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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>videoconverter.js - Convert Videos In Your Web Browser</title>
<meta name="description" content="Video Converter is a port of the FFmpeg project that allows audio/video conversion and processing in JavaScript.">
<meta name="author" content="Brian Grinstead, Aaron Marasco, and contributors">
<link rel="shortcut icon" href="site/favicon.ico">
<link href="site/site.css" rel="stylesheet">
</head>
<body>
<div class="container-fluid">
<div class='content'>
<div class='inner-content'>
<div class="header clearfix">
<div class="pull-left">
<H1><a href='./'><img src='site/logo.png' width="30" /><span>videoconverter.js</span></a>
</H1>
</div>
<div class="pull-right links">
<a href='demo/'>demo</a>
<a href='#docs'>docs</a>
<a href='http://github.com/bgrins/videoconverter.js'>source code on github</a>
</div>
</div>
<div class="clearfix">
<p class="tagline">
videoconverter.js is a program that lets you <strong>process videos in your browser</strong>.
</p>
<p>
<hr />
<center>
<a class="big" href="demo/">View a Demonstration</a>
<a class="big" href="https://video-funhouse.herokuapp.com">View a Sample Application</a><br />
or <a href='http://github.com/bgrins/videoconverter.js'>view code on github</a>
</center>
<hr />
</p>
<h2 id="about">About <a href="#about">[#]</a></h2>
<p>
Videoconverter.js was originally conceived and implemented for a project in Node Knockout 2013 called <a href="http://2013.nodeknockout.com/teams/devcomo">Video Funhouse</a>.
</p>
<p>
The idea for the application was to try and convert any video file into another video format, while allowing filters to be applied to the video – <strong>all inside of the browser, without uploading anything</strong>. And to build it in a single weekend.
</p>
<p>
This is a huge task, and we knew that existing libraries like <a href="http://ffmpeg.org/">FFmpeg</a> would do a great job. But, FFmpeg is not written in JavaScript. Luckily, there is a project called <a href="https://github.com/kripken/emscripten">Emscripten</a>, which is an LLVM to JavaScript compiler, so we were able to compile FFmpeg into JavaScript.
</p>
<p>
Here is a video demonstrating the sample application we made with this library over the weekend:
</p>
<center>
<iframe src="//www.youtube.com/embed/TR_RGeRBroI" allowfullscreen="" frameborder="0" height="315" width="560"></iframe>
</center>
<h2 id="faq">FAQ <a href="#faq">[#]</a></h2>
<h3 id="why">Why?</h3>
<p>
Why would you compile FFmpeg into JavaScript? We were curious if it would work, and it seemed like a fun project.
<p>
<h3>Who?</h3>
<p>
Most of the grunt work has been done by <a href="https://twitter.com/bgrins">@bgrins</a> and <a href="https://twitter.com/aaronm67">@aaronm67</a>.
</p>
<h3>How Big is the JavaScript File?</h3>
<p>
The <a href="https://github.com/bgrins/videoconverter.js/blob/master/build/ffmpeg.js">ffmpeg.js</a> file is around <code>24 MB</code> or so. It ends up being around <code>6MB transferred</code> if it is gzipped. The original version before optimizations was around <code>50MB</code>.
</p>
<h3>Should I Use This?</h2>
<p>
Feel free to use this program, but keep in mind the following things:
</p>
<ul>
<li>
FFmpeg has <a href="http://www.ffmpeg.org/legal.html">license terms</a> that you must abide by. The default build in this project is LGPL 2.1, but including different codecs or build parameters when <a href="#build">building it yourself</a> can change this.
</li>
<li>
It is quite a large JavaScript file, and it will take a long time to load and evaluate.
</li>
<li>
We haven't yet thoroughly tested the performance - use it at your own risk.
</li>
</ul>
<h2 id="uses">Pontential Uses <a href="#uses">[#]</a></h2>
<h3>Audio / Video Editing and Conversion</h3>
<p>
This is what we are doing in the browser with <a href="https://video-funhouse.herokuapp.com">https://video-funhouse.herokuapp.com</a>. Obviously, this could be expanded and optimized. It is quite likely to bump up against performance bottlenecks - I <a href="http://www.briangrinstead.com/blog/video-funhouse">wrote about some of the issues we bumped into</a> if you are interested in more information.
</p>
<p>
Also, it may be possible to make this run on node, and distribute this as an npm module, to make setting up video conversions on a server or desktop much easier.
</p>
<h3>Benchmarking</h3>
<p>
It would be interesting to build a benchmark to compare performance of such a large application across different browsers, node.js, and native performance.
