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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.html | |
| parent | 35994ca3a4ef6a136a16cac63b4f68540d0434e1 (diff) | |
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diff --git a/doc/rradicalpd.html b/doc/rradicalpd.html new file mode 100644 index 0000000..04d6a42 --- /dev/null +++ b/doc/rradicalpd.html @@ -0,0 +1,335 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> +<meta name="generator" content="Docutils 0.3.1: http://docutils.sourceforge.net/" /> +<title>RRADical Pd</title> +<meta name="author" content="Frank Barknecht <fbar@footils.org>" /> +<link rel="stylesheet" href="default.css" type="text/css" /> +</head> +<body> +<div class="document" id="rradical-pd"> +<h1 class="title">RRADical Pd</h1> +<table class="docinfo" frame="void" rules="none"> +<col class="docinfo-name" /> +<col class="docinfo-content" /> +<tbody valign="top"> +<tr><th class="docinfo-name">Author:</th> +<td>Frank Barknecht <fbar@footils.org></td></tr> +</tbody> +</table> +<div class="abstract topic"> +<p class="topic-title">Abstract</p> +<p>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. ;)</p> +</div> +<div class="section" id="what-it-takes-to-be-a-rradical"> +<h1><a name="what-it-takes-to-be-a-rradical">What it takes to be a RRADical</a></h1> +<p>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. ;)</p> +<p>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.</p> +<p>So for example instead of a basic <tt class="literal"><span class="pre">lop~</span></tt> 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:</p> +<ul class="simple"> +<li>a sample player (adapt Gyre?)</li> +<li>Various OSC/LFO with preset waveforms</li> +<li>drum machine</li> +<li>guitar simulator</li> +<li>grain sample player</li> +<li>more sequencers</li> +<li>basically a lot of things like these things in Reason</li> +</ul> +<p>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.</p> +</div> +<div class="section" id="problems-and-solutions"> +<h1><a name="problems-and-solutions">Problems and Solutions</a></h1> +<p>To building above system several problems are to be solved. Two key areas +already targetted are:</p> +<dl> +<dt><strong>Persistence</strong></dt> +<dd>How to save the current state of a patch? How to save more than one +state (state sequencing)?</dd> +<dt><strong>Communication</strong></dt> +<dd>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.)</dd> +</dl> +<p>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.</p> +<div class="section" id="persistence"> +<h2><a name="persistence">Persistence</a></h2> +<p>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":</p> +<blockquote> +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.</blockquote> +<p>(I'll show an example of a float object changing "state" by a message in +its right inlet here.)</p> +<p>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 <tt class="literal"><span class="pre">preset</span></tt>-object, Pd has the +<tt class="literal"><span class="pre">state</span></tt>-object which saves the current state of (some) GUI objects inside +a patch. Both also support changing between several different states.</p> +<p>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.</p> +<p>Another approach is to (ab)use some of the Pd objects that can persist +itself to a file, especially <tt class="literal"><span class="pre">textfile</span></tt>, <tt class="literal"><span class="pre">qlist</span></tt> and <tt class="literal"><span class="pre">table</span></tt>, which +works better, but isn't standardized.</p> +<p>A rather new candidate for state saving is Thomas Grill's <tt class="literal"><span class="pre">pool</span></tt> +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 <tt class="literal"><span class="pre">pool</span></tt> 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 <tt class="literal"><span class="pre">pool</span> <span class="pre">MYPOOL</span></tt> in one patch will +contain the same data as a <tt class="literal"><span class="pre">pool</span> <span class="pre">MYPOOL</span></tt> in another patch. Changes to one +pool will change the data in the other as well.</p> +<p>A <tt class="literal"><span class="pre">pool</span></tt> 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.</p> +</div> +<div class="section" id="communication"> +<h2><a name="communication">Communication</a></h2> +<p>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.</p> +<p>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 <tt class="literal"><span class="pre">send</span> <span class="pre">volume</span></tt>, +but instead use <tt class="literal"><span class="pre">send</span> <span class="pre">$0-volume</span></tt>. $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.</p> +<p>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.</p> +<p>This creates a fundamental conflict:</p> +<dl> +<dt><strong>We want borders</strong> </dt> +<dd>We want to separate our abstraction so they don't conflict with each +other.