Wikipedia:Reference desk/Archives/Computing/2008 March 3

Welcome to the Wikipedia Computing Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

March 3

Decompile

Not trying to violate any laws or anything, just curious, are there any ways to uncompile a software to raw code? —Preceding unsigned comment added by 99.226.39.245 (talk) 00:16, 3 March 2008 (UTC)

It is easy to decompile pretty much any program into machine language. Then, it is rather trivial to get byte-code or assembly language from that. If you are adept at reading assembly, you can go through the program without trouble. Most programmers cannot read assembly language at all. Turning assembly language into a high-level language (such as C++ or Java) is not a major ordeal. The problem is that all of the function and variable names are lost. So, you end up with code where every function has a name like "function12" and "function24". Every variable has a name like "int17" or "long11". There are no comments. So, once you do this, your next step is to try and figure out what the functions do and rewrite them with intelligible names. Then, if you are successful, you'll have code that you can hack away at. -- kainaw™ 00:22, 3 March 2008 (UTC)

And how exactly is decompiling breaking any laws? I'm horrified if this is some sort of common perception. http://www.gnu.org/philosophy/right-to-read.html :D\=< (talk) 01:10, 3 March 2008 (UTC)

Well, I was thinking more like...You guys would suspect me to be decompiling a program, changing it, and selling it or something. 99.226.39.245 (talk) 01:17, 3 March 2008 (UTC)

Here is a typical quote from an EULA: "You may not modify, reverse engineer, decompile, or disassemble the software product.". « Aaron Rotenberg « Talk « 04:35, 3 March 2008 (UTC)

EULAs are hard to enforce. They're just legal gunk. There are other issues though (see Decompilation#Legality). -- Consumed Crustacean (talk) 04:40, 3 March 2008 (UTC)

Why would anyone here even care about anything like that? Chill, 99. Preventive detention is not designed to prevent unauthorized copying of software. Kushal 01:51, 3 March 2008 (UTC)

Well, just about every EULA I've seen flatly prohibits reverse engineering the licensed software, and if decompilation isn't tantamount to reverse engineering, I don't know what is!

(Which is not to say that, scofflaw that I am, I wouldn't hesitate to decompile and otherwise reverse engineer some piece of software that I owned, if the need presented itself.)

One other point: when this question is asked, the request is usually for an automatic program to perform the decompilation. It's widely claimed that an automatic decompiler is impossible to write, although that hasn't stopped some people from trying (and evidently succeeding, if the number for sale is any indication). —Steve Summit (talk) 02:04, 3 March 2008 (UTC)

Reverse engineering is useful if you have a piece of legacy software whose source code is lost and you need to port it to a new platform or otherwise modify it. It is something that you might have to resort to even if you own the rights to the software. There's a big difference between being able to translate arbitrary machine code into human-comprehensible high-level language code and being able to reverse-compile code that was generated by a compiler (especially if the compiler is known). --71.162.233.9 (talk) 02:28, 3 March 2008 (UTC)

I wouldn't have much faith in trying to port old machine code to a whole new platform with a decompiler. In fact, I seriously wouldn't be able to keep a straight face.. I can see myself in a suit, meeting with the boss, him giving me the project, and my mouth working.. I can't fight it, I break into a grin.. I twist my mouth to try to distort the grin, but it doesn't work. I cover the bottom half of my face with my hand and look out, the top half a bright cherry red. A snicker cracks out from behind my hand and I have to excuse myself. :D\=< (talk) 03:35, 3 March 2008 (UTC)

There are many companies/governments that have spent billions of dollars on software that they might then need to port. Doing monumentally difficult and crufty stuff is just necessary sometimes, and if an engineer suggested "just rewriting it in X" the boss's reaction would probably be similar to the one you describe above. That said, if the software to be decompiled and ported is wildly larger than the instruction set of the machine it runs on, it can often make sense to just emulate that architecture in software on the new target platform. I remember reading that the original Parrot author did such a thing using that VM. --Sean 13:32, 3 March 2008 (UTC)

Virtualization would be a very good idea, but if an application is complex enough to require billions of funding, decompilation would be.. well, probably more expensive than writing it in the first place. If you're brilliant and have a huge team of crack computer engineers then you might be able to translate the machine code, but you'd never get any kind of maintainable source out of it, which would probably be not worth hiring a huge team of crack computer engineers. :D\=< (talk) 17:15, 3 March 2008 (UTC)

I can tell you from experience that even if you do have the original source code, porting the program or doing any big changes to it may require more work than writing the whole program from scratch. However, it might be useful in some cases to use some specific routine from old program, even by disasembling it (if you know where to find it).

