png-plucker

A little module for parsing PNGs from streams. Useful with ffmpeg using image2pipe, for example.

png-plucker exports a single function that takes a stream and a callback that is called whenever a PNG is found in the stream. It just looks for the PNG file header, and assumes everything from a header to the next header is a single PNG, so if you have other data mixed in with PNGs you will probably get weirdness.

Installation

npm install png-plucker

Useage

var pngPlucker = require('png-plucker'),
spawn = require('child-process').spawn,
fs = require('fs'),
counter = 0,
ffmpeg;
 
ffmpeg = spawn('ffmpeg', ['-i', 'some_movie.mpeg', '-y', '-f', 'image2pipe', '-'])
pngsPlucker(ffmpeg.stdout, function (error, image) {
  counter++
  fs.writeFile('file'+counter+'.png', image);
});

API

pngPlucker(stream, cb)

• stream - a stream of PNGs
• cb(err, image) - a callback function to consume the PNGs plucked out of the stream. image is a buffer.