Wednesday, 12 August 2009

Embedding the SimPL APL font on a web page using Cufón

I came across Cufón a while ago whilst browsing the excellent nettuts+ website.

Having started coding in APL I was wondering about the best way to present developed code on my blog. One option is to use my java transcoding technique to load my Soliton Sharp APL code into jEdit (my favourite editor) using my custom character set transcoder to convert the custom eight-bit ASCII encoding used by Soliton into standard Unicode APL characters.

Cufón allows you to embed any arbitrary truetype font or fonts into a webpage via javascript and then use the font directly within the html by replacing a standard html tag. You can either download the utility or use their website to process a truetype font located on your hard disk to generate a javascript file containing your selected truetype glyphs. The generated file in this example is simpl_400.font.js (see code below).

I chose the excellent free font created by Phil Chasney called SImPL to embed within this blog.

The code required within the head tag of this page to embed the font is very simple:

<script src="" type="text/javascript"></script>
<script src="" type="text/javascript"></script>
<script type="text/javascript">

The results can be seen with the following APL characters above ASCII location 127 in the SOLITON-APL encoding:


and an example of some APL code:

[0] z←mbrt1
[1] rrz←(0.1×⍳21)−1 ⍝ array from ¯1 to +1 stepsize 0.1
[2] iiz←(0.1×⍳21)−1 ⍝ array from ¯1 to +1 stepsize 0.1

[0] z← cmplsq ⍵
[2] ⍝ Function: Complex Square
[3] ⍝ Perform a complex square of the argument ⍵, returning array r,i in z
[5] r←⍵[0] ⍝ extract real part into r
[6] i←⍵[1] ⍝ extract imaginary part into i
[7] rn←(r⋆2)−(i⋆2) ⍝ real result
[8] in←r×i×2 ⍝ imaginary result
[9] z←rn,in ⍝ z is array of real and imaginary results

Saturday, 8 August 2009

DIGITAL and Alpha Powered Logos

I created a couple of high-resolution logos for DIGITAL and Alpha Powered from existing sources with transparent backgrounds as PNG files that someone might find useful! Below are two scaled images - be sure to use the links above to get the full resolution version.

Retrochallenge 2009 Summer Challenge Entry

I participate in retrochallenge - a convenient excuse to utilise retro technology for a month. For the summer 2009 challenge I coded up a fractal generator in VAX Macro-32. You can check out the challenge blog at I produce this blog on my main website because it is created using ALLIN1 on the VAX by a set of scripts I created for my winter warmup 2009 entry.

One of the images I produced has been used by the competition organiser for the winners mousemat. It can also be ordered in t-shirt format from cafepress.

The above image is also available at 4800x4800 resolution, which shows the recursive nature of the image much more clearly.

Friday, 7 August 2009

Transcoding AVCHD into DVD and Web Formats using the Command Line under Linux

I needed a way of transcoding output from my Panasonic HDC-HS300 into a DVD and web viewable format under linux. There are webpages out there that tell you how to do it, but I had to edit some of the scripts to perform this task automatically from the command line.

I've created two scripts, and which can be downloaded in the archive convert-mts.tgz. The scripts unpack into a bin directory.

In order to use the scripts you need to ensure you have the latest version of mplayer installed. My version reports:

MPlayer SVN-r29328-4.3 (C) 2000-2009 MPlayer Team

so I would suggest this version or later. The packaged version in the OpenSUSE 11.0 repository is not recent enough - I downloaded the latest source code using subversion and built it locally. The following commands download the latest version, configure and build it to /usr/local. The mplayer binary can then be found under /usr/local/bin so the last command ensures that you pick that version up in preference to a pre-packaged version that might be installed under /usr/bin for example.

svn checkout svn:// mplayer
cd mplayer
svn update
./configure --prefix=/usr/local/
make install
export PATH=/usr/local/bin:$PATH
The script is used to convert your HD video into DVD quality, suitable for directly burning to a DVD (for example using my command line tools described in a previous blog post). It contains the following commands:
rm -rf dvd/*
mkdir dvd
for f in *.mts
echo $f
mencoder -oac copy -ovc lavc -of mpeg -mpegopts format=dvd -vf scale=720:576,hh
arddup -lavcopts vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9800:vbitrate=55
000:keyint=15:aspect=16/9:threads=4 $f -ofps 25 -fps 50 -o dvd/`basename $f .mts
`.mpg -demuxer lavf >>`basename $f .mts`.log 2>&1 &
Once you have this command on your path, cd to a directory containing the files you wish to convert (which have the extension .mts) and run the command. Note that with the Panasonic Camcorder you can copy the files directly off the camera - you don't need to use the Windows utility provided. It will create a sub-directory called dvd and proceed to convert all the .mts files into DVD format. It creates a log file for each of the converted files giving any output or error messages.

Note the ampersand on the end and the wait command - this script is multi-threaded and will utilise all cores on a mult-core processor. I did some experimentation with versions of this script and found that on a machine with a decent amount of memory the most efficient way of transcoding the videos was to spawn off all the transcode commands at the same time, even when transcoding several tens of mpeg. On my quad-core machine this command completes the process almost exactly four times quicker than processing the command sequentially.

The only disadvantage of spawning all the transcodes at once is that you might impact other processes on the box (I noticed that video streaming would be interrupted for example). You could always use the nice command infront of the call to mencoder to run it at a lower priority, giving preference to existing tasks.