</p>
<h3>Processing Additional Codecs</h3>
<p>
This isn't yet compiled with support for additional codecs like zlib, x264, libvpx, etc. It should be possible to do.
</p>
<h2 id="contributing">Contributing <a href="#contributing">[#]</a></h2>
<p>
Want to help with this project? If you are interested, ping <a href="https://twitter.com/bgrins">@bgrins</a> or <a href="https://twitter.com/aaronm67">@aaronm67</a> on twitter or open an issue / pull request at <a href="https://github.com/bgrins/videoconverter.js">https://github.com/bgrins/videoconverter.js</a>.
</p>
<p>
Here are some ideas of things we'd like to do, and could use some help with:
</p>
<ul>
<li>
Have some experience with benchmarks or performance testing? We would like to benchmark FFmpeg performance in browser / node / native.
</li>
<li>
Know a bunch about <a href="https://github.com/kripken/emscripten">Emscripten</a> / <a href="http://asmjs.org/">asm.js</a>, or want to learn more? There should be ways to tweak the <a href="https://github.com/bgrins/videoconverter.js/blob/master/build/build_lgpl.sh">build script</a> and squeeze out some extra performance or trim down the size.
</li>
<li>
Good at building programs and linking libraries together? It would be cool to build in support for libraries like zlib, x264, and libvpx.
</li>
</ul>
<h2 id="docs">Usage Documentation <a href="#docs">[#]</a></h2>
<p class="note">
To see the code used in the terminal demo on this site, see <a href="https://github.com/bgrins/videoconverter.js/blob/master/demo/terminal.js">terminal.js</a> and <a href="https://github.com/bgrins/videoconverter.js/blob/master/demo/worker.js">worker.js</a> in the repository.
</p>
<p>
The only function exposed from the library is <code>ffmpeg_run</code>. It can be described by the following interface:
</p>
<!-- example-1 -->
<pre id="example-1"></pre>
<!-- /example-1 -->
<h3>Calling from a Worker</h3>
<p class="warning">
Note: while ffmpeg.js could be loaded directly from a <script> tag, it should be loaded from a <a href="https://developer.mozilla.org/en-US/docs/Web/Guide/Performance/Using_web_workers">Web Worker</a> to prevent blocking the main thread.
</p>
<p>
To load ffmpeg.js inside of a web worker, we just need to call <code>importScripts('ffmpeg.js');</code> from inside the worker. Following is a sample worker. Or, click to view a slightly bigger sample <a href="https://github.com/bgrins/videoconverter.js/blob/master/demo/worker.js">worker implementation</a> used in the <a href="demo/">demo</a>
</p>
<!-- example-2 -->
<pre id="example-2"></pre>
<!-- /example-2 -->
<p>
Then, from your page start up the worker:
</p>
<!-- example-3 -->
<pre id="example-3"></pre>
<!-- /example-3 -->
<h3>Converting to and from UInt8Array</h3>
<p>
OK, but how do you get a UInt8Array from a file? There are a few different ways to do this.
If you want to read files from the user's computer, you could use a FileReader or FileReaderSync, and call <code>readAsArrayBuffer</code>. Here is a little wrapper for this functionality that allows drag/drop, file selection, and clipboard access: <a href="https://github.com/bgrins/filereader.js/">https://github.com/bgrins/filereader.js/</a>.
You could also fetch the data from the server, like so:
</p>
<!-- example-4 -->
<pre id="example-4"></pre>
<!-- /example-4 -->
<p>
And what can I do with the results? If you want to provide a download link or a preview of the output, you could convert it into a Blob using the <a href="https://developer.mozilla.org/en-US/docs/Web/API/Blob">Blob constructor</a>, and create an objectURL. Something like this:
</p>
<!-- example-5 -->
<pre id="example-5"></pre>
<!-- /example-5 -->
<h2 id="build">Build Documentation <a href="#build">[#]</a></h2>
<p>
Want to build the ffmpeg.js file for yourself? First, make sure you have Emscripten set up:
</p>
<pre>
git clone git@github.com:kripken/emscripten.git
</pre>
<p>
Depending on your system may need to also get the SDK to make sure Emscripten will work. The have <a href="https://github.com/kripken/emscripten/wiki/Tutorial">documentation on their site</a> about getting this to work.
</p>
<p>
Once this is all set up and <code>emcc</code> is on your path, you should be able to run:
</p>
<pre>
git clone git@github.com:bgrins/videoconverter.js.git
cd videoconverter.js/build
./build_lgpl.sh
</pre>
</div>
</div>
</div>
</div>
<script type='text/javascript' src='site/site.js'></script>
</body>
</html>