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

Sample Playback Efficiency
by Juan-Pablo Caceres 28 Nov '07

28 Nov '07

Dear list, Lets say I have an array of SndBuf, and I want to playback one of the samples each time. What is the most efficient way? What I am doing is just connecting everything to dac, and then setting all but one of the gains to non-zero, something like this: SndBuf buf[20]; for ( 0 => int i; i < 20; i++ ) { sample_names[i] => buf[i].read; //assuming I have an array of //string names buf[i] => dac; 0. => buf[i].gain; } //then to playback one at the time: int isamp; while (true) { Std.rand2(0, 19 ) => isamp; 0 => buf[isamp].pos; 0.1 => buf[isamp].gain; //set gain to something different // than zero 200::ms => now; 0. => buf[isamp].gain; //bring it back to zero } This works, but doesn't feel right. All the DSP connections are made, so I would guess this is inefficient. The other option will be to connect (=>) and disconnect (=<) dynamically but that solution also feels wrong... Any ideas? Thanks so much again, Juan-Pablo

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ChucK on OLPC??
by M. Edward (Ed) Borasky 27 Nov '07

27 Nov '07

Forgive me if this is a FAQ, but has ChucK been ported to the XO laptop (One Laptop Per Child)? I'm seriously considering getting one under the Give One Get One program, and it appears to have CSound on it already. I'm thinking a bunch of them with the built-in wireless would make a nice laptop orchestra. :)

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debug print duration
by Juan-Pablo Caceres 26 Nov '07

26 Nov '07

Hello list, This is kind of a silly question, but do you guys remember how to print a duration on a specific unit? What I mean is something like this: 1::second => dur mydur; <<< mydur >>>; //see the output in seconds (or another time unit) rather than samples I remember seeing this in one of the examples, but I cannot find it! Thanks in advance, Juan-Pablo

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easy random numbers
by jakob kaiser 21 Nov '07

21 Nov '07

Hi, I want to write a small script for ear training with Chuck. Therefore Chuck should produce values that seem to be quite random. But it seems like that the standard functions here are too deterministic. I know that a non-deterministic random function would not be possible, but most programming languages provide functions that create at least new numbers every time I start the same code. However, in chuck something like the following always prints the same numbers when I run it: while(true){ 1::second => now; Math.rand2(50, 1000) => int rndNumber; <<<rndNumber>>>;} Is there an easy way to get something more unpredictable? I don't want to go deep into random generator programming. But the function does not really what you would expect of a random generator, does it? Cheers Jakob _________________________________________________________________ Connect to the next generation of MSN Messenger http://imagine-msn.com/messenger/launch80/default.aspx?locale=en-us&source=…

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overlap factor amplify input signal
by Aylon Eduard 21 Nov '07

21 Nov '07

Hi there, In the following code ifft.last() is sometimes larger than 1, but when the input signal has unity gain, it shouldn't be like this. Actually, what happens, I think, is that the amplification is proportional to the overlap factor. So should setting ifft.gain to hopsize/fftsize be the correct way to handle this? thanks eduard SinOsc s => FFT fft => IFFT ifft => dac; //blackhole; 1024 => int fftsize => fft.size; fftsize/4 => int hopsize; fftsize/2 => int specsize; Windowing.blackmanHarris(fftsize) => fft.window => ifft.window; complex spec[ specsize ]; fun void transform() { fft.upchuck(); fft.spectrum( spec ); ifft.transform( spec ); hopsize::samp => now; } while( true ) { if( Std.fabs(ifft.last() > 1) ) <<< ifft.last() >>>; transform(); }

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Reply to Kassen on shreds, functions and objects
by Jim Hinds 16 Nov '07

