Digital Audio Video_Chap3_Jul2009
Transcript of 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.
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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).
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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
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Processes
Time Stretch Window
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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.
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Processes
Insert Silence Window
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Summary
Editing interface in Sound Forge
Effects and processes in Sound Forge
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