const fs = require("fs"),
   tar = require("tar-stream");

app.get("/fileFromTar/*", (req, res) => {
   const fileWanted = req.params[0],
      readStream = fs.createReadStream('myTarFile.tar'),
      extractor = tar.extract();

   extractor.on('entry', (header, stream, next) => {
      stream.on('end', next);

      if (header.name === fileWanted) {
         const { size } = header;
         res.set({
           "Content-Type": 'audio/flac', // or whichever one applies
           "Content-Length": size,
           "Content-Range": `bytes 0-${size}/${size}`
         });
         stream.pipe(res);
      }
      else stream.resume();
   });
   readStream.pipe(extractor);
});