modules/spl-meter/client.js

@@ -17,6 +17,21 @@
 
 const FLOOR = -200;
 
+/**
+ * A dead input reads as a number, and a number on a wall is believed. Every
+ * tile therefore refuses to draw a level while the server says the input is
+ * digitally silent, and says why instead.
+ */
+function silentFor(payload) {
+  return payload && payload.silentSec ? payload.silentSec : 0;
+}
+
+function silentText(sec) {
+  if (sec < 90) return `No audio — ${sec} s`;
+  const m = Math.round(sec / 60);
+  return m < 90 ? `No audio — ${m} min` : `No audio — ${(m / 60).toFixed(1)} hours`;
+}
+
 /** Retention per frame for the RTA's smoothing setting. */
 const SMOOTHING = { off: 0, light: 0.45, medium: 0.72, heavy: 0.9 };
 
@@ -37,6 +52,9 @@ export default function create({ root, moduleApi }) {
       moduleApi.setStatus('error', payload.error);
     } else if (!payload.frame) {
       moduleApi.setStatus('connecting', 'waiting for the first reading');
+    } else if (silentFor(payload)) {
+      moduleApi.setStatus('error',
+        `No audio on the chosen input — digital silence for ${silentText(silentFor(payload)).replace('No audio — ', '')}`);
     } else if (!payload.calibrated) {
       moduleApi.setStatus('ok', 'Measuring, but uncalibrated — these are dBFS, not dB SPL');
     } else {
@@ -233,6 +251,16 @@ function readoutView(root, moduleApi) {
     render(payload) {
       const s = moduleApi.instanceSettings;
       const ch = pickChannel(payload, s);
+      const quiet = silentFor(payload);
+      if (quiet && ch) {
+        num.textContent = '––.–';
+        unit.textContent = '';
+        sub.hidden = false;
+        sub.textContent = silentText(quiet);
+        box.dataset.level = 'dead';
+        fit();
+        return;
+      }
       if (!payload || payload.error || !ch) {
         num.textContent = '––.–';
         sub.textContent = payload && payload.error ? payload.error : '';
@@ -286,6 +314,7 @@ function barsView(root, moduleApi) {
           </div>`).join('');
       }
       const s = moduleApi.instanceSettings;
+      const quiet = silentFor(payload);
       const warn = Number(s.warnAt), alarm = Number(s.alarmAt);
       const showPeak = s.peakHold !== false;
       const lo = payload.calibrated ? 40 : -80;
@@ -295,12 +324,12 @@ function barsView(root, moduleApi) {
         if (!el) continue;
         const value = readValue(c, { averaging: s.averaging });
         const pct = (v) => Math.max(0, Math.min(100, ((v - lo) / (hi - lo)) * 100));
-        el.querySelector('.spl-bar-fill').style.width = `${pct(value)}%`;
+        el.querySelector('.spl-bar-fill').style.width = quiet ? '0%' : `${pct(value)}%`;
         const peak = el.querySelector('.spl-bar-peak');
         peak.style.display = showPeak ? '' : 'none';
         if (showPeak) peak.style.left = `${pct(c.peakC)}%`;
-        el.querySelector('.spl-bar-value').textContent = fmt(value);
+        el.querySelector('.spl-bar-value').textContent = quiet ? '––.–' : fmt(value);
-        el.dataset.level = !payload.calibrated ? 'idle'
+        el.dataset.level = quiet ? 'dead' : !payload.calibrated ? 'idle'
           : value >= alarm ? 'alarm' : value >= warn ? 'warn' : 'ok';
         el.classList.toggle('clip', !!c.clip);
       }
@@ -389,10 +418,12 @@ function spectrumView(root, moduleApi, scrolling) {
       const muted = themeColor(root, '--muted', '#888');
       const border = themeColor(root, '--border', '#333');
 
-      if (!payload || !payload.frame || !payload.frame.bands) {
+      const quiet = silentFor(payload);
+      if (quiet || !payload || !payload.frame || !payload.frame.bands) {
         ctx.fillStyle = bg; ctx.fillRect(0, 0, w, h);
         ctx.fillStyle = muted; ctx.font = '12px system-ui'; ctx.textAlign = 'center';
-        ctx.fillText(payload?.error || 'Spectrum analysis is off', w / 2, h / 2);
+        ctx.fillText(quiet ? silentText(quiet)
+                     : (payload?.error || 'Spectrum analysis is off'), w / 2, h / 2);
         painted = false;
         return;
       }

modules/spl-meter/module.json

@@ -1,7 +1,7 @@
 {
   "id": "spl-meter",
   "name": "SPL Meter",
-  "version": "0.3.1",
+  "version": "0.4.0",
   "proddash": ">=1.5.0",
   "description": "Calibrated sound level, Leq and RTA from an audio input on this machine",
   "permissions": [

modules/spl-meter/server.js

@@ -30,6 +30,19 @@ const MEASURE_MS = 3000;
 /** SSE comment ping — keeps idle connections alive through sleepy Wi-Fi. */
 const PING_MS = 15000;
 
