iPhoto 11 hangs at start

Posted 8.01.12 by ajv

What a nice Sunday fighting with iPhoto ’11. This is how it went:

find . | grep -i iphoto

It is now 11:45PM and I think I spent at least 4 hours of my Sabbath with this crap – where can I send the bill? Anyway, remember to back up, kids!

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Theoretical living room acoustics - New Formula

Posted 25.12.11 by ajv

Just came across a paper where different ad hoc formulae for predicting rectangular room reverberation time are compared with actual measurements: R. Neubauer et al: Prediction of the Reverberation Time in Rectangular Rooms with Non-Uniformly Distributed Sound Absorption

In the paper, Neubauer et al also derive a “New Formula” with improved accuracy, given in equations 20-21. It seems though that the equation 21b has a typ’o negative sign prefix that seems a bit off. Anyway, I wrote a Matlab code to test it:

Haven’t tested it yet, but seems to give a figure in the same ballpark with my measurements by just picking the absorption coefficients with the Stetson-Harrison method. Now if I get to test this more with actual absorption data (available here for some basic materials and here for Ecophon Master SQ) and one could see the differences not unlike my high fidelity measurements, that’d be something. But it’s getting late already…

Update 26.12.2011 14:30. And the same in your favorite browser, caveat emptor still applies:

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How to convert videos to webm-format

Posted 2.12.11 by ajv

It took some time to figure out, how to convert videos to webm format using a bit old Ubuntu Linux, where none of the available encoders (ffmpeg, mencoder) support webm encoding.

The most straightforward way is to compile WebM encoder from source. Just clone the git-repository

git clone http://git.chromium.org/webm/libvpx.git

install yasm assembler

sudo apt-get install yasm

and do the standard

./configure && make

and copy the vpxenc to /usr/local/bin. Then have your video converted first to yuv format

ffmpeg -i myvideo.avi myvideo.yuv

and use either the fast 1-pass encoding

vpxenc myvideo.yuv -o myvideo.webm \ —i420 -w 1280 -h 720 -p 1 -t 4 \ —good —cpu-used=3 —target-bitrate=2000 —end-usage=vbr \ —fps=30000/1001 -v \ —kf-min-dist=0 —kf-max-dist=360 \ —token-parts=2 —static-thresh=1000 \ —min-q=0 —max-q=63

or the nicer quality 2-pass encoding

vpxenc myvideo.yuv -o myvideo.webm \ —i420 -w 1280 -h 720 -p 2 -t 4 \ —best —target-bitrate=2000 —end-usage=vbr \ —auto-alt-ref=1 —fps=30000/1001 -v \ —minsection-pct=5 —maxsection-pct=800 \ —lag-in-frames=16 —kf-min-dist=0 —kf-max-dist=360 \ —token-parts=2 —static-thresh=0 —drop-frame=0 \ —min-q=0 —max-q=60

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helistin.fi terve24.fi, huoltamo.com etc password analysis

Posted 28.11.11 by ajv

Now that the passwords and user names have been compromised for the above mentioned sites, we get a look into passwords differences in health-related and pre owned car sales sites .

This time around the username and passwords match in around 1600 cases (approx 2%). Salasana is the most popular one, but qwerty is left out of the top 20. Surprisingly enough, anneli is again the top 20.

# password number of occurrences
1 salasana 190
2 aurinko 145
3 johanna 123
4 vauva 91
5 nallepuh 78
6 123456 76
7 susanna 74
8 mansikka 72
9 rakkaus 67
10 katariina 61
11 pauliina 59
12 mussukka 59
13 emilia 58
14 terveys 57
15 tiikeri 56
16 hannele 51
17 kukkanen 50
18 enkeli 50
19 helistin 49
20 anneli 49

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netcar.fi password analysis

Posted 16.11.11 by ajv

As the netcar.fi username and password database with around 12000 records was compromised earlier today, I thought it’d be fun to run a simple analysis to see how many usernames and passwords match and on the other hand get the list of most used passwords. The results:

611 (about 5%) usernames and passwords match, and the most common passwords are:

# Password Number of occurrences
1. 123456 35
2. salasana 28
3. bemari 15
4. perkele 14
5. auto 14
6. 1234 14
7. mattisili 11
8. netcar 10
9. juhani 10
10. antero 10
11. yamaha 9
12. rasmus 9
13. johannes 9
14. ilmari 9
15. anneli 9
16. sierra 8
17. oskari 8
18. kissa 8
19. toyota 7
20. qwerty 7

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iMac day 400+

Posted 29.06.11 by ajv

Hard disk failure. The system began to lag / stall and finally did not even boot. When booted in verbose mode (press cmd + v at startup), it was evident that at least the book keeping of the disk had gone corrupt.

