- Family and Friends
I was setting up a new root-server machine and went for the Debian 7 minimal set-up. Thankfully the root-server provider I am using (hetzner) is connected with IPv4 and IPv6 natively. Awesome stuff!
If you’re using an IPv6 native set-up these days you STILL have to be cautious about possible side-effects with software having bugs and not knowing how to deal with these ginormous ip adresses.
So there’s a well known Jabber / XMPP server that I am using for some years now without any issues. I was even using it on native IPv6 connected machines earlier.
But with the fresh and clean set-up of Debian 7 and IPv6 by the hoster several problems started bubbling up.
1: the ‘there can only be one ipv*’ problem
Turns out that the debian team decided to set a system setting by default that lets IPv6 aware applications bind to IPv6 only. Good thing, you can disable it by adding this to your sysctl.conf:
2: the ‘who resolves first is right’ problem
When you get a IPv6 native machine it might have a resolv.conf consisting of IPv4 and IPv6 name servers. And don’t worry: Everything is going to be all-right as long as the software you’re planning to use is perfectly capably dealing with the answers of both types of servers. The IPv4 ones will default to the A records, the IPv6 ones to the AAAA record.
Now there’s OpenFire. A stable and easy to use XMPP / Jabber server implementation. It’s based upon Java and I am running it with Java 7 on my Debian machine.
Unfortunately in the current 3.9.1 version of OpenFire there’s a bug that leads to Server-to-Server XMPP connections not working when they resolv to IPv6. So for example your Google-Talk contacts won’t work at all.
The bug itself is rather stupid: Seems that OpenFire expects an IPv4 adress from the DNS lookup and crashes on an IPv6 adress.
The solution is as easy as the bug is stupid: Remove the IPv6 defaulting nameservers from your resolv.conf.
# nameserver config
“The Data Visualisation Catalogue is currently an on-going project developed by Severino Ribecca.
Originally, this project was a way for me to develop my own knowledge of data visualisation and create a reference tool for me to use in the future for my own work. However, I thought it would also be useful tool to not only other designers, but also anyone in a field that requires the use of data visualisation regularly (economists, scientists, statisticians etc).
Although there have been a few attempts in the past to catalogue some of the established data visualisation methods, there is no website that is really comprehensive, detailed or helps you decide the right method for your needs.
I will be adding in new visualisation methods, bit-by-bit, as I research each method to find the best way to explain how it works and what it is best suited for.”
Source 1: http://datavizcatalogue.com/
“Brackets is an open source code editor for web designers and front-end developers.”
Source 1: http://brackets.io/
“The internet of things” is a buzzword used more and more. It means that things around you are connected to the (inter)network and therefore can talk to each other and, when combined, offer fantastic new opportunities.
So NodeRed is a NodeJS based toolset that allows you to create so called “flows” (see picture above). Those flows determine what reacts and happens when things happen. Fantastic, told you!
How to fix a mono CS0589 Internal compiler error during parsingSystem.FormatException error on the RaspberryPi
When you want to compile some C# code using MONO on Linux on your RaspberryPi and you encounter this strange error message:
error CS0589: Internal compiler error during parsingSystem.FormatException
You need to do:
- Update your Debian by running:
sudo apt-get upgrade
sudo apt-get update
- Upgrade your RaspberryPi firmware:
- Reboot your RaspberryPi
- Retry compiling – should work now.
The reason for Mono to crap out like above: Previous Mono versions and RaspberryPi firmwares where not compatible due to one side using HardFP and the other not.
“ZFS is really the final word in filesystems. With a feature set longer than this tutorial, it can take a while to master. You can set many more options per dataset, enable disk usage quotes and much more. Once you’ve used it and seen the benefits, you’ll probably never want to use anything else. Hopefully this has been helpful to get you on your way to becoming a FreeBSD ZFS master.”
I give you: the SONOS Audiobook / Podcast Auto Bookmarker – never lose your Listening Progress again…
Since the SONOS system I’ve bought turned out to be highly hackable I’ve spent some quality-time this weekend fixing the worst downside I’ve found so far that the SONOS system had for me
I am listening to a lot of Podcasts and Audiobooks. And it turns out that those two Genre are not particularly good supported by SONOS. When you’re listening to a 4 hour podcast and you stop it to play a song in between (since you stretch the listening of that podcast to several days) the next time you start that 4 hour podcast the SONOS system did not remember the position that you stopped at the last time and restarts the podcast from the beginning.
If you did not remember where you left of the last time, you’re lost. The same goes for Audiobooks.
Now this is the first feature I am teaching my SONOS system. And I am opensourcing it so you can do it as well.
Everything you need can be run on a RaspberryPi:
- You need NodeJS and node-sonos-http-api installed and running.
- You need MONO and sonos-auto-bookmarker (change the configuration.json file in bin/Debug after you xbuilded the .sln file)
Now the Auto Bookmarker Tool will, with the help of the sonos-http-api, monitor your household and whenever something longer than 10 minutes is played and stopped it bookmarks the last played position. Whenever you restart that track it will then seek to the last known position automatically.
