Muthu

06:31 pm - Converting avi to dv

I had to convert avi files that I recorded from a cannon powershot digital camera to edit with kino. It is fairly straight forward if you have ffmpeg. I had a raw avi file. A dv file is raw but you need to resample the avi file from 30 fps to 29.97 fps which is btw the standard for NTSC (it should have been some 11 times e). All you need to do is
ffmpeg -i input.avi -s ntsc -r ntsc -aspect 4:3 -ar 48000 -ac 2 output.dv
For those who live in countries other than the united states, you must %s/ntsc/pal/g and you have a dv file in pal format.
Another small trick that I had to do in the process is to merge avi files. Its easy again
cat file1.avi file2.avi > merged.avi
mencoder -ovc copy -oac copy -o merged.avi -forceidx output.avi
The second command is basically an error correction.

Current Mood: satisfied

11:22 am - The theory gang at slope day

We call ourselves the Oceans 5

08:36 pm - The Springer GTM Test - Result

If I were a Springer-Verlag Graduate Text in Mathematics, I would be Robin Hartshorne's Algebraic Geometry. My creator studied algebraic geometry with Oscar Zariski and David Mumford at Harvard, and with J.-P. Serre and A. Grothendieck in Paris. After receiving his Ph.D. from Princeton in 1963, he became a Junior Fellow at Harvard, then taught there for several years. In 1972 he moved to California where he is now Professor at the University of California at Berkeley. My siblings include "Residues and Duality" (1966), "Foundations of Projective Geometry (1968), "Ample Subvarieties of Algebraic Varieties" (1970), and numerous research titles. My creator's current research interest is the geometry of projective varieties and vector bundles. He has been a visiting professor at the College de France and at Kyoto University, where he gave lectures in French and in Japanese, respectively. My creator is married to Edie Churchill, educator and psychotherapist, and has two human sons and one daughter. He has travelled widely, speaks several foreign languages, and is an experienced mountain climber. He is also an accomplished musician, playing flute, piano, and traditional Japanese music on the shakuhachi. Which Springer GTM would you be? The Springer GTM Test

09:53 am - Tennisable weather

Today it is clear sky and the temperature reaches 65F. So it is tennis time and I can walk around in shorts (whew, what a relief...). I have cancelled all my meetings to play tennis (nothing important though!!!).

Apparently, it is Ugadi (or Telugu/Kannada New Year) today. So HAPPY NEW YEAR to all desi folks out there.

Current Mood: excited

05:34 pm - More from spring break

I went mountain biking in Dallas with my cousin. He had bought two new mountain bikes (@ $350). This was my first experience. The weather was ideal for biking: 60F with a cool breeze. We took the Knob Hill Trail.

The trail was for beginners/intermediate. It was 5 miles long (two way). We started from a point that was one mile into the trail. The terrain was full of stones in the initial part and flat for most of the time. The last one mile was narrow, and had a few ridges. The toughest point was when we had to get across a creek.

I do not have photos since we did not want to take a camera with us. This a photo from the website. .

Ithaca has some bike trails. I will try going on a few this summer ;)

Current Mood: high

02:28 pm - Spring break at Austin

I have come to austin to spend the first half of my spring break (the other half will be in Dallas). I went kayaking with arvindn . More here

02:46 pm - Jazz concert

I went to a jazz concert for the first time yesterday. This was a jazz by Paul Smoker performed by a band from Cornell.
The band had 4 groups. Three were quintet and one was a septet. The common instruments in all the groups were the drums and bass, though there were different instruments for the bass. Three of them had a trombone. One of other instruments in the jass last night was the harp. They had the four groups spread across the auditorium.

The sound of the trombone is something that defines jazz to my ears. Since this was my first concert, I tried to concentrate in hearing each instrument. Almost till the end of the concert I could not hear the bass. It was in the background, but I could not isolate those frequencies. All the other instruments had solo pieces except the bass.