The provides the appropriate command line arguments for generating a video size 360x288 - it creates a directory called web and places the transcoded video files there.

rm -rf web/*
mkdir web
for f in *.mts
echo $f
mencoder -oac copy -ovc lavc -of mpeg -mpegopts format=dvd -vf scale=360:288,harddup -lavcopts vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=1250:vbitrate=625:keyint=15:aspect=16/9:threads=4 $f -ofps 25 -fps 50 -o web/`basename $f .mts`.mpg -demuxer lavf >>`basename $f .mts`.log 2>&1 &

Automatic Video DVD Creation under Linux using command line tools

Doing DVD creation properly is a pain. Firstly, you have to master a GUI creation tool. Secondly, every DVD you create seems to involve too much manual work. Wouldn't it be nice if you could just throw a load of mpeg files into a directory and run a couple of commands.

I couldn't find anything out there to fit the bill, so I rolled my own. You can download everything you need in dvd-create.tgz

The prerequisites are the dvdauthor, cdrtools and MPlayer packages. Use your linux distros' package manager to ensure they are installed and up-to-date.

Unpacking dvd-create.tgz gives you a directory dvd-create. Within the directory are three main control scripts:, and

Start by copying the mpeg files you want on your DVD into the dvd-create directory. The files will appear on the DVD in alphabetical order, so if required rename (or numerically prefix) them so that the directory listing shows them in the correct order. Then use the script to process the mpeg files, generate a dvd.xml control script for dvdauthor then run dvdauthor to create the DVD structure within the subdirectory dvd.

rm -f dvd.xml dvd-body.xml
chapter=$(( 0 ))
for f in *.mpg
echo " " >> dvd-body.xml
chapter=$(( $chapter+1 ))
cat dvd-head.xml dvd-body.xml dvd-foot.xml > dvd.xml
dvdauthor -o dvd -x dvd.xml
The second step is to burn the generated DVD structure to a DVD using the script. If you dvd device is not located at /dev/cdrom you will need to edit the script to use the appropriate device.

growisofs -dvd-compat -Z /dev/cdrom -dvd-video ./dvd/

The last step is to test the DVD you've just created using the play script, This fires up the mplayer media player to view the contents of the freshly created DVD.

mplayer dvd:// -dvd-device ./dvd

How quick was that!

Monitor your ADSL Connection for Outages & Uptime

I had the misfortune of choosing demon as my ISP and for the first couple of months managed to exceed my fair use policy and experience extended outages. In an effort to document my issues I wrote a couple of scripts on a NetBSD box that monitor the connection and automatically create a graph using gnuplot of the uptime.

The scripts are driven by a crontab script:

$ crontab -l
@hourly /home/msw/router/getstats
5,10,15,20,25,30,35,40,45,50,55 * * * * /home/msw/router/
5,10,15,20,25,30,35,40,45,50,55 * * * * /home/msw/router/
0,15,30,45 * * * * /home/msw/router/

Every five minutes the script attempts to ping one of the demon nameservers using its' IP address:

TIME="`date +%C%y%m%d%H%M`"
/sbin/ping -c 1 > /dev/null 2>&1
if [ "$?" == "0" ]

This generates a line in the LOGFILE which looks like this:

200907091945 1
200907091950 1
200907091955 1
200907092005 1
200907092010 1
200907092015 1
200907092020 1
200907092025 1
200907092030 1
200907092035 1

where the first number is the date and time and the second number is a '1' if the ping was successful, or a '0' if it was not.

The script turns these numbers into a nice graph with the help of GnuPlot then puts the resulting jpeg onto the local apache webserver:

sleep 30
export PATH=/bin:/sbin:/usr/pkg/bin
export RS=/home/msw/router
export HTDOCS=/usr/pkg/share/httpd/htdocs
export STATS_FILE=$RS/ping-stats.txt
export JPG_FILE=ping-stats.jpg
export SHARE_DIR=/usr/local/archive
export HTTPD_DIR=/usr/pkg/share/httpd/htdocs
cp $STATS_FILE $RS/ping-stats-copy.txt
gnuplot $RS/plot-stats.gnuplot > $SHARE_DIR/$JPG_FILE

The gnuplot script plot-stats.gnuplot that works the magic:

set terminal jpeg large size 1024, 600
#set terminal dumb
set title "Demon Internet HomeOffice 8000, hostname: waldo"
set lmargin 10
set rmargin 10
set tmargin 5
set bmargin 8
set xdata time
set format x "%d/%m"
set xlabel "Date, 2009" offset 0,-2
set ylabel "ADSL Status"
set yrange [-1:2]
set ytics 0,1,1 ("Off" 0, "On" 1)
set mxtics 6
set timefmt "%Y%m%d%H%M%S"
plot "/home/msw/router/ping-stats-copy.txt" using 1:2 with lines title
"Status at `date`"
#set title "ADSL status" offset 0,-10
# - generated on %Y%m%d %H%M"
show title

Then once every 1/4 hour the script pushes the stats up to my remote web host (assuming the connection is up of course!)

cp /usr/local/archive/ping-stats.jpg /tmp
cd /tmp
cd public_html
put ping-stats.jpg

The end result being this lovely image:

Java/Swing Mirrorbow Remote Control Program

I wrote an application a while ago that I thought would be worth sharing with the world - it's a Java/Swing Application to drive a
Mirrorbow Ethernet IO Interface. I use the interface to control the power to a number of computers and peripherals in my attic, both to make remote operation possible and also to physically isolate them from the mains supply when not in use. I noted a while back that the VAX and Alpha both drew significant power from the mains even when the power supply switch was turned off.

The application looks like this when running:

You simply click on the button to toggle the power. The application mirrors the information displayed in this Swing panel on the built in LCD display of the mirrorbow:

The application is configured using an XML file:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

I tried to make the implementation as generic as possible. The source code, compiled classes and Windows/Unix command line scripts can be found in

The unit all this controls was hand built using a equipment box, eight IDC connectors, a relay board bought off ebay, a 12 volt power module extracted from a plug in adapter and a mains lead: