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authorFrank Barknecht <fbar@users.sourceforge.net>2004-04-23 16:26:21 +0000
committerFrank Barknecht <fbar@users.sourceforge.net>2004-04-23 16:26:21 +0000
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+\documentclass[10pt,english]{scrartcl}
+\usepackage{babel}
+\usepackage{shortvrb}
+\usepackage[latin1]{inputenc}
+\usepackage{tabularx}
+\usepackage{longtable}
+\setlength{\extrarowheight}{2pt}
+\usepackage{amsmath}
+\usepackage{graphicx}
+\usepackage{color}
+\usepackage{multirow}
+\usepackage[colorlinks=true,linkcolor=blue,urlcolor=blue]{hyperref}
+\usepackage[a4paper,margin=2cm,nohead]{geometry}
+%% generator Docutils: http://docutils.sourceforge.net/
+\newlength{\admonitionwidth}
+\setlength{\admonitionwidth}{0.9\textwidth}
+\newlength{\docinfowidth}
+\setlength{\docinfowidth}{0.9\textwidth}
+\newcommand{\optionlistlabel}[1]{\bf #1 \hfill}
+\newenvironment{optionlist}[1]
+{\begin{list}{}
+ {\setlength{\labelwidth}{#1}
+ \setlength{\rightmargin}{1cm}
+ \setlength{\leftmargin}{\rightmargin}
+ \addtolength{\leftmargin}{\labelwidth}
+ \addtolength{\leftmargin}{\labelsep}
+ \renewcommand{\makelabel}{\optionlistlabel}}
+}{\end{list}}
+% begin: floats for footnotes tweaking.
+\setlength{\floatsep}{0.5em}
+\setlength{\textfloatsep}{\fill}
+\addtolength{\textfloatsep}{3em}
+\renewcommand{\textfraction}{0.5}
+\renewcommand{\topfraction}{0.5}
+\renewcommand{\bottomfraction}{0.5}
+\setcounter{totalnumber}{50}
+\setcounter{topnumber}{50}
+\setcounter{bottomnumber}{50}
+% end floats for footnotes
+% some commands, that could be overwritten in the style file.
+\newcommand{\rubric}[1]{\subsection*{~\hfill {\it #1} \hfill ~}}
+% end of "some commands"
+\title{RRADical Pd}
+\author{}
+\date{}
+\hypersetup{
+pdftitle={RRADical Pd},
+pdfauthor={Frank Barknecht {$<$}fbar@footils.org{$>$}}
+}
+\raggedbottom
+\begin{document}
+\maketitle
+
+%___________________________________________________________________________
+\begin{center}
+\begin{tabularx}{\docinfowidth}{lX}
+\textbf{Author}: &
+ Frank Barknecht {$<$}fbar@footils.org{$>$} \\
+\end{tabularx}
+\end{center}
+\subsection*{~\hfill Abstract\hfill ~}
+
+The goal of RRADical Pd is to create a collection of patches, that make
+Pd easier and faster to use for people who are more used to commercial
+software like Reason(tm) or Reaktor(tm). RRAD as an acronym stands for
+``Reusable and Rapid Audio Development'' or ``Reusable and Rapid
+Application Development'', if it includes non-audio patches, with Pd. It
+is spelled RRAD, but pronounced Rradical. ;)
+
+
+
+%___________________________________________________________________________
+
+\hypertarget{what-it-takes-to-be-a-rradical}{}
+\section*{What it takes to be a RRADical}
+\pdfbookmark[0]{What it takes to be a RRADical}{what-it-takes-to-be-a-rradical}
+
+RRAD as an acronym stands for ``Reusable and Rapid Audio Development'' or
+``Reusable and Rapid Application Development'', if it includes non-audio
+patches, with Pd. It is spelled RRAD, but pronounced Rradical. ;)
+
+The goal of RRADical Pd is to create a collection of patches, that make Pd
+easier and faster to use for people who are more used to software like Reason(tm)
+or Reaktor(tm). For that I would like to create patches, that solve real-world
+problems on a higher level of abstraction than the standard Pd objects do.
+Where suitable these high level abstractions should have a GUIs
+built in.
+
+So for example instead of a basic \texttt{lop{\~{ }}} low pass filter something more
+complete like a recreation of the Sherman filter bank could be included in
+that collection. My older sseq and angriff patches followed this idea in
+general, but there are much more patches needed. Like this:
+\begin{itemize}
+\item
+a sample player (adapt Gyre?)