16 Nov '07

Apologies: I broke mailing list rule #1: "dont use subject lines like Re: chuck-users Digest, Vol 28, Issue 23" My bad. HI. The function is a function. It is only a function and things within it (the string beep) are totally invisible to anything outside of the function definition. (That's only partly true as they theoretically could be passed by reference to something else, just ignore this fact for now.) 'beep' does not belong to the sporked object. In fact, the name 'tester' isn't likely to be known to the sporked object. Chucks object and class capabilities are growing, but as they say on the street, they are not all 'that.' It has to do with inheritance, namespaces, run-time magic, and lots of stuff that would kill the real- time capability of a shred. All these are fun problems for a computer science person, but not so very fun if you just want to make chuck sing. I usually just pretend that sporked things are not objects at all. A shred is more like an independent agent: a baby. All it knows is the function that is used to give it birth. That function must know how to do all the communication to and from the outside environment. That function can call other functions (in other classes, possibly), look at global variables (in the same source file) and such. I'm sticking with global variables, at least for the short term. Programs in chuck are usually on the smallish side and a few global variables won't hurt the music and are just a necessary evil. I give those global variables useful names like "second_violin_bow_velocity" or some such and to keep track of them better. Jim Hinds http://www.jahbini.org/ > > > On Nov 15, 2007 4:46 PM, Kassen <signal.automatique(a)gmail.com > wrote: > Dear list, > > Shreds are objects (of type Shred) and functions aren't objects. > This is all good and well but it gets harder when we spork a > function and the function becomes a Shred and hence a Object. > Consider this; > > ------------------------ > fun void tester() > { > "boom" => string beep; > while(1) > { > <<<beep>>>; > second => now; > } > } > > > spork ~ tester() @=> Shred foo; > 5::second => now; > > "clik" => foo.beep; //this doesn't work > > day=> now; > ---------------------------------------- > > It's not so clear to me *why* the offending line doesn't work. Maybe > I'm misunderstanding something or making a syntax error but I think > that what we are seeing here is a loss of namespace that would be > useful and I don't understand why this happens. > > I also tried stuff along these lines; > > ---------------------- > class Bar extends Shred > { > //stuff including variables and a constructor > } > ------------------------------ > > If I do that I can instantiate a "Bar" but all it does is run it's > constructor; I can't manage to spork a Bar or assign a sporked shred > to a Bar. I can also make a array of Bar's but all that gets me is > the constructor running; > > --------------------------- > class Bar extends Shred > { > static int number; > <<<number++>>>; > } > > //print a series of numbers, no shreds in sight > Bar array[5]; > ---------------------------------- > > So, now I'm quite happy I said so many times that there are no > "stupid n00b questions" because now it's my turn to ask exactly what > a "Shred" is because I'm starting to feel like I have no idea. :¬) > > Could somebody please explain to me exactly what's going on here? > > > Yours, > Kas. > > _______________________________________________ > chuck-users mailing list > chuck-users(a)lists.cs.princeton.edu > https://lists.cs.princeton.edu/mailman/listinfo/chuck-users > > >

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a few language questions
by Michael Heuer 15 Nov '07

15 Nov '07

Hello, I have a few chuck language questions: Is it possible to define a "growing" array? The associative portion of the array grows without bounds but I can't see how to do that with the indexed portion. Object @ list[]; for (0 => int i; i < 100; i++) { Object o @=> list[i]; } Is it possible to check a reference against null? Object @ list[100]; 0 => int size; for (0 => int i; i < list.cap(); i++) { if (list[i] is null?) { size++; } } Is there a "String toString()" or similar method on Object? I wish to override "Expressions which represent an object will print the value of that object's reference address". Do reflective methods exist on the base Object type (its "Class")? e.g. Function[] getFunctions(); ... Thanks, michael

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MAUI logic question...
by Jascha Narveson 14 Nov '07

