Mobile: live external audio input (USB) source selector

Expose the engine's live-input mode on the remote: an "Sorgente audio"
selector in the Audio tab lists the input devices the output reports and
switches between File/Playlist and a live USB capture (useInput); picking
File again stops the input. Grant the kiosk getUserMedia access with
--use-fake-ui-for-media-stream so device enumeration/labels work without a
prompt. Make reportDevices resilient (per-probe timeout, always report even
an empty list) so the UI gets feedback when no input is connected yet.

The Pi 5 has no audio input — a USB (line) sound card is required; visuals
react to the source while the audio stays on the mixer.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/css/mobile.css

@@ -34,6 +34,7 @@ button, select, input, textarea {
 button { cursor: pointer; }
 button:active { filter: brightness(1.3); }
 button.wide { width: 100%; margin-top: 10px; font-size: 15px; }
+#audio-src { width: 100%; }
 input[type=range] { -webkit-appearance: none; appearance: none; background: transparent; padding: 0; height: 34px; border: none; }
 input[type=range]::-webkit-slider-runnable-track { height: 6px; border-radius: 4px; background: rgba(255,255,255,.14); }
 input[type=range]::-webkit-slider-thumb { -webkit-appearance: none; width: 24px; height: 24px; border-radius: 50%; background: var(--accent); margin-top: -9px; box-shadow: 0 1px 4px rgba(0,0,0,.5); }

public/index.html

@@ -90,6 +90,13 @@
 
     <!-- AUDIO -->
     <section class="panel hidden" data-tab="audio">
+      <label class="lbl">Sorgente audio
+        <button id="audio-src-refresh" class="mini" title="Rileva dispositivi di ingresso">↻ Rileva</button>
+      </label>
+      <select id="audio-src">
+        <option value="">🎵 File / Playlist</option>
+      </select>
+      <div id="audio-src-hint" class="hint">Per un ingresso live serve una scheda audio USB collegata al Pi. I visual reagiscono alla sorgente (l'audio resta sul mixer).</div>
       <label class="lbl">Reattività <span id="gain-v">1.0×</span></label>
       <input id="gain" type="range" min="0" max="3" step="0.05" value="1" />
       <label class="lbl">Velocità <span id="speed-v">1.0×</span></label>

public/js/control.js

@@ -543,6 +543,27 @@ slider('bass', (v) => { $('#bass-v').textContent = v.toFixed(2) + '×'; send({ t
 slider('mid', (v) => { $('#mid-v').textContent = v.toFixed(2) + '×'; send({ type: 'bandGain', band: 'mid', value: v }); });
 slider('treble', (v) => { $('#treble-v').textContent = v.toFixed(2) + '×'; send({ type: 'bandGain', band: 'treble', value: v }); });
 
+// ---- Sorgente audio (file vs ingresso live USB) ----------------------------
+let inputDevices = [];
+function renderAudioSrc(selId) {
+  const sel = $('#audio-src'); if (!sel) return;
+  const cur = selId != null ? selId : sel.value;
+  sel.innerHTML = '<option value="">🎵 File / Playlist</option>' +
+    inputDevices.map((d) => '<option value="' + d.deviceId + '">🎚 ' + (d.label || 'Ingresso ' + d.deviceId.slice(0, 6)) + '</option>').join('');
+  sel.value = cur;
+  const hint = $('#audio-src-hint');
+  if (hint) hint.textContent = inputDevices.length
+    ? inputDevices.length + ' ingresso/i rilevato/i. Scegli la scheda USB: i visual reagiranno alla sorgente (l\'audio resta sul mixer).'
+    : 'Nessun ingresso rilevato. Collega una scheda audio USB al Pi, poi premi ↻ Rileva.';
+}
+$('#audio-src').addEventListener('change', (e) => {
+  const id = e.target.value;
+  if (id) { send({ type: 'useInput', deviceId: id }); $('#now').textContent = 'Ingresso live'; }
+  else { send({ type: 'playSilence' }); } // back to file: stops the live input
+});
+$('#audio-src-refresh').addEventListener('click', () => send({ type: 'refreshDevices' }));
+send({ type: 'refreshDevices' }); // ask the output for the current input device list
+
 // ---- Output / Rec ----------------------------------------------------------
 let recOn = false;
 $('#fs').addEventListener('click', () => send({ type: 'outputFullscreen' }));
@@ -580,6 +601,7 @@ djv.onReport((m) => {
     case 'meters':
       setMeter('m-bass', m.bass); setMeter('m-mid', m.mid); setMeter('m-treble', m.treble);
       break;
+    case 'devices': inputDevices = m.list || []; renderAudioSrc(); break;
     case 'recState': recOn = m.recording; updateRec(); break;
     case 'recSaved': $('#rec-status').textContent = '✅ Salvato: ' + m.path; break;
     case 'recError': $('#rec-status').textContent = '⚠️ ' + m.message; break;

public/js/output.js

@@ -299,12 +299,16 @@ function probeDurations(paths) {
 }
 
 async function reportDevices() {
-  try {
+  // Always answer, even with an empty list: getUserMedia can hang/reject when no
-    const inputs = await audio.listInputDevices();
+  // input device exists (e.g. before a USB sound card is plugged in), so guard
+  // each probe with a timeout and still report so the control UI isn't left hanging.
+  const withTimeout = (p, ms) => Promise.race([p, new Promise((_, rej) => setTimeout(() => rej(new Error('timeout')), ms))]);
+  let inputs = [];
+  try { inputs = await withTimeout(audio.listInputDevices(), 3000); } catch (e) { /* none/blocked */ }
   djv.report({ type: 'devices', list: inputs.map(d => ({ deviceId: d.deviceId, label: d.label })) });
-    const outputs = await audio.listOutputDevices();
+  let outputs = [];
+  try { outputs = await withTimeout(audio.listOutputDevices(), 3000); } catch (e) { /* none/blocked */ }
   djv.report({ type: 'outputs', list: outputs.map(d => ({ deviceId: d.deviceId, label: d.label })) });
-  } catch (e) { /* ignore */ }
 }
 
 // ---------------------------------------------------------------- command bus

scripts/kiosk.sh

@@ -5,6 +5,7 @@ BIN="$(command -v chromium-browser || command -v chromium || echo chromium)"
 exec "$BIN" \
   --kiosk --noerrordialogs --disable-infobars --no-first-run \
   --autoplay-policy=no-user-gesture-required \
+  --use-fake-ui-for-media-stream \
   --disable-translate --disable-features=Translate \
   --check-for-update-interval=31536000 \
   --overscroll-history-navigation=0 \