Category Archives: GStreamer

Thanks for all the applications

Jobs at Red Hat
So I got a LOT of responses to my blog post about the open positions we have here at Red Hat working on Fedora and the Desktop. In fact I got so many it will probably take a bit of time before we can work through them all. So you might have to wait a little bit before getting a response from us. Anyway, thanks you to everyone who sent me their CV, much appreciated and looking forward to working with those of you we end up hiring!

Builder campaign closes in 13 hours
I want to make one last pitch for everyone to contribute to the Builder crowdfunding campaign. It has just passed 47 000 USD as I write this, which means we just need another 3000 USD to reach
the graphical debugger stretch goal. Don’t miss out on this opportunity to help this exciting open source project!

Want to join our innovative development team doing cool open source software?

So Red Hat are currently looking to hire into the various teams building and supporting efforts such as the Fedora Workstation, the Red Hat Enterprise Linux Workstation and of course Fedora and RHEL in generaL. We are looking at hiring around 6-7 people to help move these and other Red Hat efforts forward. We are open to candidates from any country where Red Hat has a presence, but for a subset of the positions candidates relocating to our main engineering offices in Brno, Czech Republic or Westford, Massachussets, USA, will be a requirement or candidates interested in that will be given preference. We are looking for a mix of experienced and junior candidates, so regardless of it you are fresh out of school or haven been around for a while this might be for you.

So instead of providing a list of job descriptions what I want to do here is list of various skills and backgrounds we want and then we will adjust the exact role of the candidates we end up hiring depending on the mix of skills we find. So this might be for you if you are a software developer and have one or more of these skills or backgrounds:

* Able to program in C
* Able to program in Ruby
* Able to program in Javascript
* Able to program in Assembly
* Able to program in Python
* Experience with Linux Kernel development
* Experience with GTK+
* Experience with Wayland
* Experience with x.org
* Experience with developing for PPC architecture
* Experience with compiler optimisations
* Experience with llvm-pipe
* Experience with SPICE
* Experience with developing software like Virtualbox, VNC, RDP or similar
* Experience with building web services
* Experience with OpenGL development
* Experience with release engineering
* Experience with Project Atomic
* Experience with graphics driver enablement
* Experience with other PC hardware enablement
* Experience with enterprise software management tools like Satellite or ManageIQ
* Experience with accessibility software
* Experience with RPM packaging
* Experience with Fedora
* Experience with Red Hat Enterprise Linux
* Experience with GNOME

It should be clear from the list above that we are not just looking for people with a background in desktop development this time around, two of the positions for instance will mostly be dealing with Linux kernel development. We are looking for people here who can help us make sure the latest and greatest laptops on the market works great with Fedora and RHEL, be that on the graphics side or in terms of general hardware enablement. These jobs will put you right in the middle of the action in terms of defining the future of the 3 Fedora variants, especially the Workstation; defining the future of Red Hats Enterprise Linux Workstation products and pushing the Linux platform in general forward.

If you are interested in talking with us about if we can find a place for you in Red Hat as part of this hiring round please send me your CV and some words about yourself and I will make sure to put you in contact with our recruiters. And if you are unsure about what kind of things we work on here I suggest taking a look at my latest blog about our Fedora Workstation 22 efforts to see a small sample of some of the things we are currently working on.

You can reach me at cschalle(at)redhat(dot)com.

Planning for Fedora Workstation 22

So Fedora Workstation 21 is done and out and I am extremely pleased to see the positive reception and great reviews. But we are not resting on our laurels here and are already busy planning for the Fedora Workstation 22 release. As many of you might know Fedora Workstation 22 is going to come up relatively fast, so we only have about 6 more weeks of development on it feature the freezes starts to kick inn. Luckily we have a relatively long list of items that we started working on during the Fedora Workstation 21 cycle that is nearing completing and thus should make the next release. We are of course also working on bigger long term developments that you should maybe see the first outline of in Fedora 22, but not the final version. I thought it would be nice to summarize some of the bigger items we expect to land and link to the relevant blogs and announcements for each one.

