Welcome to Land of Tricks

I remember how chuffed I was when I discovered I could use my Panasonic music centre to tape my mates’ vinyl record collections. On just two C120s I recorded the Hawkwind back catalogue and still had space to tack on the best of X-ray Spex (1979 was a musically-confusing year). The music centre was the first mass-produced legal downloader and millions of us created vast vaults of tapes of our favourite bands. I don’t remember any heavies from the record industry turning up on my doorstep to threaten me with prosecution for illegal taping. And I don’t recall any sanctimonious hectoring about stealing from the mouths of starving artists. They don’t make music centres any more. But they do send the men in black round if you try to avoid paying for your albums.

Are 'Men in Black' checking your IP address on behalf of the entertainment giants?

Illegal downloading in the UK has become a massive threat to the music and film industries. In 1997, 78 million singles were sold in the UK; last year, it was just 8.6m. It is estimated that half the population has engaged in some sort of nefarious downloading in the last five years.

So what is being done to stop it and what can you expect if you are caught illegally downloading music, film and TV show files? The first thing to note is that the internet is not the law-free community that its architects had intended when it was dreamt up 30 years ago.In the 1970s and 1980s, record companies were happy to turn a blind eye to the taping of albums, largely because there had to be at least one hard copy purchase before the copying could begin. That is not the case with the huge range of downloading options offered on the internet. In Britain there is an equally-dazzling raft of copyright laws that can be invoked to prosecute offenders.

Mozilla is adding support for multiprocess browsing to Firefox. The feature, which is already found in Google Chrome, will improve the stability and security of Mozilla’s browser. Ars takes a look at the current status of the implementation and at an early demo that shows a page rendering in a separate process.

Mozilla has launched a new project called Electrolysis that aims to bring multiprocess browsing to Firefox. According to Mozilla, splitting up the page rendering workload into multiple processes will improve the browser’s performance, security, and stability. The developers have already assembled a prototype that renders a page in a separate process from the interface shell in which it is displayed.

Mozilla has explored the possibility of adopting a multiprocessing approach for Firefox in the past, but the idea didn’t gain serious traction in the Firefox developer community until it was implemented by Google and Microsoft in their respective web browsers. Google’s Chrome browser uses a separate process for each page, an architectural approach that facilitates much more effective security sandboxing and prevents page-specific rendering glitches from crashing the entire browser. Chrome even includes a process manager tool that can be used to see the status and resource consumption of each page.

Adapting Firefox to make it support multiprocess browsing will not be an easy task. Many fundamental components of the browser’s underlying infrastructure will have to be modified in order to accommodate the transition. This will partly involve using interprocess communication (IPC) to expose shared pieces of the browser to the individual tab processes. This is somewhat complicated, but you can get a clearer picture of how it will work by looking at some of Mozilla’s design documents. A particularly illuminating example is theoverview of how Firefox’s image loading and caching mechanisms will be made to work with multiprocess browsing.

The browser currently has a single image loading component that is shared between tabs. To make it work for multiprocess browsing, one approach would be to simply instantiate a separate image loader in each tab process. In order to avoid redundancy, Mozilla’s documentation explains, an alternate solution that might potentially be more effective would be to have a central image caching and loading service that makes image content accessible to the tab processes via IPC. It could be further optimized by using shared memory to to make the decoded image data accessible to the tabs, thus avoiding the IPC bottleneck for the heaviest aspect of the operation.

Last month, developer Chris Jones published a screencast which demonstrates a simple prototype that renders page content in a separate process outside of the main browser process. He shows that the page rendering process can be terminated independently of the browser, meaning that a page-specific crash would take down only the page and not the entire browser.

“Notice that only the ‘content’ disappears when the page crashes; the user interface itself keeps running as if nothing happened. This is a big step forward,” he wrote in a blog entry about the demo. “With Firefox protected from buggy pages and plugins, more fun is possible. This video shows me pressing a ‘Recover’ button that relaunches the page that just crashed. There are many more possibilities for recovering from these errors, and I’m excited to see what our user interface folks cook up.”

Jones says that his prototype represents the work that the Electrolysis developers have done to meet the requirements specified by “phase I” of Mozilla’s multiprocess roadmap. To bootstrap the development of the IPC system, Mozilla is using some code from Chromium, the open source development version of Google’s browser. The developers are contemplating the possibility of replacing existing Firefox components, such as the browser’s network stack, with additional code from Chromium.

The experimental development work that is being done by various contributors on the Electrolysis project wasrecently consolidated into a single version control repository. The developers hope to have nightly builds ready for developer testing soon, but they caution that it will not yet work on Mac OS X. They are looking for volunteer Mac developers to participate in the project.

Electrolysis is going to be a truly enormous project. It’s not clear yet if it will be ready in time for the next release of Firefox, which is codenamed Namaroka. The work on Electrolysis will be done parallel to Namaroka development, so it will not impede other plans to improve the browser. The early Electrolysis prototype and other parts that have been implemented so far are highly impressive. The project is off to a very promising start and has the potential to bring a lot of value to the Firefox browser and its users.

Researchers made progress enabling a computer to teach itself British Sign Language by analyzing video footage. The scientists from the University of Oxford and University of Leeds first programmed a machine vision algorithm so the computer could identify the shapes of hands in the video. From New Scientist:

Once the team were confident the computer could identify different signs in this way, they exposed it to around 10 hours of TV footage that was both signed and subtitled. They tasked the software with learning the signs for a mixture of 210 nouns and adjectives that appeared multiple times during the footage.

The program did so by analysing the signs that accompanied each of those words whenever it appeared in the subtitles. Where it was not obvious which part of a signing sequence relates to the given keyword, the system compared multiple occurrences of a word to pinpoint the correct sign.

Starting without any knowledge of the signs for those 210 words, the software correctly learnt 136 of them, or 65 per cent, says Everingham. “Some words have different signs depending on the context – for example, cutting a tree has a different sign to cutting a rose.” he says, so this is a high success rate given the complexity of the task.