The standard OS X Disk utility, which displays SMART. status would say the disk is “verified” and reported no errors with it. After starting the thing from OS X DVD and restoring from an old backup (a 2 days old back up could not be restored), the disk structure seemed also ok. However, comparing Disk Utility’s results with SMART utility revealed that the SMART status is in the eye of the beholder

I called the local Apple hotline, who told it’s better to send the thing to authorized service partner, who would charge 150-200€ for disk replacement. I also went to a PC shop where, when asked if they could replace a iMac HDD, they told me “Oh sure, is it a laptop, we’ll charge 25-75€”. Based on these, and especially the friendly guy at Apple hotline who specifically told me not to try replacing HDD myself, I decided to buy a Samsung 103SJ 1 TB disk and dig my torx drivers to broad day light.

Replacing the disk was a lot easier I thought it would. There is a very good tutorial available at ifixit . I even cut it a bit short and did not detach other cables between the motherboard and display than the vertical sync ribbon.

However, after replacing the old Hitachi 1TB HDE721010 SLA330 disk with the Samsung the HDD fan would start to make noise not unlike a normal PC. Apparently the factory installed hard disks in iMacs (late 2009 models and newer) have Apple’s proprietary firmware and read the HDD temperature not through SMART but through a separate thermal sensor connector.

I could not get that to work with the Samsung HDD (actually the connector would not fit like ifixit documentation advises). The noise issue was resolved by installing a piece of software, HDD Fan Control, which allows for manual tweaking of fan speed as a function of HDD temperature. And this thing gets the temperature through SMART and not by some proprietary means. The only downside was the price tag, about 30 € for such a small piece… But worked like a charm.

It still beats me, why I could not use my latest Time Machine backup to restore the system. I managed to get the disk to the state it was on 2nd of January 2011 and right now I’m restoring the home directory from the latest backup, which seems to run fine so far 55 GB / 171 GB.

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Zotac Zbox HDMI audio out on Ubuntu 10.10

Posted 13.04.11 by ajv

Got a Zotac HD-40 for replacing PS3 for browsing and playing movies on TV. Everything except audio over HDMI worked out of the box with Ubuntu 10.10. For audio, a) unmute sp/dif of nvidia card b) test it works with “speaker-test -D plughw:1,7 -c2” c) if it does, put the following in /etc/asound.conf (have to create a new file):

pcm.!default {
type hw
card 1
device 7
}

I browsed through hundreds of web pages telling to work with drivers and compiling kernel, but the above should do it. Worked for me anyway.

Edit: goddamit, spotify does not work… we’ll see.

Edit 2: audio stopped working again. Once I got rid of pulseaudio (sudo apt-get purge pulseaudio), audio was back up and Spotify works too. Nice. Oh, and I put explicitly hw:1,7 for audio device on xbmc.

Also, had to tune some vblank options in xbmc to get rid of video tearing. Could say this thing didn’t work out of the box.

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ATLAS BLAS SSE2 randomly segfaulting

Posted 26.11.10 by ajv

Last night I wrote some code using world famous BLAS dgemv to perform matrix-vector multiplication. The first thing this morning was to check out the modifications from code repository and continue hacking at work.

Turned out I’d be hunting for a bug causing segmentation fault the whole day. The code would crash at random times when dgemv was called, and I knew that it was going to be a fun day chasing the memory corrupting lines from the code. Because RAII, I had no calls to “new” or “malloc()” and pals in the code so it would be easy.

First, wrote a simple piece of code performing the same dgemv to reproduce the bug. Could not get it to corrupt memory.

