There have been several occasions in the past years that I had to quickly change the MAC address of my computer in order to get proper network connectivity. May it be a corporate network that does not allow me to use my notebook in a guest wifi because the original MAC address is “known” or any other possible reasons you can come up with…
Now this is relatively easy on Mac OS X – you can do it with just one line on the shell. But now there’s an App for that. It’s called Spoof:
“I made this because changing your MAC address in OS X is harder than it should be. The Wi-Fi card needs to be manually disassociated from any connected networks in order for the change to apply correctly – super annoying! Doing this manually each time is tedious and lame.
Instead, just run spoof and change your MAC address in one command. Now for Linux, too!”
As racing cars with petrol engines gets more and more uninteresting for the masses and even Formula 1 faces competition by Formula E.
Now having humans inside cars racing a wide track is one thing, but using relatively cheap but extremely high-tech multi-copters with first-person-view cameras mounted on them and flown by crazy guys sitting next to the “racing track” is the next big thing!
“Ever notice how people texting at night have that eerie blue glow?
Or wake up ready to write down the Next Great Idea, and get blinded by your computer screen?
During the day, computer screens look good—they’re designed to look like the sun. But, at 9PM, 10PM, or 3AM, you probably shouldn’t be looking at the sun.
f.lux fixes this: it makes the color of your computer’s display adapt to the time of day, warm at night and like sunlight during the day.
It’s even possible that you’re staying up too late because of your computer. You could use f.lux because it makes you sleep better, or you could just use it just because it makes your computer look better.”
The next time you stumble across a PDF file with security and not allowing you to print or copy/paste.
“QPDF is a command-line program that does structural, content-preserving transformations on PDF files. It could have been called something like pdf-to-pdf. It also provides many useful capabilities to developers of PDF-producing software or for people who just want to look at the innards of a PDF file to learn more about how they work.
QPDF is capable of creating linearized (also known as web-optimized) files and encrypted files. It is also capable of converting PDF files with object streams (also known as compressed objects) to files with no compressed objects or to generate object streams from files that don’t have them (or even those that already do). QPDF also supports a special mode designed to allow you to edit the content of PDF files in a text editor. For more details, please see the documentation links below.
QPDF includes support for merging and splitting PDFs through the ability to copy objects from one PDF file into another and to manipulate the list of pages in a PDF file. The QPDF library also makes it possible for you to create PDF files from scratch. In this mode, you are responsible for supplying all the contents of the file, while the QPDF library takes care off all the syntactical representation of the objects, creation of cross references tables and, if you use them, object streams, encryption, linearization, and other syntactic details.
QPDF is not a PDF content creation library, a PDF viewer, or a program capable of converting PDF into other formats. In particular, QPDF knows nothing about the semantics of PDF content streams. If you are looking for something that can do that, you should look elsewhere. However, once you have a valid PDF file, QPDF can be used to transform that file in ways perhaps your original PDF creation can’t handle. For example, programs generate simple PDF files but can’t password-protect them, web-optimize them, or perform other transformations of that type.”
“Shadertoy is the first application to allow developers all over the globe to push pixels from code to screen using WebGL since 2009.
This website is the natural evolution of that original idea. On one hand, it has been rebuilt in order to provide the computer graphics developers and hobbyists with a great platform to prototype, experiment, teach, learn, inspire and share their creations with the community. On the other, the expressiveness of the shaders has arisen by allowing different types of inputs such as video, webcam or sound.”
So it happened to one of the VU+ Duos in the house. After a clean shutdown it did not boot up as expected but instead just showed the red light. It still blinked on remote keypresses and the harddisk spun up. Nothing else happened with it.
So it was bricked.
Reading the forums about that pointed to a capacitor on the board that quite regularly seems to fail. C807 is it’s name and it’s located near the Harddisk and the power-supply part of the VU+ Duo.
When I looked at the capacitor it did not seem to be faulty or anything. So without the right tools to measure I’ve decided to just give it a shot and replace the original 16V 220uF 85 degrees celsius capacitor with a 105 degrees celsius 16V 330uF one.
In my case I’ve taken out the board, to have a little bit of extra space, and cut of the old capacitor. Desoldering would be nicer looking but, well …
Replacing it on the left-over pins of the old capacitor was a matter of seconds.
After putting the board back in, the VU+ Duo powered up and booted as new. Brilliant!
“Odd patterns of I/O latency can be hidden by line graphs and summary statistics, and revealed by histograms and heat maps. In my previous post I showed my Linux iosnoop tool, which can trace block device I/O along with timestamps and latency. This information can be visualized, revealing any odd patterns.”
“Commands have been a big part of computing ever since the 1970’s. Their power comes from their simplicity. Just type a word or two to do what you want. The time has come to bring this power together with the usability and convenience of modern interfaces.”
