ffmpeg.wasm

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

Try it: https://ffmpegwasm.github.io

Installation

$ npm install @ffmpeg/ffmpeg @ffmpeg/core

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

$ node --experimental-wasm-threads --experimental-wasm-bulk-memory transcode.js

Or, using a script tag in the browser (only works in Chrome):

<script src="https://unpkg.com/@ffmpeg/ffmpeg@0.9.4/dist/ffmpeg.min.js"></script>
<script>
  const { createFFmpeg } = FFmpeg;
  ...
</script>

Only browsers with SharedArrayBuffer support can use ffmpeg.wasm, you can check HERE for the complete list.

Usage

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

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);
})();

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

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?

Sadly, no for now. You can check this issue for more details: https://github.com/ffmpegwasm/ffmpeg.wasm/issues/106

But it might be possible one day.

What is the maximum size of input file?

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

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