+/**
+ * Below this, unweighted, the input is not quiet — it is not there.
+ *
+ * A real input always carries something: a microphone in a silent room still
+ * reads about -83 dBFS, and even a muted converter dithers around -120. Only
+ * a stream of actual zeros reaches the capture tool's -200 floor, and that
+ * means the device handed us nothing at all.
+ */
+const SILENCE_DBFS = -150;
+/** How long that has to hold before saying so, so a gap between buffers or a
+    device changing sample rate mid-stream doesn't cry wolf. */
+const SILENCE_GRACE_MS = 5000;
+
 /** Set by init(), read by routes() — both are rebuilt together on re-init. */
 let state = null;
 
@@ -100,6 +113,7 @@ module.exports = {
       meta: null,
       error: '',
       streams: new Set(),
+      silentSince: null,
       listener: null,
       lastSent: '',
       pinger: null,
@@ -143,6 +157,12 @@ module.exports = {
         state.error = '';
         state.frame = update.frame;
         state.meta = update.meta;
+        // Digital silence on every channel is a dead input, not a reading.
+        // Saying "ok" through this is what made a stopped Dante device look
+        // like a frozen module for a day and a half.
+        const dead = update.frame.ch.every(
+          (c) => !Number.isFinite(c.dbfs) || c.dbfs <= SILENCE_DBFS);
+        state.silentSince = dead ? (state.silentSince || Date.now()) : null;
         broadcast();
       },
     });
@@ -159,6 +179,11 @@ module.exports = {
       health() {
         if (state.error) return { status: 'error', message: state.error };
         if (!state.frame) return { status: 'connecting', message: 'waiting for the first reading' };
+        const quiet = silentMs();
+        if (quiet > SILENCE_GRACE_MS) {
+          return { status: 'error',
+                   message: `No audio from ${config.device} — digital silence for ${describe(quiet)}` };
+        }
         const n = state.channels.length;
         const what = `${n} channel${n === 1 ? '' : 's'} on ${config.device}`;
         return state.calibrated
@@ -351,10 +376,26 @@ module.exports = {
 
 /* ── helpers ────────────────────────────────────────────────────────── */
 
+/** How long every channel has been at digital silence, in ms. */
+function silentMs() {
+  return state && state.silentSince ? Date.now() - state.silentSince : 0;
+}
+
+function describe(ms) {
+  const s = Math.round(ms / 1000);
+  if (s < 90) return `${s} s`;
+  const m = Math.round(s / 60);
+  return m < 90 ? `${m} min` : `${(m / 60).toFixed(1)} hours`;
+}
+
 function snapshot() {
-  if (!state) return { error: 'not measuring', calibrated: false, channels: [], frame: null };
+  if (!state) return { error: 'not measuring', calibrated: false, channels: [], frame: null, silentSec: 0 };
+  // Seconds, not milliseconds: this goes on the wire 20×/s and a value that
+  // changed every frame would make the fan-out's change check useless.
+  const quiet = silentMs();
   return {
     error: state.error,
+    silentSec: quiet > SILENCE_GRACE_MS ? Math.round(quiet / 1000) : 0,
     calibrated: state.calibrated,
     channels: state.channels,
     weighting: state.meta ? state.meta.weighting : '',

modules/spl-meter/style.css

@@ -57,6 +57,11 @@
 [data-module="spl-meter"] .spl-readout[data-level="alarm"] .spl-num { color: var(--danger); }
 [data-module="spl-meter"] .spl-readout[data-level="idle"] .spl-num { color: var(--muted); }
 
+/* A dead input reads danger, not muted: silence that is a fault should not
+   look like silence that is a quiet room. */
+[data-module="spl-meter"] .spl-readout[data-level="dead"] .spl-num { color: var(--danger); }
+[data-module="spl-meter"] .spl-readout[data-level="dead"] .spl-sub { color: var(--danger); }
+
 /* ── level bars ───────────────────────────────────────────────────── */
 
 [data-module="spl-meter"] .spl-bars {
@@ -100,6 +105,7 @@
 [data-module="spl-meter"] .spl-bar[data-level="warn"] .spl-bar-fill { background: var(--warn); }
 [data-module="spl-meter"] .spl-bar[data-level="alarm"] .spl-bar-fill { background: var(--danger); }
 [data-module="spl-meter"] .spl-bar[data-level="idle"] .spl-bar-fill { background: var(--muted); }
+[data-module="spl-meter"] .spl-bar[data-level="dead"] .spl-bar-value { color: var(--danger); }
 
 /* Peak hold sits on the track rather than inside the fill, so it stays
    visible when the bar falls away underneath it. */