+
+\item
+Various OSC/LFO with preset waveforms
+
+\item
+drum machine
+
+\item
+guitar simulator
+
+\item
+grain sample player
+
+\item
+more sequencers
+
+\item
+basically a lot of things like these things in Reason
+
+\end{itemize}
+
+Not that I want to make Pd be Reason, no way. But pre-fabricated high-level
+abstractions may not only make Pd easier to use for beginners, they also
+can spare lot of tedious, repeating patching work.
+
+
+%___________________________________________________________________________
+
+\hypertarget{problems-and-solutions}{}
+\section*{Problems and Solutions}
+\pdfbookmark[0]{Problems and Solutions}{problems-and-solutions}
+
+To building above system several problems are to be solved. Two key areas
+already targetted are:
+\begin{description}
+%[visit_definition_list_item]
+\item[\textbf{Persistence}]
+%[visit_definition]
+
+How to save the current state of a patch? How to save more than one
+state (state sequencing)?
+
+%[depart_definition]
+%[depart_definition_list_item]
+%[visit_definition_list_item]
+\item[\textbf{Communication}]
+%[visit_definition]
+
+The various modules are building blocks for a larger application. How
+should they talk to each other. (In Reason this is done by patching the
+back or modules with horrible looking cables. We must do better.)
+
+%[depart_definition]
+%[depart_definition_list_item]
+\end{description}
+
+It turned out, that both tasks are possible to solve in a consistent way
+using a unique abstraction. But first lets look a bit deeper at the
+problems at hand.
+
+
+%___________________________________________________________________________
+
+\hypertarget{persistence}{}
+\subsection*{Persistence}
+\pdfbookmark[1]{Persistence}{persistence}
+
+Pd offers no direct way to store the current state of a patch. Here's what
+Pd author Miller S. Puckette writes about this in the Pd manual in section
+``2.6.2. persistence of data'':
+\begin{quote}
+
+Among the design principles of Pd is that patches should be printable,
+in the sense that the appearance of a patch should fully determine its
+functionality. For this reason, if messages received by an object
+change its action, since the changes aren't reflected in the object's
+appearance, they are not saved as part of the file which specifies the
+patch and will be forgotten when the patch is reloaded.
+\end{quote}
+
+(I'll show an example of a float object changing ``state'' by a message in
+its right inlet here.)
+
+Still, in a musician's practice some kind of persistence turns out to be an
+important feature, that many Pd beginners do miss. So there are several
+approaches to add it. Max/MSP has the \texttt{preset}-object, Pd has the
+\texttt{state}-object which saves the current state of (some) GUI objects inside
+a patch. Both also support changing between several different states.
+
+Both have at least two problems: They save only the state of GUI objects,
+which might not be all that a user wants to save. And they don't handle
+abstractions very well, which are crucial when creating modularized
+patches.
+
+Another approach is to (ab)use some of the Pd objects that can persist
+itself to a file, especially \texttt{textfile}, \texttt{qlist} and \texttt{table}, which
+works better, but isn't standardized.
+
+A rather new candidate for state saving is Thomas Grill's \texttt{pool}
+external. Basically it offers something, that is standard in many
+programming languages: a data structure that stores key-value-pairs. This
+also is known as hash, dictonary or map. With \texttt{pool} those pairs also can
+be stored in hierarchies and they can be saved to or loaded from disk. The
+last but maybe most important feature for us is, that several pools can be
+shared by giving them the same name. A \texttt{pool MYPOOL} in one patch will
+contain the same data as a \texttt{pool MYPOOL} in another patch. Changes to one
+pool will change the data in the other as well.
+
+A \texttt{pool} object is central to the persistence in RRADical patches, but it
+is hidden behind an abstracted ``API'', if one could name it that. I'll
+come back to haw this is done late.
+
+
+%___________________________________________________________________________
+
+\hypertarget{communication}{}
+\subsection*{Communication}
+\pdfbookmark[1]{Communication}{communication}
+
+Besides persistance it also is important to create a common path through
+which the RRADical modules will talk to each other. Generally the modules
+will have to use, what Pd offers them, and that is either a direct
+connection through patch cords or the indirect use of the send/receive
+mechanism in Pd. Patch cords are fine, but tend to clutter the interface.
