Tom Stepleton

02:20 pm: Should probably mention it here, too: The PITETSBKRRH story, or now, the TPEBTSAURGH story, will be on tonight's All Things Considered at about 5:15 PM EDT or so.

The interview took place at 1 PM at the WDUQ FM studios on 5th Avenue. I spoke with Robert Siegel over an ISDN line from Washington. Even in the Internet age, being told "You should be able to hear Washington now" brings an unexpected little bit of excitement.

Actually, "unexpected" is a good word for the whole deal here...

02:01 am: PITETSBKRRH is in the newspaper!
Given the topic, I'm glad readers of the story will learn that I do actually have friends...

01:15 am: vidfs
A nice nerdy post for you now.

MATLAB is slow at reading frames from movies on my Mac, for no reason I can readily discern. Like, really, really slow---about 10 FPS for a 640x480 H.264 movie.

Today I got fed up and wrote my own facility for reading movie frames. It works... differently.

stepletron:vidfs tom$ ./vidfs ~/Desktop/rawmatte/Movie\ 3\ matte.mov -f mnt &
[1] 70872
stepletron:vidfs tom$ ls -l mnt/
total 80
-rw-r--r--  1 root  wheel     3 Jul  9 13:00 INFO_depth
-rw-r--r--  1 root  wheel     4 Jul  9 13:00 INFO_height
-rw-r--r--  1 root  wheel    46 Jul  9 13:00 INFO_movie_file
-rw-r--r--  1 root  wheel     2 Jul  9 13:00 INFO_num_channels
-rw-r--r--  1 root  wheel     7 Jul  9 13:00 INFO_num_frames
-rw-r--r--  1 root  wheel     5 Jul  9 13:00 INFO_row_step
-rw-r--r--  1 root  wheel     4 Jul  9 13:00 INFO_width
dr-xr-xr-x  3 root  wheel  4096 Jul  9 13:00 MATLAB
dr-xr-xr-x  3 root  wheel  4096 Jul  9 13:00 PPMPPM
dr-xr-xr-x  3 root  wheel  4096 Jul  9 13:00 RAWRAW
stepletron:vidfs tom$ cat mnt/INFO_width mnt/INFO_height 
640
480
stepletron:vidfs tom$ file mnt/PPMPPM/15
mnt/PPMPPM/15: Netpbm PPM "rawbits" image data
stepletron:vidfs tom$ ls mnt/PPMPPM | wc -l
  188020
stepletron:vidfs tom$ umount mnt
stepletron:vidfs tom$ ls -l mnt/
[1]+  Done                    ./vidfs ~/Desktop/rawmatte/Movie\ 3\ matte.mov -f mnt
stepletron:vidfs tom$

So basically the vidfs program turns the movie file into mounted filesystem. Each frame is its own file---actually, it's three files, in three formats, in three separate folders (PPM, a raw format, and a format convenient for reading into MATLAB). You can open the frame in an image editor if you like---of course, you can't save a modified frame back into the movie, but I don't need that.

Two things make this really easy to do. The first is OpenCV---for all its ugliness, it's good at reading single frames from movies without having you deal with the QuickTime/GStreamer/whatever API. The second is FUSE, which does a wonderful job of making userspace filesystems fall-off-a-log simple to implement. You implement four callbacks and your read-only filesystem is ready to go. GNU Hurd translators on an OS that people actually use... not too shabby. VMWare Fusion installs FUSE so that you can read disk images; if you have a Mac, you may already have FUSE. Otherwise, you can get it from MacPorts or just build it yourself. Linux folks can turn to their package manager, I assume.

Right now MATLAB pulls frames from vidfs at about 50 FPS. A custom MEX routine for reading files from vidfs will likely yield improvements.

vidfs.cc, quick 'n dirty, but works on a Mac at least. Needs OpenCV and FUSE, as noted.

01:26 am: Pittsburgh morse code fail
I noticed something while watching the 4th of July fireworks...


It's supposed to spell "Pittsburgh".

10:43 pm: I came back from the UK last week. To do that, I had to come back from Scotland.



After finishing up at Cambridge, I had about ten extra days in the UK. I wanted to go someplace remote---someplace I could be sure to get lots of work done on my thesis without many distractions. Rural Scotland seemed like the key. My first stop was a guest house near Thurso, a town on the distant northern shore of Great Britain. The train journey started at 6 AM: from Cambridge to Ely, transferring there for a train to Peterborough, then another train to Edinburgh, then another for Inverness, and finally a two-carriage local for Thurso, wending its way along a shrub-choked single track on the eastern Caithness coast.

It turns out I wasn't the only one who ever thought rural Scotland was a good place to get work done...

( Read more... )

09:34 am: Yesterday over Cambridge


Afternoon showers are a good reason for an east-facing window.