BTW, in the early years of PC, many of the PC programs were made by taking an old CP/M program and running it through a machine code translator that translated 8080 code into 8086 code. It was not necessary to disassemble the code, just translate directly to the machine code of 8086. This gives much better result than emulating the original system with instruction set interpreter. -- PauliKL (talk) 09:17, 4 March 2008 (UTC)

Did you read the decompiler article? --Spoon! (talk) 03:54, 3 March 2008 (UTC)

Any free chess program that plays like a human?

Are there free chess programs that have a "human" style of chess play (instead of always playing the optimal move found by some resource-bounded searching)? --71.162.233.9 (talk) 02:11, 3 March 2008 (UTC)

I think you'll have a hard time finding any program, free or otherwise, that is truly similar to human play. Chessmaster, for instance, goes a rather long way to make its computer personalities feel "human" - by way of allowing the occasional blunder, assigning individual strengths and weaknesses, and even personal biographies and photos - but I can't say I'm impressed with the results. I'd say the current knowledge of AI techniques just isn't there yet. -- Meni Rosenfeld (talk) 12:34, 3 March 2008 (UTC)

Vista + Ubuntu computer - what kind of problems are these?

I have a desktop computer which came with Windows Vista preinstalled. The computer worked, except that it would occasionally freeze dead for no apparent reason. A while ago, I set it up to dual boot Ubuntu 6.10, which I discovered was incompatible with my USB wireless adapter (which, yes, is on a desktop). Recently, I decided to upgrade to Ubuntu 7.10, which supports my adapter better. I couldn't upgrade it by standard means since I had no internet connection, so I attempted to completely overwrite the existing installation by CD. Being a Linux n00b, I rather botched this (I now have two swap partitions for Linux, one of which is unused), but more significantly, the computer freezes all the time now on both operating systems, and the BIOS takes forever to start. As a last attempt at getting the computer into some kind of working order, I decided to wipe the whole drive and start from scratch. Using the Windows disk that came with the computer, I merged all of the partitions back into the Windows drive and formatted the whole thing as NTFS. The Windows installer gets as far as the last step of the installation, but then it produces the error message, "Windows could not update the computer's boot configuration. Installation cannot proceed."

My question is: what kind of problems are these? Is it a BIOS problem? Did the drive arrive semi-broken, and the rebooting from the multiple Ubuntu installs kill it for good? « Aaron Rotenberg « Talk « 04:29, 3 March 2008 (UTC)

You might have screwed up the partition table; try booting into gparted and deleting all the partitions and committing the change. Then go through vista install and see if it has any problems. :D\=< (talk) 06:19, 3 March 2008 (UTC)

I can say nothing about a partition table, but this sure sounds like a hardware issue to me. It might be a hardware conflict (you could try removing or disabling as much hardware as you're comfortable with); if that doesn't work, it may be internal (e.g., BIOS), and if you didn't void the warante (sp?!), you could return it. The Evil Spartan (talk) 13:23, 3 March 2008 (UTC)

Froth, what about all of Aaron Rotenberg's data? Will you recover it for him if he loses all his partitions? --Kjoonlee 15:39, 3 March 2008 (UTC) OK, I was wrong.. sorry... --Kjoonlee 15:41, 3 March 2008 (UTC)

I fixed the problem. Apparently, the first partition, which was the "recovery partition" which came with the computer (what is this irony you speak of?), somehow interfered with the MBR and was messing the BIOS' ability to detect the operating system (hence the long wait time) and the Vista installer's ability to load its bootloader. So, in fact, it was a problem with the partition table. Deleting the recovery partition solved the problem. « Aaron Rotenberg « Talk « 06:57, 4 March 2008 (UTC)

Dazzle 150 power supply-urgent

I need to know, somewhat urgently, what the power supply for the Dazzle 150 video input device should be rated, since I don't know which "wall wart" goes with it. The Dazzle 150 has an input jack that fits (physically) the connector from a power supply I found which says it puts out 12 volts, 200 ma, 4.8 VA with the center connector positive. The Dazzle 150 has no power requirements information printed on on the device or in the instruction sheet, and I would rather not fry it. If someone has one or can find out the ratings of the power supply which it is designed to work with, I would greatly appreciate the info. The Dazzle 150 is also identified as Pinnacle Systems DVC 150. Thanks. Edison (talk) 04:31, 3 March 2008 (UTC)

You know there is this amazing thing called the internet which typically contains info like this, and there is the other amazing thing called google, that helps you search that internet thing. So many people know about "google", that it has become the basis of a verb - try googling. —Preceding unsigned comment added by 219.90.184.247 (talk) 09:37, 3 March 2008 (UTC)

Dear 219.90.184.247: I had already spent considerable time Googling, finding only unanswered queries by several other owners of Dazzles whose similar questions on other fora had gone unanswered. If you have nothing to offer but uninformed sarcastic and biting responses such as that, please find other pursuits than biting people who ask questions here. Also sign your responses. Edison (talk) 13:30, 3 March 2008 (UTC)

ok don't bite.87.102.93.158 (talk) 11:07, 3 March 2008 (UTC)

To the original question: Please do your own research eg type "Dazzle 150 power supply" into a search engine and look for the answer..

