Add node version limitation

Author: jeromewu

README.md

@@ -6,6 +6,7 @@
 
 # ffmpeg.js
 
+[![Node Version](https://img.shields.io/node/v/@ffmpeg/ffmpeg.svg)](https://img.shields.io/node/v/@ffmpeg/ffmpeg.svg)
 [![Actions Status](https://github.com/ffmpegjs/ffmpeg.js/workflows/CI/badge.svg)](https://github.com/ffmpegjs/ffmpeg.js/actions)
 [![Maintenance](https://img.shields.io/badge/Maintained%3F-yes-green.svg)](https://github.com/ffmpegjs/ffmpeg.js/graphs/commit-activity)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
@@ -60,6 +61,8 @@ const worker = createWorker();
 $ npm install @ffmpeg/ffmpeg
 ```
 
+> As we use `worker_threads` which was introduced in Node.js v10.5.0, please remember to add `--experimental-worker` if you are using Node.js v10, and you don't have to add anything if you are using Node.js v12
+
 ## Documentation
 
 - [API](https://github.com/ffmpegjs/ffmpeg.js/blob/master/docs/api.md)

docs/api.md

@@ -204,6 +204,14 @@ Worker.concatDemuxer() concatenates multiple videos using concatDemuxer. This me
 })();
 ```
 
+If the input video files are the same as the output video file, you can pass an extra option to speed up the process
+
+```javascript
+(async () => {
+  await worker.concatDemuxer(["flame-1.mp4", "flame-2.mp4"], "output.mp4", "-c copy");
+})();
+```
+
 <a name="worker-run"></a>
 
 ### Worker.run(args, jobId): Promise

package.json

@@ -36,6 +36,9 @@
   "bugs": {
     "url": "https://github.com/ffmpegjs/ffmpeg.js/issues"
   },
+  "engines": {
+    "node": ">=10.5.0"
+  },
   "homepage": "https://github.com/ffmpegjs/ffmpeg.js#readme",
   "dependencies": {
     "@ffmpeg/core": "^0.6.0",