Convolver node.js V2 with OSC post

by

As of April 23 – http://cieweb.ddns.net:3000/index.html with updated comments April 26.

This internet available demonstration web application (webapp) allows selection of a sample audio recording, an impulse, plays through convolution reverb with Wet/Dry, Pitch Shift and Speed control – a work in progress. The resulting sound can be heard on the user device. On the backend web server, Open Sound Control (OSC) messages are sent so that a visitor to a gallery can use their smart phone to interact with sound sculptures as part of an electro acoustic sound art installation. This is implement primarily in Javascript JS and HTML.

Click for defintion of convolution reverb and “impulse” (IR)

An Impulse Response (IR) is a WAV file that captures the sonic “snapshot” of a speaker cabinet, microphone, or acoustic space. Used in audio processing, it acts as a high-resolution EQ and character filter, allowing users to emulate specific resonant objects or spaces.

Convolution reverb is a sample-based software based effect processor or pluging that uses an Impulse Response (IR)—a recording of a real space or hardware—to accurately simulate natural reverberation. Unlike algorithmic reverb, it captures the authentic sonic footprint of environments like halls, cathedrals, or vintage plates.

The Active ID for instance might be used to select which loudspeaker or sonic object to send a signal to. This works from most any modern browser & device (iPad, iPhone, Laptop, Destkop, Android, Raspberry Pi).

Here is a screen snapshot of the Convolution Player web application…

Overview

Here is walkthrough of generation of a node.js application using Google Gemini AI consisting principally of a server.js back end webserver source code file and index.html user interface front end that presents users with list of samples and impulses built by looking at respective folders and playing the pair through a convolution reverb with dynamic control of wet/dry balance and volume. Play and Stop emit OSC messages here send to a simple proof-of-concept Max or PD patch to demonstrate a visitors smart phone interacting with an audio multi-media site-specific sound sculpture installation in a gallery or other “found” spaces.

This is a test bed to explore a bring-your-own-device to a installation and be able to send signals to an audio back end and to give the user audio of a convolution on their smartphone, iPad or most any other device with a browser.

Key software dependencies:

Tested from browser on iPhone, iPad, Android, Desktop, Safari, Chrome. Quick test with 4 concurrent devices; wired, wifi and cellular. The implementation is highly scalable.

Note: load time of the larger samples is dependent upon network speed. Currently, there is no load progress indicator. This might be added in future verions.

Future Use

Future use includes possibilities such as access smartphone sensors (Inertial Motion Unit – IMU) or microphone that can be used in various ways. These developments are likely to be dependent upon an SSL – HTTPS connection and related security certificate. A self-signed certificate is adequate for proto-typing and full formal certificate that involves some minimal cost would be needed for a robust public usage.

Similar example of the node.js server.js and related files can be hosted on a Raspberry Pi as a low cost solution.

Other OSC listeners such as Ableton, Reaper, PD can be used instead of basic Max. For example, Python listener running on a PiZero could control DMX devices.

Related thread is running this and related apps on a public available server. Lowest cost solution is self-hosting made easy with access to the port forwarding controls on my local router. Variation is use of DDNS from no-ip.com.

Web Audio Links is a collection of links to various API for Web Audio and a number of interesting examples that can be integrated here.

The use of node.js backend server also offers possibilities for interaction between different user devices.

Simple signal analysis of microphone could be used in various interactive ways.

Working local path for development: ~/Dropbox/JS/osc-audio-app

Related Links

AI generated node.js convolution player
AI on “generate a web page to select an audio clip to play through a selected impulse convolution”
On node.js convolution

Current State as of April 23

  • adjust to device (iphone,ipad, Desktop)
  • added pitchshift
  • added play rate
  • added link to this page
  • extended OSC message schema (file names, sliders)

Current State from April 21 (with updates)

The original AI prompt and generated response source code below under link.

A series of AI prompts like the following were the feature refinements and bug fixes:

  • Take a look at this server.js… suggest improvements to keep from hanging. Works at first then after changing file selection, the code hangs.const express = require(‘express’);
    const {Client} = require(‘node-osc’) – bug fixes
  • Take a look at this server.js… suggest improvements to keep from hanging. Works at first then after changing file selection, the code hangs… (pasted server.js) – bug fixes
  • front end code … prompt to generate the HTML file
  • index.html:59 Uncaught TypeError: Cannot set properties of null (setting ‘onclick’) – a bug fix
  • show new version – instructes Gemini to integrate changes into the base code
  • add dynamic gain control – controls are live during playback not just as set before pressing “play”
  • add wet dry balance between original sample and the sample player through the convolution reverb
  • supply a favicon.ico (icon on the brower menu bar)
Click here for old front end as of April 21

Here is the QRCode to access from public internet via http://cieweb.ddns.net:3000/index.html

This is running on RaspberryPi accessed via port forwarding on home router.

