Tutorial 3 Phase&Recording

7262019 Tutorial 3 PhaseampRecording

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MUSC 5121 Tutorial 3

Modifying and Controlling the Elements of Sound

Writing Audio to a File

Frequency Amplitude and TimbreThe following examples will demonstrate how one can control

the elements of sound including frequency amplitude and

timbre

Start your server (make sure the internal srever is running)

and execute the code belowThe SinOscar generates a sine

wave at 500 Hz The scope message reads the results of that

function and plays it It also shows a graphic representation of the

sound in a new window The peaks represent the speaker moving

out and the valleys are when the speaker is moving in The graph

you see in the scope is an actual representation of how the

speakers move As the speakers move they compress and rarify

the air creating sound waves Try changing the add(ofset) argument 0 05 -05 - moreon add later



(Sinscar(500 500 0 05 0)sco$e())

(Sinscar(500 ampouser(500000) 0 05 ampouser(-05 05))sco$e())

The first argument for SinOscar isfreq set to [500 500] an

array with two values for left

and right channels Try changing the values of one or both of

those numbers Look for the

relationship between what you see in the scope and what

you hear in your headphones

Themul argument will chage the volume of the wave

making the wave shape wider or narrower

depending on the number you assign Remember use valuefrom 0 to 1

Look at the help file again for SinOsc It shows that the

arguments are freq phase mul add

We used the freq argument to change frequency Its

important to understand that the SinOsc

is generating a stream of numbers which represent the

sound wave The numbers run

smoothly from 0 up to 1 then down to -1 and back to 0 over

and over A sampling of these

numbers might be [0 1 2 3 4 5 6 7 8 9 10 9



8 7 6 5 4 3 2 1 0 -1 -2

-3 ] and so on The mul argument scales or multiplies these

numbers making the overall

wave move higher and lower If we change this value tosay 5 then all of those numbers

will be multiplied by 5 or reduced by frac12 So [0 1 2 3 4 ]

etc will become [0 05 1

15 2 ] and so on up to 5 then back down We will start

with 1 which is the maximum

amplitude the system can manage

If you exceed a value of 1 you will create distortion The are

however better ways to create distortion

remove your headphones before plaing this example

Sinscar(500 0 00)sco$e()

Periods Shpes and Timbre

The following example demonstrates a sound source that

geneates non-pitched sound

The reason we do not hear a pitch is that there is no

pattern (at least that we can perceive) to

the sound The sine wave moved smoothly from 0 to 1

0 -1 0 then repeated that motion A

sound wave (of any shape or contour) that has any type



of repeated pattern is periodic

Periodic waves are heard as a pitch Each revolution

through the pattern is called a period

wave or cycle A sound with no pattern is aperiodic and

will not be heard as pitched There is

a continuous scale between periodic and aperiodic so a

wave can be more or less periodic

The clearer the periods the clearer the pitch

hite+oisear(0)sco$e()

in+oisear(0)sco$e()

ron+oisear(0)sco$e()

1+oise0ar(0)sco$e()

2ustar(0)sco$e()

Frequency is pitch size of the wave or amplitude is

volume and wave shape is timbre We

will discuss timbre later but for now understand that

different shapes of waves generatedifferent timbres In general waves with sharp changes in

direction are brighter timbres

Below are some examples of other forms Use the mouse

(top to bottom) to hear a different



wave They are in order a sine wave a saw wave a

pulse triangle low frequency noise

dust pink noise and white noise You can resize the

scope

(utar(0 3nar(ampouse4r( )di6() )07)sco$e8utar(9 Sinscar Saar ulsear

1Triar 1+oise0ar 2ustar(00)

in+oisear hite+oisear)sco$e())

While you can clearly hear the difference between the

first four the noise examples are less

distinct The difference in wave types can change how

they sound but later we will use these

as control sources that is to shape some other

parameter In these cases it is important to

understand the shape of each wave since the parameter

being controlled (eg frequency)

inherits that shape The shape of the sine triangle saw

and pulse waves are clear The

LFNoise0 and LFNoise1 are random (aperiodic) wavesLFNoise0 generates discrete step

values LFNoise1 generates interpolated or ramped

values



Phase

In most cases the quality of sound is not affected by

changes in phase but its an important

concept in understanding how timbre phase

cancellation and constructive or destructive

interference work Here is the line of code we started

with

Sinscar(500 0 0)sco$e

The second argument (0) is phase Try changing

this argument to the values 0785 then 157 then 2355and finally 314 Why are these

numbers significant They are fractions (14 13 34) of

pi The plots of the wave will begin

at the corresponding point of its cycle 314 (pi) is halfway

through the cycle 2pi is the full

cycle SC3 understands pi so it is used in the codebelow to illustrate progressive phases