Wayland
So first out is to give an update on our work on Wayland as I know that is something a lot of people are curios about. We are continuing to make great strides forward and recently hired Jonas Ådahl to the team who many might recognize as an active Wayland and libinput developer. He will be spearheading our overall Wayland effort as we are approaching the finish line. All in all things are looking good, we got a lot of the basic plumbing in place for Fedora Workstation 21, so most works these days is mostly focused on polish and cleanups. One of the bigger items is the migration to use libinput. libinput is a library we decided to create to be able to share input device handling between X and Wayland and thus make the transition smoother and lower our workload during the transition period. Libinput itself is getting very close to feature complete and they are even working on some new features for it now taking it beyond what was in X. Peter Hutterer recently released version 0.8 and we expect to have 1.0 out and in use for both X.org and Wayland in time for Fedora Workstation 22.
In parallel we are also working on porting the needed bits in GNOME over to use libinput and remove any lingering X dependencies, like the GNOME Control Center which should also be ready for Fedora Workstation 22.

Another major change related to Wayland in Fedora Workstation 22 is that we will switch the default backends in GTK+ and SDL over to using Wayland. Currently in Fedora Workstation 21 applications are actually running on top of XWayland, but in Fedora Workstation 22 at least GTK+ and SDL applications will be default to Wayland when run under the Wayland session.
The Wayland SDL backend has been around for quite a bit, but Jonas Ådahl plans on spending some time smoothing out the last rough edges, in fact for SDL applications we hope we can actually provide noticeable performance improvement over X in some cases (not because OpenGL will be faster of course, but because we might be able to be smarter about handling different resolutions between desktop and game), but we have to wait and see if that pans out or if we have to settle for performance parity with X. We are also looking at getting the login session to use Wayland by default. All in all this should take us a huge step forward towards making using Wayland feel real.

As it looks now Wayland should be quite close to what you would define as feature complete for Fedora Workstation 22, but one thing that is going to take longer to reach maturity is the support for binary drivers, especially the NVidia ones. This of course is a task that mostly falls on NVidia for natural reasons, but we are trying to help out by Adam Jackson working to making sure Mesa works with their proposed EGLStreams and OpenGL Dispatcher proposals. So during the course of the coming year we will likely have a situation that you will be able to have a production ready Wayland session if you are running any of the open source drivers, but if you want to run Wayland on top of the NVidia binary driver that is most likely to only really be possible towards the end of the year. That said this is a guesstimate from our side as how quick the heavy lifting will happen, and how quickly it will be released by NVidia for public consumption is of course all relying on internal plans and resources at NVidia and not something we control.

Battery life
One thing we know being developers ourselves and from speaking with developers about their operating system of choice, battery life is among the top 5 reasons for what choice people make about their hardware and software. Due to this Owen Taylor has been investigating for some time now both what solutions exist today, what other operating systems are doing and what approaches we can take to improve battery life. Because a common complaint we hear from a lot of people is that they don’t feel they get great battery life when running linux on their laptops currently. Some people are able to solve this using powertop, but we feel there are a lot of room for automatically give our users better battery life beyond manual tweaking user powertop.

Improving battery life is a complex issue in many ways, including figuring out how to measure battery life. I guess everyone has seen laptops advertised with X number of hours of battery life, but it is our impression that those numbers tend to be quite bogus even when running the bundled operating system. In some testing we done we concluded that the worst offenders numbers could only true if you left your laptop idle in the corner with the screen blacked out. So gnome-battery-bench will help us achieve a couple of things, it should generate comparable battery lifetime numbers which both should help our users choose the hardware that gives the best battery life under linux and it also lets us as developers keep tracking how changes affect battery life so that we can catch regressions for instance. It also lets us verify the effect various kernel tuneables or ambient light detection schemes have on battery life in a better way than we can with existing tools. We also hope to use this to work with vendors to improve the battery life of their hardware when running Fedora or RHEL. Anyway, I suggest reading Owens Taylors blog for some more details of his work on improving battery life..

