<p align="center">
  <a href="#">
    <img alt="ffmpeg.wasm" width="128px" height="128px" src="https://github.com/ffmpegwasm/ffmpeg.wasm/raw/master/docs/images/ffmpegwasm-icon.png">
  </a>
</p>

# ffmpeg.wasm

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ffmpeg.wasm is a pure Webassembly / Javascript port of FFmpeg. It enables video & audio record, convert and stream right inside browsers.

**AVI to MP4 Demo**
<p align="center">
  <a href="#">
    <img alt="transcode-demo" src="https://github.com/ffmpegwasm/ffmpeg.wasm/raw/master/docs/images/transcode.gif">
  </a>
</p>

Try it: [https://ffmpegwasm.netlify.app](https://ffmpegwasm.netlify.app#demo)


## Installation

**Node**

```
$ npm install @ffmpeg/ffmpeg @ffmpeg/core
```

> As we are using experimental features, you need to add flags to run in Node.js

```
$ node --experimental-wasm-threads transcode.js
```

**Browser**

Or, using a script tag in the browser (only works in some browsers, see list below):

> SharedArrayBuffer is only available to pages that are [cross-origin isolated](https://developer.chrome.com/blog/enabling-shared-array-buffer/#cross-origin-isolation). So you need to host [your own server](https://github.com/ffmpegwasm/ffmpegwasm.github.io/blob/main/server/server.js) with `Cross-Origin-Embedder-Policy: require-corp` and `Cross-Origin-Opener-Policy: same-origin` headers to use ffmpeg.wasm.

```html
<script src="static/js/ffmpeg.min.js"></script>
<script>
  const { createFFmpeg } = FFmpeg;
  ...
</script>
```

> Only browsers with SharedArrayBuffer support can use ffmpeg.wasm, you can check [HERE](https://caniuse.com/sharedarraybuffer) for the complete list.

## Usage

ffmpeg.wasm provides simple to use APIs, to transcode a video you only need few lines of code:

```javascript
const fs = require('fs');
const { createFFmpeg, fetchFile } = require('@ffmpeg/ffmpeg');

const ffmpeg = createFFmpeg({ log: true });

(async () => {
  await ffmpeg.load();
  ffmpeg.FS('writeFile', 'test.avi', await fetchFile('./test.avi'));
  await ffmpeg.run('-i', 'test.avi', 'test.mp4');
  await fs.promises.writeFile('./test.mp4', ffmpeg.FS('readFile', 'test.mp4'));
  process.exit(0);
})();
```

### Use other version of ffmpeg.wasm-core / @ffmpeg/core

For each version of ffmpeg.wasm, there is a default version of @ffmpeg/core (you can find it in **devDependencies** section of [package.json](https://github.com/ffmpegwasm/ffmpeg.wasm/blob/master/package.json)), but sometimes you may need to use newer version of @ffmpeg/core to use the latest/experimental features.

**Node**

Just install the specific version you need:

```bash
$ npm install @ffmpeg/core@latest
```

Or use your own version with customized path

```javascript
const ffmpeg = createFFmpeg({
  corePath: '../../../src/ffmpeg-core.js',
});
```

**Browser**

```javascript
const ffmpeg = createFFmpeg({
  corePath: 'static/js/ffmpeg-core.js',
});
```

For the list available versions and their changelog, please check: https://github.com/ffmpegwasm/ffmpeg.wasm-core/releases

## Multi-threading

Multi-threading need to be configured per external libraries, only following libraries supports it now:

### x264

Run it multi-threading mode by default, no need to pass any arguments.

### libvpx / webm

Need to pass `-row-mt 1`, but can only use one thread to help, can speed up around 30%

## Documentation

- [API](https://github.com/ffmpegwasm/ffmpeg.wasm/blob/master/docs/api.md)
- [Supported External Libraries](https://github.com/ffmpegwasm/ffmpeg.wasm-core#configuration)

## FAQ

### What is the license of ffmpeg.wasm?

There are two components inside ffmpeg.wasm:

- @ffmpeg/ffmpeg (https://github.com/ffmpegwasm/ffmpeg.wasm)
- @ffmpeg/core (https://github.com/ffmpegwasm/ffmpeg.wasm-core)

@ffmpeg/core contains WebAssembly code which is transpiled from original FFmpeg C code with minor modifications, but overall it still following the same licenses as FFmpeg and its external libraries (as each external libraries might have its own license).

@ffmpeg/ffmpeg contains kind of a wrapper to handle the complexity of loading core and calling low-level APIs. It is a small code base and under MIT license.

### Can I use ffmpeg.wasm in Firefox?

Yes, but only for Firefox 79+ with proper header in both client and server, visit https://ffmpegwasm.netlify.app to try whether your Firefox works.

![](https://user-images.githubusercontent.com/5723124/98955802-4cb20c80-253a-11eb-8f16-ce0298720a2a.png)

For more details: https://github.com/ffmpegwasm/ffmpeg.wasm/issues/106

### What is the maximum size of input file?

2 GB, which is a hard limit in WebAssembly. Might become 4 GB in the future.

### How can I build my own ffmpeg.wasm?

In fact, it is ffmpeg.wasm-core most people would like to build.

To build on your own, you can check build.sh inside https://github.com/ffmpegwasm/ffmpeg.wasm-core repository.

Also you can check this series of posts to learn more fundamental concepts:

- https://jeromewu.github.io/build-ffmpeg-webassembly-version-part-1-preparation/
- https://jeromewu.github.io/build-ffmpeg-webassembly-version-part-2-compile-with-emscripten/
- https://jeromewu.github.io/build-ffmpeg-webassembly-version-part-3-v0.1/
- https://jeromewu.github.io/build-ffmpeg-webassembly-version-part-4-v0.2/

### Why it doesn't work in my local environment?

When calling `ffmpeg.load()`, by default it looks for `http://localhost:3000/node_modules/@ffmpeg/core/dist/` to download essential files (ffmpeg-core.js, ffmpeg-core.wasm, ffmpeg-core.worker.js). It is necessary to make sure you have those files served there.

If you have those files serving in other location, you can rewrite the default behavior when calling `createFFmpeg()`:

```javascript
const { createFFmpeg } = FFmpeg;
const ffmpeg = createFFmpeg({
  corePath: "http://localhost:3000/public/ffmpeg-core.js",
  // Use public address if you don't want to host your own.
  // corePath: 'https://unpkg.com/@ffmpeg/core@0.10.0/dist/ffmpeg-core.js'
  log: true,
});
```