</dd> +<dt><strong>We want border crossings</strong></dt> +<dd>We want to have a way to reach their many internals and control them +from the outside.</dd> +</dl> +<p>The RRADical approach adheres to this in that it enforces a strict border +but drills a single hole in it: the <strong>OSC inlet</strong>. This idea is the result +of a discussion on the Pd mailing list and goes back to suggestions by +<a class="reference" href="http://www.audionerd.com">Eric Skogen</a> and <a class="reference" href="http://www.ekran.org/ben/">Ben Bogart</a>. Every RRADical patch has (to have) a +rightmost inlet that accepts messages formatted according to the OSC +protocol. OSC stands for <a class="reference" href="http://www.cnmat.berkeley.edu/OpenSoundControl/">Open Sound Control</a> and is a network transparent +system to control audio applications remotely developed at CNMAT in Berkley.</p> +<p>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:</p> +<pre class="literal-block"> +/synth/fm/volume 85 +</pre> +<p>It sends the message "85" to the "volume" control of a "fm" module below a +"synth" module. OSC allows many parameters constructs like:</p> +<pre class="literal-block"> +/synth/fm/basenote 52 +/synth/virtualanalog/basenote 40 +/synth/*/playchords m7b5 M6 7b9 +</pre> +<p>This might set the base note of two synths, <cite>fm</cite> and <cite>virtualanalog</cite> and +send a chord progression to be played by both -- indicated by the wildcard +<cite>*</cite> -- afterwards.</p> +<p>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.</p> +</div> +</div> +<div class="section" id="trying-to-remember-it-all-memento"> +<h1><a name="trying-to-remember-it-all-memento">Trying to remember it all: Memento</a></h1> +<p>To realize the functionality requirements developed so far I resorted to a +so called <cite>Memento</cite>. <cite>"Memento"</cite> is a very cool movie by director +Christopher Nolan where - quoting IMDB:</p> +<blockquote> +A man, suffering from short-term memory loss, uses notes and tattoos to +hunt down his wife's killer.</blockquote> +<p>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.</p> +<p>Here's a scene from "Memento":</p> +<p><img alt="memento.png" src="memento.png" /></p> +<p>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.</p> +<p>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.</p> +<p>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.</p> +<p>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.</p> +<div class="section" id="memento-in-pd"> +<h2><a name="memento-in-pd">Memento in Pd</a></h2> +<p>I developed a set of abstractions, of patches for Pd, that follow this +design pattern. Memento for Pd includes a <tt class="literal"><span class="pre">caretaker</span></tt> and an +<tt class="literal"><span class="pre">originator</span></tt> abstraction, plus a third one called <tt class="literal"><span class="pre">commun</span></tt> which is +responsible for the <strong>internal</strong> communication. <tt class="literal"><span class="pre">commun</span></tt> basically is +just a thin extension of <tt class="literal"><span class="pre">originator</span></tt> and should be considered part of +it. There is another patch, the <tt class="literal"><span class="pre">careGUI</span></tt> which I personally use instead +of the <tt class="literal"><span class="pre">caretaker</span></tt> directly, because it has a simple GUI included.</p> +<p>Here's how it looks:</p> +<p><img alt="caregui.png" src="caregui.png" /></p> +<p>The <tt class="literal"><span class="pre">careGUI</span></tt> 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 <tt class="literal"><span class="pre">careGUI</span></tt> sends a +<tt class="literal"><span class="pre">bang</span></tt> message to be used as you like.</p> +<p>Internally <tt class="literal"><span class="pre">caretaker</span></tt> has a named <tt class="literal"><span class="pre">pool</span></tt> object using the global pool +called "RRADICAL". The same <tt class="literal"><span class="pre">pool</span> <span class="pre">RRADICAL</span></tt> also is used inside the +<tt class="literal"><span class="pre">originator</span></tt> object. This abstraction handles all access to this pool. A +user should not read or write the contents of <tt class="literal"><span class="pre">pool</span> <span class="pre">RRADICAL</span></tt> directly. +The <tt class="literal"><span class="pre">originator</span></tt> 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 <tt class="literal"><span class="pre">pool</span></tt> data. Each <tt class="literal"><span class="pre">originator</span> <span class="pre">SomeName</span> <span class="pre">secondarg</span></tt> 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 +<tt class="literal"><span class="pre">originator</span></tt> under the tree "/patch"</p> +<p>The second argument practically always will be $0. It is used to talk to +those <tt class="literal"><span class="pre">commun</span></tt> 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 +<tt class="literal"><span class="pre">originator</span></tt> then only can talk to <tt class="literal"><span class="pre">commun</span></tt>s inside the same patch and +will not disturb other <tt class="literal"><span class="pre">commun</span></tt> objects in other abstractions.