P2b: offline WAV render of the arrangement

scripts/render-smoke.mjs

@@ -0,0 +1,73 @@
+#!/usr/bin/env node
+// Render the current arrangement through the daemon and verify the WAV.
+import { readFileSync, existsSync } from 'node:fs';
+
+const PORT = 4317;
+const ws = new WebSocket(`ws://127.0.0.1:${PORT}`);
+const pending = new Map();
+let rendered = null;
+let resolveRendered;
+const renderedReady = new Promise((resolve) => { resolveRendered = resolve; });
+
+ws.onopen = () => ws.send(JSON.stringify({ type: 'hello', protocol: 1, token: 'dev', client: 'render-smoke' }));
+ws.onmessage = (message) => {
+  if (typeof message.data !== 'string') return;
+  const parsed = JSON.parse(message.data);
+  if (parsed.type === 'snapshot') {
+    ws.send(JSON.stringify({ type: 'command', id: 1, command: { type: 'render' } }));
+  } else if (parsed.type === 'result' && parsed.id === 1) {
+    pending.set(1, parsed.result);
+  } else if (parsed.type === 'event' && parsed.event?.kind === 'rendered') {
+    rendered = parsed.event;
+    resolveRendered();
+  }
+};
+
+await renderedReady;
+if (!rendered) throw new Error('no rendered event');
+const path = rendered.path;
+if (!existsSync(path)) throw new Error(`render file missing: ${path}`);
+const file = readFileSync(path);
+if (file.toString('ascii', 0, 4) !== 'RIFF' || file.toString('ascii', 8, 12) !== 'WAVE') throw new Error('not a RIFF/WAVE file');
+let offset = 12;
+let fmt = null;
+let data = null;
+while (offset + 8 <= file.length) {
+  const id = file.toString('ascii', offset, offset + 4);
+  const size = file.readUInt32LE(offset + 4);
+  if (id === 'fmt ') fmt = { offset: offset + 8, size };
+  if (id === 'data') {
+    data = { offset: offset + 8, size: Math.min(size, file.length - offset - 8) };
+    break;
+  }
+  offset += 8 + size + (size % 2);
+}
+if (!fmt || !data) throw new Error('missing fmt or data chunk');
+let format = file.readUInt16LE(fmt.offset);
+const channels = file.readUInt16LE(fmt.offset + 2);
+const rate = file.readUInt32LE(fmt.offset + 4);
+const bits = file.readUInt16LE(fmt.offset + 14);
+if (format === 0xfffe) format = file.readUInt16LE(fmt.offset + 24);
+if (format !== 3) throw new Error(`expected float WAV, got format ${format}`);
+if (channels !== 2 || rate !== 48000 || bits !== 32) throw new Error(`unexpected spec ${channels}/${rate}/${bits}`);
+const bytes = file.subarray(data.offset, data.offset + data.size);
+let peak = 0;
+for (let cursor = 0; cursor + 4 <= bytes.length; cursor += 4) {
+  const sample = bytes.readFloatLE(cursor);
+  peak = Math.max(peak, Math.abs(sample));
+}
+const duration = data.size / (channels * 4) / rate;
+console.log(JSON.stringify({
+  path,
+  bytes: file.length,
+  format, channels, rate, bits,
+  durationSec: Number(duration.toFixed(3)),
+  eventDurationSec: rendered.duration_sec,
+  peak: Number(peak.toFixed(3)),
+  renderedState: pending.get(1)?.state?.revision
+}, null, 2));
+if (peak < 0.01) throw new Error('render is silent');
+if (duration < 15) throw new Error('render is shorter than the arrangement');
+if (Math.abs(duration - rendered.duration_sec) > 0.05) throw new Error('duration mismatch');
+ws.close();
+console.log('render smoke passed');