Phase is also often expressed as degrees 0 is 0 983072 05pi

is 90 983072 pi is 180 983072 15pi is 270 983072 and 2pi

would be 360 983072 or full cycle



The first bit of code adds two signals of the same frequency

together but they are 180 degrees in opposition

(Sinscar(900 0 05 0)Sinscar(900 $i 05 0)sco$e)

(Sinscar(900 0 05 0)Sinscar(900 ampouser(0 $i) 05 0)sco$e

)

The next example shows an array of different phases Sinscar(900 0 05$i $i 5$i $i)sco$e

Phase does affect two aspects of synthesis the way two

waves interact (when they are

different phases) and the way a control wave interacts with

its target as we will see later

To illustrate the second way phase affects sound Im going to

jump ahead to an example thatuses the sine wave as a control (covered in depth later) The

second SinOsc in the next

example is controlling the pitch (rounded and converted from

MIDI) of the first SinOsc In



simple terms the shape of the sine wave is being applied to

a virtual piano keyboard from F4

to G5 sweeping across the keys in the same way the wave

moves up and down But as youwill hear the first example doesnt begin with F4 but rather

C4 the middle pitch Thats

because the sine wave begins at 0 then moves up to 1

down to -1 and so on When the

phase argument is changed to 05pi (or frac14 through its

phase) it will begin at its peak and

therefore the top of the F4 G5 range If set to 1pi it will

begin half way through the cycle at

0 but continue moving down 15 pi will begin at its valley

Run the first line for plots of all

four examples then each example and listen carefully to

where the pitches begin

hase you can hear (as control) all $hases 0 5 5

Sinscar(900 0 05$i $i 5$i)sco$e8

0 $haseSinscar(Sinscar(0 0 )round()midic$s 0

0)sco$e

05$i (9) $haseSinscar(Sinscar(0 05$i )round()midic$s0 0)sco$e

$i () $hase



Sinscar(Sinscar(0 $i )round()midic$s 00)sco$e

5$i (9) $hase

Sinscar(Sinscar(0 5$i )round()midic$s0 0)sco$e

Recording(Writing to a File)

There are a number of approaches that one can take when

composing electroacoustic music There is real-time DSP and

synthesis where the code you write wiil play a complete piece

There is also the classic tape music approach which uses

pre-made sounds and arranges them in to a DAW (Digital

Audio Workstation) like ProTools Digital Performer Logic

Audacity etc To use SuperCollider sounds we will need to beable to record our patches as a sound file before we can

import them into an editing program

If you want to use the record feature on the server windows

first click on the

-gtdefault button on the server you wish to use Then click ontheprepare rec button start a patch and click onrecord

Clickstop when you are done

You will find your recording in theSuperCollider Recordings



folder found in theMusic partition named something like thisSlt070=lt0=9aif

hen you record this ay your gtles ill e recordedith deault 6alues and you ill$roaly ant to rename your recording

If you need to use values other than the defaults you can use

command lines so you can set the bit depth give it a name

and set the number of channelsThe following are thecommand lines to setting the defaults number of channels

file name and starting and stopping the recording

Record bit depth channels filename

srecSam$le1ormat A BintCB8

srechannels A 8

This creates a file in the SUperCollider Recordings folder

s$re$are1orDecord8

Before running these lines go back and run a previous

example

so you have something to record



srecord

Then

ssto$Decording

Play time(CombN SinOsc abs LFNoise1 LFSaw

array) - Play around with this

change values record to a file

srecSam$le1ormat A BintCB8srechannels A 8 chnage to or stereos$re$are1orDecordsrecordssto$Decording

Using code to record to disk can be clunky so the fast and

safe way is to use the server windows to record your sound

On

the default server click onprepare rec therec thenstop

when you are finished Your recording will be saved in the

Music partition of the hard drive in a folder named

SuperCollider Recordings

3 you use the Ser6er indo to record your sounds youill need to con6ert your sound gtle into a ormat thatyour seEuencer can read To dothis o$en your sound gtle in QuickTime 7 and eF$ort as



an aif gtle 4ou can also o$en the gtle in Audacity andeF$ort the gtle rom there

( 2oule clic the $arenthesis ao6e to Euicly select

the entire $atch r use com-shit-

i A Sinscar( Sine a6e osc

as( This $rotects against negati6e 6alues1+oiser(

05 reEuency o6erall andering000 range o o6erall andering1Sar(

5 = let and right channels$eed o the indi6idual see$s

mul 50 de$th o see$add 500 range o see$

))

)00 6olume stay elo 0

)8delayom+ar(i

0 maF delay5 actual delay stay elo maF delay

C delay decayadd i)

$lay

)



Second $atch 4ou can run them at the same time or

se6eral instances o the same $atch

( G- doule clic the $arenthesisampiFar(Hrraygtll(5 not too many 6alues could crashanar(

Sinscar(Sinscar(0 rrand(0 C0) 00 500))0rand))

)00$lay)