01:31 pm: Say "Ach" to Achiltibuie!
Midwesterners will get it. Anyway, if you know anyone who needs a place to crash in Badenscallie, Scotland between 13 and 20 June, let me know; I've got extra room. Make sure they're quiet---I'll be working on my thesis.

02:16 pm: flying pinto

11:32 pm: About a month ago, a British friend of my flatmate's asked me if I could name any of the English counties, to which I replied, yes, a few, and after that I'd get a few more by simply enumerating varieties of cheese and breeds of dogs and cows. Some names of Cambridge colleges are susceptible to an exaltation of the same strategy, as there are Trinity, Emmanuel, and Christ's Colleges, and most ingenious of all, Jesus College.

This evening I visited Jesus College, where the topic was Jesus, as related by the Apostle John and scored by J.S. Bach. It was just wonderful, so intricate and nourishing that you think even if these five months here had been a complete loss otherwise, it would nearly have been worth it to have had the chance to go. Hyperbolic, okay sure, but not by too much...

I am fortunate to own a very fine recording of the St. John Passion, whose excellent production renders every sound so crisply that, I'm convinced, there is no seat in any music hall anywhere that delivers such a precise acoustic vantage of each musician. You would need a network of ears, which I suppose a recording studio has. It still can't match the sights, spontaneity, and booming fullness you experience being present at a live performance by a very talented choir, and Jesus has a very, very talented choir. The college, I mean. I was fifteen feet from the performers!

07:59 pm: Video dump 2

09:35 pm: Beaufort force 7
WHEN riding your ingenious folding bicycle through the countryside at the crest of a 30-knot gust vanguarding an onrushing March cold front, flanked by squalls and cupped in the sweeping hand of the gale, you are at least riding quickly, faster than you ever have on the flat, churning the pedals desperately in the highest gear. At speed, the roar of the wind subsides to the hush of a breeze and there, for the first time in hours, it's quiet. Trees bow, leaves and grass and debris school and dart at knee height, and you hear yourself breathe. The hedges thrum strangely as you pass.

05:31 pm: A conversation with an acquaintance from Zimbabwe brought up the curious phenomenon of eBay auctions for one Zimbabwe dollar notes. These were printed in 2007 despite being worth a miniscule fraction of an American dollar then; today, by my rough reckoning, they have a currency value of $7x10^-14, or 0.000000000007 cents. I could be off by a few orders of magnitude, and I don't care to figure the real value through all the revaluations and so on, so let's assume for that reason alone that they are actually worth 0.00000007 cents, surely a gross overestimation. That's not very much money; on my modest graduate student stipend, I might earn that much every 300 nanoseconds or so. That's assuming my arithmetic isn't off, which it almost certainly is, and anyway everyone knows that Zimbabwean currency isn't worth much and decreases in value all the time. No news here.

The point is the auction. This money is only valuable because it's so totally worthless.

11:42 pm: why oh why did I travel across an ocean to go to BARF SCHOOL??



(don't have it. yet.)

10:24 pm: CMU bilked on $49 million investment, Pitt on $65 million. Today, arrests.

09:01 am: There's something special about Cambridge, England. See if you can figure out what it is.


(available in HD on YouTube)

11:07 pm: I met an emeritus professor of evolutionary biology. He took me for a glider ride:

10:18 am: Cambridge video dump 1
Some videos off of my mini camcorder:

07:36 pm: The annual damaged inventory sale at the Cambridge University Press

09:19 pm: British beers: YES

British folding bicycle: YES





British weather in January: well, two out of three ain't bad.

...actually, it's quite like Pittsburgh.


I am so jazzed about this bike, a 3-speed Brompton M type. It is an extravagant purchase, but worth the money, and assuming that I don't manage to get it stolen while I'm here, it will last me years and years. The engineering of the thing is a delight, and it's tempting to go back downstairs right now and fold and unfold it a few more times. It comes with lights, a rack, and even a tiny tire pump clipped to the frame. I wonder where we'll go over the next few months...

edit: evidently the annual racing championship for this bike requires participants to wear shirt, jacket, and tie, and has an award for "best dressed".

08:18 am: Duxford
I'm a big fan of the etymological transparency of these English town names. "Cambridge" is simple enough---presumably there was an eponymous bridge over the Cam River. "Oxford" was called that because oxen crossed the Thames there. We can only assume that the Cambridgeshire village of Duxford was named for similar reasons.

Luckily for me, Duxford is the UK's version of Dayton, and it's only ten miles south of my house, an easy bus ride away. I went, and didn't have enough time to see it all. The only camera I had with me was my pocket HD device (look for this on a cell phone in a few months, I'm sure), which is bad news for you, since you get a ploddingly artistique, super-shaky movie instead. At least there's no sound.