering an audio file when editing :

1. Nondestructive editing

Refers to editing that takes place when effects areapplied to audio files and the result may be rendered toa new file while keeping the original.

When an audio file is opened, a copy of that file is

made to protect the original file.

This allows mistakes or poor judgment to be correctedwithout any loss to the original file

D t t i d N d t t i


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Dest ruc t ive and Nondest ruc t iveEdi t ing

2. Destructive editing

Refers to editing that is applied directly to the data of anoriginal audio file, the result of which may then be

saved.

When a file is directly worked on and the mistakes anderrors are made, the only way to recover back to the

point before the mistake is to undo.

Always make backups of the original audio files even when you aresure of the types of editing you are using

Always make backups of the original audio files even when you aresure of the types of editing you are using


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Rec ord ing Audio

Windows Audio Recording Interface


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Mic rophone t o Com put er

Most sound cards have a mic in and line in port.

Just plug a microphone into the 1/8 inch jack on the sound

card and record.

Noise might exist due to the radio frequencies inside the

computer tower and cable length also plays a role in noise

during recording.


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DC Offset

It occurs when a signal coming into the sound card from aninput device does not line up properly on the zero baseline.

This is due to an electrical mismatch between the input

device and the sound card.

Some software allows DCadjust before recording


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Soft w are Rec ord ing In t erfac e

Key area to look for : Control panel (recording

button and playback for

audio) Level meters

Should be around -6dBto -3dB to avoidclipping.

Clipping occurs when asignal entering the

system is morepowerful than thesystem can handle.

It result in poorrecording.

Clipping indication


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Clipping

Well recorded signal

Signal with clipping


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Edi tor

1. Stereo editor An application that facilitates the digital recording and

editing.

User can decides whether to record the audio asmono track or stereo track file.

Can mix multiple stereo files on top of one another but

will not be able to edit and manipulate any of thespecific tracks

2. Multi track editor

Can mix multiple tracks and master them. User will be able to edit or manipulate each track

separately.


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View ing Audio Fi les

1. Mono

Mono recording is a single file

Showed as a single graphical representation ofthe audio file.

Used primarily for voice recording and for

preparation for broadcasting or Internetdistribution.

The sampling rate and bit depth play an important

part but the size of mono file is half the size ofstereo file because it is only a single channel.


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View ing Audio Fi les

2. Stereo

Consist of 2 channels (left and right)

Used for most projects but the size of these audiofiles must be considered.

Always make the highest quality recording and

downgrade it when you need to.


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Ef fec ts

Less is better than more

Below are some common effects in audio editing

applications :

Reverb

Echo

Pitch Shift/ Pitch Bend Noise Gate

Compressor

Chorus

Flange/Wah-wah


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Ef fec ts

Reverb

Think of reverb as a series of echo that overlap

This overlapping of signals creates a continuoussound that eventually decays to zero.

Used to sweeten up a dialogue track or to create

the impression that the sound is in a acousticallyreverberant room.

e.g. concert halls usually have a decay of about

1.5 to 2.5 seconds long and smaller halls mayhave 1- to 1.5- second reverb times.


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Ef fec ts

Reverb Window


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Ef fec ts

Echo Echo is what you hear in very large spaces with

reflective walls.

It simply is the decaying repeat of an entire soundsignal.

A simple echo effect can create a sense of great

size and depth. Use it only when it is useful for the sound designs

intention.

Overuse of this effect becomes redundant andboring.


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Ef fec ts

Echo Window


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Ef fec ts

Pitch Bend Window

Pitch Shift Window


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Ef fec ts

Noise Gate

Noise gate removes all audio content below a

given threshold.

Used to wipe out unwanted noise, tape hiss and

low-level hum, which is usually present in less

than fantastic studios.


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Ef fec ts

Noise Gate Window


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Ef fec ts

Compressor

Can bring audio material up to specification with

professional recordings.

Used to even out an audio file.

It shrinks the dynamic range of a piece of music.

The quietist or loudest parts will become closer toeach other dynamically.


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Ef fec ts

Chorus

It takes the original signal and slightly delays the

signal.

All of this is heard at the same time, giving a very

solid thick sound.

It creates many voices or sounds from a singlevoice or sound.


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Ef fec ts

Chorus Window


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Ef fec ts

Flange/Wah-wah

Create a kind of sweeping or full sound.

Electric guitars are heard with some kind offlanger or wah-wah.


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Ef fec ts

Flange/Wah-wah Window


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Processes

Other form of effects

Can be used to alter and enhance sounds.

Below are some processes:

Equalization (Graphic and Parametric, Paragraphic)

Volume Control

Reverse/Invert Normalizing

Time Stretch

Insert Silence


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Processes

Graphic EQ Window


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Processes

3 types of equalizers:

2. Paragraphic

Used to specify a select group of frequencies,

depending on the paragraphic EQ used, forattenuation or for boosting.

Very useful to notch or cut out certain

frequencies like hum from an undergroundwire.


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Processes

Paragraphic EQ Window


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Processes

3 types of equalizers:

3. Parametric

The most specific equalizer.

Allows very discrete changes to be made to asound file.

Usually there are a set of filters thataccommodates this :

Low-frequency shelf filter

High-frequency shelf filter

Band-pass filter

Notch filter


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Processes

Parametric EQ Window


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Processes

Volume Control Allows the volume of the file to be reduced entirely or

in part by selecting a region and applying the effect.


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Processes

Reverse/Invert In reverse the audio file is reversed.

Mixing fragments of reversed audio on top of other

files has a particular effect.

Inverting a sound reverse the polarity of the soundwave.

P


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Processes

Normalizing It is like Adjusting the volume of the audio file.

It takes the highest peak and pulls it up to the level set

by the user (in dB).

P


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Processes

Time Stretch The process whereby the length of a sound file can

be increased.

Different types of sound applications have differentparameters, but usually there are three ways :

By time

By tempo

By percentage

P


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Processes

Time Stretch Window

P


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Processes

Insert Silence The process of inserting silence into a file has the

effect of extending it naturally.

Useful when creating a narration track.

When voice needs to synchronize with a video track,the silence that is inserted can strategically be placed.

Also useful to add reverb to a file that was edited tooshort in length.

P


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Processes

Insert Silence Window

S


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Summary

Editing interface in Sound Forge

Effects and processes in Sound Forge


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