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2014-12-23 [E] [D]
bash Comments 0

Just for quick reference: to take the md5sum of a cd one can not just do md5sum /dev/cdrom0, because the physical CD also includes trailing empty space, changing the hash.

This quick oneliner will calculate the md5sum of a cd at device $DEVICE (e.g. /dev/cdrom0) such that it can be used to compared with an ISO at location $ISO. You can ofcourse replace md5sum with something else like sha256sum.

DEVICE=/dev/cdrom0; ISO=/media/isos/archlinux.iso; dd if="${DEVICE}" bs=2048 count="$(expr $(stat -c '%s' "$ISO") / 2048)" | md5sum

A more userfriendly script which does this [and which is just copied from Ubuntu's help site, can be downloaded from cmp-iso-cd-md5.sh.

2014-11-24 [E] [D]
music Comments 0

Beautiful visualization of Brad Mehldau's song Don't Be Sad on the album Highway Rider, the melody of which keeps haunting me, and that's a good thing.

https://www.youtube.com/watch?v=DACRXmimmpg

A transcription of the initial part can be found on this wordpress

2014-11-20 [E] [D]
bash,code Comments 0

For my research I often need to simulate video traffic. The obvious best way is to get a real video, and then "transfer" it in the simulated network. However, this needs a video parser that can handle all the video containers and compressions that are used.

A better method is to just use the data that we actually need.

http://trace.eas.asu.edu contains a nice collection of video traces, and even offers a tool to create the traces yourself. It is, however, a Windows only tool.

Therefore, I set out to create my own cross-platform tool.

The requirements are python, ffmpeg and youtube-dl (the latter only if you plan on downloading from youtube) You can download the script from extract_video_data.py.

CLI usage is as follows: python extract_video_data.py [-h|--help] [--exclude-video] [--include-audio] [--limit-t t] (FILE_IN|--youtube url). It generates output similar to traces.eas.asu.edu, except it does not contain the final columns relating to quality and such.

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Aah, Rome, Caput Mundi! A friend asked me if I wanted to join in on a trip to Rome. As my Roman knowledge (of my Latin class which taught me a lot about ancient Rome and its customs), my long-ago visit to Rome were fading so horribly from memory and my Italian could use some practice, I decided Roma deserved another visit!

So, welcome to Italia!


Italia!  map

According to the legend, firstly written down by the Roman writer Virgil, the city was founded on 21st of April 753 BC. Romulus and Remus, the twin sons of god of war Mars and Vestal Virgin Rhea Silvia, the twins were left to die in a reed basket on the river Tiber, after their mother was killed. However, they were really lucky, as they floated safely to the bank, where a wolf finds and feeds them for a while, until they are discovered by a shepherd. Much later, they decided to found a new city on the Palatine Hill, one of the seven hills of Rome, which form the heart of the city, and were very important in Roman mythology, religion and politics. And then, Romulus killed Remus, and became the first king of Rome.

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2014-10-21 [E] [D]
music,live,record Comments 0

Tuesday 21st of October, I went to see the legendary Buena Vista Social Club in Ancienne Belgique in Brussels. As this was their farewell tour, it was a concert I had to see, given their amazing eponymous album.

Not many of the original members are left now (I counted three), but the other members sure brought out some vibes I couldn't stand still to :)

I didn't find much coverage of the concert.

I also made a crappy recording of this concert. If you're interested, you can download the MP3 with the corresponding cue file (or just stream it from http://audio.jerous.org/2014-bvsc/)! It's a 133MB download, as I couldn't re-encode the stereo to mono without lowering the quality even further :(

If you happen to recognize any unnamed songs, please tell me! :)

2014-08-30 [E] [D]
hardware Comments 0

Media player. Small, good life time, bit small screen. It works awesome with rockbox :)

A while ago, I got the offer to join a group of people that was going to travel to Iceland, during my university's closing week. An offer I couldn't refuse, as I had nothing planned (even if I had something planned, I might have skipped it :p), and this was just the perfect opportunity to explore this country whose beauty is often heard of, but probably only known for its elves, dóttirs and sons, its almost bankruptcy during the financial crash and that volcano that paralyzed air travel in large parts of Europe in 2010.

Our trip led us, a jolly group of 6, from our HQ and capital Reykjavik in the Capital Region to the Southern and Western Region in a Dodge 4WD!


Approximate itinerary

Let us first introduce Iceland a bit, but as this post already is quite long, I'll keep it down to one sentence!

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To model computer networks a traffic model is needed. One can have a traffic model used for generation of traffic, and one for analysis of traffic. This post is about the latter. Such traffic model captures properties of traffic in such a way that analysis is possible, and these results can then be used to dimension a network. E.g. some people are interested in loss, others in delay, and others need to analyze the multiplexing gain so they can calculate the necessary bandwidth.

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2014-07-16 [E] [D]
programming Comments 0

PieCrust, this site's backend, is getting slower as more posts and pictures are added. I guess this is mainly due it being written in php, a scripted language.

So I've been checking out alternatives.

I wanted something that worked fast, offered all or most of PieCrust's features that I used and was fun to tinker with so I could implement the missing features.

Since most dynamic languages are slower than the compiled ones, I preferred something compiled, which reduced the number of options significantly. Furthermore, even though I love Haskell, it can be quite difficult to get it to compile on shared hosting.

This more or less left a couple of options in go. And my companion was found in gostatic, a very fast static site generator written in go, using golang templates with a small code base that was quite understandable.

As it is written in go with only three dependencies, it's quite easy to compile and get working. It didn't offer all features that I wanted (such as pagination, including files and assets), but the source code was small enough so I could implement all features and a compatibility layer with PieCrust (so I did not to have to rewrite all pages and posts).

And, as I was updating the site, I also added lazy image loading for posts, quite useful for my travel posts with lots of images :)

As for now, it seems to do pretty well for my setup, generating the complete site in 10-20s on dreamhost (the large variance is due to it being on a shared host), and less than 5s on my main computer, compared to PieCrust's +60s.

2014-07-13 [E] [D]
music,jazz,live Comments 0

Gent Jazz is an old familiar to me, where I've seen B.B. King perform, and two years ago Paco de Lucía (RIP, sniff sniff).

This time Joshua Redman, Hiromi Uehara and Chick Corea were the same day at a festival. How could one say no to that?

It was a rainy day, but the music made it all worthwile; Joshua played some great tunes, Hiromi was amazing, and Chick Corea & Stanley Clarke were just perfect. And of course, the duet Hiromi - Corea with Spain at the end of the day was just a pure pleasure to watch and listen.

This page is intended for footage, pictures and reviews of that day.

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