I always wanted a networked multi-room audio solution as you can easily see here and here and here and here. Now it seems I’ve finally found something that integrates very well into our music listening habits and our infrastructure. And on top of that it turned out to be highly hackable.
I’ve went with SONOS for that multi-room solution. After trying two speakers for two rooms I’ve invested the budget into the full-house solution (not all speakers on below picture). And finally everything is as I always wanted.
Be warned: If you buy one speaker, you will definitly buy more.
So what’s in those boxes? Besides beautiful and high-quality speakers there’s a 250 Mhz linux powered computer inside each speaker. It got 64Mbytes of memory and wireless adapters to span it’s own wireless mesh network (hidden by default).
Each speaker on it’s own can be controlled and accessed through the SONOS controller applications (Windows/Mac/iOS/Android) or through several tools that open up new possibilities.
There will be more articles coming on the topic of hacking SONOS, adding functionality and using it for things not officially planned for by the manufacturer. Yoy!
Source 1: http://splok.org/sonos_interface
How to install NodeJS and NPM on the RaspberryPi without getting “Illegal Instruction” error messages
I tried a couple of times to compile NodeJS on the RaspberryPi and failed miserably. It not only takes ages to compile NodeJS on the Pi. After the successful compile and install run most of the time running it just results in an error message “Illegal Instruction” or “Ungültiger Maschinencode”.
Now there’s a pretty easy way to do that on your own. Run these commands:
After the download is finished successfully you can install it by running this as root:
sudo dpkg -i node_latest_armhf.deb
This will have installed a relatively new NodeJS built as well as NPM on your RaspberryPi. Don’t panic when NPM is slower than you would expect… just be patient.
“You want to extract one paragraph of text from a pdf your coworker sent you? One quote from your professor’s presentation? A couple of code lines from this tutorial clip on your favourite movie platform? It’s just one hotkeypress away. OCR everything on the fly.
Condense is the product of many frustating years of using overly complicated OCR software. “Take a screenshot, boot up your OCR suite, select the area you want to extract, select an output file…” Oftentimes typing out is faster than walking through this procedure.”
Source 1: http://www.condenseapp.com/
Having live streams of common german news radio handy when in other countries is essential. Here’s a good offer (not made by the radios :-))
Source 1: http://www.drad.io/
Source 1: http://flets.com/freewifi/service.html
“Swagger is a specification and complete framework implementation for describing, producing, consuming, and visualizing RESTful web services. The overarching goal of Swagger is to enable client and documentation systems to update at the same pace as the server. The documentation of methods, parameters, and models are tightly integrated into the server code, allowing APIs to always stay in sync. With Swagger, deploying managing, and using powerful APIs has never been easier.”
An exciting new feature has been added to the Miataru service! It’s now possible to embed the location of a device into any website. Here’s an example:
It’s a pretty easy process. When your device is available on the standard public miataru service you only have to embed an iFrame into the website. Just like this:
<iframe width=”320″ scrolling=”no” height=”240″ frameborder=”0″ src=”http://miataru.com/client/embed.html#BF0160F5-4138-402C-A5F0-DEB1AA1F4216;Demo Device”></iframe>
Playing with OpenStreetMap resources lately I came to the point where I wanted to calculate routes between points based on the OSM data. Now there is GraphHopper to the rescue! It’s opensource and awesome!
“GraphHopper offers memory efficient algorithms in Java for routing on graphs. E.g. Dijkstra and A* but also optimized road routing algorithms like Contraction Hierarchies. It stands under the Apache License and is build on a large test suite.”
Source 1: http://graphhopper.com
It’s impressive what these browsers started to become these days. Here you have a quite convincing wave simulation right in your browser with some knobs to play with:
Useful advice is right ahead! This cheat sheet gives some very interesting thoughts and advices for your own or others business.
I particularly liked:
“21) Should I ever focus on SEO? No.
22) Should I do social media marketing? No.”
Some might know AmbiLight – a great invention by Philips that projects colored light around a TV screen based upon the contents shown. It’s a great addition to a TV but naturally only available with Philips TV sets.
Not anymore. There are several open-source projects that allow you to build your very own AmbiLight clone. I’ve built one using a 50-LEDs WS2801 stripe, a 5V/10A power supply, a RaspberryPi, and the BobLight integration in RaspBMC (this is a nice XBMC distribution for the Pi).
“Boblight is a collection of tools for driving lights connected to an external controller.
Its main purpose is to create light effects from an external input, such as a video stream (desktop capture, video player, tv card), an audio stream (jack, alsa), or user input (lirc, http). Boblight uses a client/server model, where clients are responsible for translating an external input to light data, and boblightd is responsible for translating the light data into commands for external light controllers.”
The hardware to start with looks like this:
I’ve fitted some heat-sinks to the Pi since the additional load of controlling 50 LEDs will add a little bit of additional CPU usage which is desperately needed when playing Full HD High-Bitrate content.
