Working with Csound WAAW

Web Csound
#1

Fellow Csounders!

If I want to make a simple WebAssembly Audio Worklet with Csound and use it with other Web Audio Nodes, what would be the right workflow?

Currently I’m doing it as following:

  • create new AudioContext
  • using this context create Web Audio Nodes
  • Initialize those Web Audio Nodes
  • using that same context create CsoundObj
    • using this CsoundObj compile some orc string e.g.:
      nchnls=1
0dbfs=1
instr 1                
    ;ain1 in
    ain1 = poscil:a(0.2, 600)
    out ain1
endin
schedule(1,0,-1);
    • start that CsoundObj
    • get Csound Web Audio node from that CsoundObj using getNode() method
    • disconnect() that node from default context output
  • connect nodes
  • start generator nodes like oscillators

Do I understand this correctly?

I’m writing this in Rust and, since I’m still new with Rust’s wasm-bindgen, it’s a bit messy but I hope you can understand it…

let ctx = web_sys::AudioContext::new()?;

// Create our web audio nodes.
let primary = ctx.create_oscillator()?;
let gain = ctx.create_gain()?;

// Initialize them
primary.set_type(OscillatorType::Sine);
primary.frequency().set_value(440.0); // A4 note
gain.gain().set_value(0.3); // starts muted

//-------------------------------------
// Csound integration
//-------------------------------------
let csound_params = js_sys::Object::new();
js_sys::Reflect::set(&csound_params, &JsValue::from_str("audioContext"), &ctx.clone().into())?;
let csound_object = get_csound_obj(csound_params).await;

// -------------------------------------
let orc = r#"
    nchnls=2
    0dbfs=1
    instr 1                
        ain1, ainr ins
        out ain1, ainr
    endin
    schedule(1,0,10);
    "#;

// compile orc
let compile_orc_promise = csound_object.compileOrc(orc);
JsFuture::from(compile_orc_promise).await?;

// start csound
let start_promise = csound_object.start();
JsFuture::from(start_promise).await?;

// get csound node
let csound_node = csound_object.getNode();
let csound_node = JsFuture::from(csound_node).await?;
let csound_node: AudioNode = csound_node.into();
console::log_1(&csound_node);

//-------------------------------------

// Connect the nodes up!
primary.connect_with_audio_node(&csound_node)?;
csound_node.connect_with_audio_node(&gain)?;


// Then connect the gain node to the AudioContext destination (aka
// your speakers).
gain.connect_with_audio_node(&ctx.destination())?;

// Start the oscillators!
primary.start()?;

......

When I print on console my csound_node I’m getting this:

AudioWorkletNode {parameters: AudioParamMap, port: MessagePort, onprocessorerror: null, context: AudioContext, numberOfInputs: 1, …}
channelCount: 2
channelCountMode: "max"
channelInterpretation: "speakers"
context: AudioContext {baseLatency: 0.01, outputLatency: 0, onerror: null, sinkId: '', onsinkchange: null, …}
numberOfInputs: 1
numberOfOutputs: 1
onprocessorerror: null
parameters: AudioParamMap {size: 0}
port: MessagePort {onmessage: null, onmessageerror: null, onclose: null}
[[Prototype]]: AudioWorkletNode

And the problem is that I don’t get any sound when I’m using csound node. Any ideas?