Category Archives: Qt

Embedded Linux Conference Europe and GStreamer Conference

This week I am in Cambridge getting to know my colleagues at Collabora Multimedia and attending both the ELC and the GStreamer Conference, which were co-locating.
ELC was interesting. There were a lot of talks dealing with user interface and multimedia issues, and I was pleasantly surprised to find out several presenters mentioning Qt, usually in conjunction with MeeGo. I remember that four or five years ago Qt was relatively unknown, at least in the free software events I used to attend. Nowadays this is clearly not the case: a presenter from Alcatel had a lecture where he compared the available solutions for embedded Linux products. It was a nice presentation, covering all the different SoC architectures as well as the frameworks and toolkits. When he reached the toolkit section there was a big chart with 7 or 8 different solutions, and Qt was clearly a contender for the top position.

The GStreamer conference was a pleasant surprise for me as well, as I was not expecting that many developers. There were at least 150 people there from different projects and companies, and the quality of the presentations was great. I was very pleased to meet another Brazilian developer, Luciana Fujii from Holoscopio. She presented about Landell, a GStreamer-based recording and streaming solution that was used for the last FISL conference in Brazil. It looks very interesting and could possibly help us solve some of the challenges related to recording and streaming content for the next Desktop Summit. On-the-fly camera switching and titling are possible, as well as recording and streaming using different settings. It is Python-based and seems very simple to operate.

I also met several other developers working with GStreamer either professionally or in their pet projects. One I found particularly interesting to watch in action was Stefan Kost’s Buzztard: a pretty impressive music composition environment. I recommend a visit to the site: it can work with both samples and generated sounds, has a built-in sequencer/tracker and can even work with legacy Buzz Windows plugins. For some songs Stefan told me that the internal GStreamer pipeline created by Buzz uses up to 500 elements! (mixers, effects, sound generators…) And it all runs at real time: in his machine this was using 25% of the CPU, but of these only 5% were really being used to play the track, as the rest was mostly consumed by the GUI.

Finally, I collected some initial feedback about the current QtGStreamer implementation and possible use cases. I think we are in the right track so far, and I hope we can see the results of this work pretty soon in the form of applications as cool as the ones I have seen in this conference.

QtGStreamer – an introduction

For the past couple of weeks I have been working on a very cool project, one started and lead by one of our brilliant KDE hackers-that-came-from-GSoC, George Kiagiadakis (gkiagia). I remember that the project got my attention when it was first announced. But I was very busy at that time, and could only follow it from a distance, until now.

As the title of this post reveals, I am talking about QtGStreamer, the Qt-style bindings for the GStreamer multimedia framework.

The project has been progressing during the past year, mostly because it is used in George’s kcall. The structure of the bindings is very flexible, as it follows the powerful pipeline model that is the strength of GStreamer’s design without falling into the trap of trying to map the GStreamer API 1:1. This gives us something that is friendly to the Qt/KDE developer, but at the same time allows things that are very difficult (or impossible) to do with the multimedia APIs we have currently, like displaying a webcam and transcoding the video at the same time with a few lines of code, or streaming audio/video from a remote location transparently.

Even if QtGStreamer is already functional for simple applications it is of course not complete. There is still a lot of work to be done. So as part of my job with Collabora Multimedia I have been assigned to help it reach a feature-complete status. This does not mean the whole GStreamer API will be wrapped: we are aiming for something that is directed specifically to application developers, and I hope it will allow us to help developers code better multimedia experiences for both Qt, MeeGo and KDE users.

My work on the project started recently, and there is still much I have to learn. Luckily George has been around to mentor me, and Collabora Multimedia has a LOT of expertise in GStreamer, of course. I spent the first few weeks doing a full review of the existing GStreamer bindings for all languages, and identifying the missing pieces that we needed to provide. Oh, and making stupid mistakes as well πŸ™‚ You can follow the development of course at the current QGStreamer repository, and don’t be shy if you think you can help, or have a specific request. At this time it is important for us to identify the use cases we have not envisioned for QtGStreamer and do our best to provide an easy API to make them possible, so your input is much appreciated.

I plan to blog regularly about the status of this project. For now, I will already answer the inevitable initial questions:

a) No, it is not meant to replace Phonon. Different use cases, different priorities.
b) No, we could not make this work as part of the Phonon-gstreamer backend. Although the Phonon-gstreamer backend could possibly be ported to QtGStreamer in the future, if there is interest in doing it.
c) No, this does not conflict with the QtMobility/MultimediaKit API. Again, the use case is different, and they might interoperate in the future.

My work on this project is being sponsored by Nokia/MeeGo. As you might know, GStreamer is the official media framework for the MeeGo project, much like Qt is the official developer API. So this project aims to provide the link between those two powerful elements in the MeeGo ecosystem. I will keep you posted about our development, and thanks for reading so far!

