Pure Data another integrated computer music environment
Miller S Puckette
Department of Music UCSD La Jolla Ca msp ucsd edu
Kunitachi College of Music Reprinted from Pro ceedings Second Intercollege Computer
Music Concerts Tachikawa pp
May
Abstract making software systems which were really usable
by non computer scientists was addressed by the
A new software system called Pure Data is in the
Max program Max was an attempt to make
early stages of development Its design attempts to
a screen based patching language that could imi
remedy some of the de ciencies of the Max program
tate the mo dalities of a patchable analog synthesizer
while preserving its strengths The most imp ortant
Many other graphical patching languages had b een
weakness of Max is the di culty of maintaining com
prop osed that did not su ciently address the real
p ound data structures of the type that might arise
time control asp ect and many other researchers had
when analyzing and resynthesizing sounds or when
by then prop osed much more sophisticated real time
recording and mo difying sequences of events of many
control strategies without presenting a clear and fun
di erent types Also it has proved hard to integrate
to use graphical interface Max was in essence a com
non audio signals video for instance and also au
promise that got part way toward b oth goals
dio sp ectra into Max s rigid tilde ob ject system
Finally the whole issue of maintaining two separate
As so on as Philipp e Manoury s Pluton was realized
copies of all data structures one to edit and one to
using Max thus proving Max to b e an interesting
access in real time has caused much confusion and
environment for real time computer music a stream
di culty Pd s working prototype attempts to sim
of criticisms of Max started to app ear Max wasn t
plify the data structures in Max to make them more
originally intended as a programming language yet
readily combined into novel user de ned data struc
many users treated it as one As such Max had obvi
tures Also the relationship b etween the graphical
ous shortcomings some of which are rep orted in
pro cess and the real time one which is handled in
Also the original version of Max b eing written for
one way on the Macintosh and another way on the
a Mac Plus computer didn t address the question of
ISPW is replaced by yet a third solution
computer generated audio remaining instead in the
realm of MIDI This was addressed in but only
Introduction
for sp ecial hardware
The design of real time computer music systems has
b een a sub ject of active research since the RTSKED The question of how to use Max to amass and use
program By several authors were prop os data arose in IRCAM during the design phase of the
ing formal or semi formal real time proto cols some ISPW A new software idea called Animal was pro
times in the guise of complete systems for doing p osed and implemented Many ideas in Pd owe
real time computer music The question of their origin to the Animal program way to restore saved do cuments as in message passing N=32
−2 for real time computer music control and synthesis
Blackman
In this example the new canvas ob ject is the
window which names itself X The third command
to X is to create a graph which then receives its
−3
own messages b efore the rst p op message resets
X to p oint to the original canvas Text can b e added either to the graph in the graph s own co ordinates
−4
like N or to the canvas in centimeters like
the string Blackman The data to b e graphed are
from a le in this case but supp ort is also N=2048 taken
−5 included for embedding the data in the Pd le
0 1 2 3 Canvasses which currently can hold only text and
graph ob jects will so on supp ort the style Max
b oxes and interconnections and also a framework
Figure Sample Pd generated graph
for collections which will generalize Max s explode
feature Pd will therefore incorp orate three window
types of Max patch table explo de into a single new
Design
window type
Pd s rst application has b een to prepare the gures
for an up coming signal pro cessing pap er by Puck
Templates
ette and Brown Commercially available software for
graphing data proved unsuitable for this application
In Pd the notion of a patch as in Max and the
The same can often b e said of music software The
notion of a dialog for searching for instance or for
rst exercise for Pd has b een to render graphs such
setting the range of a slider are uni ed There is
as in Figure There is as yet no editor for these
one exception the le selection panels will b e normal
graphs The source for the one shown follows
dialogs not patches If for instance we op en a
Max style number b ox a template window app ears
N canvas noise sim bla
as in Figure
X font helvetica medium r
Another example of a template would corresp ond
X text Blackman
to a p oint of the graph of Figure its two entries
X graph noise sim bla plot
would b e for the x and y values of the p oint In
X xticks
this case it would b e p ermissible to add a eld to the
X xlabel
template which would add the corresp onding eld to
X yticks
all the p oints b elonging to that template This could
X ylabel
either b e the p oints of one of the curves of the graph
X style point
all the p oints of the graph or all the p oints of several
more style lines omitted
graphs
X text N
Templates di er from the abstractions of Max
X text N
in that the template is not re instantiated for each
X pop
invocation a single template acts as a non mo dal di
X pop
alog window for all instances of the data structure it
The format is very much like the Max le format controls If an anonymous data structure a one o
which features embedded descriptions of patchers As member of a heterogenous sequence in e ect a Max
