gstreamer-superficial

Superficial GStreamer binding

What?

This is a superficial binding of GStreamer to Node.js. It does not attempt at being a complete binding, and will hopefully one day be replaced by (or implemented with) node-gir.

How?

const gstreamer = require('gstreamer-superficial');
const pipeline = new gstreamer.Pipeline(`videotestsrc ! textoverlay name=text
	! autovideosink`);
	
pipeline.play();

Then, you can find an element within the pipeline, and set its properties:

const target = pipeline.findChild('text');

target.text = 'Hello';
Object.assign(target.text, {
	text: 'Hello', 
	'font-desc': 'Helvetica 32',
})

(see also examples/basic-pipeline.js)

Pipeline also knows .stop(), .pause() and .pollBus(), the elements returned by .findChild() getting and setting all properties the real GObjects do, appsinks also support .pull() (see below).

Seeking and Querying Position and Duration

There is a simple .seek(position, flags) function. Normally you should pass 1 for flags (GST_SEEK_FLAG_FLUSH). See Flags and Seek Docs.

You can query the pipeline's duration and current position with .getDuration() and .getPosition() (both might return -1). All time position values are in Seconds.

(see also examples/seek.js)

Polling the GStreamer Pipeline Bus

You can asynchronously handle bus messages using Pipeline.pollBus(callback):

pipeline.pollBus(msg => {
	console.log(msg);
});

(see also examples/bus.js)

Handling binary data

You can feast off GStreamer's appsink to handle binary data. .pull starts a background work queue and calls your callback whenever a buffer is (or caps are) available:

const appsink = pipeline.findChild('sink');

function onData(buf, caps) {
	if (caps) {
		console.log('CAPS', caps);
	}
	if (buf) {
		console.log('BUFFER size', buf.length);
		appsink.pull(onData);
	}

	// !buf probably means EOS
}

appsink.pull(onData);

(see examples/appsink.js)

A simple Ogg/Theora streaming server

should be working as implemented in examples/streaming/
run server.js (requires express) and point your browser to http://localhost:8001. (Tested only with Chromium). This handles retaining the streamheader to feed first to every newly connected client.

Who?

gstreamer-superficial was originally written by Daniel Turing, and has received contributions from various individuals as seen on github and in package.json.

Requisites

• libgstreamer-plugins-base1.0-dev
• libgstreamer1.0-dev
• nan