Took an evening to get the AI output to this more functional state…

Another evening with Gemini to iron out stability issues.

Added:

  • wet/dry slider
  • dyamic changes to control
  • OSC messages working
  • Tested OSC simple maxpat
    • send more complete set of parameters: gain, wet/dry, sample name, impulse name, instance number (ID)

Next steps

  • other features from Web Audio Links examples (loop, starting point, frequency shift as independent variable)
  • build out audio back end using the “ID:” as audio channel selector
  • consider adding capability to embed via iframe
  • seems that rapid changes to variables halts playing
  • add pause & resume
  • Location specific file sets based on GPS input
  • Parameter control from IMU

Explanation and Diagram (from Gemini)

Note: diagram showing duplicate Playback Rate rather than separate Pitch shift and Rate. This is not exactly as intended but a good approximation. “Works as coded”.

Based on the latest index.html source code from April 23 provided on this page, here is the signal path diagram for the Web Audio API implementation:

Signal Path Architecture

The application uses a parallel routing structure to allow for real-time convolution and dynamic “Dry/Wet” mixing:

  1. Audio Source: An AudioBufferSourceNode loads and plays the selected sample file.
  2. Parallel Split: The signal from the source is split into two paths:
    • Dry Path: Connects directly to the dryGain node.
    • Wet Path: Connects to a ConvolverNode (using the selected impulse response), which then outputs to the wetGain node.
  3. Mixer Stage: * The dryGain and wetGain levels are inversely linked via the Mix slider.
    • Both gain nodes then converge into a mainGain node, which acts as the master volume control.
  4. Destination: The signal finally reaches ctx.destination (the device’s physical speakers or headphones).

Key Components & Controls

ComponentFunctioncode Reference
Playback RateAdjusts both pitch and speed via source.playbackRate.source.playbackRate.setTargetAtTime()
ConvolverApplies the impulse response buffer to the sample.ctx.createConvolver()
Mix (Dry/Wet)Uses setTargetAtTime for smooth transitions between processed and unprocessed sound.updateMix(value)
Active IDTriggers an external OSC message via the Node.js backend.fetch('/play-trigger/${selectedId}')

server.js (lastest as of April 23)

const express = require('express');
const { Client } = require('node-osc');
const fs = require('fs').promises;
const path = require('path');

const app = express();
//const HOST = '192.168.254.25';
const HOST = '192.168.254.50';
const PORT = 3000;
const oscClient = new Client(HOST, 3333);

app.use(express.static('public'));
app.use('/samples', express.static(path.join(__dirname, 'samples')));
app.use('/impulses', express.static(path.join(__dirname, 'impulses')));

app.get('/files', async (req, res) => {
    const filter = f => f.match(/\.(mp3|wav|ogg)$/i);
    try {
        const [samples, impulses] = await Promise.all([
            fs.readdir('./samples'),
            fs.readdir('./impulses')
        ]);
        res.json({ samples: samples.filter(filter), impulses: impulses.filter(filter) });
    } catch (err) { res.status(500).json({ error: "Disk read error" }); }
});

// OSC Routes
app.get('/play-trigger/:id', (req, res) => {
    oscClient.send('/play', parseInt(req.params.id), () => res.sendStatus(200));
});

app.get('/stop-trigger', (req, res) => {
    oscClient.send('/stop', () => res.sendStatus(200));
});

app.get('/pitch-trigger/:value', (req, res) => {
    oscClient.send('/pitch', parseFloat(req.params.value), () => res.sendStatus(200));
});

app.get('/speed-trigger/:value', (req, res) => {
    oscClient.send('/speed', parseFloat(req.params.value), () => res.sendStatus(200));
});

app.get('/gain-trigger/:value', (req, res) => {
    oscClient.send('/gain', parseFloat(req.params.value), () => res.sendStatus(200));
});

app.get('/file-names', (req, res) => {
    oscClient.send('/names/sample', req.query.sample || "none");
    oscClient.send('/names/impulse', req.query.impulse || "none", () => res.sendStatus(200));
});

app.listen(PORT, HOST, () => console.log(`Server: http://${HOST}:${PORT}`));

index.html (lastest as of April 23)

