A Tasty Pixel » Posts

Wider implications for popups!

There’s a story on Arstechnia about a substitute teacher who was nearly imprisoned for 40 years for allegedly showing porn to students, after an event that can only be explained by a fairly standard popup attack on an unprotected classroom computer: She went to the bathroom, and returned to find students clustered around the attacked machine.

Through some bizarre hole in the legal system, she was found guilty of intentionally exposing the students to pornography and was looking down the barrel of 40 years imprisonment. After the completion of the original trial, the computer in question was re-examined, and the judge admitted there are new findings that contradict the original findings.

The teacher’s attorney was quoted saying “the lesson from this is all of us are subject to the whims of these computers.” It worries me what this says about the legal system! Lets hope this gap is filled soon.

Creating applications in XCode using frameworks

Defining a proper, logical structure to a new project is an important early step. It will save time later, when you realise you really need to enforce a bit of order, and will make development easier over the life span of the project.

One useful structure that can be fairly well managed in XCode makes use of frameworks to contain the bulk of your project’s code. A framework can be created as a ‘sub-project’, and a build step added to your main target that builds the framework before continuing. This can aid in enhancing the readability and maintainability of your code, and helps to encourage and enforce the use of the model-view-controller paradigm.

Automatic iTunes track rating based on listening patterns

I have written an application that analyses listening patterns in iTunes and generates track ratings automatically. This is particularly useful when using Party Shuffle. The application awards a high score to tracks that are listened to frequently, and penalises tracks that are skipped frequently.

It uses the formula:

rating = (100 * ( (play frequency – lower) / (upper – lower) ) – skips per month * 5

Where upper is the main play frequency + 2 standard deviations, and lower is the mean play frequency – 2 standard deviations

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Download AutoRate 1.0 here

Run-down on Mac OS X media center software

Update: Matt Hansson has written a more up-to-date overview of the offerings. His findings: He still prefers Mediaportal on Windows to the currently available Mac solutions. Damn.

We’ve recently set up a home entertainment centre, consisting of a 40″ Samsung LCD TV, a Yamaha 6.1 audio setup and a Mac Mini.

In order to drive it all, I was after a full-screen media center suite (movies, music, DVD, etc), to hide the fact that it’s a computer – we don’t wanna see that muck!

It had to have a high usability, and a high WAF (Wife Acceptance Factor…Actually, partner, but you know), which means no hardcore key combinations, or dropping to terminal to kill -9 anything. I’m looking at you, Xhub.

It had to be relatively fast – no waiting around for five minutes for the music library to appear.

…And it had to offer some moderately easy way to share screen-time with EyeTV, the digital TV viewer/recorder.

OS X performance tweak?

While looking around for information on some fairly irritating memory leaks I’ve been encountering in OS X (some common library seems to be chewing up memory, so that after a few days of running, all my apps take up enormous amounts of memory), I found this old tip regarding setting the maxvnodes parameter.

A comment attached to the tip above quotes one of Apple’s kernel developers: “Increasing the value of maxvnodes will increase the number of files that get cached in RAM. This will make subsequent access to those files much faster. But the downside is that more of your RAM will be used up for this disk caching and thus you will have less RAM available for normal application use.”

Thus, by default, Apple specify a value that is apparently a compromise for best overall performance.

That said, I increased the value to 84672, despite not having large amounts of free RAM:

sudo sysctl -w kern.maxvnodes=84672

My machine, after running for a few days without a reboot, often runs quite sluggishly, with lots of swap activity. For example, bringing up the Dashboard after not using it for a while can take a good 5-15 seconds, depending on what else is running.

After tweaking the maxvnodes value, all the widgets in Dashboard refreshed within 2 seconds (it had been a fair while since I last brought it up) – just coincidence, or did it actually make a difference?

The system does feel snappier; I can do things like start apps, bring up menus, load webpages, switch desktops and use Quicksilver without the irritating delay that I usually get. Maybe it’s all in my head, but maybe not. Worth a go!

If it does work, the command can be put into /etc/rc to be run on boot (as settings are forgotten after reboot). Instructions are outlined in the comments accompanying the tip.

[Edit]: This command might aid in establishing an optimal value:

sysctl -w kern.maxvnodes=$(echo $(sysctl -n hw.physmem) 
   '33554432 / 512 * 1024 +p'|dc)

DVD-R media guide

I’ve been using some ‘mag media’ blank DVDs I bought at JB HIFI, and they’ve given me a bit of grief. I’ve had a number of failed burns, and in one instance, my DivX player wouldn’t read a disc that had been burned a couple of weeks earlier.

I’m almost out of blanks, so I thought I’d dig a little deeper to see if I could find a brand that would be more reliable. I came across this blank DVD media quality guide, which gives a rundown on the different blank DVD media out there.

Pioneer, Verbatim, Hitachi Maxell, Sony and TDK, among others, are apparently very good. Some discs produced by Ricoh and Ritek and others are decent. Discs by Samsung, Princo, InfoMedia (which is where the disks I currently have came from) are questionable in quality, and media from…a whole lot of other manufacturers I’ve never heard of, are apparently ‘pathetic garbage’ (this is the ‘no name’ stuff you’ll find on eBay and in the crappier stores).

Mail’s ‘Entire Message’ search gives ‘0 found’

Mail just stopped returning search results when I did a full text email search. I did a bit of googling and found some discussion on the problem with 10.4.7 that was fixed with 10.4.8. So, not that. Someone in that thread mentioned that they forced a re-index of their entire drive in Spotlight.

Scott, another individual who mentioned the problem on his blog said he attempted to just re-index the local Mail repository, but to no avail (he noted that there was a problem with the Spotlight filter for Mail). He also forced a rescan of the drive.

I didn’t feel like doing an entire rescan, so I checked for the Spotlight filter with mdimport -L. Lucky for me, the Mail importer seemed to show up. I quit Mail, re-indexed its data with mdimport -f ~/Library/Mail, waited a few minutes and re-opened Mail to find search working again.

So, just forcing a re-index of the Mail directory seems to work under 10.4.8 Intel.

Suck those clicking earplugs

I’ve been having trouble with my left iPod earplug, which has been clicking and distorting beyond a (relatively low) volume – making listening very annoying. I was making plans today to go and visit the Apple store where I bought the iPod, when I remembered reading something about sucking on the troublesome earplug. I gave it a go, and it fixed the problem! Just apply some suction to the earplug, and it seems to unstick something inside.

I couldn’t find the article I read that suggested this, but credit goes to someone out there for this quick fix.