cwebp

node-webp

Node.js wrapper for cwebp and dwebp binaries from WebP image processing utility.

Installation

npm install cwebp

Getting latest version of WebP

You can get latest WebP source, pre-compiled binaries and installation instructions from its official website, or from its downloads repository.

Linux users may use this installation script to automatically download and install latest WebP binaries:

curl -s https://raw.githubusercontent.com/Intervox/node-webp/latest/bin/install_webp | sudo bash

MacOS users may install WebP using MacPorts:

sudo port selfupdate
sudo port install webp

If none of it suit your needs, you may build the WebP utilities yourself.

Alternative ways to install WebP

MacOS users may install webp 0.4.0 using homebrew:

brew install webp

You may also install webp 0.3.x as npm module:

npm install webp

Important: Using old WebP versions

Old versions of WebP (prior to 0.4.1) are not compatible with the latest node-webp version.

If you're using old version of WebP, please, use node-webp 0.1.x.

Check this section for more info about new streaming features of the latest WebP version.

Usage

var CWebp = require('cwebp').CWebp;
var DWebp = require('dwebp').DWebp;

var encoder = new CWebp(source_image);
var decoder = new DWebp(source_webp);

or

// new is optional
var encoder = CWebp(source_image);
var decoder = DWebp(source_webp);

or

// Backward-compatibility with cwebp@0.1.x
var CWebp = require('cwebp');

Specifying path to cwebp binary

By default node-webp looks for cwebp and dwebp binary in your $PATH.

Specifying path as a constructor option

var Webp = require('cwebp');
var binPath = require('webp').cwebp;

var webp = new Webp(source, binPath);

Changing default behaviour

var CWebp = require('cwebp').CWebp;
CWebp.bin = require('webp').cwebp;

var encoder = new CWebp(source);

var DWebp = require('cwebp').DWebp;
DWebp.bin = require('webp').dwebp;

var decoder = new DWebp(source);

N.B.: webp npm module provide old webp 0.3.x binaries.

Available source types

When source is a string node-webp treats it as a file path.

var CWebp = require('cwebp').CWebp;
var DWebp = require('dwebp').DWebp;

var encoder = new CWebp('original.jpeg');
var decoder = new DWebp('converted.webp');

It also accepts Buffers and Streams.

var encoder = new CWebp(buffer);

var decoder = new DWebp(stream);

Note that node-webp will start listening to the data in a source stream only when .write(), .stream() or .toBuffer() is called.

Encoding and decodind WebP images

encoder.write('image.webp', function(err) {
    console.log(err || 'encoded successfully');
});

decoder.write('image.png', function(err) {
    console.log(err || 'decoded successfully');
});

Getting output image as a Buffer

decoder.toBuffer(function(err, buffer) {
    // ...
});

Getting output image as a readable Stream

var stream = encoder.stream();

stream.pipe(destination);
stream.on('error', function(err) {
  // something bad happened
});

Working with Streams

Different versions of WebP have different level of streaming support:

Feature	Older WebP versions	WebP 0.4.1	node-webp 0.1.x	node-webp 1.x
cwebp stdin streaming	no	no	mock	mock
cwebp stdout streaming	no	native	mock	native
dwebp stdin streaming	no	native	mock	native
dwebp stdout streaming	no	native	mock	native

mock means that node-webp acts as if the feature is supported, mocking it using temporary files.

So, converting Stream into a Buffer with node-webp 0.x will cause two temporary files to be created and then removed (one to store input stream, and another to read output buffer from).

Note that node-webp native streaming will work only if your WebP version have native support for the corresponding stream, while mock streaming will work with any version of WebP.

IMPORTANT: If you're using old version of WebP, please, use node-webp 0.1.x.

Using promises

node-webp supports A+ promises.

encoder.write('image.webp').then(function() {
    // ...
});

encoder.toBuffer().then(function(buffer) {
    // ...
});

decoder.stream().then(function(stream) {
    // ...
});

node-webp uses when.js library.

Specifying conversion options

node-webp provides helper functions for most of cwebp and dwebp conversion options. For the full list of available helpers see methods.json file.

encoder.quality(60);
decoder.tiff();

Sending raw command

encoder.command('-d', 'dump.pgm');

Verbose errors reporting

node-webp returns any error reported by cwebp or dwebp. By default it uses standard error reporting mode, but it's possible to enable cwebp verbose error reporting.

var CWebp = require('cwebp').CWebp;

new CWebp(source).verbose().toBuffer(function (err, res) {
    // err.message contains verbose error
});

dwebp don't support verbose error reporting.

Changing default behaviour

var CWebp = require('cwebp').CWebp;
CWebp.verbose = true;

new CWebp(source).toBuffer(function (err, res) {
    // err.message contains verbose error
});

Changelog