A quickie: watching 3D movies on a Philips TV (7000 line)

Recently, I was struggling a bit with our new Philips TV. It can do 3D and it can play *.avi and *.mkv movies but it seemed not to be able to play these in 3D even though they had the 3D information encoded (side by side).

After some fiddling, I found out: it works perfectly. The only thing that’s blocking the 3D feature is that the samples I tried were not in HD. Apparently the TV requires the source file to have a 1920×1080 resolution. Once you got the file in the right format, it works like a charm and you can enable the 3D feature via the on-screen menu.

Here is a quick command to re-encode a clip in the right resolution and in a format that the TV can definitely read:

$> mencoder 3d-sample-in.avi -vf scale=1920:1080 -o 3d-sampe-out.avi \\
   -oac mp3lame -ovc lavc -lavcopts vbitrate=2200

Mencoder is part of the mplayer software package. I have not optimized the above line for performance or size… using different encoder options may result in a much better result.

Color your shell – 1: colorful ls

Preface:

This is a series of posts that explain how to get to a nicely colored shell by tweaking your .bahsrc.

I am aware that each of these hints has been discussed on the Internet forever. However, it took me a little while to get all into my .bashrc, so I hope this will be useful for someone.

Colorful directory listings (ls)

Getting color to ls is fairly easy. You basically just turn it on. However, depending on your OS, you may have to push different buttons to get it working.

Some words on malloc and memset

Some people seem to have a particular strategy when it comes to using malloc and memset. The strategy is simple:

Use malloc often, then memset everything. [don't do this at home]

The bad thing about that strategy is that it leads to complex code and non-obvious bugs. The following mini-tutorial is based on some slides I prepared for a small tutorial for our students at RWTH Aachen University.

pbcopy and pbpaste

pbcopy and pbpaste are two very simple shell commands that help you to streamline your copy & paste operations.

pbcopy copies stdin to the OSX clipboard. pbpaste copies the clipboard content to stdout. Combining both allows you to perform complex operations on your clipboard contents. Need an example:

pbpaste | fmt -s -w 80 | pbcopy

will format the text in your clipboard so that it breaks at a text width of 80 characters. very good if you need to write technical documents with fixed character width. I guess you can easily imagine any text-based workflow. Just think of what stream processing you can do with html tidy, aspell, etc.

Of course, putting your pbpaste/pbcopy chain to a script that you can conveniently run from any shell or binding it to a key combination will make the whole thing even more useful.

I found this works for OSX. Maybe there is an equivalent for Linux as well. Any hints?

RFC2828: A very useful document for network security terms

I have been searching for such a thing for a very long time. I have no clue why it took me so long to find it but the more I am happy that I can now be certain to use the right words.

RFC2828 is a must for everyone writing about network security:

http://www.ietf.org/rfc/rfc2828.txt

Filemerge / opendiff confuses me

This post is an attempt to remove my confusion when using opendiff AKA filemerge. Opendiff is a very handy and quick tool for visually comparing files. However, the way it visualizes the portions of two files that are to be merged into one keeps confusing me. The symbol is an arrow, However, I always wonder whether the direction of the arrow symbolizes the direction of the changes (text at the blunt edge of the arrow will survive) or if the pointed part of the arrow points at the text that will survive.

The message to me is:

“THE TEXT AT THE ARROWHEAD WILL SURVIVE”.

Keep this in mind, Tobias!

Change svn commit message after commit

D’oh! A mistake in a svn commit message. And now it’s there forever…. or at least until you fix it with:

svn propedit svn:log --revprop -r N --editor-cmd vim

of course, you have to replace N with the proper version number. Pick another –editor-cmd if you don’t fancy vim.

Use filemerge with svn diff

Looking at diffs is essential when working with svn. However it can be quite cumbersome because the default behavior is not very user friendly. The output is ugly and hard to read and it is a pain to the eye. Fortunately you can easily substitute the default diff function of svn with something more fancy – filemerge on Mac (it comes with the xcode tools) or vimdiff.

First create a wrapper file that will handle the calling of filemerge or vimdiff. I put it into ~/bin/svndiffwrap.sh

#!/bin/sh
DIFF="$(which opendiff)"
DIFF $6 $7

opendiff is the command line tool for filemerge. Put vimdiff there if you like vim better.

Mobile Collaboration Systems Workshop

I am co-organizing the “Mobile Collaboration Systems” workshop in Aix-en-provence next week. The workshop will be a platform to share and discuss theories, understandings, experiences and lessons learned in the field of mobile collaboration systems. The workshop is held in conjunction with the COOP’10 conference.

From the call for papers: Mobile devices are expected to soon become the “primary computer” and tool for sharingand connecting with others. In our thriving world of mobile communication, technologicaladvances have brought a number of novel and improved ways of collaboration; in business, commerce, healthcare, education, and society in general. Collaboration can help to overcome the limitations of a single user, device, and network. However, creating mobile collaborative applications and systems requires careful consideration and design. This workshop aims to bring together designers, practitioners and researchers who share an interest in the study and design of mobile collaborative systems.

UPDATE: The workshop was very interesting and productive. We benefitted from a very diverse set of people, research areas and opinions. A perfect combination for a topic that spans social and technical aspects.

New paper: PiSA-SA: Municipal Wi-Fi Based on Wi-Fi Sharing

A new paper related to Wi-Fi sharing and municipal Wi-Fi will be published this summer at ICCCN (IC3N) in Zurich. The paper is eight pages long and can be downloaded HERE. The paper covers the service architecture that we developed for the Mobile ACcess project. Here comes the paper abstract:

Large-scale municipal wireless networks are currently being established all around the world. These networks provide a rich set of local services, such as tourist guides, environmental information, pedestrian navigation, and local shopping guides. As recent financial failures of prominent municipal wireless networks show, it is economically challenging to achieve the bandwidth and coverage that is necessary for such a network. At the same time, Wi-Fi-sharing communities achieve high bandwidth and good coverage at a very low cost by capitalizing on the dense deployment of private access points in urban areas. However, from a technical, conceptual, and security perspective, Wi-Fi sharing community networks resemble a patchwork of heterogeneous networks instead of one well-planned, uniform and secure network as required for the economic success of a municipal Wi-Fi project. In this paper, we show how to realize municipal wireless services on top of a Wi-Fi-sharing infrastructure in a technically sound and economically attractive fashion while taking into account legacy devices and mobile clients. Our solution cleanly separates the roles of controlling and administering the network from providing bandwidth and wireless access. This allows municipalities to focus their resources on municipal wireless services instead of providing Wi-Fi access.