One important effort we want to undertake here, which might not all make it for Fedora Workstation 22, is taking advantage of the ambient light detectors in many modern laptops. One of the biggest battery drains in your system is the screen brightness setting and by using the ambient light detection hardware we hope to be able to put in place some intelligent behavior for different situations. This is a hard problem though and it was attempted solved in GNOME before, but the end result back then was that people felt they where “fighting” GNOME over their laptop brightness settings, so in the end it was dropped completely, so we need to careful to not repeat that outcome.

Application bundles
Another major effort that is not going to ready for Fedora Workstation 22, but which we might have some preview of is Application bundles. Matthias Clasen recently sent out an email to the Fedora Desktop mailing list outlining the state of the application bundles work. This is a continuation of the Sandboxed Applications in GNOME proposal from Lennart Poettering. The effort is being spearheaded by Alexander Larsson and the goal is to build the infrastructure needed to do sandboxed desktop applications efficiently. There is a wiki page up already detailing Sandboxed Apps and there are some test applications already available. For instance you can grab an application bundle of Builder, the cool new IDE project from Christian Hergert. (Hint, make sure to support his Builder crowdfunding effort if you have not already.). Once this effort matures it will revolutionize how desktop applications are built and distributed. It should make life easier for application developers as these bundled applications are designed to be distribution agnostic and the sandboxing aspect should help improve security. Also the transition should put the application developers directly in charge of the update cycle of their applications enabling them to better support their users.

3rd Party Application handling
So the ever resourceful Richard Hughes has been working on adding support for handling 3rd party applications in GNOME Software. He outlined this effort in a recent blog post about GNOME Software.

While the end goal here it to offer 3rd party application bundles as described in the section above, the feature has also a lot of near term advantages. We have seen that over the course of the last years we moved from a model where you use your browser to search for software online to users expecting to find all software available for a system through its app store. With this 3rd party application support available in GNOME Software we can start working to make that expectation a reality also in Fedora. We took great strides forward in Fedora Workstation 21 with having metadata available for most of the standard applications packaged in Fedora, but there is also a lot of popular applications and other things out there that people tend to install and use which we for various reasons are not interested or able to ship in Fedora. The reason for this can range from licensing issues, to packaging issues to simply resource issues. With Richards work we will be able to make such software discoverable in Fedora, yet make a clear distinction between the software we have vetted and checked and the software you get from 3rd parties.

How to deal with 3rd party software has been a long and ongoing discussion in the Fedora community, and there are a lot of practical and principal details to deal with, but hopefully with this infrastructure in place it will be a lot easier to navigate those issues as people have something concrete to relate to instead of just abstract ideas and concepts.

One challenge for instance we have to figure out is that on one side we don’t want 3rd party software offered in Fedora to be some for of endorsement or sign of being somehow vetted by the Fedora Project on an ongoing basis, yet on the other side the list will most likely need to be based on some form of editorial process to for instance protect both Red Hat and Fedora from potential legal threats. I plan on sending an initial proposal to the Workstation Working Group soon for how this can work and once we hashed out the details there we will need to bring the Working groups proposal into the wider Fedora community as this also affects our Cloud and Server offering.

File Manager
A lot of people these days use Google Drive, be that personally or because their company has a corporate Google apps account. So to make life easier for our users we are making sure that Nautilus are able to treat your Google drive as just another drive on the system, letting you drag and drop files off or on it. We also dedicated some effort to clean up and modernize the file manager in general, with Carlos Soriano blogging about his efforts there just before Christmas. All in all I think these are improvements that should improve the life of our developer and sysadmin target audience, but of course they are also very useful improvements to the general linux using public.

