chore: import upstream snapshot with attribution

2026-07-13 12:58:35 +08:00
commit 85453da49f
4031 changed files with 710987 additions and 0 deletions
@@ -0,0 +1,95 @@
+#!/usr/bin/env node
+/*
+ * audio-envelope.cjs — extract a per-50ms RMS loudness envelope from the source audio.
+ *
+ *   node audio-envelope.cjs <project-dir>     → <project>/envelope.json
+ *
+ * { hop: 0.05, rms: [linear 0..1 per hop] }
+ *
+ * Used by lib-dna.cjs to couple the hero's entrance amplitude to how hard the word was
+ * actually SPOKEN (percentile of the hero window's loudness within the clip). ffmpeg
+ * astats over fixed windows — deterministic, no network, no Python.
+ */
+const path = require("path");
+const fs = require("fs");
+const cp = require("child_process");
+
+const HOP = 0.05;
+
+function findSource(project) {
+  for (const c of ["source.mp4"].concat(
+    fs
+      .readdirSync(project)
+      .filter(
+        (f) =>
+          /\.(mp4|mov|webm|mkv|m4v|wav|m4a|mp3)$/i.test(f) &&
+          !/^(final|bg_plus_caps|fg_caps|rail|index)/.test(f),
+      ),
+  )) {
+    const p = path.join(project, c);
+    if (fs.existsSync(p)) return p;
+  }
+  return null;
+}
+
+function main() {
+  const project = path.resolve(process.argv[2] || "");
+  if (!process.argv[2]) {
+    console.error("usage: audio-envelope.cjs <project-dir>");
+    process.exit(1);
+  }
+  const src = findSource(project);
+  if (!src) {
+    console.error("[envelope] no source media found");
+    process.exit(2);
+  }
+
+  // asetnsamples groups audio into fixed windows; astats prints RMS per window
+  const sr = 16000,
+    n = Math.round(sr * HOP);
+  let out;
+  try {
+    // resample INSIDE the filter chain — an output-option -ar applies after the
+    // filtergraph, which would make each window n/<input-rate> seconds instead of HOP
+    out = cp.execFileSync(
+      "ffmpeg",
+      [
+        "-v",
+        "info",
+        "-i",
+        src,
+        "-map",
+        "a:0",
+        "-af",
+        `aresample=${sr},aformat=channel_layouts=mono,asetnsamples=n=${n}:p=0,astats=metadata=1:reset=1,ametadata=mode=print:key=lavfi.astats.Overall.RMS_level:file=-`,
+        "-f",
+        "null",
+        "-",
+      ],
+      { encoding: "utf8", maxBuffer: 64 * 1024 * 1024, stdio: ["ignore", "pipe", "pipe"] },
+    );
+  } catch (e) {
+    // ffmpeg writes the metadata to stdout before exiting; some containers still exit 0 — re-throw only if nothing parsed
+    out = (e.stdout || "") + "";
+    if (!out.includes("RMS_level")) {
+      console.error(`[envelope] ffmpeg failed: ${e.message}`);
+      process.exit(2);
+    }
+  }
+  const rmsDb = [];
+  for (const line of String(out).split("\n")) {
+    const m = line.match(/lavfi\.astats\.Overall\.RMS_level=(-?[\d.]+|-inf)/);
+    if (m) rmsDb.push(m[1] === "-inf" ? -90 : Math.max(-90, parseFloat(m[1])));
+  }
+  if (!rmsDb.length) {
+    console.error("[envelope] no RMS windows parsed");
+    process.exit(2);
+  }
+  const rms = rmsDb.map((db) => +Math.pow(10, db / 20).toFixed(5)); // linear 0..1
+  fs.writeFileSync(path.join(project, "envelope.json"), JSON.stringify({ hop: HOP, rms }));
+  const peakAt = rms.indexOf(Math.max(...rms)) * HOP;
+  console.log(
+    `[envelope] ${rms.length} windows @ ${HOP}s → envelope.json (loudest beat ~${peakAt.toFixed(2)}s)`,
+  );
+}
+main();