Next, checking what’s going on using valgrind (gotta love it). It reported “Use of uninitialised value of size 4” on every call to dgemv. Double checked the parameters and matrices & vectors. Quadro-checked. Used —track-origins=yes. Valgrind told something wrong inside blas’ stack. Damn.

Tried the same code on a different machine on different blas (2pm). Everything works. Double checked with valgrind. No complaints altogether. Tried to change blas implementation on the development machine, using update-alternatives. Would not work but always link to the SSE2 version. Removed atlas sse2 libraries altogether and tried 3dnow optimized version (4pm). Everything works. Can go home now. Not a very productive day.

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Matlab clone on your browser

Posted 26.09.10 by ajv

MathCloud

Now if someone came up with implementation that supports plot() through Google Visualization API or something.

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N8 turns any screen to touch screen

Posted 20.09.10 by ajv

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My first Finnish phishing

Posted 21.08.10 by ajv

Very convincing:

Hyvä tilin käyttäjä,

Olemme tällä hetkellä päivitystä meidän tietokanta ja keskustan sähköpostitilejä eli kotisivu mieltä. Microsoft poistaa sähköpostitilejä, ikä ei enää aktiivisesti luoda enemmän tilaa uusia tilejä users.we myös tutkineet koko järjestelmän turvallisuuden tarkastus parantaa ja laajentaa meidän nykyinen turvallisuustilanne.

Edelleen käyttää meidän palveluja tarvitaan päivittää ja uudelleen comfirmed tilisi pyydetyt tiedot sähköpostitse alla.

Viimeistele uuden tilin vahvistus, sinun täytyy vastata tähän viestiin välittömästi ja anna tilitietosi pyynnön alla.

Käyttäjätunnus: ………………
Sähköposti Käyttäjätunnus …………..
Salasana: ………………
Vahvista salasana :…………
Syntymäaika :…………..
Tulevat Salasana :…………

Muuten tilisi välittömästi käytöstä tietokannastamme ja palvelu ei ole katkaistu, koska tärkeät viestit voivat myös kadota vähentää uudelleen comfirmed tilitietosi
meille.

Pahoittelemme häiriötä tämän tekee tänä aikana, mutta luottaa siihen, että olemme täällä palvella sinua paremmin ja antaa enemmän teknologiaa, joka kiertää sähköposti ja internet.

Se on myös asiaan, ymmärrätte, että tärkein huolenaihe on asiakkaillemme, sekä turvallisuuden tiedostot ja tiedot.

Vahvistuskoodi: -/93-1A388-480 Webmail teknistä tukiryhmää.

I’ve used a special filter in my email account (which is not hotmail), which allows through all email in Finnish. Hope this is not a trend setter.

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Century old photos

Posted 20.08.10 by ajv

On The Big Picture

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Assembly 2010 democompo winner

Posted 9.08.10 by ajv

Strange.

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Staying up too late in front of a screen?

Posted 2.08.10 by ajv

Some people think f.lux works.

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Using myLogger / traxmeet on Mac OS X

Posted 21.07.10 by ajv

The mylogger GPS device used by traxmeet service is the same as i-gotU There is a command-line & GUI hack for it called igotu2gpx which works in Linux and OS X. I could download tracks with Mac but cannot erase the memory…

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Amazon cloud tailored for high performance computing

Posted 15.07.10 by ajv

As contemplated in the past, Amazon EC2 cloud released support for HPC.

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Ubuntu finally working

Posted 7.07.10 by ajv

Every now and then I’ve tried out Wubi installation of Ubuntu on my laptop. In 2008 wireless lan would not work without tweaking and 2009 sound card would not play a sound. But 2010, with Ubuntu 10.4 everything work straight out the box. The only minor issue is to get Spotify to work under Wine emulator…

Now it is possible to be a Windows free household again. Was under the oppression of the evil empire during 2007-2010.

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Another in the camera does not matter series

Posted 6.07.10 by ajv

Some fashion photos taken with iPhone

The iPhone Fashion Shoot - Lee Morris Shoots With The 3GS from FStoppers on Vimeo.

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Circling the square

Posted 5.07.10 by ajv

Russell Kirsch says he’s sorry

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Intel playing mythbuster gone wrong

Posted 29.06.10 by ajv

“GPUs Are Only Up To 14 Times Faster than CPUs” says Intel

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