This one controls the three dimensions o sound $itcham$ and timre

(6ar trig out delay8trig A 3m$ulser(C)8 trigger rateout A li$ar( TDandr(97 trig)midic$s range in midi o$itches TDandr( trig) range o timre

maF(0 TDandr(-05 09 trig)) am$litudes)8out A anar(out TDandr(-0 0 trig))8out A outIn6Jenr(In6$erc(0 ) trig)8out A ampiFar(outdu$(C))08delay A omar(out 0 9C C)8



$lay)

HnthonyKs modigtcation

(6ar trig out delay $lay8trig A Sinscr(7000 0 05 05)8trig A 2ustr(trig 05)8trig A 3m$ulser( TDandr(5 50 trig))8

out A li$ar( TDandr(97 trig)midic$s TDandr( trig)maF(0 TDandr(-05 09 trig))

)8 out A anar(out TDandr(-0 0 trig))8

out A outIn6Jenr(In6$erc(0 ) trig)8out A ampiFar(outdu$(C))08

delay A omar(out 0 9C C)8

$lay A delay8

1reeLerar($lay ampouser(0 ) ampouse4r(0 )

05 07 0)

$lay)

M to more8 the gtrst uses a Sa as a control



(note the rising sound) The second illustrates ho 2ust can e used totrigger e6ents

(ampiFar(Hrraygtll(5 numer o oscillatorsarg c8anar(Sinscar( e sure the add is greater

than the mul1Saar((c0 ) mul 500 add 00)

) 1+oise0r()) $an s$eed)

)0$lay)

(ampiFar(anar(Mlanar(NHrraygtll( eF$rand(000 0000)) Hrraygtll( rrand(0 90))2ustar( 0))

1Trir(rrand(0 00)))du$(0)) $lay8)

one more



(6ar out nums8

nums A 008out A ampiFgtll(nums

Sinscar(eF$rand(00 0000)) Sinscar(eF$rand(000 )) 00)8utar(0 out)$lay)



(Sinscar(500 500 0 05 0)sco$e())

(Sinscar(500 ampouser(500000) 0 05 ampouser(-05 05))sco$e())

The first argument for SinOscar isfreq set to [500 500] an

array with two values for left

and right channels Try changing the values of one or both of

those numbers Look for the

relationship between what you see in the scope and what

you hear in your headphones

Themul argument will chage the volume of the wave

making the wave shape wider or narrower

depending on the number you assign Remember use valuefrom 0 to 1

Look at the help file again for SinOsc It shows that the

arguments are freq phase mul add

We used the freq argument to change frequency Its

important to understand that the SinOsc

is generating a stream of numbers which represent the

sound wave The numbers run

smoothly from 0 up to 1 then down to -1 and back to 0 over

and over A sampling of these

numbers might be [0 1 2 3 4 5 6 7 8 9 10 9



8 7 6 5 4 3 2 1 0 -1 -2
































in+oisear(0)sco$e()


1+oise0ar(0)sco$e()

2ustar(0)sco$e()













scope
















values



Phase






with


















)































0)sco$e


$i () $hase




5$i (9) $hase












first click on the














srechannels A 8


s$re$are1orDecord8


example




srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8





8 7 6 5 4 3 2 1 0 -1 -2
































in+oisear(0)sco$e()


1+oise0ar(0)sco$e()

2ustar(0)sco$e()













scope
















values



Phase






with


















)































0)sco$e


$i () $hase




5$i (9) $hase












first click on the














srechannels A 8


s$re$are1orDecord8


example




srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8














in+oisear(0)sco$e()


1+oise0ar(0)sco$e()

2ustar(0)sco$e()













scope
















values



Phase






with


















)































0)sco$e


$i () $hase




5$i (9) $hase












first click on the














srechannels A 8


s$re$are1orDecord8


example




srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8








scope
















values



Phase






with


















)































0)sco$e


$i () $hase




5$i (9) $hase












first click on the














srechannels A 8


s$re$are1orDecord8


example




srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8





Phase






with


















)































0)sco$e


$i () $hase




5$i (9) $hase












first click on the














srechannels A 8


s$re$are1orDecord8


example




srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8









)































0)sco$e


$i () $hase




5$i (9) $hase












first click on the














srechannels A 8


s$re$are1orDecord8


example




srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8























0)sco$e


$i () $hase




5$i (9) $hase












first click on the














srechannels A 8


s$re$are1orDecord8


example




srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8






5$i (9) $hase












first click on the














srechannels A 8


s$re$are1orDecord8


example




srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8













srechannels A 8


s$re$are1orDecord8


example




srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8





srecord

Then

ssto$Decording







On
















))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8













))


)8delayom+ar(i


C delay decayadd i)

$lay

)







)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8









)00$lay)






$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8





$lay)







$lay A delay8


05 07 0)

$lay)








)0$lay)



one more



(6ar out nums8









)0$lay)



one more



(6ar out nums8





(6ar out nums8



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Tutorial 3 Phase&Recording