Newbie: qrcode decoder filter - request for comments

[Fabrix Xm]

Hi all,

I'm new to GStreamer and glib, C etc..

Looking for a project to learn something new I had the idea to write
an application for GNOME to read QRCodes from the webcam[2].

I started the project using Vala, and the obvious choice to show the
webcam was to use gstreamer and gtksink.
Then to decode the qrcodes in frames I decided to write a gstreamer
plugin to wrap quirc[0] library.

I used the gst-template from documentation[1] and build from there.

The plugin get a raw RGB video at 320x240 (completely arbitrary limit.
I was experimenting with caps), convert to grayscale and pass it
to the quirc library.
When a qrcode is found in frame a signal is emitted.

As I said in object, I would like some comments on code. Be kind, It's
my first time :-)

Thank you

_0: https://github.com/dlbeer/quirc
_1: https://gstreamer.freedesktop.org/documentation/plugin-development/basics/boiler.html
_2: https://github.com/fabrixxm/cuer