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Convolution Player</title>
    <style>
        body { font-family: sans-serif; padding: 20px; max-width: 800px; margin: auto; background: #f4f4f4; }
        .card { background: white; padding: 20px; border-radius: 8px; box-shadow: 0 2px 10px rgba(0,0,0,0.1); }
        h1 { font-size: 1.5rem; color: #333; }
        
        /* Layout Grid */
        .control-group { margin-bottom: 20px; }
        label { display: block; font-weight: bold; margin-bottom: 5px; }
        
        select, input[type="range"] { width: 100%; margin-bottom: 10px; }
        
        .btn-row { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 20px; }
        button { padding: 12px 20px; cursor: pointer; border: none; border-radius: 4px; background: #007bff; color: white; font-weight: bold; }
        button:active { background: #0056b3; }
        #stopBtn { background: #dc3545; }
        
        .info { font-size: 0.9rem; color: #666; margin-top: 10px; }
        footer { margin-top: 40px; padding-top: 20px; border-top: 1px solid #ddd; font-size: 0.8rem; text-align: center; }

        /* Responsive Adjustments */
        @media (min-width: 768px) {
            h1 { font-size: 2rem; }
            .selectors { display: flex; gap: 20px; }
            .selectors > div { flex: 1; }
        }
    </style>
</head>
<body>

<div class="card">
    <h1>Convolution Player</h1>

    <div class="control-group selectors">
        <div>
            <label>Sample</label>
            <select id="sampleSelect"></select>
        </div>
        <div>
            <label>Impulse</label>
            <select id="impulseSelect"></select>
        </div>
    </div>

    <div class="control-group">
        <label>Active ID Selection</label>
        <div class="btn-row">
            <button onclick="setId(1)">1</button>
            <button onclick="setId(2)">2</button>
            <button onclick="setId(3)">3</button>
            <button onclick="setId(4)">4</button>
            <span id="currentId" style="align-self: center;">Active ID: 1</span>
        </div>
    </div>

    <div class="control-group">
        <label>Volume</label>
        <input type="range" id="vol" min="0" max="1" step="0.01" value="0.5">
        
        <label>Mix (Dry/Wet)</label>
        <input type="range" id="mix" min="0" max="1" step="0.01" value="0.5">
        
        <label>Pitch: <span id="pitchDisplay">1.00x</span></label>
        <input type="range" id="pitch" min="0.5" max="2.0" step="0.01" value="1.0">
        
        <label>Playback Speed: <span id="speedDisplay">1.00x</span></label>
        <input type="range" id="speed" min="0.2" max="3.0" step="0.01" value="1.0">
    </div>

    <div class="btn-row">
        <button id="playBtn" style="flex: 2; background: #28a745;">PLAY</button>
        <button id="stopBtn" style="flex: 1;">STOP</button>
    </div>
</div>

<footer>
    <p>Project documentation: <a href="https://composers-inside-electronics.net/cie-wp20/convolver-node-js-v2-with-osc-post/" target="_blank">CIE-WP20 Convolver Node.js V2</a></p>
</footer>

<script>
    window.addEventListener('DOMContentLoaded', () => {
        const ctx = new AudioContext();
        let source, selectedId = 1;
        
        const mainGain = ctx.createGain(); 
        const wetGain = ctx.createGain();  
        const dryGain = ctx.createGain();  
        
        mainGain.connect(ctx.destination);
        wetGain.connect(mainGain);
        dryGain.connect(mainGain);

        const playBtn = document.getElementById('playBtn');
        const stopBtn = document.getElementById('stopBtn');
        const sampleSelect = document.getElementById('sampleSelect');
        const impulseSelect = document.getElementById('impulseSelect');
        
        const volControl = document.getElementById('vol');
        const mixControl = document.getElementById('mix');
        const pitchControl = document.getElementById('pitch');
        const speedControl = document.getElementById('speed');

        const sendFileNames = () => {
            fetch(`/file-names?sample=${sampleSelect.value}&impulse=${impulseSelect.value}`);
        };

