Chef de Cambuse, cruising and wine

Entries in the Category “coherence”

Stranded in San Francisco

written by Frank, on Apr 20, 2010 4:40:00 AM.

Having time to write a post here - doesn’t that sound very suspicious?

But this happens - more or less only - due to being “stranded” in the United States.

I was invited to do a talk about Mirabeau and Coherence at this years CELF Embedded Linux Conference in San Francisco.

Tim Bird and Ueda-san during the closing session of ELC

Following that I had the pleasure to attended the Linux Foundation Collaboration Summit, which was co-located with the ELC.

Jim Zemlin - opening keynote LCS

Very remarkable talks in both conferences, met a lot of interesting people and gained quite some new insights.

And being already here I thought of adding one more weekend to do some sight-seeing, exploring the city, watch the annual Northern California Cherry Blossom festival, visiting Muir Woods, which I last had the chance some six years ago.

The one and only bridge
Cable car at Stockton/California
you don't see shops like this very often, and great ice-cream too
sushi & cherry blossoms
stone garden in the Golden Gate Park's Japanese Tea Garden
awe-inspiring trees, been there before the iPad and will be long after that

And along came Eyjafjallajökull.

Not only for me, pretty much all the flights of the European attendees of the conferences have been canceled. As mine was scheduled for todays afternoon I had some hope that it might be just in time for the European air space getting opened up again, but failed. Lufthansa seems to operate as of now at least partially from Frankfurt again, but Star Alliance partner United Airlines decided to keep their planes on ground.

After some first evil tidings - next possible flight to Europe would be 25th, no, 26th, no, hang on, not before 27th - Nadine, event manager of the Embedded Linux Conference - who, together with her team, did a really tremendous job in organizing the conference, managed to get me rerouted on a flight for Thursday 22nd.

Nadine, thank you so much!

Now I unintentionally will get the chance to see some of the United States airports - leaving San Francisco in the early morning, going to Denver, from there to Washington, changing plane there for the leg over the ocean, arriving in Zürich on Friday morning and, one last hop, should be in Frankfurt around noon.

Probably more endurance testing than travel, but never mind, it will get me home. And, not to be sneezed at, within my supply of insulin and blood sugar checks.

With that option available I decided to stay in my very comfortable room in the Kabuki in Japantown, use the wifi here to do some work and maybe even find time to check in some long outstanding Coherence patches, and enjoy some more days of Japanese food and culture.

A trace of Zen
chance encounter
geeky lunch, had even a nicer platter around
Under my umbrella
Do not ask, I've no idea
The art of eating ramen - delicious Karaage Ramen at Suzu's

Going to FOSDEM 2010

written by Frank, on Feb 5, 2010 5:50:00 PM.


Actually I just arrived in the really nice hotel in Brussels


after a remarkable unspectacular flight.

Will later meet Philippe for dinner and probably discuss some last-minute modifications - nah, just kidding - of our Mirabeau presentation about creating personal media networks and bridging UPnP over XMPP on Saturday 6th in the Jabber/XMPP dev-room at 16:00 o’clock.

Having dinner before the beer-event is actually quite a good idea™.

I’ll do another presentation on Sunday morning in the CrossDesktop room at 11:00 o’clock titled Coherence - the Digital Living room and beyond.

Stop by if you are at FOSDEM too.

This time I had planned to fly out on Monday evening, to have some time for sight-seeing, but we have decided to take part in the XMPP Dev Challenge.

So probably again no time for visiting the Atomium.


Pont Mirabeau - an UPnP bridge

written by Frank, on Jun 30, 2009 10:56:00 PM.

What started over a year ago as a vague idea and got more concrete in a first prototype last October, is now ready for a first public beta - Mirabeau, an application level proxy for UPnP devices using XMPP as a transport to establish a connection between two or more local networks over the Internet.

Or in less technical terms, it allows the DLNA capable TV at your parents place to access for instance the images of your last vacation stored on an UPnP MediaServer in your home.

Mirabeau is part of Coherence and utilizes the D-Bus interface there to create a transport layer over XMPP with the help of Telepathy’s tubes.

Philippe and I will give a presentation about it during this years Gran Canaria Desktop Summit.

Mirabeau addresses the issue that UPnP is only meant to be used in a local network. With Mirabeau we are able to easily interconnect two or more networks and the UPnP devices therein. All that with a simple, well-used setup - Jabber, and without the need for complicated VPN-tunnels or similar techniques.

Philippe wrote already about our first successful - world premiere - connection with our two networks in Spain and here in Germany, where we tested the whole infrastructure with the UPnP-Inspector.

What I would like to highlight here is the point that arbitrary UPnP devices do participate in this.
Mirabeau is a transparent bridge for UPnP devices on the application level, not only an ‘I can share my media collection between two instances of the same software’ setup.
Which is of course nice too, but we lifted that to a more higher level and instantly integrate everything that can talk UPnP - PS3, Xbox 360, Totem

Nokia MediaStreamer browsing Phil's server in Spain

An unmodified UPnP application on the N810 - Nokia’s MediaStreamer is browsing Phil’s server in Spain.

And the same by a Playstation 3:

PS3 browsing Phil's server in Spain PS3 browsing Phil's server in Spain

So if you are interested in this or want to know more don’t miss our talk @ GCDS, or join us on IRC freenode #coherence.

working at (train à) grande vitesse

written by Frank, on Jun 6, 2009 9:31:00 PM.

I’m usually not using trains, the city I live isn’t that well connected to the German railway system, so usually I’m faster by car or for longer distances I go by plane.

