March 2007 - chuck-users - lists.cs.princeton.edu

Strategies for Complex Timing
by Veli-Pekka Tätilä 18 Mar '07

18 Mar '07

Hi list, Here's an abstract question for a change: If I'd like to create a large-scale patch in which various UGens need to work at various different, and possibly changeable rates, what would be a good strategy to go about this? What kind of tacs do you currently use? Here's a fictitious example. Say I have two of my OneOfN switches for oscs that are updated at 10 Hz to save CPU cycles, an envelope follower that is updated every sample and a couple of short delays that are synchronized based on the notion of a musical beat and tempo. Computing musical time given the meter and tempo in bpm is not a problem nor is figuring out the sampling rate, though utility functions would be appreciated. The basic issue is that when you do add something to the now time, pardon my Cakewalk lingo, you'll have to take that addition into account when timing all the rest of the modules. And if you have multiple instances of a module that should run at the same rate, you'll have to structure the code in such a way that these modules get updated at the same time, if I've understood things correctly. This can soon get very messy. Here are some tacs that come to mind: Have a counter that is inced every sample and divide its frequency by various rates using the modulo operator to continuously, say poll the input attached to my OneOfN switch. This is the method they use in basic digital logic frequency dividing a high frequency clock source to get various nicer rates out. But the counter might overflow some day and branching takes a bit of CPU. Or another thing. IMplement an infrastructure for timers in which, a particular method of all attached objects gets called when-ever a specified amount of time has elapsed. THen spork a child process for each such timer and have them run concurrently , without having to worry about timing after the initial setup. I'm not sure how heavy context-switches are inside the VM shreads, though. Lastly, this came to mind. Or don't try to save CPU at all and let chucK update everything at virtually every sample, even though you know a human is not able to generate controller events very fast, for example. I think SynthEDit uses this last tak. I have a nagging feeling somewhere in my head that I've misunderstood something about timing. That if I just keep adding an arbitrary amount to the now time everything will just get automagically updated every sample. The only thing i'd have to explicitly worry about then Would be the stuff I need to poll periodically. I'm still a bit unsure. So any comments and hints appreciated. With kind regards Veli-Pekka Tätilä (vtatila(a)mail.student.oulu.fi) Accessibility, game music, synthesizers and programming: http://www.student.oulu.fi/~vtatila/

2 1

chuck~ for PD
by martin robinson 17 Mar '07

17 Mar '07

Here is the first release of chuck~ for PD for anyone interested in that sort of thing: http://www-static.cc.gatech.edu/ugrads/m/mjr/chuck~-0.1.tar.gz It may still crash now, given weird input, though it's generally stable. I'd love to hear feedback from anyone who is using it or would like it to do something else. I'm particularly indebted to Brad Garton for the idea and the jumping off point for this. A little bit of documentation and a few example files are included. Feel free to send along questions or comments. -- martin robinson

7 22

chuck-1.2.0.8-rc4 available
by Spencer Salazar 15 Mar '07

15 Mar '07

Howdy, Release candidate 4 of chuck-1.2.0.8 is available for download and testing: http://chuck.cs.princeton.edu/release/files/snapshot/ Current release candidates of miniAudicle and Audicle are also available. Please note that the ADSR UGen has been changed such that the .attackTime, .decayTime, and .releaseTime now all accept a dur, not a float. This may make existing code fail to compile in this release candidate. Also, this version of miniAudicle has a buffer size preferences option, which some folks have been asking for. Please let us know soon of any bugs or other difficulties! thanks, spencer