with Max the message system is used in the same message as in a Max qlist is op ened a made to order tcl numbox Pd Pd−gui Max
type: int Pd implementation show: text Figure
top: 100
Pure Data also will get rid of one ma jor annoyance signal
bottom: 0 in Max which is the necessity of sp ecifying
ob jects to provide constant inputs Pd will allow tilde
ob jects to query their connections if no signals are
connected to a signal input but a oating p oint outlet
Figure The template for a number b ox
is connected a scalar input version of the tilde ob ject
will b e called if available otherwise a signal ob ject
template is created to show it
will b e provided automatically
To supp ort templates a new eld ob ject is in
tro duced Fields di er from numbers in having eld
names as in Figure Max style patchable ob jects
Implementation
can query a template patch for the onset of a eld of a
given name so patches can traverse data structures
Pd is in two parts as shown in Figure The real
through their templates Also any data structure
Pd shown at left do es real time computations using
which could b e called a Pure Datum can b ecome
a Max FTS like message interpreter and scheduler
a Max message handled in the usual way
All Pd do cuments reside in the address space of Pd
The other pro cess named Pd gui talks to the com
puter s window system through the tk to olkit
DSP
This should allow p ortability to the X MS and Mac
intosh window systems although the current proto
Max FTS which was the predecessor of Pd had a
type runs only on SGI hardware
severely limited notion of audio signals which has
proven to o restrictive for working with frequency The real time non real time divide works very dif
domain or non audio signals In Pd users may create ferently from that of Max FTS the editor resides
DSP blo cks in which sample rate and vector size in the real time Pd layer not in Pd gui in Max FTS
vary This is done using two new tilde ob jects the four di erent editors all reside in the GUI layer
clock and reclock The rst of these allows the Max This choice re ects an imp ortant change that
user to attach a symbolic name to a sp eci c combi has o ccurred in computer hardware in the last ten
nation of sample rate and vector size This notion years multiprocessors like the X and ISPW are now
replaces the switch mechanism of Max FTS any giving way to unipro cessors at least in computer mu
clock can b e turned on and o The reclock ob sic applications This year we can exp ect to see a
ject simply converts a signal to any desired clo ck For unipro cessing computer announced which will equal
example preparing a signal for overlap FFT analy the six pro cessor ISPW in sp eed at less than half the
sis is simply re clo cking to a clo ck with the necessary cost For the ISPW it was necessary to make the do c
prop erties the overlap add step for converting back ument the patch reside in the graphical layer b e
into the time domain is accomplished by re clo cking cause otherwise there would b e six do cuments This
to the usual clo ck caused nightmarish problems in keeping the two data
sets Max s and FTS s coherent In Pd we sidestep ference San Francisco Computer Music Asso
this problem by putting all calculations b oth editing ciation p
moves and real time audio rendering in a single pro
Anderson D and R Kuivila A Mo del
gram Pd is therefore badly suited to multiprocessing
of Real Time Computation for Computer Mu
but more in line with current hardware developments
sic Pro ceedings of the International Com
than Max FTS
puter Music Conference San Francisco Com
Pd should provide near patch level compatibility
puter Music Asso ciation pp
with Max from IRCAM and near source com
patibility with externs Most of the di erences
Boynton L et al MIDI LISP A LISP
will b e minor design changes argument types of li
Based Music Programming Environment for the
brary functions for example which can easily b e
MacIntosh Pro ceedings of the Interna
aliased in an include le At the patch level cer
tional Computer Music Conference San Fran
tain ob jects such as FFT will b e replaced and the
cisco Computer Music Asso ciation pp
nefarious downsampling argument to line and sig
will probably b e replaced with the symbolic name of
Puckette M The Patcher Pro ceedings
a clock ob ject Pd will probably read Max patches
of the International Computer Music Con
but only save les in the Pd format The C source
ference San Francisco Computer Music Asso
co de will b e made freely available to the public
ciation pp
Lewis G ref lewis A Max Forum Ar
Conclusion
ray pp
Puckette M FTS A Real time Monitor
It is to o early to say whether or not Pd will re
for Multipro cessor Music Synthesis Computer
place Max as a real time computer music environ
Music Journal
ment The success of Max re ects a lucky con uence
of many events the rise of the Macintosh the arrival
Lindemann E ANIMAL a Rapid Pro
at IRCAM of di Giugno s X machine which pro
totyping Environment for Computer Music Sys
vided the problem that Max had to solve David Zi
tems Computer Music Journal pp
carelli s brilliant work in getting Max published not
to mention his almost rewriting the entire program
much to its improvement and the contributions of
Osterhout J K Tcl and the Tk toolkit
Zack Settel Cort Lipp e Philipp e Manoury Chris
Reading Massachusetts Addison Wesley
Dobrian David Wessel and literally dozens of others
to the design do cumentation and creative abuse of
the program The success or failure of Pd will ride
as much on its nding a similar community as on its
design sp eci cs
References
Mathews M and J Pasquale RTSKED
a Scheduled Performance Language for the Cru
mar General Development System Pro ceedings
of the International Computer Music Con