+Sends and receives on the other hand will have to make sure, that no name
+clashes occur. A name clash is, when one target receives messages not
+intended for it. A patch author has to remember all used send-names, but
+this gets harder, if he uses prefabricated modules, which might use their
+own senders.
+
+So it is crucial, that senders in RRADical abstractions use local senders
+only with as few exceptions as possible. This is achieved by prepending the
+RRADical senders with the string ``{\$}0-''. So you'd not use \texttt{send volume},
+but instead use \texttt{send {\$}0-volume}. {\$}0 makes those sends local inside their
+own patch borders. This might be a bit difficult to understand to the
+casual Pd user, but is a pretty standard idiom in the Pd world.
+
+Still we will want to control a lot of parameters and do so not only
+through the GUI Pd offers, but probably also through other ways, for
+example through Midi controllers, through some kind of score on disk,
+through satellite navigation receivers or whatever.
+
+This creates a fundamental conflict:
+\begin{description}
+%[visit_definition_list_item]
+\item[\textbf{We want borders} ]
+%[visit_definition]
+
+We want to separate our abstraction so they don't conflict with each
+other.
+
+%[depart_definition]
+%[depart_definition_list_item]
+%[visit_definition_list_item]
+\item[\textbf{We want border crossings}]
+%[visit_definition]
+
+We want to have a way to reach their many internals and control them
+from the outside.
+
+%[depart_definition]
+%[depart_definition_list_item]
+\end{description}
+
+The RRADical approach adheres to this in that it enforces a strict border
+but drills a single hole in it: the \textbf{OSC inlet}. This idea is the result
+of a discussion on the Pd mailing list and goes back to suggestions by
+\href{http://www.audionerd.com}{Eric Skogen} and \href{http://www.ekran.org/ben/}{Ben Bogart}. Every RRADical patch has (to have) a
+rightmost inlet that accepts messages formatted according to the OSC
+protocol. OSC stands for \href{http://www.cnmat.berkeley.edu/OpenSoundControl/}{Open Sound Control} and is a network transparent
+system to control audio applications remotely developed at CNMAT in Berkley.
+
+The nice thing about OSC is that it can control many parameters over a
+single communication path. This is so, because OSC uses a URL-like scheme
+to address parameters. An example would be this message:
+\begin{ttfamily}\begin{flushleft}
+\mbox{/synth/fm/volume~85}
+\end{flushleft}\end{ttfamily}
+
+It sends the message ``85'' to the ``volume'' control of a ``fm'' module below a
+``synth'' module. OSC allows many parameters constructs like:
+\begin{ttfamily}\begin{flushleft}
+\mbox{/synth/fm/basenote~~~~~~~~~~~~~~52}\\
+\mbox{/synth/virtualanalog/basenote~~~40}\\
+\mbox{/synth/*/playchords~~~~~~~~~~~~~m7b5~M6~7b9}
+\end{flushleft}\end{ttfamily}
+
+This might set the base note of two synths, fm and virtualanalog and
+send a chord progression to be played by both -- indicated by the wildcard
+* -- afterwards.
+
+The OSC-inlet of every RRADical patch is intended as the border crossing:
+Everything the author of a certain patch intends to be controlled from the
+outside can be controlled by OSC messages to the rightmost inlet.
+
+
+%___________________________________________________________________________
+
+\hypertarget{trying-to-remember-it-all-memento}{}
+\section*{Trying to remember it all: Memento}
+\pdfbookmark[0]{Trying to remember it all: Memento}{trying-to-remember-it-all-memento}
+
+To realize the functionality requirements developed so far I resorted to a
+so called Memento. ``Memento'' is a very cool movie by director
+Christopher Nolan where - quoting IMDB:
+\begin{quote}
+
+A man, suffering from short-term memory loss, uses notes and tattoos to
+hunt down his wife's killer.
+\end{quote}
+
+If you haven't already done so: Watch this movie! It's much better than
+Matrix 2 and 3 and also stars Carrie-Anne ``Trinity'' Moss.
+
+Here's a scene from ``Memento'':
+
+\includegraphics{memento.png}
+
+We see the film's main character Leonard who has a similar problem as Pd: he
+cannot remember things. To deal with his persistence problem, his inability
+to save data to his internal harddisk he resorts to taking a lot of photos.
+These pictures act as what is called a Memento: a recording of the current
+state of things.