        // OSC & Audio Updates
        volControl.oninput = (e) => {
            const val = parseFloat(e.target.value);
            mainGain.gain.setTargetAtTime(val, ctx.currentTime, 0.02);
            fetch(`/gain-trigger/${val}`);
        };

        pitchControl.oninput = (e) => {
            const val = parseFloat(e.target.value);
            document.getElementById('pitchDisplay').innerText = val.toFixed(2) + "x";
            if (source) source.playbackRate.setTargetAtTime(val, ctx.currentTime, 0.05);
            fetch(`/pitch-trigger/${val}`);
        };

        speedControl.oninput = (e) => {
            const val = parseFloat(e.target.value);
            document.getElementById('speedDisplay').innerText = val.toFixed(2) + "x";
            // Applying speed to playbackRate as well
            if (source) source.playbackRate.setTargetAtTime(val, ctx.currentTime, 0.05);
            fetch(`/speed-trigger/${val}`);
        };

        sampleSelect.onchange = sendFileNames;
        impulseSelect.onchange = sendFileNames;
        mixControl.oninput = (e) => { updateMix(e.target.value); };

        function updateMix(value) {
            const mix = parseFloat(value);
            dryGain.gain.setTargetAtTime(1 - mix, ctx.currentTime, 0.02);
            wetGain.gain.setTargetAtTime(mix, ctx.currentTime, 0.02);
        }

        async function init() {
            try {
                const res = await fetch('/files');
                const data = await res.json();
                data.samples.forEach(s => sampleSelect.add(new Option(s, s)));
                data.impulses.forEach(i => impulseSelect.add(new Option(i, i)));
                sendFileNames();
            } catch (e) { console.error("Init failed", e); }
        }

        window.setId = (id) => { 
            selectedId = id; 
            document.getElementById('currentId').innerText = `Active ID: ${id}`; 
        };

        async function play() {
            if (playBtn.disabled) return;
            playBtn.disabled = true;
            try {
                if (source) source.stop();
                if (ctx.state === 'suspended') await ctx.resume();
                
                const [sBuf, iBuf] = await Promise.all([
                    fetch(`/samples/${sampleSelect.value}`).then(r => r.arrayBuffer()).then(b => ctx.decodeAudioData(b)),
                    fetch(`/impulses/${impulseSelect.value}`).then(r => r.arrayBuffer()).then(b => ctx.decodeAudioData(b))
                ]);

                source = ctx.createBufferSource();
                const convolver = ctx.createConvolver();
                source.buffer = sBuf;
                convolver.buffer = iBuf;

                // Set initial speed/pitch from sliders
                source.playbackRate.value = parseFloat(speedControl.value);

                source.connect(dryGain);
                source.connect(convolver).connect(wetGain);
                source.start();

                await fetch(`/play-trigger/${selectedId}`);
            } catch (err) { console.error(err); } finally { playBtn.disabled = false; }
        }

        playBtn.onclick = play;
        stopBtn.onclick = async () => { if (source) source.stop(); await fetch('/stop-trigger'); };
        init();
    });
</script>
</body>
</html>

OSC Message Schema

AddressData TypeValue RangeDescription
/playint1–4Triggers playback using the selected Active ID.
/stopnone—Stops all active audio playback.
/gainfloat0.0 – 1.0Sends the current master volume level.
/pitchfloat0.5 – 2.0Sends the current pitch multiplier.
/speedfloat0.2 – 3.0Sends the current playback speed multiplier.
/names/samplestring—Broadcasts the filename of the selected sample.
/names/impulsestring—Broadcasts the filename of the selected impulse response.

Max Example Listener

PD Example Listener

Diagram for Initial Development

File: nodejs webaudio.drawio

Public Internet Access

Click here details of access via http://cieweb.ddns.net:3000/index.html

Public internet access using DDNS from no-ip.com.

You may see this privacy popup. At future point in time I’ll hang a certificate and update to https to eliminate the popup. An interim step might be a self-signed certificate.

“Adavanced” button gets you here…

Ok to “Proceed”. The warning is more applicable to web sites where it is important to avoid man-in-the-middle attacks and spoofing. Limited risk for this read only prototype.

Original AI Prompt

“generate a node.js application that builds a list of audio file from a sample folder and a list of audio impulse from an impulse folder and allows a user to select the sample and play that through the selected convolution. add a volume control. add a button to select a number of 1 to 4. when the play button is pressed, send and OSC message to IP address 192.168.254.25. Host server.js on the same IP address.  add a button to stop playing and send an OSC message on stop.”

Response from AI

To build this application, you will need a Node.js environment with Express for the web server and osc.js for handling Open Sound Control messages. This setup uses the Web Audio API to perform real-time convolution in the browser.