Luckily not all of us are in a bad mood today .. here http://forum.videohelp.com/topic249736.html

gives the answer

http://forum.videohelp.com/topic249736.html

INPUT: 100-240V ~ 50-60Hz 0.4A

OUTPUT: +5V---2.8A

You still need to know that the plug you are plugging in has the correct polarity - there should/might be an indication of the polarity type near the input..87.102.93.158 (talk) 11:06, 3 March 2008 (UTC)

Again, it is not necessary or desirable to preface every response with :"Please do your own research." I spent considerable time Googling variations of Dazzle 150 power supply without getting any useful info. With thousands of these gadgets installed, I thought someone might be able to just look at the power supply and provide the needed info. Now perhaps when people Google they will find this response. With respect to questions like this, there have been a number of people looking for the information apparently without finding it. Some manufacturers neglect to print the power supply info on the device or to address such mundane questions anywhere on their own web site or in the instruction books. The power supplies are not always identified as being for the device they are supplied with, and there is no standard for what size plug goes with what voltage or polarity. Thanks again for the information. Edison (talk) 13:39, 3 March 2008 (UTC)

I searched for "dazzle 150 power supply rating" - it must have been the last word that helped - it can be something of an art finding stuff....87.102.93.158 (talk) 13:49, 3 March 2008 (UTC)

Obviously DONT plug in your 12V supply.....87.102.93.158 (talk) 11:07, 3 March 2008 (UTC)

Does anyone have access to one of these, to inform what the polarity required is? Center positive or center negative? Thanks!!Edison (talk) 19:36, 3 March 2008 (UTC)

Video editing: seeking program to strip audio off video

Hi all,

I have a video file ( MPG format ) and I want to cut the sound track off of it so it is silent. Are there any easy programs that you recommend? Trialware or shareware is okay. Guroadrunner (talk) 07:41, 3 March 2008 (UTC)

errr, just turn the sound down on your computer :D If not, iMovie can strip sound, sure Windows movie maker can do the same. Radiofred (talk) 11:13, 3 March 2008 (UTC)

I believe VirtualDub will do what you require plus its free and runs standalone. --211.28.214.119 (talk) 11:50, 3 March 2008 (UTC)

I may be wrong but doesn't VirtualDub only work with avi files? Think outside the box 12:03, 3 March 2008 (UTC)

You might want to try VirtualDubMod Think outside the box 12:03, 3 March 2008 (UTC)

Hmmm, you may be correct though I have a suspicion, that VirtualDub can in fact open .mpg's but can only save as .avi which may or may not be a problem for the op --211.28.214.119 (talk) 12:21, 3 March 2008 (UTC)

Quicktime Pro does this very easily (you can easily delete individual video and audio tracks in a whole number of formats.) It's not free, but it's cheap and does this sort of job and other small editing jobs (like trimming out small pieces of video and splicing them together, or converting to and from a whole host of formats) extremely well and reliably, better than any of the "free" programs I have long struggled with. --98.217.18.109 (talk) 14:19, 3 March 2008 (UTC)

I've done the reverse; stripping MPEG-1 video and saving MPEG-1 layer 2 audio, in other words, turning video CDs into MP2 files. Your best bet is to search for an MPEG-1 demuxer. If quality is very important, you should definitely look into demuxing (cutting), not transcoding (conversion). --Kjoonlee 15:02, 3 March 2008 (UTC)

You want to try using Super (Simplified Universal Player Encoder & Renderer), it's free --Dave (talk) 17:47, 6 March 2008 (UTC)

ipod touch wifi browsing

I have a DSL modem which does not have wifi and ipod touch. But what should I do to browse Internet in ipod touch using wifi in that modem? —Preceding unsigned comment added by 59.96.139.114 (talk) 10:25, 3 March 2008 (UTC)

Well, uhh, you can't. Since it doesn't have it. You can buy a wireless router, hook it up to the modem, and use that. -- Consumed Crustacean (talk) 10:44, 3 March 2008 (UTC)

There are also DSL modems with built-in WiFi, which will reduce the wiring mess of ethernet cords and power cables. --70.167.58.6 (talk) 23:00, 9 March 2008 (UTC)