Before the concert I was warned that I would hear disharmonious music, but at the end of it I did enjoy it. In two weeks, there is a carnatic concert by Sanjay Subramanyam.

Current Mood: energetic

08:47 pm - latex notes - mod, pmod, bmod and pod

Writing congruence relations in latex.
1. x \mod a : there will be a long gap between x and mod.

x   mod a

x mod a

x (mod a)

x (a)

05:39 pm - How to use weather forecast effectively in winter?

Last winter, I never managed to find the right piece of clothing for the day. I used to check the forecast, but I never paid attention to the finer details. I checked the current temperature before leaving home and decided what to wear. This turned out to be ineffective in Ithaca, because on many days the weather in the afternoon was different from what it was in the morning.

This year, I began looking at the hour by hour forecast to decide on the clothing. This was not enough!! I needed to know, what were the chances of precipitation, because I would slip easily if I wore snickers and walked on ice. Off late, I watch the wind speed because it feels a lot more colder with heavy winds. Based on the weather forecast for the day, I have the following algorithm to decide what I must wear.

what_to_do_in_winter(weather_forecast today){// all temperatures are expressed in Fahrenheit 
<th colspan="2" align="left">
switch(min(today.feels_like)){ // You need to look at the hour by hour forecast to find minimum
case greater_than(50) : Invalid input. You are not in Ithaca!!!. exit(0) 
case between(32,50) : Use fall-jacket
 
case less_than(32) : Apply moisturizer to skin and chapstick to lips. Use down-jacket.
case less_than(10) : Wear thermal inner garments
}

if (((today-1).precipitation or today.precipitation) = snow and 25 < today.temperature < 35){
 
// If the temperature today is around freezing point of water (=32F) and 
//  it snowed yesterday or it is snowing today
 
Wear snow-shoes 
}
else Wear snickers

switch(today.wind_speed){
case lesser_than(10mph) : Wear beanie hat and gloves
case otherwise : Wear scarf, beanie hat and thicker gloves
}
}

Current Mood: cheerful

05:28 pm - Changing Screen Orientation in Xorg

In order to change the screen orientation from portrait to landscape (or vice versa) in a Xorg X-window system (with nvidia), (if you have installed Ubuntu on your desktop, xorg gets installed by default) then you need to have the package xrandr installed. Search for xrandr using synaptic and install all the libxrand* packages. Edit the /etc/X11/xorg.conf file. Your device section should look like this:

Section "Device"

Current Mood: excited

10:42 am - Cornell CS and Visit day

Before reading this, you must know that I am a grad student in Cornell, which is in Ithaca (a city in upstate New York). It is widely known that Ithaca has four seasons June(spring), July(summer), August(fall) and Winter (covered in snow).

It is a usual practice for all schools, after offering admissions to students to their graduate program, to invite them for a tour of their campus. This occasion is known as the "visit day". This happens once in Spring and once in Fall, though the former is grand because the intake is high during this time of the year.

In Cornell, the Spring visit day is scheduled in the first week of March and most of us would think that with high probability Ithaca must be covered with snow during this time, but that has not been the case for quite some years. It has been very pleasant during visit day for the past few years, as a result of which the students who come here to visit get the false impression that the weather is good around this area. But this year, the visit day is scheduled to be today and there is a predicted snow storm from morning till evening (about 6 to 8 inches).

Finally, this year would be a true test on the incoming students, to get their priorities right and make an unbiased decision!!!

Current Mood: anxious

07:33 pm - found a spam link

Google for "CSE 533 PCP" and the first hit links to a spam page. I guess there are many such spam pages on the web, but this is the first one I found. It is amusing that the contents of a webpage like that can be used for spamming. It actually links to an msn page in chinese or japanese. Now the page does not have any of the contents that were part of the original website. But, the cached link has the same contents as the course webpage of university of washington.

