Send Data

If you want to send data to a Pd patch, you can use the following functions:

Pd4Web.sendBang

Send a bang to Pd.

Pd4Web.sendBang("myreceiver")

The bang will be received by [r myreceiver].

Pd4Web.sendFloat

Send a number to Pd.

Pd4Web.sendFloat("myreceiver", 5)

To receive this use one object [r myreceiver] in Pd.

Pd4Web.sendSymbol

Send a symbol to Pd.

Pd4Web.sendSymbol("myreceiver", "mysymbol")

To receive this use one object [r myreceiver] in Pd.

Pd4Web.sendList

Send a list to Pd.

Pd4Web.sendList("myreceiver", [5, "mysymbol"])

To receive this use one object [r myreceiver] in Pd.

Pd4Web.sendFile

Pd4Web uses an internal file system within the AudioWorklet. This is great because it keeps everything safe and secure, but it also means that to load audio files, text files, or anything else inside Pd, you first need to send those files into the Pd4Web file system. To do that, you must send the file’s binary data.

For example, suppose your HTML page includes:

<input id="someAudioInput" type="file" accept="audio/*" />

You can then use this JavaScript code:

document.getElementById("someAudioInput").addEventListener("change", async (e) => {
    const file = e.target.files[0];
    if (!file) return;
    const arrayBuffer = await file.arrayBuffer();
    Pd4Web.sendFile(arrayBuffer, file.name);
});

This is how you can use upload files in your PureData Patch.

Pure Data arrays

The array must already exist in the open Pure Data patch, for example as [array define samples].

Pd4Web.readArray

Read every value from a named Pure Data array. The returned value is a Float32Array, so it can be used directly as audio sample data.

const samples = Pd4Web.readArray("samples");

if (samples) {
    console.log(samples);
}

If no patch is open or the named array does not exist, readArray logs an error and returns undefined.

Pd4Web.writeArray

Write an array of numbers or a Float32Array into a named Pure Data array. The Pure Data array is automatically resized to match the number of supplied samples.

const samples = new Float32Array([0, 0.25, 0.5, 0.25, 0]);
const written = Pd4Web.writeArray("samples", samples);

if (!written) {
    console.error("Could not write the samples");
}

Audio decoded with the Web Audio API can be written directly:

const samples = audioBuffer.getChannelData(0);
Pd4Web.writeArray("samples", samples);

writeArray returns true on success. If no patch is open or the named array does not exist, it logs an error and returns false. Pure Data clips a resize of zero samples to an array size of one.