Qt Theming
One of the things we had to postpone for Fedora Workstation 21 was the Adwaita theme for Qt applications. We are expecting it to hit Fedora Workstation 22 though and you can get the theme to install and test from Martin Briza copr repository. The end goal here is wether you run a pure Qt application like Skype or Scribus, or a KDE application like Krita or Amarok, you should get an Adwaita look and feel to the application. Of course desktop integration isn’t just about a theme, there is a reason the GNOME HIG exists, but this should be an improvement over the current situation. The theme currently targets Qt4, but of course Qt5 is also on the roadmap for a later release.

Further terminal improvements
As I mentioned in an earlier blog entry about Fedora Workstation we realize that the terminal is the most important application for many developers and sysadmins. So we are also hoping to land some more of the terminal improvements we been working on in Fedora Workstation 21. The notifications for long running jobs being maybe the thing I know a lot of developers are excited about getting their hands on. It will let you for instance start a long compile in a terminal and know that you will be notified once it is completed instead of having to manually check in from time to time.

More development tools
In my opinion the best IDE for Python development currently is PyCharm. And not only is it the best from a functionality standpoint they also decided to release an open source version last year. That said we have been struggling a bit with the packaging of PyCharm, and interestingly enough it is one of those applications I think will benefit greatly from the application bundle work we are doing, but in the meantime we at least do have a Copr of PyCharm available. It is still an open question, but we might make this CoPR one of our testcases for the 3rd party application support in GNOME Software as mentioned earlier. Anyway if you are a Python developer I strongly recommend taking a lot at it. Personally I looked at various Python IDEs over the years, but always ended up just going back to Gedit, but when trying PyCharm it was the first time I felt that the application actually offered me useful functionality beyond what a text editor like Gedit does. Also in recent versions they also deal well with the introspection based Python bindings for GTK3 which was a great boon for me.

We are also looking at improving the development story around Vagrant and doing Fedora and RHEL development, more details on that at a later point.

ABRT improvements
The ABRT tool has become a crucial development tool for us over the last couple of years. The Fedora Retrace server is one of our main tools
for prioritizing which bugs to look at first and a crucial part of our goal of making Fedora a solid
distribution. That said, especially its early days, ABRT has had its share of detractors and people
being a bit frustrated with it, so Bastien Nocera and Allan Day has been working with the ABRT team to both integrate
it further with the desktop, for instance ensuring that it follows your desktop wide privacy settings
and to make sure that the user experience of submitting a retrace report is as smooth and intuitive as possible
and not to mention as unobtrusive as possible, for instance you don’t want ABRT to choke your system while trying to generate
a stack trace for us. The Fedora Workstation Tasklist contains links to bugzilla and github so you can track their progress.

Still a lot to do!
So making our vision for the Fedora Workstation come through takes of course a lot of effort from a lot of people. And we are really lucky to be part of such a great community where so much cool stuff is happening all the time. I mean the Builder effort from Christian Hergert as I talked about earlier is one of them, but there are so many other things happening too. So if you want to get involved take a look at our tasklist and see if there is anything that interests you or for that matter if there is something that you think should be worked on, but isn’t on the list yet. Then come join us either on #fedora-workstation on the freenode IRC network or join the fedora-desktop mailing list.

Time has come to support some important projects!

If you read this blog entry it is very likely that you are a direct beneficiary of open source and free software. Like myself you probably have been able to get hold of, use and tinker with software that in the old world of closed source dominance would all together have cost you maybe ten thousand dollars or more. So with the spirit of the Yuletide season fresh in mind it is time to open your wallet and support some important open source fundraising campaigns.