4 7

cfp: Loss Livecode festival, Sheffield 20-22 July 2007
by alex 14 Mar '07

14 Mar '07

Hi ChucKers! A festival/conference for on-the-fly programming in Sheffield, UK this summer... Send your proposals for talks and performances - commissions available! ====================================================================== _ ___ ____ ____ _ _ ____ _ | | / _ \/ ___/ ___| | | (_)_ _____ / ___|___ __| | ___ | | | | | \___ \___ \ | | | \ \ / / _ \ | / _ \ / _` |/ _ \ | |__| |_| |___) |__) | | |___| |\ V / __/ |__| (_) | (_| | __/ |_____\___/|____/____/ |_____|_| \_/ \___|\____\___/ \__,_|\___| ---------------------> LOSS Livecode Festival <----------------------- Sheffield, UK -- 20-22 July 2007 http://livecode.access-space.org/ In association with Access Space, TOPLAP and lurk When we improvise music, we are creating music while it is being performed. "Live Coding" is the creation of software while it is being executed; the software in turn generating music or video. Thanks to dynamic programming languages, the live coder is able to modify and extend their program without restarts, their music and/or visual growing with the code that describes it. This way of working allows instant results for every sourcecode edit. Programming becomes a fast, creative process - expressive enough that a whole audio/visual performance may be created as software. Live Coding began during the 1980s, primarily with FORTH and Lisp. In recent years new live coding environments and languages such as Chuck, Fluxus, Impromptu and SuperCollider 3 have appeared, with enthusiastic communities growing around them. Live Coding performances have also used Smalltalk, PureData, Scheme, Perl, Haskell, Ruby, Python... In early 2004 the "Temporary Organisation for the Promotion of Live Algorithm Programming" (TOPLAP) was formed to support open dialog between all live coders. Since its early beginnings in a smoky bar in Hamburg, TOPLAP has reached 178 members worldwide, gaining coverage in mass media and collaboratively organising several international meetings. In 2005 Access Space initiated the L.O.S.S. project (http://loss.access-space.org) to support free music creativity and distribution. It featured a series of commissions leading to a Creative Commons licensed audio CD and repository website produced entirely with open source tools. Continuing their series of LOSS commissions and events, Access Space have teamed up with TOPLAP and lurk to create a three day international festival, bringing live coding musicians and video artists together to explore and showcase new approaches in live performing and participatory arts. ---> CALL FOR PARTICIPATION <----------------------------------------- Your performance and/or presentation proposal is called for. For the latest version of this call, please refer to http://livecode.access-space.org/ Commissions are available to help realise ambitious projects and performances. Presenters and performers will gain free entry throughout the festival, and those without institutional support may apply for a small bursary. ---> IMPORTANT DATES <--- * 14th March - Call for participation * 14th April - Deadline for proposals * 1st May - Notification of acceptance * 16th June - Copy deadline for proceedings (to be confirmed) * 20th-22nd July - Conference - schedule TBA ---> PRESENTATIONS <--- Short (up to 20 minute) presentations during a day long symposium. The remit is broad, but possible subjects may include * A demo of a novel live coding language/environment * Historical context of live coding * Live coding without computers * Critique of live coding practice * Live patching * Reflections on live coding experiences * Adapting general purpose languages to live coding * Analysis of live coding performances * Live algorithms that live code * Life coding * Portable live coding devices * Reflective/self-modifying code * Live visualisation of sourcecode * Collaborative networked live coding * ... Proposals do not have to be long - however much or little you need to explain your ideas is fine. If you are unsure if you can make it, submit your idea anyway - we may be able to accommodate a small number of remotely streamed presentations for those unable to attend in person. There will also be time for a brief (around three hours) introductory workshop. Please indicate if you would like to be involved. ---> PERFORMANCES <--- There will be at least two evenings of performances, ranging from 10 to 40 minutes. Please outline what you would like to perform, including technical requirements. We plan to have at least three data projectors, many pairs of small speakers for participatory improvisations, enough headphone amps for 100 pairs of headphones, and a big stereo sound-system for 'traditional' performances. Please state your preference, and feel free to be creative (see commissions below). We are also thinking about a pre-event in London, UK some days before the festival, let us know if you would like to take part. ---> PROCEEDINGS <--- If your proposal is accepted you will be encouraged to submit short texts and images for publication in the proceedings. All speakers and performers will receive a free copy at the beginning of the conference. ---> COMMISSIONS <--- If you would like time or resources to develop a new way of performing, some new language or software feature, or something else interesting then please include a short estimated budget in your brief, which may include an artist fee. Note that due to funding constraints the project should have a strong audio component. The maximum commission will be of £1000 (about 1470 euro). ---> BURSARY <--- A small bursary is available to contribute towards travel and accommodation. Please include an estimated budget for your attendance and we will apportion this money based on need. Money is however very short, if you are a member of an academic institution we are keen to help you apply for local funding. ---> PROPOSAL SUBMISSION <--- Preferably in plaintext, but all common formats are accepted. Supporting material including web links to previous work, audio and video files are welcome but not mandatory. Proposals should arrive before midnight, 14th April 2007. Proposals are accepted by email (preferred): livecode(a)access-space.org Or by post: LOSS Livecode c/o Alex McLean Access Space 1 Sidney Street Sheffield S1 4RG Royaume Uni If sending via email please do not include large attachments - either include URLs or contact us in advance. If sending via post include an email address so that we may confirm receipt. ---> MAILING LIST <--- As members of the "keep avant garde internet tidy" campaign, we keep our cross posts to a minimum. To continue receiving news of the conference, please sign up to our mailing list: http://lists.lurk.org/mailman/listinfo/lc/ ---> ABOUT ACCESS SPACE <--- Based in Sheffield, Access Space is the UK's first "Free Media Lab" - a community space equipped with locally recycled computers running free, open source software. It provides a framework, resources and support for self-directed learning, arts and creativity. Taking part is totally free, and anyone can walk in and contribute: http://access-space.org ---> FOR MORE INFORMATION <--- Don't hesitate to email with questions to the submission address above. The conference website is not yet ready, but more information about live coding may be found at the official TOPLAP wiki: http://toplap.org/ Hope to see you in July! LOSS Livecode is funded by Arts Council England, Yorkshire and The PRS Foundation. ====================================================================== -- Alex McLean http://yaxu.org/ http://slub.org/ http://lurk.org/ http://doc.gold.ac.uk/~ma503am/

