Committed and Pushed by ButtonClick

programs/input.js

@@ -0,0 +1,49 @@
+// programs/input.js
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+
+function byIdCaptureCandidates() {
+  const dir = '/dev/v4l/by-id';
+  try {
+    if (!fs.existsSync(dir)) return [];
+    return fs.readdirSync(dir)
+      .filter(n => n.endsWith('-index0'))
+      .map(n => fs.realpathSync(path.join(dir, n)));
+  } catch {
+    return [];
+  }
+}
+
+function naiveVideoNodes() {
+  try {
+    return fs.readdirSync('/dev')
+      .filter(n => /^video\d+$/.test(n))
+      .map(n => path.join('/dev', n))
+      .sort((a, b) => Number(a.replace(/\D/g, '')) - Number(b.replace(/\D/g, '')));
+  } catch {
+    return ['/dev/video0', '/dev/video2'];
+  }
+}
+
+function pickDevices(env = process.env) {
+  const DEV0 = env.DEV0 || null;
+  const DEV1 = env.DEV1 || null;
+
+  if (DEV0 && DEV1) return [DEV0, DEV1];
+
+  const byId = byIdCaptureCandidates();
+  if (DEV0 || DEV1) {
+    const pool = byId.length ? byId : naiveVideoNodes();
+    const d0 = DEV0 || pool[0];
+    const d1 = DEV1 || pool.find(d => d !== d0) || pool[1];
+    return [d0, d1];
+  }
+
+  if (byId.length >= 2) return [byId[0], byId[1]];
+  const naive = naiveVideoNodes();
+  return [naive[0], naive[1]];
+}
+
+module.exports = { pickDevices };