The first one is the Builder, an IDE of our GNOME which is an effort by the unstoppable Christian Hergert to create a truly powerful and modern IDE for GNOME. Christian has already made huge strides forward with his project since quiting his dayjob to start it, and helping fund him to cross the finish line would be greatly beneficial to us all. And I think it would make a wonderful addition to the Fedora Workstation effort, so this is an easy way for you to help us move that effort forward too. So head over to the fundraiser webpage or start by viewing the great fundraiser video below:

The second effort I want to highlight is the still ongoing fundraiser for the PiTiVi video editor. Since they started that effort they have raised 22190 USD of the 35 000 USD they need to get PiTiVi to a level where they are confident to make a 1.0 release. And I think we all agree that having a top notch video editor avaiable, especially one that uses GStreamer and thus helps improve our general multimedia story is very important. This effort also has a nice introduction video if I want to know more:

I have personally contributed money to both these efforts and I hope you will too! Both projects are crucial for the long term health of the ecosystem and both are done by credible teams with the right skills to succeed. So for those of us out of school and in paying jobs, setting aside for example 100 USD to help these two efforts should be an easy choice to make, the value we will get back easily dwarfs that amount.

Transmageddon Video Transcoder version 1.5 released

So just a quick update. I pushed out the 1.5 release of Transmageddon today. No major new features just fixing a regression in terms of dealing with files where you only have a video track or where you want to drop the audio track as part of the transcoding process. I am also having some issues with Intel Hardware encoding atm, but I think those are somewhere lower in the stack, so I hope to file a bug against either GStreamer or the libva project for that issue, but for now I recommend not having the Intel VA plugins for GStreamer installed.

As always you find the latest release on linuxrising.org.

I also submitted a Transmageddon update to Fedora 21, so if you are a Fedora user please test the build there and give it some Karma

GStreamer Conference 2014 talks online

For those of you who like me missed this years GStreamer Conference the recorded talks are now available online thanks to Ubicast. Ubicats has been a tremendous partner for GStreamer over the years making sure we have high quality talk recordings online shortly after the conference ends. So be sure to check out this years batch of great GStreamer talks.

Btw, I also done a minor release of Transmageddon today, which mostly includes a couple of bugfixes and a few less deprecated widgets :)

Transmageddon 1.2 ‘All bugs must die’

Update: I had actually managed to disable the VAAPI encoding in 1.2, so I just rolled a 1.3 release which re-enabled it. Apart from that it is identical

So I finally managed to put out a new Transmageddon release today. It is primarily a bugfix release, but considering how many critical bugs I ended up fixing for this release I am actually a bit embarassed about my earlier 1.x releases. There was for instances some stupidity in my code that triggered thread safety issues, which I know hit some of my users quite badly. But there were other things not working properly either, like dropping the video stream from a file. Anyway, I know some people think that filing bugs doesn’t help, but I think I fixed every reported Transmageddon bug with this release (although not every feature request bugzilla item). So if you have issues with Transmageddon 1.2 please let me know and I will try my best to fix them. I do try to keep a policy that it is better to have limited functionality, but what is there is solid as opposed to have a lot of features that are unreliable or outright broken.

That said I couldn’t help myself so there are a few new features in this release. First of all if you have the GStreamer VAAPI plugins installed (and be sure to have the driver too) then the VAAPI GPU encoder will be used for h264 and MPEG2.

Secondly I brought back the so called ‘xvid’ codec (even though xvid isn’t really a separate codec, but a name used to refer to MPEG4 Video codec using the advanced-simple profile.).

So as screenshot blow shows, there is not a lot of UI changes since the last version, just some smaller layout and string fixes, but stability is hopefully greatly improved.
transmageddon-1.2

I am currently looking at a range of things as the next feature for Transmageddon including:

  • Batch transcoding, allowing you to create a series of transcoding jobs upfront instead of doing the transcodes one by one
  • Advanced settings panel, allowing you to choose which encoders to use for a given format, what profiles to use, turn deinterlacing on/off and so on
  • Profile generator, create new device profiles by inspecting existing files
  • Redo the UI to switch away from deprecated widgets

If you have any preference for which I should tackle first feel free to let me know in the comments and I will try to allow
popular will decide what I do first :)

P.S. I would love to have a high contrast icon for Transmageddon (HighContrast App icon guidelines) – So if there is any graphics artists out there willing to create one for me I would be duly greatful

Transmageddon 1.0 released!

