I have mentioned before that Peter Brinkmann's jReality package, written in 
Java, for mathematics visualization and sonification can use Csound to 
attach sounds to visual objects. Here is Peter's source code, which I helped 
him to write, from jReality SVN for sending audio output from Csound to the 
audio backend of jReality. I have heard this code run. I imagine similar 
code would work in Lua, and I may verify that if I have time.

The key lines are as follows, with my comments added:

// SWIG-generated wrapper for an array of MYFLT.
  spout = new CsoundMYFLTArray();
// Set the SWIG wrapper for Csound's spout buffer pointer to the MYFLT array 
wrapper. The "Ptr" is a SWIG wrapper for a C MYFLT * pointer.
// In other words, in SWIG-generated code you never see a truly raw pointer.
// THIS IS PROBABLY YOUR MISSING STEP, GENTLEMEN.
  spout.SetPtr(csnd.GetSpout());
// Create a native host language buffer for sending monophonic audio to the 
backend.
  cumulativeBuffer = new float[ksmps];

// Call on Csound to synthesize ksmps worth of audio.
// ANOTHER POSSIBLE "GOTCHA": MUST USE csoundPerformKsmps NOT 
csoundPerformBuffer.
   csnd.PerformKsmps();
// Transfer audio, framewise, from the SWIG wrapper for spout to my native 
buffer.
// I.e., j is the SAMPLE FRAME index.
   for(int j=0; j
To: 
Sent: Thursday, November 26, 2009 8:51 PM
Subject: Re: [Cs-dev] bus opcodes


>
>
>
> You may remember that i failed to get the JAVA API to access audio
> channels last summer, and there still is no explanation
> ==John ffitch
>
> Hi John,
> This was some old java code posted a long time ago which is supposed to 
> show
> channel communication to/from a java host using .csnd.jar methods.  I'm no
> Java expert but sort of have this working.  Maybe Steven Yi or J.P. 
> Lemoine
> are better at java.  The code I was working on was mostly using chnget to
> get a k-value for frequency from the java host using the 
> csoundGetChannelPtr
> method and passing the java wrapped value of MYFLT **p to csound.
>
> //Main.java
> public class Main {
>    public static void main(String[] args) {
>        chntest_thread  c = new chntest_thread();
>    }
> }
> //--------------
> //chntest_thread.java
>
> import csnd.*;
>
> public class chntest_thread {
>    SWIGTYPE_p_void myvoid;
>    //SWIGTYPE_p_void myvoid = null;//if above gives compiler error
>    SWIGTYPE_p_CSOUND_ mycsound = csnd.csoundCreate(myvoid);
>    Csound csound = new Csound();
>    CsoundMYFLTArray myfltarray = new CsoundMYFLTArray();
>    CsoundMYFLTArray chn1 = new CsoundMYFLTArray();
>    CsoundMYFLTArray chn2 = new CsoundMYFLTArray();
>    CsoundMYFLTArray chn3 = new CsoundMYFLTArray();
>    CsoundMYFLTArray chn4 = new CsoundMYFLTArray();
>    CsoundMYFLTArray chn5 = new CsoundMYFLTArray();
>
>    chntest_thread() {
>        run();
>    }
>
>    public void run() {
>    int err, ksmps, kcnt = 0;
>    double phs = 0.0, phs_inc;
>    err = csound.Compile("chnTest.csd");
>    if (err == 0) {
>      err |= csnd.csoundGetChannelPtr(mycsound, chn1.GetPtr(), "k_in",
>                                  csndConstants.CSOUND_CONTROL_CHANNEL
>                                  | csndConstants.CSOUND_INPUT_CHANNEL);
>      err |= csnd.csoundGetChannelPtr(mycsound, chn2.GetPtr(), "a_in",
>                                  csndConstants.CSOUND_AUDIO_CHANNEL
>                                  | csndConstants.CSOUND_INPUT_CHANNEL);
>      err |= csnd.csoundGetChannelPtr(mycsound, chn3.GetPtr(), "S_in",
>                                  csndConstants.CSOUND_STRING_CHANNEL
>                                  | csndConstants.CSOUND_INPUT_CHANNEL);
>      err |= csnd.csoundGetChannelPtr(mycsound, chn4.GetPtr(), "k_out",
>                                  csndConstants.CSOUND_CONTROL_CHANNEL
>                                  | csndConstants.CSOUND_OUTPUT_CHANNEL);
>      err |= csnd.csoundGetChannelPtr(mycsound, chn5.GetPtr(), "S_out",
>                                  csndConstants.CSOUND_STRING_CHANNEL
>                                  | csndConstants.CSOUND_OUTPUT_CHANNEL);
>      if (err == 0) {
>        chn1.SetValue(0, 3.14159265);
>        chn3.SetStringValue("String Input Value", 
> csound.GetStrVarMaxLen());
>        phs_inc = 2.0 * 3.14159265 * 440.0 / csound.GetSr();
>        ksmps = csound.GetKsmps();
>        do {
>          for (int i = 0; i < ksmps; i++) {
>            chn2.SetValue(i, 0.7071 * Math.sin(phs));
>            phs += phs_inc;
>          }
>          err = csound.PerformKsmps();
>          if (kcnt == 0) {
>            String s = chn5.GetStringValue();
>            System.err.printf("Values sent: %g, '%s'\n", chn4.GetValue(0),
> s);
>          }
>          kcnt++;
>        } while (err == 0);
>      }
>    }
>         csound.Reset();
>        java.lang.System.exit(1);
>    } //end run method
> }//ends chntest_thread
> //-----------
> //chnTest.csd
>
> 
> 
> -s -d -+rtaudio=ALSA -odac:hw:0,0 -b1024 -B16384
> 
> 
> sr =  44100
> ksmps =  32
> nchnls =  2
> 0dbfs =  1
>        chn_k "k_in", 1
>        chn_a "a_in", 1
>        chn_S "S_in", 1
>        chn_k "k_out", 2
>        chn_S "S_out", 2
>
>        chnset 2.71828, "k_out"
>        chnset "Output String Value", "S_out"
>
>        instr 1
> ichn1 chnget "k_in"
> achn2 chnget "a_in"
> Schn3 chnget "S_in"
>
>        printf_i "Values received: %g, '%s'\n", 1, ichn1, Schn3
>        outs achn2, achn2
> endin
>
> 
> 
> i 1 0 2
> e
> 
> 
>
> -- 
> View this message in context: 
> http://old.nabble.com/bus-opcodes-tp26362662p26535852.html
> Sent from the Csound - Dev mailing list archive at Nabble.com.
>
>
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