michaelcarden.net

Sometimes it really is a loose wire

A week or so ago, Colin gave me a Healing branded digital set top box that he’d repaired. Like many small domestic electronic devices, it suffered from poor quality electrolytic capacitors in its switchmode power supply. Col had engaged in a ’shotgun’ replacement of capacitors and produced a working STB which he generously donated to me.

We plugged it in to my antenna and TV, only to find it as dead as it was when he first received it. “Never mind,” I said, “I’ll see if I can fix it when I get a chance.”

So on the weekend I pulled it apart and to my astonishment I found that one of the wires delivering mains power to the circuit board had not been soldered very well at the factory and had come away. A few moments’ work at the kitchen table with a soldering iron and it was better than new. Over the years I have lost track of the number of people handing me something to fix and saying, “I think it’s just a loose wire.” I can’t recall an occasion when it’s actually been true before though.

The upshot of this is that I can now receive ABC2 and SBS2 on the big telly. The tuner finds quite a few other digital streams but right now they mostly just carry the same content as the main stream for the channel. So Prime views 2, 3 and 4 are no more use than Prime for example. Maybe in the months and years to come I’ll see more choice. Meanwhile, I have a couple more channels and digital picture quality rather than analogue.

Thanks Col.

Cleaning up after yourself

A recent power failure had me rebooting my main home machine and as the KDE desktop came up I received an alert telling me that I was very low on disk space. Guessing that something was caching piles of data in some hidden directory, I used this to get a list of how big everything in my home directory is, sorted to show me the biggest offender:

du -sk .[A-z]* *|sort -n

And nothing looked too bad. So I popped up to the root, added a ’sudo’ to the front and tried again. This time something obvious leapt out at me. /var was very large indeed. You may have guessed where this is going.

Moments later I had narrowed it down to 5.5G worth of apt package cache. Yep, a couple of years of installing software without cleaning up after myself. I know I could configure apt to automagically clean the cache, but it’s a bit like all the junk in my garage. I never know when I might need it.

Anyway, a quick:

sudo apt-get clean

…and I have my disc space back again. Now it can fill up with junk until next time!

Getting Video Online

My recent experience in getting a short video hosted on a video sharing site has taught me a couple of lessons that I’d like to share.

The video in question is 11 minutes and 7 seconds long. It’s Theora video and Vorbis audio in an ogg container so the file extension is ogv. This is all open format stuff and at the moment most of the online sharing sites don’t deal well with open formats.

My first port of call was Youtube where I found that they like mp4 formatted videos. I used VLC’s transcoding Wizard to make an mp4 version of my video and I uploaded that. After a long wait for the upload and another long wait for Youtube to process it, I found that I had a few seconds too much video and I would not be able to host it on Youtube.

So I searched for other hosting sites and came across Vimeo who claimed not to have a 10 minute limit. I joined up and tried to upload my video there but some rogue scripting in their interface would lock Firefox solid every time I tried to upload, rendering my browser useless. Scratch Vimeo.

Next cab off the rank was Livevideo.com and I did the same again. Joined up and waited patiently to upload my file. This time all went well until Livevideo declared that it didn’t like my mp4 so I went back to the drawing board to make a new version. This time I searched the web for a while and came up with the fact that these hosting sites like video in h264 format and audio in aac.

This meant a command line transcode with ffmpeg, but that caused problems too. It turns out that the version of ffmpeg packaged for my Kubuntu system doesn’t have support for aac audio coding. So here’s what I did:

I used apt-get to remove ffmpeg:
sudo apt-get remove --purge ffmpeg

I used apt-get to grab ffmpeg’s build dependencies:
sudo apt-get build-dep ffmpeg

I installed a bunch of libraries that ffmpeg might need:
sudo apt-get install liblame-dev libfaad-dev libfaac-dev libxvidcore4-dev liba52-0.7.4 liba52-0.7.4-dev

I grabbed the source package for ffmpeg:
sudo apt-get source ffmpeg

Changed to that directory:
cd ffmpeg-0.cvs20070307/

Ran the configure script with all the options I’d need:
./configure --enable-gpl --enable-pp --enable-libvorbis --enable-libogg --enable-liba52 --enable-libdts --enable-dc1394 --enable-libgsm --disable-debug --enable-libmp3lame --enable-libfaad --enable-libfaac --enable-xvid --enable-pthreads --enable-x264

Compiled:
make

Made a deb package:
sudo checkinstall -D make install

Popped up a directory:
cd ..