</p> +<p>The <tt class="literal"><span class="pre">commun</span></tt> 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 <tt class="literal"><span class="pre">commun</span> <span class="pre">/vol</span> <span class="pre">$0</span></tt>.</p> +<p><tt class="literal"><span class="pre">commun</span></tt> has one inlet and one outlet. What comes in through the inlet is +send to <tt class="literal"><span class="pre">originator</span></tt> who stores it inside its Memento under the key, that +is specified by the <tt class="literal"><span class="pre">commun</span></tt>'s first arg. Actually <tt class="literal"><span class="pre">originator</span></tt>. The +outlet of a <tt class="literal"><span class="pre">commun</span></tt> will spit out the current value stored under its key +inside the Memento, when <tt class="literal"><span class="pre">originator</span></tt> tells it to do so. So <tt class="literal"><span class="pre">commun</span></tt>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:</p> +<p><img alt="communslider.png" src="communslider.png" /></p> +<p>In this patch, every change to the slider will be reflected inside the +Memento. The little print button in <tt class="literal"><span class="pre">careGUI</span></tt> can be used to print the +contents to the console from which Pd was started. Setting the slider will +result in something like this:</p> +<pre class="literal-block"> +/mypatch 0 , /volume , 38 +</pre> +<p>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:</p> +<p><img alt="moresliders.png" src="moresliders.png" /></p> +<p>Moving the /pan slider will let careGUI print out:</p> +<pre class="literal-block"> +/mypatch 0 , /volume , 38 +/mypatch 0 , /pan , 92 +</pre> +<p>The <tt class="literal"><span class="pre">originator</span></tt> can save several substates or presets by sending a +<tt class="literal"><span class="pre">substate</span> <span class="pre">#number</span></tt> message to its first inlet. Let's do just this and +move the sliders again as seen in the next picture:</p> +<p><img alt="substates.png" src="substates.png" /></p> +<p>Now careGUI prints:</p> +<pre class="literal-block"> +/mypatch 0 , /volume , 38 +/mypatch 0 , /pan , 92 +/mypatch 1 , /volume , 116 +/mypatch 1 , /pan , 27 +</pre> +<p>You see, the substate 0 is unaffected, the new state can have different +values. Exchanging the <tt class="literal"><span class="pre">substate</span></tt> message with a <tt class="literal"><span class="pre">setsub</span></tt> message will +autoload the selected state and "set" the sliders to the stored values +immediatly.</p> +</div> +<div class="section" id="osc-in-memento"> +<h2><a name="osc-in-memento">OSC in Memento</a></h2> +<p>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 <tt class="literal"><span class="pre">/mypatch/volume</span> <span class="pre">#number</span></tt> and +<tt class="literal"><span class="pre">/mypatch/pan</span> <span class="pre">#number</span></tt> as shown in the next stage:</p> +<p><img alt="osccontrol.png" src="osccontrol.png" /></p> +<p>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 <strong>OSC-outlet</strong> of +<tt class="literal"><span class="pre">originator</span></tt> can be used, which is the rightmost outlet of the +abstraction. It will print out every change to the current state. +Connecting a <tt class="literal"><span class="pre">print</span> <span class="pre">OSC</span></tt> debug object to it, we get to see what's coming +out of the OSC-outlet when we move a slider:</p> +<pre class="literal-block"> +OSC: /mypatch/pan 92 +OSC: /mypatch/pan 91 +OSC: /mypatch/pan 90 +OSC: /mypatch/pan 89 +</pre> +</div> +</div> +<div class="section" id="putting-it-all-to-rradical-use"> +<h1><a name="putting-it-all-to-rradical-use">Putting it all to RRADical use</a></h1> +<p>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:</p> +<dl> +<dt><strong>Rapidity</strong></dt> +<dd>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.</dd> +<dt><strong>Reusability</strong></dt> +<dd>Don't reinvent the wheel all the time. Reuse patches like instruments +for more than one piece by just exchanging the Caretaker-file used.</dd> +</dl> +<p>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 <tt class="literal"><span class="pre">rrad.tpl</span></tt> 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 +<tt class="literal"><span class="pre">commun</span></tt>-objects. Several usecases show example applications of the +provided abstractions.</p> +</div> +</div> +</body> +</html> |