14 Nov '07

Ahoy, ChucKists - I've just coded myself a perfectly serviceable metronome, and it works fine except for a small nagging thing in the MAUI. In my metronome, I have 2 toggle type buttons, "thirds" and "sixteenths". If one is on, the other is off, so i'm always subdividing the pulse one way or the other. As it is, if I turn "thirds" on and off, the "sixteenth" button dutifully goes off and on in a complementary way. If I do this, though: - toggle "thirds" on ("quarters" stays off) - toggle "quarters" on ("thirds" politely turns off) - toggle "thirds" on At this point they're *both* on. I can get back to a one-or-the- other state by fussing around and toggling the right combo of things, but i'd rather not do that. I've attached just the button-related code below - i've got two functions set up that are turning the other button on or off depending on whether or not they're off or on. It's bending my brain a bit to figure out why it sometimes behaves the way it does - any insights out there? thanks, as always, j. ------code------ MAUI_View view; view.size(400,200); MAUI_Button thirds; thirds.toggleType(); thirds.size(110,110); thirds.position(0, 100); thirds.name("thirds"); view.addElement(thirds); MAUI_Button sixteenths; sixteenths.toggleType(); sixteenths.size(110,110); sixteenths.position(110, 100); sixteenths.name("sixteenths"); view.addElement(sixteenths); view.display(); fun void controlThirds() { while (true) { thirds => now; sixteenths.state(0); <<<"thirds on">>>; thirds => now; sixteenths.state(1); <<<"thirds off">>>; } } fun void controlSixteenths() { while (true) { sixteenths => now; thirds.state(0); <<<"sixteenths on">>>; sixteenths => now; thirds.state(1); <<<"sixteenths off">>>; } } spork ~ controlThirds(); spork ~ controlSixteenths(); while (true) { 1::second => now; }

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fft issues
by eduard aylon 14 Nov '07

14 Nov '07

Hello list, some time ago I reported the following as a possible bug on the wiki: * Assigining window to ifft seems to yield "poorer" results than not assigning it. Try it in /examples/win.ck and you'll notice a rougher (faster beating) sound. (eduard) However, looking again at the code of win.ck I realised the size of the window was set to the half of fft_size. Unless zero-padding is performed, shouldn't window_size and fft_size be the same? Anyway, setting the window size to fft_size (both for forward fft and iverse fft) yields correct results in examples/win.ck. This applies to some of my previous emails where brick wall filters and vocoder were discussed. That is, window_size should be set to fft_size and resulting spectrum to fft_size/2. But now I am also concerned about the size of the spectrum. In chuck this is FFT_SIZE/2, but shouldn't it be FFT_SIZE/2+1 or does the first value in spectrum hold both DC and Nyquist components? By the way, could chuck perform zero-padding when window_size < fft_size? eduard

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Phoneme Recognition with ChucK
by Inventor-66＠comcast.net 14 Nov '07

14 Nov '07

Hi, On the electro-music.com forum we've been discussing a phoneme recognizer based on ChucK. So far we have an FFT grabber that gets its samples off the dac so you can ChucK-up any input file to it including a microphone listener, rec_in.ck, a little bit of feature extraction and a rules-based phoneme recognizer. It can basically tell an "ee" phoneme from an "ay" phoneme, and I plan to add all the vowels, a e i o u really soon. To help with the project, I was wondering if anyone from the list would like to contribute some suggestions or comments about our technique. Basically we are shunning the hidden markov models that are often used to recognize words from phonemes in favor of creating a simple phoneme recognizer. This way we offload much of the computation from the machine into the human user's brain, thus enabling a compact ChucK implementation as well as someday a simple dsPIC processor-based handheld product that streams text from a mic for the hearing impaired. For example, if you said "Mary had a little lamb", the device might output "mehry hahd ah letl lam" and it is up to the user to interpret that into regular speech. In this way a very compact little product with just a few chips could be produced that would retail for twenty dollars or lower, making it affordable and portable for the hearing impaired to use. I was Just curious as to what your thoughts may be, I'm doing the code and Kassen plus others like dewdrop_world are commenting and pointing me in the right direction as we go. Please feel free to offer suggestions and/or constructive criticism. Thanks, Les

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