+
+In software development Mementos are quite common as well. The computer
+science literature describes them in great detail. To make the best use of
+a Memento science recommends an approach where certain tasks are in the
+responsibility of certain independent players.
+
+The Memento itself, as we have seen, is the photo, i.e. some kind of state
+record. A module called the ``Originator'' is responsible for creating this
+state and managing changes in it. In the movie, Leonard is the Originator,
+he is the one taking photos of the world he is soon to forget.
+
+The actual persistence, that could be the saving of a state to harddisk,
+but could just as well be an upload to a webserver or a CVS check-in, is
+done by someone called the ``Caretaker'' in the literature. A Caretaker could
+be a safe, where Leonard puts his photos, or could be a person, to whom
+Leonard gives his photos. In the movie Leonard also makes ``hard saves'' by
+tattooing himself with notes he took. In that case, he is not only the
+Originator of the notes, but also the Caretaker in one single person. The
+Caretaker only has to take care, that those photos, the Mementos, are in a
+safe place and noone fiddles around with them. Btw: In the movie some
+interesting problems with Caretakers, who don't always act responsible,
+occur.
+
+
+%___________________________________________________________________________
+
+\hypertarget{memento-in-pd}{}
+\subsection*{Memento in Pd}
+\pdfbookmark[1]{Memento in Pd}{memento-in-pd}
+
+I developed a set of abstractions, of patches for Pd, that follow this
+design pattern. Memento for Pd includes a \texttt{caretaker} and an
+\texttt{originator} abstraction, plus a third one called \texttt{commun} which is
+responsible for the \textbf{internal} communication. \texttt{commun} basically is
+just a thin extension of \texttt{originator} and should be considered part of
+it. There is another patch, the \texttt{careGUI} which I personally use instead
+of the \texttt{caretaker} directly, because it has a simple GUI included.
+
+Here's how it looks:
+
+\includegraphics{caregui.png}
+
+The \texttt{careGUI} is very simple: select a FILE-name to save to, then
+clicking SAVE you can save the current state, with RESTORE you can restore
+a state previously saved. After restore, the outlet of \texttt{careGUI} sends a
+\texttt{bang} message to be used as you like.
+
+Internally \texttt{caretaker} has a named \texttt{pool} object using the global pool
+called ``RRADICAL''. The same \texttt{pool RRADICAL} also is used inside the
+\texttt{originator} object. This abstraction handles all access to this pool. A
+user should not read or write the contents of \texttt{pool RRADICAL} directly.
+The \texttt{originator} patch also handles the border crossing through OSC
+messages by it's rightmost inlet. The patch accepts two mandatory
+arguments: The first on is the name under which this patch is to be stored
+inside the \texttt{pool} data. Each \texttt{originator SomeName secondarg} stores
+it's data in a virtual subdirectory inside the RRADICAL-pool called like
+its first argument - SomeName in the example. If the SomeName starts with a
+slash like ``/patch'' , you can also accesse it via OSC through the rightmost inlet of
+\texttt{originator} under the tree ``/patch''
+
+The second argument practically always will be {\$}0. It is used to talk to
+those \texttt{commun} objects which share the same second argument. As {\$}0 is a
+value local and unique to a patch (or to an abstraction to be correct) each
+\texttt{originator} then only can talk to \texttt{commun}s inside the same patch and
+will not disturb other \texttt{commun} objects in other abstractions.
+
+The \texttt{commun} objects finally are where the contents of a state are read
+and set. They, too, accept two arguments, the second of which was
+discussed before and will most of the time just be {\$}0. The first argument
+will be the key under which some value will be saved. You should use a slash
+as first character here as well to allow OSC control. So an example for a
+usage would be \texttt{commun /vol {\$}0}.