“Xiki is open and flexible. It’s open source, and brings together tools, languages, shells, and text editors, rather than competing with them. Open formats and languages are the best thing for the tech ecosystem. HTML and JSON made the web what it is today. And the web arguably made everything else.
Xiki strives to be the simplest possible way (and ways) to create interactive interfaces. This means a text in and text out interface. Since everything is text, almost nothing is against the rules when you’re creating an interface in Xiki. Xiki stands for “expanding wiki”, and is inspired by the wiki philosophy of fully editable text, with simple syntaxes (like “>” for a heading, and “-” for a bullet). Xiki extends wiki ideas to user interface in general.”
“The Infinadeck is the world’s first affordable omnidirectional treadmill that is designed to work both in augmented and virtual reality. This revolutionary device provides the missing link making it now possible to have a true Holodeck experience. You might say, “Reality just got bigger”.”
If you ever experienced a missmatch between the performance you expected from a server or application running on Linux you probably started to debug your way into it why the applications performance is not on the expected levels.
With Linux being very mature you get an enormous amounts of helpers and interfaces to debug the performance aspects of the operating system and the applications.
Want to see proof? Here – a map of almost all the thingies and interfaces you got:
After setting up Boblight on two TVs in the house – one with 50 and one with 100 LEDs – I’ve used it for the last 5 months on a daily basis almost.
First of all now every screen that does not come with “added color-context” on the wall seems off. It feels like something is missing. Second of all it has made watching movies in a dark room much more enjoyable.
The only concerning factor of the past months was that the RaspberryPi does not come with a lot of computational horse-power and thus it has been operating at it’s limits all the time. With 95-99% CPU usage there’s not a lot of headroom for unexpected bitrate spikes and what-have-you.
So from time to time the Pis where struggling. With 10% CPU usage for the 50 LEDs and 19% CPU usage for the 100 LEDs set-up there was just not enough CPU power for some movies or TV streams in Full-HD.
So since even overclocking only slightly improved the problem of Boblight using up the precious CPU cycles for a fancy light-show I started looking around for alternatives.
“Hyperion is an opensource ‘AmbiLight’ implementation controlled using the RaspBerry Pi running Raspbmc. The main features of Hyperion are:
Low CPU load. For a led string of 50 leds the CPU usage will typically be below 1.5% on a non-overclocked Pi.
Json interface which allows easy integration into scripts.
A command line utility allows easy testing and configuration of the color transforms (Transformation settings are not preserved over a restart at the moment…).
Priority channels are not coupled to a specific led data provider which means that a provider can post led data and leave without the need to maintain a connection to Hyperion. This is ideal for a remote application (like our Android app).
HyperCon. A tool which helps generate a Hyperion configuration file.
XBMC-checker which checks the playing status of XBMC and decides whether or not to capture the screen.
Black border detector.
A scriptable effect engine.
Generic software architecture to support new devices and new algorithms easily.
Especially the Low CPU load did raise interest in my side.
Setting Hyperion up is easy if you just follow the very straight-forward Installation Guide. On Raspbmc the set-up took me 2 minutes at most.
If you got everything set-up on the Pi you need to generate a configuration file. It’s a nice JSON formatted config file that you do not need to create on your own – Hyperion has a nice configuration tool. Hypercon:
So after 2 more minutes the whole thing was set-up and running. Another 15 minutes of tweaking here and there and Hyperion replaced Boblight entirely.
What have I found so far?
Hyperions network interfaces are much more controllable than those from Boblight. You can use remote clients like on iPhone / Android to set colors and/or patterns.
It’s got effects for screen-saving / mood-lighting!
It really just uses a lot less CPU resources. Instead of 19% CPU usage for 100 LEDs it’s down to 3-4%. That’s what I call a major improvement
The processing filters that you can add really add value. Smoothing everything so that you do not get bright flashed when content flashes on-screen is easy to do and really helps with the experience.
All in all Hyperion is a recommended replacement for boblight. I would not want to switch back.
When traveling you might find yourself in the situation that you get a new SIM card into your iPhone and it’ll start and do it’s automatic magic for you. And eventually you well end up with the right provider settings by default.
But there are some cases when it picks the wrong provider settings. Like in my case. It picked NTT docomo in Japan with the default NTT docomo settings. In my case I was using a reseller for NTT (as described here) and that demanded different provider settings to work.
Unfortunately in all it’s wisdom the iPhone did not allow me to set the carrier settings. It just displayed the “Automatic” choice. So I went to the APN Changer website, entered the settings and installed a custom provider setting to my device. This works without any Jailbreak with iPhones without SIM Lock.
Airplay allows you to conveniently play music and videos over the air from your iOS or Mac OS X devices on remote speakers.
Since we just recently “migrated” almost all audio equipment in the house to SONOS multi-room audio we were missing a bit the convenience of just pushing a button on the iPad or iPhones to stream audio from those devices inside the household.
