Phillips Webcam with Linux

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I bought three Phillips SPC  900 NC webcams because they claim to support up to 90fps and I have had good luck using linux with the PWC drivers in the past.  Plugged into a generic Ubuntu 7.10 install, I found that 640×480 resolution was automatic, with 15fps. 320×240 worked at 30fps. (I tried 160×120 resolution, but wasn't able to get a speed faster than 26fps with that, so I'm doubtful of the 90fps claim from Phillips, at least with the stock Ubuntu drivers.)

This useful website looks to provide nice OpenCV support for this camera. 

I have also archived the relevant files on my site, in case the above link goes down. 

Webcam to OpenCV package

Webcam software manual

Hacking the iPod Touch – Jailbreak to 1.1.3 w/ extra apps

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General info:

How to put an ipod touch into restore mode: Plug it into your computer, and turn on iTunes, then: hold the power and home buttons down until it resets. Release the power button, but keep the home button held until it enters recovery mode.

How to restore to a specific version of the firmware that you have downloaded to your computer: Use iTunes but instead of just clicking the "Restore" button, you hold the shift key down and then clicking the "Restore" button. This gives you a file selecton dialog that you can select a specific firmware file on your local hard drive. NOTE: You can also "upgrade" to a specific firmware version in the same way, but shift-clicking on the "Upgrade" button. At some points the difference between a Restore and an Upgrade is very important! (e.g. after jailbreaking a 1.1.1 and running OktoPrep, you should UPGRADE to 1.1.2, not restore!)

VERY IMPORTANT: Turn off "Auto-Lock" in the General->Auto Lock control panel!!! You will have to do this every time you upgrade/restore to a new firmware. Nothing messes up a firmware upgrade like the ipod locking halfway through it and turning off!

Here are a few guides that I found to be the most useful for jailbreaking/hacking the ipod Touch:

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Fixing Program Guide data on MythTV after Daylight Savings Time switch

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I'm running MythTV (Subversion Trunk) on a Ubuntu 7.10 box. After the daylight savings time changeover, my mythtv box had the correct time, but the Program Guide data was still off by an hour.  Manually running a mythfilldatabase didn't fix it. After checking to make sure that my timezone xmltv settings were set to Auto, I decided to manually erase all of the program data from the database.

(After using mysql to connect to the database, I issued the "delete from program;" command to delete all of the program entries.)

Then I re-ran mythfilldatabase and everything was fixed. (I still don't understand why this didn't automatically fix itself when the ubuntu box changed it's timezone, as all of the program data is supposed to be stored under UTC…)

Human powered generator

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Diagram of the generatorLots of people have built human powered generators. I like this one for two reasons:

1. It's designed to harvest waste energy. (It helps your body stop your knee from swinging at the end of the forward swing, something your body uses energy to do anyways.)

2. The evaluation included serious medical studies to determine the amount of metabolic energy it "takes" from the human.  (to get a watt of power, it increases the human's load by less than a watt. By comparison, a hand crank generator takes 6.4 watts from the human for each watt harvested)

Mythtv gotchas when upgrading from Ubuntu 7.04 (Feisty) to 7.10 (Gutsy)

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I upgraded my Mythtv server from Feisty to Gutsy for no good reason (other than I like the pain).

Gotchas I ran into when trying to get MythTV working again:

1. The upgrade lost/removed the libqt3-mysql support from my computer. This resulted in the MythTV applications (frontend and backend) giving "unable to connect to database" errors. As the upgrade had also upgraded my MySQL install, I spent a good amount of time checking that the mythtv user still existed and had the proper permissions before I figured out it was a QT database library problem.
  apt-get install libqt3-mt-mysql fixed it.

2. LIRCD stopped receiving commands from my HDHomeRun receiver from SiliconDust. Turns out you have to change the LIRCD_ARGS="-d 5000" line in the /etc/lirc/hardware.conf file to LIRCD_ARGS="-H udp -d 5000".  After this, typing irw showed that LIRCD was now receiving the command codes as it was supposed to.

3. The module name for my D-Link GWL-G122 usb wifi-adaptor have changed, so I had to change entry in the /etc/modprobe.d/blacklist  file to reflect the new name(s) of: rt2x00usb and rt2500usb.

Riced Dynamo flashlight

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On our van trip across the country my aunt and uncle gave us two hand crank (dynamo) LED flashlights which are really useful to keep in the van. The self-charging nature of the flashlights are very nice, in that we can leave them in the van and just wind them up when we need light. Unfortunately, one of the flashlights started to dim and refused to hold a charge. When I got home and opened it up, I found that the rechargeable Li-Ion coin cell inside had died. It originally used a 2032 coin cell rated at 40mAh. 

Dynamo flashlight opened

Once I had it open, I decided I may as well fix it, and if I was going to be replacing the battery I may as well buy a bigger one (or two) and give the flashlight Continue reading →

On the fly external monitor support (mirroring / spanning) on Ubuntu 7.10

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My IBM X31 laptop has the capability to drive an external VGA monitor in addition to it's built in XGA (1024×768) Laptop Video Display Screen (LVDS). The new xrandr extension allows non-privlidged users to change monitor layouts on-the-fly. And now, thanks to my friend Tracy, I know the "extra magic" to make it all work.

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Failing power supply

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Catastrophic failure of a power supply

For my MythTV media computer I use a network based HD-TV tuner from SiliconDust . I've been very pleased with how it works, the form factor and feature set. However, over christmas it suddenly went dead due to no fault of it's own. The 5V 2A power supply had failed. (It is plugged into a UPS with surge suppressor, so I'm relatively sure it was caused by a component failure and not bad input power.) If you look at the photo of the failed power supply (left) next to the replacement component that SiliconDust sent me (right), you can clearly see where something inside melted (and/or forced) the plastic case to bubble out, leading me to believe it was a relatively catastrophic failure.

This reminds me of the trouble I had with the original iRobot Roomba. I had my initial robot replaced under warranty two times  (3 total robots) due to power supply and battery charging issues. Each replacement had a completely new (and different) power supply system, and it was clear that iRobot was iterating through  designs until they found one that was robust.  I only hope that this power supply failure was due to one bad unit, and isn't indicative of the average lifespan of the power supplies supplied with the HDHomerun.

My Reading Habits: Korean

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Google Reader (a web based RSS reader that I use to track and read various sites and blogs) has a recommendation system that will give you recommended blogs to subscribe to. It uses the RSS feeds that you are currently subscribed to, and then looks to see who else is also subscribed to those feeds. It then looks for feeds your "neighbors" are subscribed to that you are not subscribed to, and recommends them.

Two of my top three recommendations were in Korean. Juding from the pictures and a few babelfish translations, they are a news website and a fashion/entertainment website.  Two possible conclusions to draw from this:

 1. I'm more like an average korean reader than an average US reader. (Somewhat possible given the  technically orientated blogs I subscribe too.)

2. A lot more Korean uses use Google Reader to read their RSS feeds than English users and are polluting the recommendation system.

My suggestion: Don't recommend a feed that is in a language that the user has never subscribed to before. But wading through a few useless recommendations didn't take much time, and near the bottom of my list was a suggestion for the Girl Genius comic, which I did find useful, so overall I found the recommendation system useful.