February 2009 - chuck-users - lists.cs.princeton.edu

negative zero
by Robert Poor 01 Mar '09

01 Mar '09

I'm troubled by ChucK's handling of negative zero. A variable set to -0.0 is indistinguishable from a variable set to 0.0, except in printing. This is not a problem in everyday practice, but it seems likely that it will cause trouble when you pass to an external program. [Why would you set a variable to -0.0 in the first place? Try this: (-3.0 % 1.0) => float bar;] Comments? ==================== 0.0 => float foo; -0.0 => float bar; // even though foo and bar print differently... <<< "foo = ", foo, " bar = ", bar >>>; // in ChucK's eyes, they are both considered to be zero... <<< "sgn(foo) = ", Std.sgn(foo), " sgn(bar) = ", Std.sgn(bar) >>>; // and they are equal... if (foo == bar) { <<< "equal" >>>; } ==================== produces ==================== % chuck test.ck foo = 0.000000 bar = -0.000000 sgn(foo) = 0.000000 sgn(bar) = 0.000000 "equal" : (string) ====================

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converting from dur to float
by Robert Poor 28 Feb '09

28 Feb '09

Is there truly no way to cast from a dur to a float? I'm writing a sketch of a TapTempo object. It measures the duration between events to estimate a tempo (in my case, expressed in Hz), which of necessity means *somewhere* I need to convert from a dur to a float. But I haven't figured out how to do that. Suggestions? - r

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small note on LiSa.feedback()
by Kassen 26 Feb '09

26 Feb '09

Dear Dan, readme_LiSa2.ck lists; // mylisa.feedback(float); set feedback amount [0,1] for recording As far as I can tell it takes numbers larger than this as well as negative ones; -------8<-------------- LiSa l => dac; -5.0 => l.feedback; <<<l.feedback()>>>; -------------8<-------------- Amounts with a magnitude of over 1 may be unpractical/dangerous but since we will potentially be dealing with a especially perverted (and interesting!) form of Karplus Strong here I feel the option to use negative number here is rather relevant. Yours, Kas.

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Re: [chuck-users] Introducing the KNoW Wave Generator
by Les Hall 23 Feb '09

23 Feb '09

Sounds very interesting, especially the beginning. After a while my own pattern recognition kicks in and it becomes a bit predictable. I wonder if you could use your boolean walker to generate more dynamics in the storyline, to make it more expressive, or to have more distinction between rhythmic parts and freeform. I must say I never heard of No Wave before, so perhaps this makes no sense in this genre. Arthur Hi Arthur, Yes, its all in how you code the logic matrix of the boolean sequencer. What I'm doing is drawing a diagonal line in the matrix with a decreasing probability of ones as you move away from the line. It looks like this: 0 0 0 0 1 1 1 1 0 1 0 1 1 1 1 1 1 1 1 0 0 1 1 1 1 1 0 1 0 0 1 1 0 1 1 0 1 0 0 0 1 0 1 1 1 1 0 1 1 0 1 0 1 1 1 1 0 1 1 0 0 0 0 1 0 1 1 1 0 1 0 0 0 0 1 1 1 1 0 0 0 1 0 0 1 1 1 0 1 0 1 0 0 1 0 0 0 1 0 1 1 0 0 1 0 0 1 1 0 1 1 1 1 0 0 1 1 0 0 0 1 1 1 0 0 1 0 0 0 0 1 0 1 1 0 0 1 1 1 1 0 0 1 0 If you stare at that matrix a little while you'll see the diagonal line from lower left to upper right of greater ones density, plus plenty of random bits strewn about. I suppose that much randomness is what makes it seem predictable. It's predictably unpredictable. But I can write code that makes other kinds of boolean sequencer logic matrices. In the past, in my soft synthesizer that has one of these as an array of MAUI buttons, I have had good results drawing circles, lines, and triangles. I was able to make some good rock guitar riffs that way. Actually the randomness is intentional for No Wave, which is supposed to be composed of a mix of wandering notes and hard driving rhythms. But for something else you wouldn't want so many bits strewn about in the logic matrix. So yes, coding the matrix in different ways will give completely different results. Les (Inventor)

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Introducing the KNoW Wave Generator
by Les Hall 22 Feb '09