1. Project Setup

Create a project folder and the following directory structure:

/my-audio-app
  /samples   (place your audio files here)
  /impulses  (place your IR wav files here)
  /public
    index.html
  server.js
  package.json

2. Node.js Server (server.js)

This server scans your local folders, serves files to the browser, and handles outgoing OSC messages.

const express = require('express');
const osc = require('osc');
const fs = require('fs');
const path = require('path');

const app = express();
const HOST = '192.168.254.25';
const PORT = 3000;

// OSC Setup to send messages to the specified IP
const udpPort = new osc.UDPPort({
    localAddress: "0.0.0.0",
    localPort: 57121,
    remoteAddress: HOST,
    remotePort: 57120, // Common default OSC port
    metadata: true
});
udpPort.open();

app.use(express.static('public'));
app.use('/samples', express.static(path.join(__dirname, 'samples')));
app.use('/impulses', express.static(path.join(__dirname, 'impulses')));

// Route to get list of files for the UI
app.get('/files', (req, res) => {
    const filter = f => f.match(/\.(mp3|wav|ogg)$/i);
    res.json({
        samples: fs.readdirSync('./samples').filter(filter),
        impulses: fs.readdirSync('./impulses').filter(filter)
    });
});

// OSC Triggers
app.get('/play-trigger/:id', (req, res) => {
    udpPort.send({ address: "/play", args: [{ type: "i", value: parseInt(req.params.id) }] });
    res.sendStatus(200);
});

app.get('/stop-trigger', (req, res) => {
    udpPort.send({ address: "/stop", args: [] });
    res.sendStatus(200);
});

app.listen(PORT, HOST, () => console.log(`Server: http://${HOST}:${PORT}`));

3. Frontend Interface (public/index.html)

The frontend uses a ConvolverNode to apply the selected impulse response to the sample.

<!DOCTYPE html>
<html>
<body>
    <h1>Convolution Player</h1>
    <div>
        Sample: <select id="sampleSelect"></select>
        Impulse: <select id="impulseSelect"></select>
    </div>
    <div style="margin:10px 0">
        ID: <button onclick="setId(1)">1</button><button onclick="setId(2)">2</button>
        <button onclick="setId(3)">3</button><button onclick="setId(4)">4</button>
        <span id="currentId">Active ID: 1</span>
    </div>
    <div>
        Volume: <input type="range" id="vol" min="0" max="1" step="0.05" value="0.5">
    </div>
    <button id="playBtn">PLAY</button> <button id="stopBtn">STOP</button>

    <script>
        const ctx = new AudioContext();
        let source, convolver, gainNode, selectedId = 1;

        async function init() {
            const res = await fetch('/files');
            const data = await res.json();
            data.samples.forEach(s => sampleSelect.add(new Option(s, s)));
            data.impulses.forEach(i => impulseSelect.add(new Option(i, i)));
        }

        function setId(id) { selectedId = id; document.getElementById('currentId').innerText = `Active ID: ${id}`; }

        async function play() {
            if (source) source.stop();
            ctx.resume();
            
            source = ctx.createBufferSource();
            convolver = ctx.createConvolver();
            gainNode = ctx.createGain();
            
            const [sBuf, iBuf] = await Promise.all([
                fetch(`/samples/${sampleSelect.value}`).then(r => r.arrayBuffer()).then(b => ctx.decodeAudioData(b)),
                fetch(`/impulses/${impulseSelect.value}`).then(r => r.arrayBuffer()).then(b => ctx.decodeAudioData(b))
            ]);

            source.buffer = sBuf;
            convolver.buffer = iBuf;
            gainNode.gain.value = document.getElementById('vol').value;

            source.connect(convolver).connect(gainNode).connect(ctx.destination);
            source.start();
            fetch(`/play-trigger/${selectedId}`);
        }

        playBtn.onclick = play;
        stopBtn.onclick = () => { if(source) source.stop(); fetch('/stop-trigger'); };
        init();
    </script>
</body>
</html>

4. Dependencies (package.json)

{
  "dependencies": {
    "express": "^4.18.2",
    "osc": "^2.4.4"
  }
}

Would you like to add visual feedback like a waveform display or looping options for the audio samples?

package_json = {
  "name": "osc-convolution-player",
  "version": "1.0.0",
  "main": "server.js",
  "dependencies": {
    "express": "^4.18.2",
    "osc": "^2.4.4"
  }
}

server_js = """
const express = require('express');
const osc = require('osc');
const fs = require('fs');
const path = require('path');

const app = express();
const port = 3000;
const HOST = '192.168.254.25';