1 0

Linux Audio Conference / ChucK users in Berlin?
by Scott Wheeler 14 Mar '07

14 Mar '07

LAC is coming up in a couple of weeks, so I thought I would see if there's anyone else on the list that will be around. If there are enough I might see if we can get a BoF going or something. http://www.kgw.tu-berlin.de/~lac2007/ On a related note, I'll probably be doing a short presentation / demo on ChucK at a local electronic musicians get-together in a few weeks (probably in German), so if there are folks in the area I can post the details when they're finalized. Cheers, -Scott

1 0

Doing something to all members of a class?
by Kassen 14 Mar '07

14 Mar '07

Hi, list! I'm having a bit of a issue with classes. Say I have a class that has a member that's simply a integer used for counting something. I'll have a few instances (ten or so) and they will all be counting their own little thing on their own. So far so good. Now something happens and I'd like to reset all the counters to zero after which they should be independant again. How to go about this in a efficient way? I tried writing a static function to do this but it seems I misunderstand static functions. I thought that if I'd call a static function as a member of the class (not of a particular instance) then this function would be executed for all instances. That turns out not to be true; it only gets executed a single time. To make it more confusing (to me) referencing non-static int member of the class inside of a static function makes ChucK die while complaining about a nullpointer exception. In fact it will also die if I call the same function as a member of a particular instance. When I reference the number as "this.my_number" instead of just as "my_number" ChucK is a bit nicer about it and informs that "this" isn't allowed in static functions and refuses to run at all (better then suddenly dieing with cryptic complaints!). My attempt to figure out what's going on; =========================== class Foo { int my_number; fun static void bar() { <<<my_number>>>; } } Foo A; Foo B; 1 => A.my_number; 2 => B.my_number; <<<"so far">>>; //here we die Foo.bar(); ====================== "A.bar();" as a last line would also make ChucK die, BTW. Is this a bug (the nullpointer, I mean)? Am I completely misunderstanding static functions? Is the only way to go about this to make a array of type Foo and loop over it going "0 => ArrayOfFoos[n].my_number" or something to that effect? Thanks, Kas.

5 11

Sndbuf: Unclear Error Message
by Veli-Pekka Tätilä 13 Mar '07

13 Mar '07

Hi list, A minor gripe about error handling. When the sndbuf module cannot find a file it says in my Win XP machine (ChucK 1.2.0.7): [chuck](via sndbuf): cannot stat file '../data/snare.wav'... This is very unclear unless you are a Unix programmer. I mean, to the average musician whether or not the stat system call is used and fails is of littel relevance. Where as something like file not found, would describe the error in much more abstract terms. This is a very minor thing I know, and Unix is full of such attitude, but I still don't like it from a usability point of view. Thought I'd let you know, anyway. -- With kind regards Veli-Pekka Tätilä (vtatila(a)mail.student.oulu.fi) Accessibility, game music, synthesizers and programming: http://www.student.oulu.fi/~vtatila/

1 0

Audio Range and Zero-crossings, Performance, Hashes and Future DIrections
by Veli-Pekka Tätilä 10 Mar '07