The puzzle pieces need to be put together as described by the very good AdaFruit diagram:
As you can see the Pi is powered directly through the GPIO pins. You’re not going to use the MicroUSB or the USB ports to power the Pi. It’s important that you keep the cables between the Pi and the LEDs as short as possible. When I added longer / unshielded cables everything went flickering. You do not want that – so short cables it is
When you look at aboves picture closely you will find a CO and DO on the PCB of the LED. on the other side of the PCB there’s a CI and DI. Guess what: That means Clock IN and Clock OUT and Data IN and Data OUT. Don’t be mistaken by the adapter cables the LED stripes comes with. My Output socket looked damn close to something I thought was an Input socket. If nothing seems to work on the first trials – you’re holding it wrong! Don’t let the adapters fitted by the manufacturer mislead you.
Depending on the manufacturer of your particular LED stripe there are layouts different from the above image possible. Since RaspBMC is bundled with Boblight already you want to use something that is compatible with Boblight. Something that allows Boblight to control each LED in color and brightness separately.
I opted for WS2801 equipped LEDs. This pretty much means that each LED sits on it’s own WS2801 chip and that chip takes commands for color and brightness. There are other options as well – I hear that LDP8806 chips also work with Boblight.
My power supply got a little big to beefy – 10 Amps is plenty. I originally planned to have 100 LEDs on that single TV. Each LED at full white brightness would consume 60mA – which brings us to 6Amps for a 100 – add to that the 2 Amps for the PI and you’re at 8A. So 10A was the choice.
To connect to the Pi GPIO Pins I used simple jumper wires. After a little bit of boblightd compilation on a vanilla Raspbian SD card (how-to here). Please note that with current RaspBMC versions you do not need to compile Boblight yourself – I’ve just taken for debugging purposes as clean Raspbian Image and compiled it myself to do some boblight-constant tests. Boblight-constant is a tool that comes with Boblight which allows you to set all LEDs to one color.
If everything is right, it should look like this:
Now everything depends on how your LED stripes look like and how your TVs backside looks like. I wanted to fit my setup to a 42″ Samsung TV. This one already is fitted with a Ultra-Slim Wall mount which makes it pretty much sitting flat on the wall like a picture. I wanted the LEDs to sit right on the TVs back and I figured that cable channels when cut would do the job pretty nicely.
To get RaspBMC working with your setup the only things you need to do are:
- Enable Boblight support in the Applications / RaspBMC tool
- Login to your RaspBMC Pi through SSH with the user pi password raspberry and copy your boblight.conf file to /etc/boblight.conf.
The configuration file can be obtained from the various tutorials that deal with the boblight configuration. You can choose the hard way to create a configuration or a rather easy one by using the boblight configuration tool.
I’ve used the tool
Now if everything went right you don’t have flickering, the TV is on the wall and you can watch movies and what-not with beautiful light effects around your TV screen. If you need to test your set-up to tweak it a bit more, go with this or this.
Source 1: http://en.wikipedia.org/wiki/Ambilight
Source 2: http://www.raspberrypi.org/
Source 3: https://code.google.com/p/boblight/
Source 4: http://www.raspbmc.com/
Source 5: http://learn.adafruit.com/light-painting-with-raspberry-pi/hardware
Source 6: How-To-Compile-Boblight
Source 7: Boblight Config Generator
Source 8: Boblight Windows Config Creation Tool
Source 9: Test-Video 1
Source 10: Test-Video 2
Quite an interesting read of things to have in mind when doing, you know… life
“Make time to pursue your passion, no matter how busy you are.“
A very interesting find that I wanted to blog about for a while now – loads of stuff to read and watch through – let it be art or history.
“Google has partnered with hundreds of museums, cultural institutions, and archives to host the world’s cultural treasures online.
With a team of dedicated Googlers, we are building tools that allow the cultural sector to display more of its diverse heritage online, making it accessible to all.
Here you can find artworks, landmarks and world heritage sites, as well as digital exhibitions that tell the stories behind the archives of cultural institutions across the globe.”
Source 1: http://www.google.com/intl/en/culturalinstitute/about/
Source 2: D-Day
Interesting concept: By allowing you to play sounds of coffee shops and lounges – the chattering and mumbling of people in the background – this website tries to boost creativity.
The wikipedia tells about JSON:
Unfortunately complex JSON can get a bit heavy on the structure itself with over and over repetitions of data-schemes and ids.
There’s RJSON to the rescue on this. It’s backwards compatible and makes your JSON more compressible:
“RJSON converts any JSON data collection into more compact recursive form. Compressed data is still JSON and can be parsed with
JSON.parse. RJSON can compress not only homogeneous collections, but also any data sets with free structure.
RJSON is single-pass stream compressor, it extracts data schemes from document, assign each schema unique number and use this number instead of repeating same property names again and again.”
Of course this is all open-source and you can get your hands dirty here.
While I am using Xcode a lot lately I quickly got used to one or two keyboard shortcuts that come in handy once every while. This cheat sheet aims at bringing you a lot of shortcuts that are pretty hard to remember if you’re not using them all the time (at least for me).