But for the travel from Valras-Plage to the Trophees du Libre in Soissons I had chosen to use the TGV - there is a direct train connection between Beziers and Paris that covers the distance in a bit more than four hours.

I booked première class - it was only a few €s more than seconde, and I had learned from my trip to Paris for the KDE/Coherence sprint that there is no power outlet at the seats in the second class in a TGV.

The ambience in the train was very decent. A lot of space - I had booked a single seat with a table, no people yelling into their mobiles, more or less all have been muted, and everybody speaks with a lowered voice.

In that pleasant atmosphere I used the ~ six hours time to work on some of the loose ends in Coherence.

  • creating a picture-frame MediaRenderer that should serve as an example on how to implement a simple MediaRenderer
  • the implementation of a Digital Security Camera device, based on the general purpose GStreamer pipeline element from the TestStore backend
As you might see on the first result, I’m quite pleased with it.

1st webcam image

And I do now understand people a bit better who always told me how great traveling by train is.


written by Frank, on Jun 6, 2009 10:48:00 AM.

Coherence has been awarded the “Prix spécial du Jury” - out of the 130 competitors of this years Trophées du libre contest and in addition made second place in the “Media” category.

N’est-ce pas magnifique!

A huge MERCI to all of you making this possible, to the jury and to the organizers of the Trophées.

Erwan and Frank being very happy Erwan and Frank being very happy
Champagne and snacks at the Mairie of Soissons Champagne and snacks at the Mairie of Soissons
PS3, Sheevaplug, Denon amp and Prizes PS3, Sheevaplug, Denon amp and Prizes

The Sheevaplug was kindly donated by Marvell to support further development on this truly awesome device - thx again Rabeeh, and DENON France has graciously provided us with one of their high-end DLNA-enabled amplifier to demonstrate a real user living-room experience.

Presenting Coherence on the Trophées du Libre Days

written by Frank, on Jun 5, 2009 2:18:00 PM.

Erwan and I are presenting Coherence here in Soissons.

setup @ Soissons

We just had our first presentation to the jury of the ‘Media’ category, more will come in the afternoon.

So keep your fingers crossed!

Coherence/KDE sprint - day one

written by Frank, on May 9, 2009 7:09:00 PM.

Bonjour from Paris.

This morning we - Philippe, Erwan, Adriaan, Bart, Benjamin and myself - meet at the offices of Mandriva, who kindly offered to host the sprint

and started with our work to integrate Coherence into KDE, mainly to create a kio network slave and an Amarok plugin - both connecting to Coherence over DBus.

Over the typical French lunch break there has been some serious discussion between Adriaan, Bart and Erwan about French cheese.


written by Frank, on Apr 24, 2009 8:12:00 PM.

Coherence is one out of four finalists in the category “Media”
of this years Trophées du libre.

Kudos once more to Erwan Velu for his magnificent promotion!

media collection playing - the DLNA way

written by Frank, on Apr 23, 2009 3:00:00 PM.

Media collections - being it all songs from one album, a list of favorites, or an image slideshow - have not attracted much attention in the world of UPnP A/V.

Of course there are the ContentDirectory objects playlistContainer and playlistItem, but these - if at all - are mostly used to point to some M3U file. And in addition, the client has to support that format. Another drawback is that M3U files don’t fit very well into the UPnP A/V philosophy. A ControlPoint will only know about the M3U file, but not which item of it is played at the moment. Or what metadata is associated with that item. Neither are next and previous operations implementable.

So the task of handling the collection was handed off to the ControlPoint. It was responsible now for holding a list of items to play and to instruct the MediaRenderer to load and play the next item in the list the moment the previous was finished. With the drawback that this list has to be created somehow first.

Same for the autonomous MediaClient, like the Playstation 3 or the XBox 360, their internal part of a ControlPoint usually just continues with the next item in the container.

Now that wasn’t a big issue in the days when we had only autistic autonomous MediaClients, but now more and more real MediaRenderers - meaning alongside to their internal client UI they are (remote) controllable by a ControlPoint - are available. The new Sony Bravia TV 4500 or 5500 series are maybe the most prominent example.

But the DLNA specification offers an interesting approach - they created the dlna-playcontainer URI.

That’s the uri for an additional res element a MediaServer can add automatically to an existent container.
Encoded in the uri is

  • the UDN of the device, the MediaServer
  • the service type, usually a ContentDirectory
  • the container id
  • the id of the first item
  • the index of the first item
  • the optional sort-criteria
  • the max-depth information - aka the level of subcontainers, optional too
It looks a bit like this:


With that information a MediaRenderer is now able to call a Browse action on the ContentDirectory service of that device and retrieve all the items of that container. And propagate with AVTransportURI/AVTransportURIMetaData the “dlna-playcontainer” uri and with CurrentTrackURI/CurrentTrackMetaData the track item uri and the corresponding metadata.

I’ve started to add that functionality to the Coherence MediaServers and to the GStreamer MediaRenderer.
It will be part of the upcoming 0.6.4 release of Coherence and the 0.2.2 release of the UPnP-Inspector.

As the specification doesn’t describe the whole thing in detail and I haven’t seen yet an UPnP A/V MediaServer beside Coherence supporting this I’m glad about any feedback.

Participating in the Trophées du Libre 2009 contest

written by Frank, on Apr 12, 2009 1:33:00 PM.

Tl09 banner

Thanks to the assiduous work of Erwan Velu, Coherence is one of the participants of the Trophées du Libre 2009 contest in the category ‘Media’.

The finalists will be announced April 22nd - please keep your fingers crossed.