Collabora Multimedia

For the past 6 years I have been working on several open source projects as a volunteer. But it has been difficult to find the time to continue to do so on a regular basis after my son was born, in August 2009. There are only 24 hours in a day, and these are not enough to care for the baby, continue my work on Tabuleiro (my small commercial software development company), keep in touch with my friends and family and still make meaningful contributions to KDE and other projects.

During my years with Tabuleiro I accumulated a good deal of experience working with multimedia technology for Windows/OSX, and recently I even managed to convince the bulk of my multimedia customers to do LGPL or GPL projects using Qt as well. But a full transition from closed source to the open source development model was always at my mind. At last Akademy I could witness the number of new companies working strictly with open source projects, most of them leveraging Qt as the main development toolkit, and being able to generate revenue for its developers and maintain a healthy relationship with the community.

And then I realized that I really wanted to work full time on open-source development, after 15 years doing commercial software. This was an easy realization: I did not want to cut on the time spent with my son or with my friends, so changing my work was the only other possible solution πŸ™‚

A few weeks ago the opportunity arrived. I am happy to say that I am now working for Collabora Multimedia on a Qt-based project that I hope will be very useful to Meego and KDE. It is really, really cool. But this is the subject of another post…. For now I just want to say that I am loving the opportunity to work with some of my KDE friends at the same company on a daily basis, as well as having the chance to meet several new developers with different backgrounds.

Updates on Linux Educacional

Linux Educacional (LE) is a distro packaged by the SEED team at the Ministry of Education in Brazil. I posted about the previous versions already, you can find more info on the archives here and here.

The LE team has been working on the 2011 version for a while. Previous releases used KDE 3.5, and the next one is going to be the first deployed over a KDE 4.x desktop. Helio Castro and I went to Brasilia a few months ago to field some questions, discuss a couple of design decisions that are important for the transition and to offer the help of the KDE community, if needed. We were very happy to learn that among all the options available the decision was made to stick with KDE as the LE desktop: one of the reasons was the possibility of deep and easy customization offered by the Plasma environment; as well as the need to preserve the existing investment in training for teachers and IT people and the familiarity of teachers and students with the existing KDE-Edu software.

Then, during Akademy, we saw a lot of interest on this project coming from members of the Plasma, Edu and Oxygen teams. The plan was to foster collaboration between the KDE and the LE teams, and if possible to develop most of the customization features they needed upstream. A mailing list and a wiki page were created, and some ideas floated around.

But… working upstream proved to be very difficult for this project. There were language barriers, and also issues related to timing and the decision-making chain. I find it understandable, but personally frustrating. Development is happening mostly at closed doors, as I was told the team is under a very tight schedule. Apparently a portion of the project is now being handled by the computer science department of UFPR, a federal university in the ParanΓ‘ state in Brazil. Their staff is known for its technical excellence and skill, so I have high hopes for the quality of the final implementation. Some of the people involved have been spotted on the #kde-brasil IRC channel, and the KDE community at large is still available to help of course, if required.

So, even if we could not really collaborate in the true open source fashion for now, it is nice to know that the work we are doing is useful and relevant to the educational community, and that a KDE4-based LE will equip thousands of computer labs next year. And I can see as well that this is a slow learning process, and maybe one day we will have the opportunity of really working together on a global scale on a deployment like this.

Thanks to all members of the KDE community who spent some time during Akademy and in the following weeks thinking about the educational desktop and how to contribute to efforts like the LE customization. I am sure we will have the opportunity to build on several of these ideas when the right time comes. For now, the “we build it and they use it” paradigm remains the most common, and it is not a bad one per se. But I still hope upstream development and collaboration slowly becomes the norm and not the exception.

Blog v3

Well, the last few months have been very busy. And I realized I have not blogged since Akademy. Of course, this is the perfect excuse to change blog hosts again πŸ™‚ Livejournal has been good, but ultimately the amount of spam on comments is just too much, even for a semi-alive blog like mine. So WordPress, here we go, with a new and shining address. As a bonus I collected all the posts (minus comments) from my previous blogspot and livejournal addresses, and archived them here, for posterity.

Let’s get back to Akademy 2010, then. What can I say? Perfect location, perfect organization, and perfect company. It was great to meet old friends again (David! Neja! Jure! lots of people…) as well as make new ones (hi Nuno!.) Too bad I could only stay for 4 days. At the last morning I conducted a BoF about the involvement of KDE with the Linux Educacional project going on in Brazil, an effort that we attempted to jumpstart and that generated a lot of interest inside the KDE Plasma and Edu communities. I will update you guys on how the project is going in my next blog entry.

Akademy 2010

Akademy also marked the very first time I was away from my son for more than a day. It was not easy for me, although I heard that he managed it very well πŸ™‚