January 2017 - chuck-users - lists.cs.princeton.edu

inheritance question
by Voytek Lapinski 23 Jan '17

23 Jan '17

Hi All, Just getting into ChucK and have a language question. I have some base classes which I have written and am struggling with how to get the inheritance to do what I want. I have a class Voice, and a class Polysynth which contains an array of Voices as data, like so: public class Polysynth { { Voice voices[]; // methods which work on the objects in 'voices', // .. } I want to be able to set up a patch which defines (for example) a MySynth_Voice (subclassing Voice) and MySynth (subclassing Polysynth). MySynth objects will thus contain an array of Mysynth_Voice objects. I want to then be able to call methods on MySynth that are defined in Polysynth, that uses the array of MySynth_Voices as data. The problem is, because they are expecting Voice objects, they aren't happy to receive MySynth_Voices instead (even though MySynth_Voice inherits from Voice). I can't cast them in the Polysynth methods that use it because it won't compile unless 'voices' is declared. It has to be declared as 'Voice', and if I try to override it in the subclass (eg. "MySynth_Voice voices[]"), it won't compile saying saying it "has already been defined in super class 'Polysynth'". I tried a bunch of different ways to do this, but the only way I can find to do it was to cast the voices array in the subclass as follows. class MySynth extends Polysynth { fun void init (int num_voices) { MySynth_Voice voices_temp[num_voices]; Voice voices_temp2[num_voices]; for (0=>int i; i < num_voices; i++) { voices_temp[i] $ Voice @=> voices_temp2[i]; } voices_temp2 @=> voices; } } Firstly, is it possible to do this without having to do this casting bit? It seems like a common inheritance set up, so am wondering if I have just missed something. Failing that, is there a better way to do the casting step? I tried to do in obvious ways like 'MySynth_Voice $ Voice[] @=> voices' but that, and other possible permutations I could think of, wouldn't compile. The iterating over the whole array and doing each member explicitly seemed to be the only thing that worked. It's certainly no big deal and I can live with it, but am just curious if there's a nicer way to do it. Thanks all... -voytek

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Re: [chuck-users] chuck-users Digest, Vol 138, Issue 8
by Stuart McDonald 21 Jan '17

21 Jan '17

HI Mark, Ok, some news from the front: I've got what I want going on a pi with alsa's snd-aloop module (see https://www.alsa-project.org/main/index.php/Matrix:Module-aloop). This sets up an input device which loops back to an output device. So I used chuck --probe to get the corresponding dac number for the input, sent chuck into that by specifying --dac, and then set up darkice to listen to the output device. >From there the data gets sent to icecast on the same pi. The whole system seems to run stably and generate audio constantly (I've got a shell script restarting the chuck process after it finishes (c. half an hour for each go). Since I now have an rpi with a bunch of cobbled together configuration I'd like to formalise it and make it repeatable, so I'll be looking at your and mheuer's docker work :) Thanks, Stuart > ---------- Forwarded message ---------- > From: Mark Cerqueira <mark.cerqueira(a)gmail.com> > To: ChucK Users Mailing List <chuck-users(a)lists.cs.princeton.edu> > Cc: > Date: Mon, 16 Jan 2017 20:01:24 -0800 > Subject: Re: [chuck-users] ChucK => internet audio stream? <snip> > Stuart - I think you could accomplish your idea with some work over my Docker image. AFAIK, the --silent flag does not mean no sound is produced; it just means no audio is outputted during the running of the program. You could set something up like: > > 1. Let ChucK produce 30 seconds of audio (with --silent it should take less than 30 seconds to produce 30 seconds of audio) and save it to an audio file. Look at export.ck in the chuck-renderer repo for how to do this. > 2. Streaming clients grab this 30 seconds of audio and start playing it. > 3. While the above is occurring, you produce another 30 seconds of audio. > 4. Send the next audio file to clients and they queue it up after the first segment ends. > 5. Rinse, repeat. > > This has the added benefit of letting ChucK shut down between producing segments to do garbage collection. :) You might need some annealing to get the separate audio to sound "together" but this should get you a "Hello, World ChucK stream." > > Good luck! > > mc

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Re: [chuck-users] ChucK => internet audio stream?
by Stuart McDonald 16 Jan '17

16 Jan '17

Thanks to those who responded; will look at Jack, DarkIce and Liquidsoap. What I was ideally hoping to do is running chuck => DarkIce/Liquidsoap => Icecast on an Amazon EC2 appliance, but a lack of soundcard on these machines complicates things. Cheers ears, Stuart

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Re: [chuck-users] ChucK => internet audio stream?
by Stuart McDonald 16 Jan '17

16 Jan '17

Oh nice, I was looking at possibly using my project as a way of teaching myself Docker. The problem I have is I want to operate ChucK continuously, basically like an internet radio station. I get around memory leaks by restarting the ChucK process periodically, so in itself it should be steady state. This means I can't really use --silent -- unless I'm not understanding how that flag works. I'm not looking for answers to these questons, just sort of stating what I'm up to in case it is of interest. :) I haven't started on the streaming part of this project yet (still working on core app), but will advise if anything interesting comes up. Thanks Stuart > ---------- Forwarded message ---------- > From: Mark Cerqueira <mark.cerqueira(a)gmail.com> > To: ChucK Users Mailing List <chuck-users(a)lists.cs.princeton.edu> > Cc: > Date: Fri, 13 Jan 2017 17:16:54 -0800 > Subject: Re: [chuck-users] ChucK => internet audio stream? > I set up a Docker image this week that lets you pass it ChucK source code or file, it runs it for up to 30 seconds (with --silent flag so it does this step much faster than 30 seconds), saves the output to .wav, converts the .wav to .m4a to make the file smaller, and then hosts the file for download/streaming. > > Demo container running Docker image: http://chuck-renderer.4860ca31.svc.dockerapp.io:9000/debug > > Source code: https://github.com/markcerqueira/chuck-renderer > > Image on Docker hub: https://hub.docker.com/r/markcerqueira/chuck-renderer/ > > Cheers! > > mc

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Cannot assign array of Oscs to UGen[]
by Karim Sumun 07 Jan '17

07 Jan '17

Given the following declarations: SinOsc s0; SqrOsc s1; TriOsc s2; The following gives an error: [s0, s1, s2] @=> UGen A[]; $ ... cannot resolve operator '=>' on types 'Osc[]' and 'UGen[]'... But the following works fine: [s0, s1, s2] @=> Osc A[]; It is not a problem, but would like to understand this behaviour. It would seem that assigning to UGen[] would be ok because it looks like a superclass of Osc[]. Aaah! Is this to do with co/contra-variance?

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ChucK => internet audio stream?
by Stuart McDonald 07 Jan '17

07 Jan '17

Hi, I'd like to send ChucK's audio output to an internet streaming application (like icecast). Ideally ChucK wouldn't write to the dac at all, but to an IP:port or socket or similar. The only info Google provides is a note in passing for the documentation for chuck --silent: "This is useful for synthesizing audio to disk or network" ...which makes it sound like this is possible, but provides no information on how to do it. Has anyone been down this path? Was it fun? Thanks Stuart

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