Fix syntax error in app.js and add ffmpeg conversion

server/routes/recognize.js

@@ -18,9 +18,18 @@ router.post('/', upload.single('audio'), async (req, res) => {
   const filePath = req.file.path;
   
   try {
-    // 1. Generate fingerprint using fpcalc
+    // 0. Convert uploaded file to WAV using ffmpeg to guarantee fpcalc can read it
+    const wavPath = filePath + '.wav';
+    await new Promise((resolve, reject) => {
+      execFile('ffmpeg', ['-i', filePath, '-ar', '44100', '-ac', '2', '-f', 'wav', wavPath], (err, stdout, stderr) => {
+        if (err) return reject(new Error('ffmpeg failed: ' + stderr));
+        resolve();
+      });
+    });
+
+    // 1. Generate fingerprint using fpcalc on the WAV file
     const { duration, fingerprint } = await new Promise((resolve, reject) => {
-      execFile('fpcalc', [filePath], (error, stdout, stderr) => {
+      execFile('fpcalc', [wavPath], (error, stdout, stderr) => {
         if (error) {
           return reject(new Error('fpcalc failed: ' + stderr));
         }
@@ -41,6 +50,9 @@ router.post('/', upload.single('audio'), async (req, res) => {
       });
     });
 
+    // Clean up WAV file
+    fs.unlink(wavPath, () => {});
+
     // 2. Query AcoustID API
     const acoustidKey = process.env.ACOUSTID_API_KEY;
     if (!acoustidKey) {