The program

Family birthday wishes

After waking up way too early, I spent some time listening to an episode of the “Linux Outlaws” podcast. At about 6:15, my family came in to my bedroom to wish me a happy birthday. For all you materialistic consumers out there, my gifts were a DVD of Pink Floyd The Wall, an 8GB USB stick, and some money.

School

After some gentle reminders most of my friends at Marcellin College acknowledged my birthday. Overall the school day was pretty ordinary, but I did get a lovely rendition of “Happy Birthday to You” sung by my Maths teacher of 3 years!

Relaxing at home

After school I had some time to check RSS feeds and emails and play some games before it was time to prepare for going out.

Dinner at Nonna’s

We ate dinner at my Nonna’s (grandmother’s) house, where I met up with one of my uncles as well. Once we had finished eating, Nonna, my sister and her friend went to the ballet. Mum, Dad and me waited around a bit, watching “Dirty Jobs” on TV until it was time for us too to leave.

The Whitlams

Now for the main event: seeing The Whitlams live at the Corner Hotel. We arrived at Richmond much too early, so Mum stopped for a coffee to kill some time. After what seemed like a long time we were finally able to enter the Corner Hotel. As it’s an over-18 venue, I must have been the youngest one there – Mum got real kicks out of the bouncer asking to see my ID. The support acts were good, but there was no disputing that The Whitlams were the main entertainers there. I couldn’t stop smiling throughout the performance, and the set list was fantastic!

Tim Freedman had a little trouble with a broken stool and had to do a few songs standing (like “No Aphrodisiac”), but this didn’t seem to faze him much at all. Since this was the first “pub band” that I’d seen, I was shocked by how loud it was (my ears are still ringing now). When the band first walked off the stage, I was left thinking “wow, what a great show”. However, the first encore really was the icing on the cake, “Oh! You pretty Things” going down brilliantly for me as a Bowie fan.

Conclusion

The day was great. I had the chance to see both my family and friends, and the live music exceeded my expectations. Thanks to Mum, Dad and everyone else my 18^th birthday will be a memorable one.

Xiph.Org's logo

Ogg bitstreams have become increasingly prominent in recent years, yet Ogg is still a commonly misunderstood format. As the creator of ruby-ogg I have spent some time deciphering Xiph.Org’s technical documentation, and now I have decided to pass some of that knowledge on to you, dear reader (of course, you could read the specification yourself!).

Ogg isn’t Vorbis

The popularity of “.ogg” audio files has lead to much confusion over what Ogg actually is. In such audio files, the music data is compressed according to the Vorbis specification and then stored in an Ogg bitstream. The Ogg container format itself is independent of content type – it can happily hold video, audio and even text. In fact, Vorbis-encoded music doesn’t need to be stored within an Ogg bitstream either, but the Ogg-Vorbis combination is especially common due to the fact that the Xiph.Org Foundation created both of them. For the insanely small file sizes and excellent audio quality you can thank the Vorbis guys. For the ability to stream, seek and recover from the partial corruption of songs you can thank the good folks who work on Ogg.

Let’s get technical

OK, so now that we’ve firmly established that Ogg is a container format independent of content type, we can move on to the technical details.

It is assumed that data encapsulated by an Ogg bitstream is broken into smaller chunks called packets. The semantics of a packet varies – in the case of Vorbis a single packet may contain metadata (the song title, artist and so forth), decoding information or a snippet of audio data. In order to store these packets, the Ogg bitstream divides things up into pages. Each page can contain part of a packet, a whole packet or even multiple packets. The diagram below may make it easier to visualise the way in which things may be stored:

Graphical representation of a sample Ogg file

In the example above, page #1 contains two complete packets, packet #3 spans both pages #2 and #3 and packet #4 spans pages #3 and #4.

Reading pages

Since there is no “index” to an Ogg bitstream, the header of each page must provide enough information to enable reading and validation of the encapsulated data. The advantage of this is that if you begin reading at any point in the stream it is possible to detect the next page header and read the ensuing data. Not only does this enable the recovery from an encounter with a corrupted page, but it is also theoretically enables the commencement of decoding halfway through a stream. Here is a summary of the process for page detection:

1. Read from the stream until the 4-byte sequence representing the ASCII string ‘OggS’ is encountered.
2. Read the following data as an Ogg page header.
3. Compare the checksum field with a cyclic redundancy check (CRC) on the entire page with the checksum field set to zero.
4. If the CRC is successful, we have found a valid, uncorrupted Ogg page. Otherwise, seek back to just after the ‘OggS’ and return to step 1.

The view from a height

For Rubyists, ruby-ogg provides a nice abstraction from the entire concept of pages, simply allowing you to call a “read_packet” method. This does the page detection, optional checksum validation (CRCs are slow in Ruby) and joins packet segments that span multiple pages.

Here’s a demo video of Sprung 0.3.0 in action:

UPDATE: rdoc.info has ears everywhere, and the new project page has been modified to address my little gripe. Yay!

There is a metric buttload of Firefox add-ons out there, some good and some bad. In order to make the process of finding the best extensions a little easier, I have shortlisted a few of my favourites.

Adblock Plus

Whenever I install Firefox, Adblock Plus is never far behind. This handy extension conserves your bandwidth by preventing the browser from downloading unwanted Flash banners and other nasty advertisements. Please be aware that many good, free projects depend on ads for funding, so consider adding exceptions to Adblock Plus for these sites.

DownThemAll!

As much as I love Firefox, the default download manager does leave something to be desired. Thankfully DownThemAll! is available to achieve the browser’s full file retrieving potential, adding features such as download acceleration and better management of files. On top of this, DTA also has the ability to scan through links in a web page, enabling you to do things such as download all linked MP3 files.

Flagfox

On the more whimsical end of the line is Flagfox, a simple extension which places a little flag icon in the address bar indicating the server’s location. Whilst not as useful as the other add-ons listed here, it is interesting to see which country you are pulling web data from.

Greasemonkey

It is quite surprising just how much some sites rely on Javascript for functionality. Unfortunately, some sites (*cough* LyricWiki *cough*) use Javascript for evil rather than good, doing things like disabling the ability to copy content onto the clipboard. Enter Greasemonkey, an extension which enables you to modify the client-side functionality of websites with user-made scripts. There is a nice repository of such scripts at Userscripts.org, including a fix for the aforementioned LyricWiki nastiness.

UnPlug

UnPlug is by no means original or unique, as there are many tools around for downloading embedded media. However, I have found UnPlug to be the Firefox extension best suited to my needs, with support for YouTube and Vimeo along with DownThemAll! integration. It just works really well.

Readability

There are some nicely formatted websites out there, and there are also some absolute shockers. What if you find an informative article, but the layout hurts your eyes? Readability solves this dilemma by adding the ability to format information in a clean, eye-friendly way. Of course, you wouldn’t need it on my blog, because I only use excellent themes