It has been a long time in the making, but I have finally cut a new release of the Transmageddon transcoder application. The code inside Transmageddon has seen some major overhaul as I have updated it to take advantage of new GStreamer APIs and features. New features in this release include:

  • Support files with multiple audio streams, allowing you to transcode them to different codecs or drop them from the new file
  • DVD ripping support. So know you can use your movie DVDs as input in Transmageddon, be aware though that you need to install things like lsdvd and the GStreamer dvdread plugin from gst-plugins-ugly for it to become available. And you probably also want libdvdcss installed to be able to transcode most movie DVDs.
  • Another small feature of the release is that you can now set language information on files with one audio stream inside. I hope to extend this to also work with files that have multiple audio streams. If you rip a DVD with multiple audio streams Transmageddon will preserve the existing audio information, so in that case you shouldn’t need to set the language metadata manually.
  • Enabled VP9 support in the code.

There are some other smaller niceties too, like the use of blue default action buttons to match the GNOME 3 style better and I also switched to new icon designed by Jakub Steiner. There is also an appdata file now, which should make Transmageddon available in a nice way inside the new Fedora Software Installer’

Also there is now an Advanced section on the Transmageddon website explaining how you can create custom presets that allow you to do things like resize the video or change the bitrate of the audio.

And last, but not least here is a screenshot of the new version.
transmageddon-1.0-blue-button

You can download the new version from the Transmageddon website, I will update the version in Fedora soon.

Update from GStreamer Hackfest at Google Office in Munich

To give the wider community a chance to see what happened during the GStreamer hackfest last weekend I put together this blog post is based on an summary written by Wim Taymans, so a big thanks to Wim for letting me reuse parts of his summary.)

So last weekend 21 GStreamer hackers got together at the Google office in Munich to spend the weekend hacking on their favourite GStreamer bits. At this point in time we didn’t have any major basic plumbing tasks that needed tackling so the time was spent hacking on a lot of different projects and using the opportunity to discuss design and challenges with each other.

We where 3 people attending from Red Hat and Fedora; Wim Taymans, Alberto Ruiz and myself.

With the Release of GStreamer 1.0 in September 2012, we drastically changed the way memory is handled in the multimedia pipeline and the large body of work is still in exploring, improving and porting elements to this new memory model. We’re also mostly working on improving the existing elements with comparatively little new infrastructure work.

We’re also seeing a lot of people from different companies that contribute significant amounts of code to the official GStreamer repositories. This has traditionally been a much more closed effort with various pieces of code living in multiple repositories, especially for the hardware acceleration bits. It is good to see that the 1.0 series brings all these efforts together again with more coordination and a more coherent story.

HW acceleration

One of the large ongoing tasks is to improve our support for hardware accelerated decoding, effects and display. With 1.0 we can finally get this done cleanly and efficiently in very many use cases.

Matthew Waters to flew in from Australia to move the gst-plugins-gl set of plugins to the core GStreamer plugins packages. He has been working on these plugins for a while now. Their goal is to use OpenGL to apply operations on the video, like rotation on a cube or applying a shader. With the 1.0 memory management it becomes possible to do this efficiently with a minimal amount of texture upload/downloads. More work is needed here, we can optimize things some more by delaying the work and running the shaders as part of the rendering operation.

Andoni Morales (Fluendo) has also been working on improving hardware acceleration on android. He used some of the new features of 1.0 to make the android codecs use zero-copy by implementing the texture-upload meta data on buffers. This allows the video sink to efficiently create a texture from the decoded data for display. Andoni also ported winks, a video capture source on Windows, to GStreamer 1.0.

Nicolas Dufresne (Collabora) has been working on adding a new set of decoders based on the mem2mem API in v4l2. Not many drivers provide this API yet but it is implemented in some Samsung Exynos SOCs. We would also like to support other m2m operations later, such as color conversion but for that we need to make some of our base classes support the required asynchronous behaviour of mem2mem. The memory management in our v4l2 elements has been gone through several iterations of improvements during the 1.0 cycle but it still is not entirely what it should be. We agreed on what we should do to fix this in the near future. We also briefly discussed the need for a new event that can be used to reclaim memory from a pipeline; many elements that use hardware buffers need to free those before they can negotiate a new format with the hardware so we need a way to make that possible.