22 Feb '09

Hello ChucK fans, <begin = "shameless self promotion"> I'd like to tell you about my newest way cool ChucK program, 700 lines of automatic music-generating fun! You can read all about it on the ChucK forum here: http://electro-music.com/forum/viewtopic.php?p=228469#228469 Well, it's actually under the composition sub-forum, not the ChucK sub-forum, but there you go. Source code and sample audio file included, so have a look. I've gotten several compliments from music folks about it, so I think you will like it. Comments and suggestions are welcome as always. <end = "shameless self-promotion"> Les (Inventor)

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Literature 2 Music has been Launched...
by Alpha Core 22 Feb '09

22 Feb '09

Hello Everyone, I have finally deployed Literature 2 Music a rails music composing application. This application takes literature aka text and converts it into a music composition that can later be used to in any software synth... www.literature2music.com Compose share & Enjoy... Thanks for your time and support.. Gabriel G

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Summer DSP Course (in ChucK)
by Ge Wang 21 Feb '09

21 Feb '09

Dear all, Perry and I will be teaching a 1-week intensive summer course on Sound Synthesis and Digital Signal Processing in ChucK, to take place from July 6th - July 10th, at CCRMA, Stanford University. The course fee is $650 and includes the course textbook "Real Sound Synthesis for Interactive Applications" by Perry (see below for more information). Should be fun! We sincerely hope you can join us! All the best, Perry and Ge! --- Here is more information: http://ccrma.stanford.edu/workshops/2009/ July 6-10 Sound Synthesis and Digital Signal Processing in ChucK Perry Cook, Ge Wang Description: This 1-week course will introduce basic concepts in sound synthesis, digital signal processing, and programming in the ChucK language. This workshop is intended for: If you know programming (C, Java, C++ Objective C, etc.) then you'll know ChucK thoroughly by the end of this course. If you don't, then you'll know some programming and some ChucK. If you have math background, then you'll know quite a lot of DSP by the end of this course. If not, then you'll have an intuitive grip on many of the concepts. If you know DSP but not physical modeling or other sound synthesis techniques, then you'll know those by the end of the course. Workshop structure: Morning lectures will cover time and frequency domains, additive, subtractive, FM, and physical modeling synthesis, and basics of ChucK programming. Afternoon labs will reinforce course topics through hands-on exercises and individual work based on participant interests. Text: Real Sound Synthesis for Interactive Applications (included in course fee).

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idiom for requiring a class file?
by Robert Poor 18 Feb '09

18 Feb '09

More questions: What's the proper ChucK idiom for automagically loading a class file from a file that uses that class? I can manually add MyClass.ck to the VM before loading the calling file, but that doesn't seem particularly scalable. Is there an idiom that is equivalent to "include" or "require" in other languages? - Rob

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recording audio input under ChucK control
by Robert Poor 18 Feb '09

18 Feb '09

fellow chukka's: I have not yet found an obvious way to record audio input under ChucK control. The SndBuf.write() method is documented as "not yet implemented", and test code appears to confirm that it isn't implemented. I want to use ChucK to record snippets during a live performance using MIDI input to control when the recording starts, then use ChucK to play back processed snippets. I *really* don't want to be switching apps (more specifically -- I don't want to be fiddling on a Mac keyboard), so I need Chuck to control it all. So my gambit -- yet to be tested -- is to use ChucK to spawn a command line function to do the recording, such as: def void recordSnippet(string toFilename) { system ("sndrecord " + toFilename); } ... where sndrecord is a command-line recorder (such as /Developer/ Examples/CoreAudio/Services/AudioFileTools/afrecord). Questions, always questions: - Given my constrains (real-time recording must be controlled from a MIDI device, not from a Mac keyboard) is this a sensible approach? How have other people managed this? - in the ChucK system() call, is there a way to attach to stdin / stdout of a spawned process? In this particular case, I would like to send it a string to stdin of the spawned process to tell it when to stop recording. - Aside from the afrecord utility in Mac OS /Developer, are there other command-line recording apps that people use and like? Thanks. - Rob

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dur frame?
by Kassen 17 Feb '09

17 Feb '09

Fellow ChucKists, suppose we have a stream of data coming in over HID (or MIDI or whatever). Suppose we wish to have something done based on the data that came in over the last frame and we want to make sure this gets done before the next frame starts and hence before any new data could come in. This would be useful to create smooth transitions based on HID data at the expense of lagging one frame. How would we go about this? I don't think we can without introducing "magic numbers" based on our settings. I'd like to propose the introduction of a duration named "frame" of a length of a "n::samp" where n is the size of a single frame in samples. Yours, Kas.

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