I get a mention on the BBCi blog

February 23, 2009 Leave a comment

Today’s post on the BBCi Labs blog briefly mentions  a Pong game I wrote for Freeview/Freesat set-top boxes a while ago.  A couple of the guys in the BBCi team took my game and tried to make it multiplayer by passing players’ movements over the internet.  I don’t think they were totally sucessful though in getting it to work though…

Here’s the link.  The ‘Pong challenge’ section is the where it’s at…

Also see here for a video of the Pong game (the single player version), it’s the third game shown in the video.


Signing .deb packages

February 5, 2009 27 comments

Okay, so here’s the scenario: you distribute .deb packages without an apt repository, but want to start signing your packages to ensure they aren’t corrupted or tampered with during transit to your users. I say “without an apt repository” since apt has its own mechanism for signing whole releases, via SecureApt.

The tools you are expected to use for this purpose are debsign and debsig-verify. Unfortunately I found the documentation for these to be pretty thin and ended up having to read the source of debsig-verify to work out what was expected of a signed package.

So hopefully to prevent others from having to trawl through source code, below are steps you could follow to sign your own .deb packages. My method is somewhat contra to the prescribed method from Debian, however it is the only way I’ve managed to get working.  Please suggest better methods if you know them.

The steps I performed were:

  1. Create your GPG signing key, run
    $ gpg --gen-key
    and follow the steps.
  2. Read more…

Tags: , , ,

MHEG+ Game Development Tutorial, Part #2 — Animation

December 14, 2008 6 comments

In part #1 of this series we built a basic MHEG+ scene which was capable of firing timer events at a consistent rate.  In this part we will look to extend the code by adding an animating graphic to the scene.

A further aim of this part is to explain some more of the language features exclusive to MHEG+, including foreach loops, sequential blocks and ifs.

Adding our graphics to the scene

I have hand crafted the following 5 png graphics to use for this tutorial:


Using an MHEG+ foreach loop, we can add all these graphics to our scene in one fell swoop:

  foreach num (0..4) {
    {:Bitmap bmpPac<num> = [constPacObjectIdOffset + <num>]
     :OrigPosition          [(720 - 32) / 2] [(576 - 32) / 2]
     :OrigBoxSize           32 32
     :OrigContent           :ContentRef ('/tut/<num>.png')
     :InitiallyActive       false
  } endfor

There a number of subtleties of this loop which are probably worth discussing:-

  • foreach loops are preprocessor instructions, not run-time loops.  Because of this we can use foreach loops around object declarations, or in fact any code section at all.
  • In this case, the contents of the foreach loop will be duplicated 5 times, this is controlled by the (0..4) range on the first line.  This range need not be numeric, text may also be used, for example: foreach key (red, green, yellow, blue) is allowed.
  • The Bitmaps we declare will be named bmpPac0 through bmpPac4, <num> is substituted with each value in the range.
  • The object identifiers for the Bitmaps will be 100 through 104, assuming constPacObjectIdOffset has the value 100.  We use the MHEG+ notation: objectname = objectid to declare both names and object identifiers for our Bitmaps.
  • <num> is also substituted in the png filename

Read more…

MHEG+ Game Development Tutorial, Part #1 — Timing

November 26, 2008 5 comments

Introduction to this Series

One of the joys of my job at the BBC is staying back after hours and trying to nut out how best to write real-time games on current interactive television platforms.  That is, trying to write the kind of games that you might have once played in an arcade, or maybe on your BBC Micro, but allowing you to play them via the ‘Red Button’.  See this post for a video of some of my efforts so far.

Here in these tutorials I hope to share with you some of my findings in trying to get the best out of the MHEG platform.  I also hope to demonstrate the power of the MHEG+ programming language, an extension to MHEG.  MHEG+ has been developed in-house at the BBC and compiles down to traditional MHEG/ASN, but is a far richer langauge than its predecessor.

For these tutorials I will assume you have some background in programming generally and hopefully some experience writing MHEG or interactive TV applications (MHP, OpenTV, etc.).  The code samples will all be in MHEG+ which at time of writing is not available outside the BBC, however efforts are being made to attempt to open source MHEG+ development tools, so watch this space…

I guess for the time being then you most likely won’t be able to compile or run these applications, but hopefully one day soon you will be able to.  Therefore I suppose the code herein is currently just for educational purposes, but then that is the point of the series 🙂

So, without further ado…

Part #1: Timing

The first significant challenge that I came across when writing MHEG games was that of timing.  How could I ensure my game would run at virtually the same speed on any set top box?

Unlike more sophisticated languages (yes, I openly admit that MHEG is not the most sophisticated language, but then it was never designed to be) MHEG does not provide the developer with a means of retrieving accurate clock information.  The most fine-grained time information you can retrieve (achieved by a call to the GetCurrentDate resident program) provides no better than whole second precision. Read more…

Screengrab Ubiquity Script

October 5, 2008 14 comments

Firefox users with the Ubiquity extension installed might like to try my Screengrab script which provides the commands:-

  • ‘screengrab’ — saves the current browser window to the clipboard, and
  • ‘screengrab-to-file’ — saves the current browser window to a png image file.

Once the screengrab command has been issued, the image can be simply pasted from the cilpboard into webmail emails such as GMail.

I’d like to eventually extend the script to provide a ‘screengrab-and-email’ command.

Downloads and more details here.

Here’s a screenshot:

Video: Games I’ve written in MHEG

September 19, 2008 4 comments

MHEG is a programming language & middleware found in digital set top boxes in the UK and elsewhere around the world.  This video briefly shows a few games I have written in MHEG while working at the BBC.

The games shown in the video are:-

  1. ‘Nibbler’ – a Snake clone.
  2. ‘Bounce!’ – really more of a tech demo than a finished game, but surprisingly fun.  Catch the green blobs but avoid the red one.
  3. ‘Ping Pong’ – pretty self explanatory I think.

The games have never been broadcast.  I am hoping the powers that be at the BBC will let them go to air.  What do you think?  Would you like to be able to ‘Press Red’ and play games such as these?

Obviously the graphics could do with some work, but these games do at least prove the technology…

Leave a comment if you’d like to see the BBC do classic arcade style games on interactive TV.

ooooooooside 2007-10-31 and 2007-12-06 between 0000-00-00 and 9999-99-99

April 15, 2008 1 comment

Seen at the bottom of an email from my Mum & Dad, just before the Yahoo! mail tagline:

ooooooooside 2007-10-31 and 2007-12-06 between 0000-00-00 and 9999-99-99

A Google search reveals that indeed this message does pop up from time to time. My guess is that it is generated by a code library and is meant to be some sort of debugging information… but I could be wrong.

Have you seen this? What does it mean? Where does it come from? Please help!

Update: Yahoo! have stated the problem is a technical issue.