diff options
| author | Frank Barknecht <fbar@users.sourceforge.net> | 2003-04-28 16:33:36 +0000 |
|---|---|---|
| committer | Frank Barknecht <fbar@users.sourceforge.net> | 2003-04-28 16:33:36 +0000 |
| commit | ea5a56e8748e6ba32a38343ef6be257744e6531e (patch) | |
| tree | 9fe60dddcaa443f960d1ff29cad39e4024d73a6d /doc/tutorials/footils/pddrums/pddrums.html | |
| parent | fa93163aaee7f2d27cdc3067a840dd23bb5715a5 (diff) | |
Added start of the unfinished drum making tutorial to doc.
svn path=/trunk/; revision=598
Diffstat (limited to 'doc/tutorials/footils/pddrums/pddrums.html')
| -rw-r--r-- | doc/tutorials/footils/pddrums/pddrums.html | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/doc/tutorials/footils/pddrums/pddrums.html b/doc/tutorials/footils/pddrums/pddrums.html new file mode 100644 index 00000000..9d87077e --- /dev/null +++ b/doc/tutorials/footils/pddrums/pddrums.html @@ -0,0 +1,192 @@ +<?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 lang="en"> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> +<meta name="generator" content="Docutils 0.2.8: http://docutils.sourceforge.net/" /> +<title>Building Drums in PD</title> +<link rel="stylesheet" href="default.css" type="text/css" /> +</head> +<body> +<div class="document" id="building-drums-in-pd"> +<h1 class="title">Building Drums in PD</h1> +<table class="docinfo" frame="void" rules="none"> +<col class="docinfo-name" /> +<col class="docinfo-content" /> +<tbody valign="top"> +<tr class="field"><th class="docinfo-name">Autor:</th><td class="field-body">Frank Barknecht</td> +</tr> +<tr><th class="docinfo-name">Contact:</th> +<td><a class="first last reference" href="mailto:fbar@footils.org">fbar@footils.org</a></td></tr> +</tbody> +</table> +<div class="abstract topic"> +<p class="topic-title">Abstract</p> +<p>This quicktoot describes how PD can be used to build a simple drum +synthesizer with graphical controls and a step sequencer.</p> +</div> +<div class="contents topic" id="contents"> +<p class="topic-title"><a name="contents">Contents</a></p> +<ul class="simple"> +<li><a class="reference" href="#small-is-beautiful" id="id1" name="id1">Small is beautiful</a></li> +<li><a class="reference" href="#the-creator" id="id2" name="id2">The Creator</a></li> +<li><a class="reference" href="#bring-the-noise" id="id3" name="id3">Bring The Noise</a></li> +<li><a class="reference" href="#let-it-swing" id="id4" name="id4">Let It Swing</a></li> +<li><a class="reference" href="#going-faster" id="id5" name="id5">Going faster</a></li> +</ul> +</div> +<div class="section" id="small-is-beautiful"> +<h1><a class="toc-backref" href="#id1" name="small-is-beautiful">Small is beautiful</a></h1> +<p>Pure Data - or short PD - is a multimedia software environment written +by Miller Puckette and others that can be used to make art in several +media like music, sound or graphics. In this quicktoot we will use the +sound generating capabilities of PD to build a module for drum sounds. +Our drum synthesizer will use a synthesis algorithm that's very +similar to the early analog or digital drumsynths of the eighties. We +will not use pre-recorded samples but instead employ simple sound +generators. You will be surprised, how effective this is and how much +variety is possible with just two or three sound sources. On the other +hand our design leaves room for improvment. By the end of this article +you will be able to add these on your own. Our drummer includes a +preset database: When you have found a sound, that you like, you can +save it and recall it again later.</p> +<p>I will not go into much detail on how to install or how to use PD: You +should read the documentation that comes with PD for that. I will of +course explain the more advanced features of PD used and everything +that is needed to follow this tutorial.</p> +</div> +<div class="section" id="the-creator"> +<h1><a class="toc-backref" href="#id2" name="the-creator">The Creator</a></h1> +<p>Creating something in PD is very much like the genesis of a world as described +in, well, the Bible's first book "Genesis". In the beginning you have nothing, +just a large white area. You, the Creator, can create objects by a simple +button press "Ctrl-1", which actually means "Let there be an object". And there +was an object. But your first object is a small empty rectangle and it can do +nothing, it has no way of communicating, it isn't alive yet. To create a living +object you have to give it a name, you have to call it by typing the name onto +the object, for example "noise~". And there was noise. With time you can +populate the area with more objects, you can let them talk to each other, you +can create more worlds, and you will create by giving all of them names. We +maybe come to <tt class="literal"><span class="pre">[moses]</span></tt> later. Our drumsynth will have the name "angriff", +which is german for "attack". So our goal is, that someone can create a +drumsynth by typing the name "angriff" on a new object.</p> +<p>This is achieved in PD by a so called "abstraction". An abstraction is +simply a saved PD patch. So our very first and basically unusable +version of angriff is this: A nearly empty patch with a noise~ object +inside, saved under the name "angriff-01.pd".</p> +<div class="figure"> +<p><img alt="angriff-01.png" src="angriff-01.png" /></p> +<p class="caption">angriff-01.pd, an unusable first version.</p> +</div> +<p>Even this can be used as an object. Just create a new, empty patch +(with "Ctrl-n"), put an object in it and call it "angriff-01", i.e. the +name of our first drum patch without the .pd-suffix.</p> +<p>Using the unusable angriff-01.pd in another patch.</p> +<p>PD searches for something that matches the object "angriff-01" in +several places: in the list of builtin objects like "noise~", in +external libraries or in its path for abstractions. If angriff-01.pd +is in the same directory as the using patch or in a path known to PD +through the startup option "-path /a/pd-path/", it gets found. If you +click on angriff-01, you can open it to see, what's inside. +Abstractions itself can use other abstractions so it's a good idea to +put often used functionality into abstractions. As our final drumsynth +should have a sound generating part and a GUI to control this, we will +seperate both parts from each other by use of abstractions. For the +synthesis of sound we will build and use an abstraction called "drumcenter" +inside of the main "angriff" patch. The main patch includes the control +elements for the parameters provided by "drumcenter". This way our +synthesis model and the view to the user are separated.</p> +</div> +<div class="section" id="bring-the-noise"> +<h1><a class="toc-backref" href="#id3" name="bring-the-noise">Bring The Noise</a></h1> +<p>How do drums drum? Although human dummers can spend hours tuning their +drumset, drums are generally non-pitched, percussive sounds. So for +our first usable version of a drumsound we take some noise as a sound +source and put an amplitude envelope around the noise. A simple, +builtin envelope generator in PD is line~. drumcenter-01.pd show the +noise, the envelope and both multiplied together.</p> +<div class="figure"> +<p><img alt="drumcenter-01.png" src="drumcenter-01.png" /></p> +<p class="caption">Enveloped noise, drumcenter-01.pd</p> +</div> +<p>If you listen to this patch, it already sounds a bit like a snare, +doesn't it? To make this sound a bit more variable we can use filtered +noise, for example with a lowpass or highpass filter. PD comes with +both, so lets use them. Her's the noise filtered with the lop~ filter +at a cutoff frequency of 400 Hertz:</p> +<div class="figure"> +<p><img alt="drumcenter-02.png" src="drumcenter-02.png" /></p> +<p class="caption">Lowpass filtered and enveloped noise, drumcenter-02.pd</p> +</div> +<p>Now our patch is beginning to get a bit crammed and chaotic, so let's +replace some chords with "send" and "receive" pairs, abbreviated "s" and "r". +If we give those pairs names starting with $0, they get names starting +with unique numbers instead of the $0 while performing. This way, we +can later use several instances of our patches without conflicts +between their own send and receive variables. We can also hide stuff +we don't need to see in so called subpatches. Subpatches are areas +inside a patch that are hidden in an object box starting with <tt class="literal"><span class="pre">[pd]</span></tt>. +They are like curtains hiding things in a room, but the hidden objects +are a full part of the surrounding patch. The special objects <tt class="literal"><span class="pre">[inlet]</span></tt>, +<tt class="literal"><span class="pre">[outlet]</span></tt>, <tt class="literal"><span class="pre">[inlet~]</span></tt> and <tt class="literal"><span class="pre">[outlet~]</span></tt> create points of connections between +the surroundig patch and the subpatch. They work with abstractions as well.</p> +<div class="figure"> +<p><img alt="drumcenter-03.png" src="drumcenter-03.png" /></p> +<p class="caption">Cleaning up in the house, drumcenter-03.pd</p> +</div> +</div> +<div class="section" id="let-it-swing"> +<h1><a class="toc-backref" href="#id4" name="let-it-swing">Let It Swing</a></h1> +<p>I lied in the previous chapter: Drums are indeed pitched, although +just a little bit pitched. If a drummer kicks a bassdrum, the drum +begins to oscillate slightly at a low frequency. But this oscillation +is soon damped to an even lower frequency and then disapears. To +simulate this behaviour, we use PD's <tt class="literal"><span class="pre">[osc~]</span></tt> object with an added +frequency envelope as show in drumcenter-04.pd:</p> +<div class="figure"> +<p><img alt="drumcenter-04.png" src="drumcenter-04.png" /></p> +<p class="caption">Percussive oscillator, drumcenter-04.pd</p> +</div> +<p>The right inlet of <tt class="literal"><span class="pre">[osc~]</span></tt> is used here to set the start phase of the +oscillator. If we wouldn't set it, it would be different everytime we +start the envelope, because an object like the <tt class="literal"><span class="pre">[osc~]</span></tt> is always on and +goes through its cycle even if we don't listen to it. The main inlet +sets the frequency, that's going from a starting value to a lower +frequency in a short time.</p> +</div> +<div class="section" id="going-faster"> +<h1><a class="toc-backref" href="#id5" name="going-faster">Going faster</a></h1> +<p>So far we used <tt class="literal"><span class="pre">[line~]</span></tt> for all envelopes and a controlling message +like <tt class="literal"><span class="pre">[1,</span> <span class="pre">0</span> <span class="pre">50(</span></tt>. This tells <tt class="literal"><span class="pre">[line~]</span></tt> to first go immediatly to 1, then +start going to 0 for 50 milliseconds. For our oscillator frequency +this is fine, but instantly going to an amplitude of 1 produces +clicks, as you might have heard. So we need to specify an attack time, +in that the amplitude raises from 0. The first guess would be a +message like <tt class="literal"><span class="pre">[1</span> <span class="pre">10,</span> <span class="pre">0</span> <span class="pre">50(</span></tt>, but that simply doesn't work. So this has to +be solved with two messages to the <tt class="literal"><span class="pre">[line~]</span></tt> object, for example <tt class="literal"><span class="pre">[1</span> <span class="pre">10(</span></tt> +to go in 10 msecs to 1 and then the release: <tt class="literal"><span class="pre">[0</span> <span class="pre">50(</span></tt>. Between them a +<tt class="literal"><span class="pre">[del]</span></tt> is placed, that delays for as long as the first line segment's +duration is. But this also has a problem, as shown in the next figure: +a <tt class="literal"><span class="pre">[del]</span></tt> always delays in blocks of 64 samples, and that is a time of +around 1.45 msecs at a sampling rate of 44100 Hertz. A bit too long +for the short attack times used in drum synths.</p> +<div class="figure"> +<p><img alt="fastline.png" src="fastline.png" /></p> +<p class="caption">Two line~ segments started with delay, fastline.pd</p> +</div> +<p>This problem isn't trivial at all and it appears everywhere, one wants +to contol messages in PD quicker than the signal blocksize allows, for +example in granular synthesis patches. A solution to this are " +Time-Tagged Triggers" (T3) as proposed by Gerhard Eckel and Manuel +Rocha Iturbide for Max/FTS. In PD T3-objects are made available as +externals in IEMLIB. Time-Tagged Triggers are a replacment for the +standard "bang" message that is normally used in PD or Max. Eckel +writes: "In Max/FTS, a T3 is nothing else than a message containing one +floating-point number which specifies the delay in ms after which, +counting from the current tick, the trigger should go off." We will now +use the T3 break point envelope generator <tt class="literal"><span class="pre">[t3_bpe]</span></tt> to generate faster +envelopes.</p> +</div> +</div> +</body> +</html> |