10 Mar '07

Hi list, I'm new here. I'm a 20 something sight-impaired programmer and musician from Finland. I've got experience using analogs both virtual and real and know how to build Reaktor patches as well as program in Java, Perl and C. Now I've picked up the basics of ChucK and read through the PDF manual that comes with the program. Looks good and certainly a great deal more accessible than recent versions of Reaktor if you're using magnification and a screen reader program. I've got a flurry of questions I'll ask here. ChucK says it is: chuck version: 1.2.0.7b (dracula) exe target: microsoft win32 1. What's the range of the audio float datatype and what would be the best way to detect zero crossings? My aim is to write a simple app that counts the samples in the low and high phases of a pulse wave and prints out the pulse width whenever it changes. If I can also get MIDi input into the app it would be quite easy to determine how pulse width in percentages changes as the function of the pulse width knob in my virtual and real analogs, whose exact values are not documented. Here's some prototypical code (this is my first real chucK script): Code: 100::ms => dur blockSize; // Processing resolution. until(adc.last() < 0) // Measure low-phase first. blockSize => now; // SAmple counters: 0 => int positive; 0 => int negative; while(true) { adc.last() => float sample; if(sample > 0) ++positive; else if(sample < 0) { ++negative; if(positive > 0) // Measured at least one cycle. <<< "Width: ", 100 * negative / (negative + positive) >>>; 0 => positive => negative; // Reset counters. } // else if // Ignore the pure 0 value. blockSize => now; } // while End code. However, when I run this, the app doesn't ever seem to get past the until loop. I'm assuming here that samples are floats or doubles from -1 to 1 as in VST, as I didn't find the range in the manual. Is this correct? IF not, it's no wonder the code won't work, <smile>. Of course the rather grainy test processing rate, ten times a sec, affects matters greatly but I don't ever seem to get negative sample values even in arbitrary audio. The adc and dac modules do work. IF I patch them together and record from the wave input I get a delayed copy of the input in the output I guess this is the audio equivalent of "cat". 2. Why is it that ChucK locks up when I try to process things at the rate of 1::samp? This is what I'd use in the working code but when I try that CPU usage peaks and I have a hard time killing ChucK. Might ChucK be polling som system wide keyboard hooks or something. I'm using a screen reader which I run together with ChucK. I do know it has blocking hooks deep in the OS both in keyboard handling and graphics i.e. GDI or DirectDraw. The OS is XP Pro SP2 English and this laptop is an HP NX8220. The reader and magnifier is Dolphin Supernova 7.03 beta 7. 3. Is there any way to decrease the latency on WIndows platforms for true realtime MIDI playback and audio processing similar to Reaktor? DirectSound latency is pretty bad as my audio machine, which isn't this laptop, would have both WDM kernel streaming and ASIO support in it. 4. How does one use the ZeroX module for detecting zero crossings? What's the value range and what is the output method of that module called i.e. which thing should I poll to detect the crossings? The manual says: Quote: Emits a single pulse at the the zero crossing in the direction of the zero crossing (see examples/zerox.ck) End quote. That path is slightly outdated, by the way. I found the example in: .\examples\basic\zeroX.ck The example uses the module patchd in the DAC directly, so I never see the values it produces in processing. 5. Continuing with modules I've discovered that there are the low level programming constructs, a few basic ugens and then fancy entities that would be instruments in Reaktor speak and remind me of Korg's physical modelling. Are additional basic modules going to be added in the future? Ideally, I'd like, in addition to implementing the constructions as program code, use ChucK as a more conventional modular synthesizer. Reaktor has got very very generic modules in it stuff like digital gates and sequential circuits, multiplexing and demultiplexing, comparators, waveshaping, variable delays, lookup tables, step sequencers and so on. YOu get the picture. While it is true that many of these things can be simulated easily and even more flexibly in program code, that doesn't feel like programming a modular synth, if you know what I mean. But then again, that might not be the aim of ChucK. Maybe I could use ChucK itself to model some of those, if that's possible, inheriting from a ugen that is. Is there example code for something like that, whose primary focus is not the audio processing itself as it often is in DSP? I'm not actually much good in higher math. 6. How do you use the array datatype in ChucK as a hash? I read that you can index the array with strings much like a Perl hash, except that numbres and strings are totally separate. If I get handed a hashtable whose keys I don't know beforehand, is there a keys or each function for iterating through the hash's keyset? Is the hash portion of the array unordered as one might expect in an implementation e.g. an array of pointers to linked-lists? Thanks for any help in advance. And sorry about these complaints, I just thought ChucK would have been a more complete piece of software than it currently is. Well, it has developed loads since I read the manual last time and decidedd back then it isn't quite ready yet, however. Now it is complete enough that I could imagine using it as a Reaktor and VSt plug substitute for some things. Another bonus is that it is available for LInux, so one of my friends whose into Linux and music could use it, too. i've already hyped the prog. I'm much more comfortable handling memory and doing processing in ChucK or Java than I am in C++, for instance. -- With kind regards Veli-Pekka Tätilä (vtatila(a)mail.student.oulu.fi) Accessibility, game music, synthesizers and programming: http://www.student.oulu.fi/~vtatila/

