28 Oct 2016

Waltham: a generic Wayland-style IPC over network

I have recently been occupied with a new project (and being with a cold all this week), so I have not been much present in the Wayland community. Now I can finally say what I and Emilio have been up to: Waltham! For more information, please see our annoucement.

1 Mar 2016

Wayland has been accepted as a Google Summer of Code organization

Now is a high time to start discussing what you might want to do, for both student candidates and possible mentors.

Students, have a look at our project idea examples to get a feeling of what kind of projects you could propose. First you will need to contribute at least a small but significant patch to show that you understand the workflow, we have put some first task ideas together.

There are our application instructions for students. Of course all the pages are reachable from the Wayland GSoC wiki page and also the Wayland organization page.

If you want to become a mentor, please contact me or Kat, the contact details are on the Wayland GSoC wiki page.

Note, that students can also apply under the X.Org Foundation organization since Wayland is within their scope too and they also have other excellent graphics project ideas. You are welcome to submit your Wayland proposals to both projects.

16 Feb 2016

A programmer's view on digital images: the essentials

How is an uncompressed raster image laid out in computer memory? How is a pixel represented? What are stride and pitch and what do you need them for? How do you address a pixel in memory? How do you describe an image in memory?

I tried to find a web page for dummies explaining all that, and all I could find was this. So, I decided to write it down myself with the things I see as essential.

11 Feb 2015

Weston repaint scheduling

Now that Presentation feedback has finally landed in Weston (feedback, flags), people are starting to pay attention to the output timings as now you can better measure them. I have seen a couple of complaints already that Weston has an extra frame of latency, and this is true. I also have a patch series to fix it that I am going to propose.

To explain how the patch series affects Weston's repaint loop, I made some JSON-timeline recordings before and after, and produced some graphs with Wesgr. Here I will explain how the repaint loop works timing-wise.

Original post Feb 11, 2015.
Update Mar 20, 2015: the patches have landed in Weston.

25 Jul 2014

Wayland protocol design: object lifespan

Now that we have a few years of experience with the Wayland protocol, I thought I would put some of my observations in writing. This, what will hopefully become a series rather than just one post, considers how to design Wayland protocol extensions the right way.

This first post considers protocol object lifespan and the related races between the compositor/server and the client. I assume that the reader is already aware of the Wayland protocol basics. If not, I suggest reading Chapter 4. Wayland Protocol and Model of Operation.

5 Jun 2014

From pre-history to beyond the global thermonuclear war

This is a short and vague glimpse to the interfaces that the Linux kernel offers to user space for display and graphics management, from the history to what is hot and new, to what might perhaps be coming after. The topic came current for me when I started preparing Weston for global thermonuclear war.

31 Jan 2014

Improving presentation on Wayland

In the last two (or three?) weeks at Collabora I have been looking into a Wayland protocol extension that would allow accurately timed presentation. Accurate timing is essential for two quite different use cases: video playback with audio/video synchronization, and interactive GUI with just-in-time redrawing. Video playback with A/V sync was our primary goal when we started working on this, and there is Frederic Plourde's first proposal from October 2013. Since then I have realized that also other kinds of applications need timings, especially feedback on when their content updates were shown, and when is the next chance to show an update (vblank). Primarily my re-design started with the aim to improve resizing performance when I got the assignment from Daniel Stone to push Wayland presentation protocol forward. The RFC v2 of Wayland presentation extension is now out for review and discussion.