To retrofit the Airplay functionality there are two options I know of:
1: Get Airplay compatible hardware and connect it to a SONOS Input.
You have to get Airplay hardware (like the Airport Express/Extreme,…) and attach it physically to one of the inputs of your SONOS Set-Up. Typically you will need a SONOS Play:5 which has an analog input jack.
2: Set-Up a RaspberryPi with NodeJS + AirSonos as a software-only solution
You will need a stock RaspberryPi online in your home network. Of course this can run on virtually any other device or hardware that can run NodeJS. For the Pi setting it up is a fairly straight-forward process:
You start with a vanilla Raspbian Image. Update everything with:
sudo apt-get update
sudo apt-get upgrade
Then install NodeJS according to this short tutorial. To set-up the AirSonos software you will need to install additional avahi software. Especially this was needed for my install:
The public transportation feature of Google Maps works like a charm. It’s accurate as it can be and offers even walking instructions to get to the right platform or train station.
Notice the colored lines next to the different stations. That’s the color you’re looking for on the train. They are color coded! To find your right platform just take the information that Google gives you and look out for it. It will be written on signs “Rinkai towards Tokyo Teleport”.
Problem: Okay I know which train I have to use. But before I enter the platform I have to pass the ticket gate. How do I buy a ticket? How do I know which one?
Solution: Get a Suica card and charge it! If you’re a group travelling: Look out for cheap group ticket offerings.
A Suica card (aka “Super Urban Intelligent Card”) can be used instead of buying a ticket. You can buy it where you can buy the tickets – most of the time it’s 500 Yen + charge. Charging it with some Yen is crucical since the gates will not let you in when your card is not at least charged with 210 Yen.
You may ask: If I buy a ticket from A to B I have to pay the price upfront. When I use the Suica how does it work then? Easy answer: When you enter the train station through the ticket gate you pass it with your Suica card. It will start a journey for you. When you exit it will end the journey. The card and system is intelligent enough to calculate all steps in between, add them up and substract the fare price from your Suica balance. It always takes the cheapest price for single travellers.
If you’re on your way as a group you might want to use the ticket machines before going through the ticket gates. The Suica is a personal card and only suited for one person to be used. So you cannot pass it through the ticket gate back and enter the ticket gate again without causing panic with the service personell.
To buy tickets for groups I suggest to switch the terminals to english – most of them will offer that option. You then have to specifically know where you want to go. Sometimes it’s the easiest way to just go to the counter and buy them there.
Sometimes when you bought tickets you find out that you made a mistake. Fear not! You can give them back and by doing so get your money back. Service personell is awesome and will help you at any time! DO NOT PANIC!
Another awesome feature you get ‘for free’ by having a Suica card is that you can use it with all the vending machines available everywhere in the train stations. Just pick the beverage you want and swipe the card. Done!
Beware: fill the card up before going out of the ticket gate when you used it all up!
If you happen to have a NFC enabled device (like most Android phones) you can install the Suica Reader app from the Google Store and get information about what happened to your card so far.
Tsung is an open-source multi-protocol distributed load testing tool
It can be used to stress HTTP, WebDAV, SOAP, PostgreSQL, MySQL, LDAP and Jabber/XMPP servers. Tsung is a free software released under the GPLv2 license.
The purpose of Tsung is to simulate users in order to test the scalability and performance of IP based client/server applications. You can use it to do load and stress testing of your servers. Many protocols have been implemented and tested, and it can be easily extended.
It can be distributed on several client machines and is able to simulate hundreds of thousands of virtual users concurrently (or even millions if you have enough hardware …).
How many times did you experience a connection loss on your terminal window in the last week? Yeah I know – like everytime you close the lid of your notebook and move to a different place. So like a dozen times every day.
And everytime you reconnect to your servers and you use things like screen to keep your terminals open and your programs running while you’re disconnected.
On the other hand – did you ever curse the internet gods while you tried to do a very important check or bugfix to a machine whilst on a train or mobile roaming network? It’s not what I would call fun-times. When there are no constant disconnects the lag is just infuriating. MOSH also solves this since it’s predicting and responding way faster then vanilla SSH. Your terminal becomes useable again!
So there’s now MOSH to the rescue:
Remote terminal application that allows roaming, supports intermittent connectivity, and provides intelligent local echo and line editing of user keystrokes.
Mosh is a replacement for SSH. It’s more robust and responsive, especially over Wi-Fi, cellular, and long-distance links.
Mosh is free software, available for GNU/Linux, FreeBSD, Solaris, Mac OS X, and Android.
The purpose of TIME-WAIT is to prevent delayed packets from one connection being accepted by a later connection. Concurrent connections are isolated by other mechanisms, primarily by addresses, ports, and sequence numbers