Clearly, these spammers take stuff from random pages to make their page appear for some searches, because this page cannot be the most popular page.

Anyways, as long as there are people who are vulnerable to these spam links, the spam industry will persist.

Current Mood: amused

08:20 pm - PCP theorem via Gap amplification

At last !!! I know the proof of PCP theorem, thanks to Irit Dinur for giving a short proof, and Venkatesan Guruswami and Ryan O'Donnell for posting a self-contained lecture notes on this proof online (link).

The PCP theorem states that all languages in NP, can be verified using constant queries on the proof and O(log n) bits of randomness. The original proof was given by Sanjeev Arora et al. and can be found in his Ph.D thesis. This is pretty long (I have not read that), and as I hear it involves heavy machinery from algebra. The proof by Irit Dinur, that is to appear in the proceedings of STOC 2006, uses mostly combinatorial arguments and is elegant.

I found the lecture notes by Guruswami and O'Donnell an easy read (minus a few trivial typos) and very illustrative. I plan to work in complexity theory and this is where I begin my venture into this vast subject.

Current Mood: content

10:55 pm - Brain as a simulator

Our brain has remarkable capabilities of simulation. Last night, I was watching the women's figure skating in the olympics. Figure skating, is a good example to understand angular momentum. There was a particular step, that bothered me as to how the woman balanced herself. I worked a little on the torques and found that the torque generated by the centrifugal force compensates the torque generated by the weight and she maintains balance.

The funny thing, is that I dreamed that I was figure skating (, note that I am neither thin nor flexible). The beautiful part was that I could feel the forces when I did the move. This I think, is the most remarkable thing about the brain. In our dreams, our brain can simulate nerve impulses that we feel in daily life. For instance, we can artificially generate impulses of touch. Imagine that you are touching the table in your dream, you would have the same feeling as you touched it when you were awake. You can imagine other things too but let me stop with this example ;)

One might say that you can imagine all this while you are awake too. I think, we can simulate things with better concentration in our dreams. This is something that has been bothering me for a while. Imagine you are standing in front of a blackboard with chalk in your dream. Let us say, you could write two ten digits numbers on the board and multiply. This means you have just multiplied two long numbers all inside your brain without pen and paper. In retrospect, I think we cannot do it in the dream . May be everything is very fuzzy in the brain.

Current Mood: confused

11:08 pm - Quote for the day

A must record quote for the day. My office-mates and I went to Nine's for dinner and at the end, we all had to pay. We needed to break $20 and one of my officemates remarked,
"I can break $15!!!".
This is the most amusing thing, I have heard for a while.

Current Mood: amused

06:15 pm - Shifting balance while skiing

After skiing 6 times in greek peak, I finally managed to go on the black slope. From the beginning, I could turn to my right comfortably but turning to the left was awkward. I always had my weight on my right feet irrespective of which turn I took. The main problem is that, I could not convince my brain that I could balance on my left feet, so that I could shift weight on to that feet when I turn left. Later, I realized that if I had a sitting posture (i.e. knees bent), then my weight automatically shifted to the right and left feet.

Though I went on the black slope 4 times today, every time, I did it in stages, where in each stage I would do at the maximum of 4-5 turns and then stop. It was good and I think once the rhythm is set you get going. I still have to figure out, how to do the same while ice-skating. It is kind of the same problem. I can balance myself on my right feet and lift my left feet off the ground,but I can't to do it vice-versa.

Do other people have similar experiences while skiing or skating? Is there something that would help my skating?

Current Mood: tired

05:48 pm - nerd score

A bad beginning for my journal entry. But who cares. I saw this nerd test on another live journal entry by vinodv. So, I thought I might as well take the test. I took it to see what questions were there. I found there were many more things that were nerdy that were'nt in the list, like do you like coming to your office on weekends and read random stuff. How long can you sit on the comp doing non-work related stuff? Anyways, my score is here

Current Mood: excited