ffmpeg.js


This library provides FFmpeg builds ported to JavaScript using Emscripten project. Builds are optimized for in-browser use: minimal size for faster loading, asm.js, performance tunings, etc. Though they work in Node as well.

Builds

Currently available builds (additional builds may be added in future):
* ffmpeg-webm.js - WebM encoding (VP8 & Opus encoders, popular decoders).
* ffmpeg-worker-webm.js - Web Worker version of ffmpeg-webm.js.
* ffmpeg-mp4.js - MP4 encoding (H.264 & AAC & MP3 encoders, popular decoders).
* ffmpeg-worker-mp4.js - Web Worker version of ffmpeg-mp4.js.

Note: only NPM releases contain abovementioned files.

Version scheme

ffmpeg.js uses the following version pattern: major.minor.9ddd, where:
* major - FFmpeg's major version number used in the builds.
* minor - FFmpeg's minor version.
* ddd - ffmpeg.js own patch version. Should not be confused with FFmpeg's patch version number.

Example: 2.7.9005

Usage

See documentation on Module object for the list of options that you can pass.

$3

ffmpeg.js provides common module API, ffmpeg-webm.js is the default module. Add its name after the slash if you need another build, e.g. require("ffmpeg.js/ffmpeg-mp4.js").

``js
var ffmpeg = require("ffmpeg.js");
var stdout = "";
var stderr = "";
// Print FFmpeg's version.
ffmpeg({
arguments: ["-version"],
print: function(data) { stdout += data + "\n"; },
printErr: function(data) { stderr += data + "\n"; },
onExit: function(code) {
console.log("Process exited with code " + code);
console.log(stdout);
},
});
`

Use e.g. browserify in case of Browser.

$3

ffmpeg.js also provides wrapper for main function with Web Worker interface to offload the work to a different process. Worker sends the following messages:
* {type: "ready"} - Worker loaded and ready to accept commands.
* {type: "run"} - Worker started the job.
* {type: "stdout", data: ""} - FFmpeg printed to stdout.
* {type: "stderr", data: ""} - FFmpeg printed to stderr.
* {type: "exit", data: ""} - FFmpeg exited.
* {type: "done", data: ""} - Job finished with some result.
* {type: "error", data: ""} - Error occurred.

You can send the following messages to the worker:
* {type: "run", ...opts} - Start new job with provided options.

`js
var stdout = "";
var stderr = "";
var worker = new Worker("ffmpeg-worker-webm.js");
worker.onmessage = function(e) {
var msg = e.data;
switch (msg.type) {
case "ready":
worker.postMessage({type: "run", arguments: ["-version"]});
break;
case "stdout":
stdout += msg.data + "\n";
break;
case "stderr":
stderr += msg.data + "\n";
break;
case "exit":
console.log("Process exited with code " + msg.data);
console.log(stdout);
worker.terminate();
break;
}
};
`

This works in Browser as is, use e.g. webworker-threads Web Worker implementation in Node.

$3

Empscripten supports several types of file systems. ffmpeg.js uses MEMFS to store the input/output files in FFmpeg's working directory. You need to pass Array of Object to MEMFS option with the following keys:
name (String)* - File name, can't contain slashes.
data (ArrayBuffer/ArrayBufferView/Array)* - File data.

ffmpeg.js resulting object has MEMFS option with the same structure and contains files which weren't passed to the input, i.e. new files created by FFmpeg.

`js
var ffmpeg = require("ffmpeg.js");
var fs = require("fs");
var testData = new Uint8Array(fs.readFileSync("test.webm"));
// Encode test video to VP8.
var result = ffmpeg({
MEMFS: [{name: "test.webm", data: testData}],
arguments: ["-i", "test.webm", "-c:v", "libvpx", "-an", "out.webm"],
// Ignore stdin read requests.
stdin: function() {},
});
// Write out.webm to disk.
var out = result.MEMFS[0];
fs.writeFileSync(out.name, Buffer(out.data));
`

You can also mount other FS by passing Array of Object to mounts option with the following keys:
type (String)* - Name of the file system.
opts (Object)* - Underlying file system options.
mountpoint (String)* - Mount path, must start with a slash, must not contain other slashes and also the following paths are blacklisted: /tmp, /home, /dev, /work. Mount directory will be created automatically before mount.

See documentation of FS.mount for more details.

`js
var ffmpeg = require("ffmpeg.js");
ffmpeg({
// Mount /data inside application to the current directory.
mounts: [{type: "NODEFS", opts: {root: "."}, mountpoint: "/data"}],
arguments: ["-i", "/data/test.webm", "-c:v", "libvpx", "-an", "/data/out.webm"],
stdin: function() {},
});
// out.webm was written to the current directory.
`

Build instructions