testav.js

#!/usr/bin/env gjs

const Lang = imports.lang;
const GLib = imports.gi.GLib;
const GObject = imports.gi.GObject;
const Gst = imports.gi.Gst;
const Mainloop = imports.mainloop;

let TestAV = new Lang.Class({
    Name: "Helloworld",
    Extends: GObject.Object,
    Signals: {
	'eos': {}
    },
    _init: function(params) {
	this.parent(params);
	Gst.init_check(null);
	this.__elements_init();
    },
    __elements_init: function() {
	this.pipeline = new Gst.Pipeline();
	this.video = {src: Gst.ElementFactory.make('autovideosrc', null),
		      sink: Gst.ElementFactory.make('autovideosink', null)};
	this.audio = {src: Gst.ElementFactory.make('autoaudiosrc', null),
		      sink: Gst.ElementFactory.make('autoaudiosink', null)};
	this.pipeline.add(this.video.src);
	this.pipeline.add(this.video.sink);
	this.pipeline.add(this.audio.src);
	this.pipeline.add(this.audio.sink);
	this.video.src.link(this.video.sink);
	this.audio.src.link(this.audio.sink);
	this.msgbus = this.pipeline.get_bus();
	this.msgbus.add_watch(GLib.PRIORITY_DEFAULT, Lang.bind(this, this.__msgbus_cb));
    },
    __msgbus_cb: function(bus, message) {
	switch(message.type) {
	case(Gst.MessageType.ERROR):
	case(Gst.MessageType.EOS): {
	    this.pipeline.set_state(Gst.State.NULL);
	    this.emit('eos');
	} break;
	case(Gst.MessageType.STATE_CHANGED): {
	    let states = message.parse_state_changed();
	    print(message.seqnum
		  + ': state changed from '
		  + Gst.Element.state_get_name(states[0])
		  + ' to '
		  + Gst.Element.state_get_name(states[1])
		  + ' on '
		  + message.src.name
		  + ' ...');
	} break;
	default: {
	    print(message.seqnum
		  + ': received '
		  + Gst.MessageType.get_name(message.type)
		  + ' from '
		  + message.src.name + ' ...');
	}
	}
	return true;
    },
    play: function() {
	this.pipeline.set_state(Gst.State.PLAYING);
    }
});

let testav = new TestAV();
testav.connect('eos', function(){Mainloop.quit()});
testav.play();
Mainloop.run();