Mathieu Bourron (Collabora) has been working on libva, the library for GPU based video decoding and encoding on Intel hardware, and spent his time at the Hackfest fixing up the SPU overlay element to enable hardware accelerated subpicture overlays in the video sink. Traditionally GStreamer would use the CPU to overlay the subpictures (of DVD, for example) on top of the video images. With new GL-based sinks, and hardware accelerated decoders this is very undesirable and can be done much more efficient as part of the final rendering. In 1.0 we have the infrastructure to delay this overlay operation by attaching extra metadata (with the subpicture) to the video images when the video sink knows how to overlay them. We have been doing this with subtitles in cluttersink and other sinks for a while now and soon we can also do this with subpictures.

Plugin Hacking

Arun Raghavan, GStreamer hacker and Pulse Audio maintainer, worked on disabling the audio and video filters in playbin when passthrough mode was selected. In passthrough mode, a video or audio sink can directly handle the encoded media (think a bluetooth headset that can handle mp3 directly or a hardware sink that takes encoded data). He expaned on that work in blog entry.

As a cool hack, Arun also made a source element to read from torrent files so you can watch a movie while you torrent it. He provides more information on that element in his blog, it is actually really cool.

Thiago Santos (Collabora) was continuing with his work to improve the DASH demuxer, reworking the buffering code to make it buffer less and smoother. Dash is one of the new formats (with HLS and MSS) to stream media over HTTP while adapting to bandwidth changes. On the server side, it makes media available in various bitrates while a client switches between bitrates depending on its measured network conditions. Andoni Morales also worked on a new dashsink element that implements the server side of the DASH
format.

Mathieu Duponchelle, a former GSoC student was trying to improve support for seeking in MPEG Transport Streams in order to use them in PiTiVi. Seeking in MPEG TS is not an easy thing because they are really optimized for streaming only. He got help from Thibault Saunier (Collabora), who was also hacking on PiTiVi and who was preparing a new release of gnonlin, GES and gst-python 1.2 (which he released on Sunday). Mathieu is one of the developers able to work fulltime on PiTiVi now thanks to the PiTiVi fundraiser, so be sure to contribute to that!

Jan Schmidt (Centricular), a long time GStreamer core hacker was working on debugging some DVB issues and also ended up taking part in a lot of the general design and troubleshooting discussions happening during the hackfest, helping other people move forward with their projects.

Long time GStreamer hacker Edward Hervey (Collabora) was planning to do a lot of DVB hacking but had to give up on that effort when it was clear that Google had signal isolated the office for security reasons, so there was no DVB signal in the Google office. Instead he worked on merging some pending DVB patches and implemented GAP support in the mpeg transport stream plugin. GAP support deals with streams that have long periods of no media (like missing audio for some time in DVD). It makes sure that downstream elements keeps processing the silence instead of waiting for more data.

Applications

Meg Ford, a GSOC student mentored by Sebastian Dröge (Centricular) was working on Gnome Sound Recorder and fixing up the last bugs, preparing it for a new release.

Myself, Christian Schaller (Red Hat) was on a bug fixing spree in Transmageddon (a transcoding application written in python and GStreamer) and managed to reduce the number of known bugs to only 1. Fixed that last bug once I got home, so now I just need to hammer at Transmageddon for a bit to make sure I caught all the corner case issues so I can do a major new release with new features such as handling files with multiple audio streams, handling DVD ripping, handling VP9 encoding, handling setting audio stream language information, reducing decoding overhead for streams that we are going to throw away and more. Also had help reviewing and cleaning up the Transmageddon code from Alberto Ruiz, freeing Transmageddon from some ugly code that had survived many library updates and rewrites.