// OSC Setup
const udpPort = new osc.UDPPort({
    localAddress: "0.0.0.0",
    localPort: 57121,
    remoteAddress: HOST,
    remotePort: 57120,
    metadata: true
});

udpPort.open();

app.use(express.static('public'));
app.use('/samples', express.static(path.join(__dirname, 'samples')));
app.use('/impulses', express.static(path.join(__dirname, 'impulses')));

app.get('/files', (req, res) => {
    const samples = fs.readdirSync('./samples').filter(f => f.match(/\\.(mp3|wav|ogg)$/));
    const impulses = fs.readdirSync('./impulses').filter(f => f.match(/\\.(mp3|wav|ogg)$/));
    res.json({ samples, impulses });
});

app.get('/play/:id', (req, res) => {
    udpPort.send({
        address: "/play",
        args: [{ type: "i", value: parseInt(req.params.id) }]
    });
    res.sendStatus(200);
});

app.get('/stop', (req, res) => {
    udpPort.send({ address: "/stop", args: [] });
    res.sendStatus(200);
});

app.listen(port, HOST, () => {
    console.log(`Server running at http://${HOST}:${port}`);
});
"""

index_html = """
<!DOCTYPE html>
<html>
<head>
    <title>Audio Convolution Player</title>
    <style>
        body { font-family: sans-serif; padding: 20px; background: #f0f0f0; }
        .control-group { margin-bottom: 20px; background: white; padding: 15px; border-radius: 8px; }
        select, button { padding: 10px; margin: 5px; }
        .active { background: #4CAF50; color: white; }
    </style>
</head>
<body>
    <h1>Audio Convolution Player</h1>

    <div class="control-group">
        <label>Sample:</label>
        <select id="sampleSelect"></select>
        <label>Impulse Response:</label>
        <select id="impulseSelect"></select>
    </div>

    <div class="control-group">
        <label>ID (1-4):</label>
        <button onclick="setId(1)" class="id-btn">1</button>
        <button onclick="setId(2)" class="id-btn">2</button>
        <button onclick="setId(3)" class="id-btn">3</button>
        <button onclick="setId(4)" class="id-btn">4</button>
    </div>

    <div class="control-group">
        <label>Volume:</label>
        <input type="range" id="volume" min="0" max="1" step="0.1" value="0.5">
    </div>

    <button id="playBtn" style="background:#2ecc71">Play</button>
    <button id="stopBtn" style="background:#e74c3c">Stop</button>

    <script>
        const audioCtx = new (window.AudioContext || window.webkitAudioContext)();
        let source, convolver, gainNode;
        let selectedId = 1;

        async function init() {
            const res = await fetch('/files');
            const { samples, impulses } = await res.json();
            
            const sSelect = document.getElementById('sampleSelect');
            const iSelect = document.getElementById('impulseSelect');
            
            samples.forEach(s => sSelect.add(new Option(s, s)));
            impulses.forEach(i => iSelect.add(new Option(i, i)));
        }

        function setId(id) {
            selectedId = id;
            document.querySelectorAll('.id-btn').forEach(b => b.classList.remove('active'));
            event.target.classList.add('active');
        }

        async function playAudio() {
            if (source) source.stop();
            
            audioCtx.resume();
            source = audioCtx.createBufferSource();
            convolver = audioCtx.createConvolver();
            gainNode = audioCtx.createGain();

            const sampleRes = await fetch(`/samples/${document.getElementById('sampleSelect').value}`);
            const impulseRes = await fetch(`/impulses/${document.getElementById('impulseSelect').value}`);
            
            source.buffer = await audioCtx.decodeAudioData(await sampleRes.arrayBuffer());
            convolver.buffer = await audioCtx.decodeAudioData(await impulseRes.arrayBuffer());
            
            gainNode.gain.value = document.getElementById('volume').value;

            source.connect(convolver);
            convolver.connect(gainNode);
            gainNode.connect(audioCtx.destination);

            source.start();
            fetch(`/play/${selectedId}`);
        }

        document.getElementById('playBtn').onclick = playAudio;
        document.getElementById('stopBtn').onclick = () => {
            if (source) source.stop();
            fetch('/stop');
        };

        init();
    </script>
</body>
</html>
"""

print("### package.json")
print(package_json)
print("\n### server.js")
print(server_js)
print("\n### public/index.html")
print(index_html)