And installed it:
sudo dpkg -i ffmpeg_0.cvs20070307-1_i386.deb

Whew. The hard yards done. Next was some fun and games discovering the magic incantation I’d need to turn my ogv into h264 with aac audio in an mp4 container. The full path to ffmpeg used because my PATH environment variable is out of step with the real world:

/usr/local/bin/ffmpeg -i MOV016.ogv -map 0:1 -map 0:2 -acodec aac djvu.mp4

All of which turned my 76 megabyte ogv into a 25 megabyte mp4, which uploaded cleanly to livevideo.com. Here:
http://www.livevideo.com/video/0F9D446BFD44422DA67D5DB8C5C4FF2E/djvu-presentation.aspx

My FOSSD course presentation

The first stage of the assessment for the ANU’s FOSS development course was a ten minute presentation to the class and lecturers. During the course’s lab sessions we were tasked with selecting an Open Source project somewhere in the world, researching it and interacting with it. On the Saturday at the end of the course’s intensive first week, each student had to deliver their ten minute presentation during which several key aspects of the project under consideration had to be made clear.

With some people not selecting a project until Thursday or even Friday, and the need to do the research, digest it, turn some of it into presentation slides and rehearse a script… it was a tight timeline. The remainder of the course’s assessment revolves around writing up the process of contributing to a chosen project, but if a project is found to be a bit quiet or unresponsive or hostile to outsiders, the course guidelines allow for ‘jumping ship’ to another project for the ‘contribution’ part of the assessment.

I chose the djvu file format and djview viewers for my project, but during my research found the project a little quiet and old enough to be not much in need of contributions. So I will likely use something like the Open Source Texas Holdem poker engine (pokerth) for my remaining assessment.

Still, I trawled through the various bits of djvu’s source code, built the viewers, browser plugins and encoders. I found djvu content on the net, read about the very clever people who first created the format then carried it forward as a free format - all quite inspiring. And from all of that I crafted the skeleton of a presentation. Or at least a bunch of slides designed to help me talk for ten minutes.

It’s fair to say that I was more than a little nervous as I made my way to the lectern to deliver my ten minutes of extemporising. I was worried that my slides would be over in five minutes and I’d be up there fishing for something to say. I was worried that I would run way over time (time limits were strictly enforced) and miss half of what I needed to cover. I was worried that I’d make a twit of myself one way or another.

Bob Edwards recorded all of the presentations on the day and has subsequently transcoded them all to OGG and made them available to the students who created them. Mine is a 72 Megabyte file that nobody except me would want to download. I transcoded it to H264 because YouTube likes that format but even then it’s 52 megabytes. And because the video is a few seconds over 10 minutes, YouTube rejects it. I looked for alternative hosting sites and chose Vimeo… which froze my browser. So I looked further afield and found livevideo.com… which gave me an ‘encoding error’ and died. After I had signed up, waited an age to upload then another age to watch it fail to encode. What fun.

After jumping through a convoluted maze of hoops, I think I have finally managed to get it on line:

Having watched the video, I’m fairly pleased with the way it went and most of my terror isn’t as obvious as I thought it might be.

FOSS Development Course (almost) complete

The five days of the FOSSD course passed in the blink of an eye. Now that the intensive lecture and tutorial part is over I have several weeks in which to write up the papers that will form the majority of my assessment.

The lectures and labs were most instructive and I think I learned several new things each day in spite of the fact that I work in and am surrounded by the culture of Free and Open Source. There is always more to know!

The very good news to come from the course is for YOU, if you weren’t there. All of the lectures were video recorded and all of the lecture notes have been released under a Creative Commons licence. So from the comfort of your net connected device, you can experience some of what the 23 or so students this week experienced. http://cs.anu.edu.au/students/comp8440/lectures.php

Open Source Community at University

I’m beavering away at a Masters degree at the Australian National University in, you guessed it, Information Technology. That’s no huge surprise. Doing so while holding down a full time job is a bit tricky and has made for some fraught deadlines. Scheduling is always an issue. So imagine my delight when I discovered that the ANU would offer a course this year in Free and Open Source Software, and do it in a compressed format during the mid-semester break. Yay! No time lost each week for lectures or tutes. Just a week off after Easter and some Saturdays. Awesome.

Now, it helps to understand just who is driving this bus. The course is being run by two very valuable people. They are Robert ‘Bob’ Edwards, head of the ANU School of Computer Science tech support team, networking lecturer, core member of the Canberra Linux User Group and accomplished hardware hacker, and… Dr Andrew ‘Tridge’ Tridgell, former ANU student, creator of Samba, rsync and more useful code than you can poke a stick at.

The course will look at all aspects of FOSS, including history, community, social structure and engagement. There may even be some code somewhere.

I’m excited by my participation in this ground breaking course. I know that time spent with Bob and Tridge is always educational. Now all I need to do is find a suitable FOSS project to focus on as my Project within the course.

A project more than a couple of years old with at least several developers, regular source updates, a user community, good governance and (ideally for me) perhaps in java… Any ideas?