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author | Frank Barknecht <fbar@users.sourceforge.net> | 2004-04-23 16:26:21 +0000 |
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committer | Frank Barknecht <fbar@users.sourceforge.net> | 2004-04-23 16:26:21 +0000 |
commit | 28e7d308d91556ec078f708b6c4ac855ac340fcc (patch) | |
tree | b406f3f4e426f3bb03acce88bb5027babd9b4a6b /doc/rradicalpd.tex | |
parent | 35994ca3a4ef6a136a16cac63b4f68540d0434e1 (diff) |
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diff --git a/doc/rradicalpd.tex b/doc/rradicalpd.tex new file mode 100644 index 0000000..157aace --- /dev/null +++ b/doc/rradicalpd.tex @@ -0,0 +1,511 @@ +\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} |