+
+\texttt{commun} has one inlet and one outlet. What comes in through the inlet is
+send to \texttt{originator} who stores it inside its Memento under the key, that
+is specified by the \texttt{commun}'s first arg. Actually \texttt{originator}. The
+outlet of a \texttt{commun} will spit out the current value stored under its key
+inside the Memento, when \texttt{originator} tells it to do so. So \texttt{commun}s
+are intended to be cross-connected to some thing that can change. And
+example would be a slider which can be connected as seen in the next
+picture:
+
+\includegraphics{communslider.png}
+
+In this patch, every change to the slider will be reflected inside the
+Memento. The little print button in \texttt{careGUI} can be used to print the
+contents to the console from which Pd was started. Setting the slider will
+result in something like this:
+\begin{ttfamily}\begin{flushleft}
+\mbox{/mypatch~0~,~/volume~,~38}
+\end{flushleft}\end{ttfamily}
+
+Here a comma separates key and value pairs. ``mypatch'' is the toplevel
+directory. This contains a 0, which is the default subdirectory, after that
+comes the key ``/volume'', whose value is 38. Let's add another slider for
+pan-values:
+
+\includegraphics{moresliders.png}
+
+Moving the /pan slider will let careGUI print out:
+\begin{ttfamily}\begin{flushleft}
+\mbox{/mypatch~0~,~/volume~,~38}\\
+\mbox{/mypatch~0~,~/pan~,~92}
+\end{flushleft}\end{ttfamily}
+
+The \texttt{originator} can save several substates or presets by sending a
+\texttt{substate {\#}number} message to its first inlet. Let's do just this and
+move the sliders again as seen in the next picture:
+
+\includegraphics{substates.png}
+
+Now careGUI prints:
+\begin{ttfamily}\begin{flushleft}
+\mbox{/mypatch~0~,~/volume~,~38}\\
+\mbox{/mypatch~0~,~/pan~,~92}\\
+\mbox{/mypatch~1~,~/volume~,~116}\\
+\mbox{/mypatch~1~,~/pan~,~27}
+\end{flushleft}\end{ttfamily}
+
+You see, the substate 0 is unaffected, the new state can have different
+values. Exchanging the \texttt{substate} message with a \texttt{setsub} message will
+autoload the selected state and ``set'' the sliders to the stored values
+immediatly.
+
+
+%___________________________________________________________________________
+
+\hypertarget{osc-in-memento}{}
+\subsection*{OSC in Memento}
+\pdfbookmark[1]{OSC in Memento}{osc-in-memento}
+
+The whole system now already is prepared to be used over OSC. You probably
+already guess, how the message looks like. Any takers? Thank you, you're
+right, the messages are built as \texttt{/mypatch/volume {\#}number} and
+\texttt{/mypatch/pan {\#}number} as shown in the next stage:
+
+\includegraphics{osccontrol.png}
+
+Sometimes it is useful to also get OSC messages out of a patch, for example
+to control other OSC software through Pd. For this the \textbf{OSC-outlet} of
+\texttt{originator} can be used, which is the rightmost outlet of the
+abstraction. It will print out every change to the current state.
+Connecting a \texttt{print OSC} debug object to it, we get to see what's coming
+out of the OSC-outlet when we move a slider:
+\begin{ttfamily}\begin{flushleft}
+\mbox{OSC:~/mypatch/pan~92}\\
+\mbox{OSC:~/mypatch/pan~91}\\
+\mbox{OSC:~/mypatch/pan~90}\\
+\mbox{OSC:~/mypatch/pan~89}
+\end{flushleft}\end{ttfamily}
+
+
+%___________________________________________________________________________
+
+\hypertarget{putting-it-all-to-rradical-use}{}
+\section*{Putting it all to RRADical use}
+\pdfbookmark[0]{Putting it all to RRADical use}{putting-it-all-to-rradical-use}
+
+Now that the foundation for a general preset and communication system are
+set, it is possible to build real patches with it that have two main
+characteristics:
+\begin{description}
+%[visit_definition_list_item]
+\item[\textbf{Rapidity}]
+%[visit_definition]
+
+Ready-to-use highlevel abstraction can save a lot of time when building
+larger patches. Clear communication paths will let you think faster and
+more about the really important things.
+
+%[depart_definition]
+%[depart_definition_list_item]
+%[visit_definition_list_item]
+\item[\textbf{Reusability}]
+%[visit_definition]
+
+Don't reinvent the wheel all the time. Reuse patches like instruments
+for more than one piece by just exchanging the Caretaker-file used.
+
+%[depart_definition]
+%[depart_definition_list_item]
+\end{description}
+
+I already developed a growing number of patches that follow the RRADical
+paradigm, among these are a complex pattern sequencer, some synths and
+effects and more. The RRADical collection comes with a template file,
+called \texttt{rrad.tpl} that makes deploying new RRADical patches easier and
+lets developers concentrate on the algorighm instead of bookeeping. Some
+utils (footils?) help with creating the sometimes needed many
+\texttt{commun}-objects. Several usecases show example applications of the
+provided abstractions.
+
+\end{document}