10 43

key up
by Ryan Spangler 10 Mar '07

10 Mar '07

Am I missing it? I am using KBHit for key downs but I can't find a way to track key ups! I have looked all over the documentation/examples and several creative google attempts all for naught. Thanks! --------------------------------- Need Mail bonding? Go to the Yahoo! Mail Q&A for great tips from Yahoo! Answers users.

2 1

User-Module Fundamentals AKA Extending Ugen
by Veli-Pekka Tätilä 08 Mar '07

08 Mar '07

Hi list, A quick question I'll post tonight before replying in the other thread I've started. To gain some experience in ChucK and make it feel more like Reaktor, in terms of modules, I thought I should try implementing some Reaktor modules in ChucK itself. of course, it makes no sense to create something as simple as an audio adder as we have the infix plus binary operator already in the language. So I dug up an ancient Generator module (Generator was the product before they named it Reaktor), and picked a relatively simple example namely a wave made up of series of up and down counts as folows: Quote ancient Generator manual: Multistep Oscillator 4-Ramp Oscillator for 4-ramp waveform with logarithmic pitch control and linear amplitude modulation. The level of each of the breakpoints which are connected by ramps can be set independent of the others. w P: Logarithmic event input for controlling the pitch (oscillator frequency). Value in semitones (69.0 = 440 Hz, but also see DAC Tun). 112 w A: Audio input for controlling the amplitude. The output signal moves between +A and - A. w S1: Event input for controlling the level of the first breakpoint. w S2: Event input for controlling the level of the second breakpoint. w S3: Event input for controlling the level of the third breakpoint. w S4: Event input for controlling the level of the fourth breakpoint. w Out: Audio signal output for the ramp waveform. End quote. Although in this case my aim would be to create a Multistep Oscillator n-Ramp to make it more flexible. In stead of multiple getters and setters I'll create just one with an index parameter, makes life much easier. I read that constructors having parameters are not supported, so I might as well use an initializer method to set parameters after instanciation. I've been looking into ./class/dinky.ck and it claims that one cannot yet inherit from a Ugen, ouch. Is that still true? Well if classes are duck-typed as in Perl or Ruby, i.e. common method names are good enough for polymorphism, then that's not a problem I suppose. I've been trying to grasp how a uGen operates, too, where is it documented thoroughly? The manual says all uGens have certain common parameters. But how should I implement something like: Quote manual: . .chan - (int) - returns a reference on a channel (0 ->N-1) End quote. For my class which should work like a uGen, i.e. what to return and where do I get the object I'm supposed to return? Ideally I'd like to create modules that make no difference between event and audio signals as in a true modular. Howabout modules with multiple inputs. Another thing I'm thinking of creating would be a simple multiplexer named OneOfN which has n inputs and a selectN adress bus. It connects the input addressed by selectN to the output. This is a generalization of the Reaktor modules audio switch 2, 4, 8 and event switch 2, 4, 8. Are such multi in/out modules currently feasible? Do I have to advance time in such a module, as it is a (stateless)combination circuit, not a state machine? Lastly, how do I import my classes in a project ii.e. is there some C:ish preprocessor include syntax or a Java-like classpath environment variable? I find there ar a number of things the manual and a quick glance at the examples doesn't answer adequately. Well, I'm glad we have this list. And sorry to bother you with pretty obvious newbie Qs, I mean if one has ever created an instrument, all or most of these must have been answered already, or else I'm seriously lost, <smile>. Is there a FAQ or archive? -- With kind regards Veli-Pekka Tätilä (vtatila(a)mail.student.oulu.fi) Accessibility, game music, synthesizers and programming: http://www.student.oulu.fi/~vtatila/

2 2