Alessandro Decina(Spotify) kept working on his patches to update the Firefox GStreamer backend to GStreamer 1.0. We hope to deploy this work in Fedora in the not to distant future. As a hack for the hackfest he provided patches to implement audio and video capture.

Wim Taymans (Red Hat) was hacking on a new library that can parse and generate MIKEY messages (RFC 3830). He want to use this in the GStreamer RTSP server to negotiate SRTP (secure RTP) encryption parameters.

We had 2 people from the Swedish company AXIS, who provide network cameras that all run GStreamer and who contribute on a regular basis to the RTP and RTSP elements and libraries. Ognyan Tonchev was mostly writing some unit tests for RTSP and multicast handling in the RTSP server. Sebastian Rasmussen had been hacking on our watchdog element and the payloaders.

Infrastructure

Long time GStreamer hacker Stefan Sauer (Google) gave a demo of his idea for a tracing infrastructure in GStreamer. The idea is to place trace macros at strategic places that would send structured data to pluggable tracer modules. Some of the tracer modules could, for example measure CPU usage of a plugin or measure the latency. The idea would be to gradually replace our extensive (but unstructured) logging with this new trace infrastructure. This would allow us to do new interesting things, like send debug log to a remote machine or produce STF (Structured Trace Format) to analyse with standard tools. No immediate plans were made to merge this but there seems to be very little resistance to get this merged soon.

Core hacker Sebastian Dröge (Centricular) has been going over the current Stream selection ideas. One of the long outstanding issues is that of switching streams between different languages: you have a movie in different languages and you want to switch between them. To achieve low-latency old data should be kept around for the streams that are not currently selected and be quickly and sent to the audio device. The idea is a combination of events to select a stream and to have the demuxer seek back in the stream on
switches. No final conclusion or plan that can solve all requirements has been reached yet.

Also investigations have begun to make decodebin deal with renegotiations. For example, when a new stream is selected, we might need to use a different decoder for this stream but also when new input is received, decodebin should be able to reconfigure itself. The decodebin code is a complicated beast so any change to it should be done carefully.

GStreamer maintainer Tim-Philipp Müller (Centricular) spent his time merging the new device probing and monitoring API (written by Olivier Crête from Collabora) that had been sitting in bugzilla for a while now. The purpose is to be able to probe devices and their capabilities such as v4l2 and ALSA devices. It’s also possible to be notified when devices appear and disappear in the system. An implementation for pulseaudio devices and another for v4l2 devices using gudev has been committed as well. This reimplements a
feature that was in 0.10, but got cut from 1.0 due to us not being happy with the old design. One of the complications with that was the fact that we ran out of bits in one of our enums so we needed to find a good solution for that.

We briefly discussed how to implement the SKIP seek flag. This extra flag can be used when doing fast forward or reverse and instructs the decoders that it is allowed to throw away data to more efficiently perform the trick mode (at reduced accuracy). There was a prototype for AVI playback that I implemented once that we discussed a bit. We’ll see if someone takes up the task to finalize this work and implement SKIP mode in more demuxers.

I took some photos during the event to capture the spirit and put them on Google Plus for your viewing pleasure.

A big thank you to Google for hosting us and providing us with free lunch and free drinks through the weekend.

PiTiVi fundraiser pass the 10 000 Euro mark

Hi, so I wrote A blog entry asking people to contribute to the PiTiVi fundraiser effort last week. I am happy to see them having already reached 10K Euro, but their goal of course is to get more. I am also happy to say that the GStreamer Project decided to support the fundraiser using some of the money we earned over the years doing Google Summer of Code and organizing the GStreamer Conference, which added 2500€ to the effort. You can read about the GStreamer donation here.

Anyway, I would once again want to ask people to contribute to this effort. There is a proven team behind this fundraiser, so this is not like a kickstarter where people are starting from scratch and you have no idea where they will end up going or what they might achieve. This is an existing project that just needs some polish to get it to critical mass. So visit the fundraising page and make your pledge.