Damaged video files on bittorrent

Often from bittorrent I download a movie file, such as "steamy Sex Video leaked online.wmv", and when I play the file all I get is colored shapes and mangled audio. I've tried VLC and downloading codecs but nothing helps. What is wrong with the file? How can I play it? Weasly (talk) 11:24, 3 March 2008 (UTC)

Did you wait for the entire download to finish? It is common for bittorrent programs to stick the data blocks of an entire download into seemingly random blobs. When the entire download (every single file) finishes, it rearranges the data blocks and puts them in the correct order to make the files. If you try to play a file while the torrent is still downloading, you'll get weird random shapes and mangled audio. The same goes for MP3s. If you try to play one while the torrent is still downloading, you'll get mangled audio. -- kainaw™ 13:07, 3 March 2008 (UTC)

Yes, brainiac, I did wait for the download to finish. There was something wrong with the file - in fact I've had this happen several times on many different files, all of which were videos. Just so you know I'm not a computer gizhead, and I download hundruds of movie and mp3 files all of which work fine. Its just some movies which have this problem, mainly porn movies from isohunt. Is it some idiot uploading shit to annoy others or do I need to decrypt the video of something? Weasly (talk) 13:27, 3 March 2008 (UTC)

It probably is, you shouldn't be using public trackers and you should be reading comments. Even if it isn't someone uploading garbage, someone else might have the same problem :D\=< (talk) 17:11, 3 March 2008 (UTC)

That happens sometimes. You might want to research well on the person who is providing the torrent, and comments that other users have posted on it. 75% of the time its some guy who just likes messing with people by posting unusable files.--Dlo2012 (talk) 15:45, 3 March 2008 (UTC)

This is due to the fact that the file is encrypted. VLC will play garbage but if you play it in windows media player it will open a web page where you can buy the license key necessary to play the file. However, know that most of the encrypted wmv you'll get from bittorrent/edonkey are really spam, designed to take you to an add-ridden website. Morana (talk) 15:51, 3 March 2008 (UTC)

One more reason to stick with VLC. Kushal 05:20, 4 March 2008 (UTC)

P2P slowing down my internet connection

Hi. Whenever I am running a P2P client (eMule, BitTorrent 6...), my internet connection (browsing, unrelated downloads) slows down considerably, even though the client itself only downloads at a small fraction of my bandwidth. Any idea why that might be so? Thanks. -- Meni Rosenfeld (talk) 12:20, 3 March 2008 (UTC)

Have you limited the upload limit of your bittorent client, or is it running at unlimited. By allowing a client to use the vast majority of your upload speed you can slow down speed of other unrelated things such as browsing as they too require small amount of uploads, maybe limiting your upload speed on your client to 70-80% of your max could do the trick. Again this may not apply to you but this a relatively common problem so I hope this helps. --211.28.214.119 (talk) 12:43, 3 March 2008 (UTC)

Thanks. Limiting the client's upload problems lessens the problem, but it still exists. Even when I limit it to 10% of the max, my download speed drops to 50%. Any other suggestions? -- Meni Rosenfeld (talk) 13:06, 3 March 2008 (UTC)

What kind of internet connection are you using? Dial up? DSL? Cable? T1? -- kainaw™ 13:08, 3 March 2008 (UTC)

DSL. -- Meni Rosenfeld (talk) 13:15, 3 March 2008 (UTC)

Just to get a better idea, you might try limiting it to 0% and then 1%, and seeing if that helps. If it does, you might limit it even further (it might be misreading your internet speed). However the fact you're using DSL tells me something, because DSL is famous for having a high latency, and the p2p might be making a lot of requests to your machine. The Evil Spartan (talk) 13:20, 3 March 2008 (UTC)

Well, it looks I had some measurement error. I've experimented more carefully and it seems that moderately reducing the upload limit eliminates most of the problem after all. Thanks for the help. -- Meni Rosenfeld (talk) 13:28, 3 March 2008 (UTC)

I normally limit it's upload speed to 20 KB/s. That's a nice share, and it gives you enough bandwidth for other operations. I also found, it may be the client itself, that if you limit or zero out the upload speed, then your download speeds will be minimal. -- User:Mac_Davis 00:00, 4 March 2008 (UTC) —Preceding unsigned comment added by 216.120.217.92 (talk)

reboot

am not sure whats the problem but hear this.i recently installed deep freeze by faronics.i was just trying a software i got,any ways any change i made to my pc disappeared once i rebooted my machine.it returns to the state that it was.if i created a folder,the folder disappears.even if i delete a file it re-appears after rebooting.somehow..i think,,i unistalled it.everything was fine for a while...i recently installed a vista theme sw called vista inspirant.ever since i installed it the deep freeze thing occurs.if i uninstall a program it re-appears.even when i switch to safe mode it has the vista theme,i think it was attached with a virus or sumthin.another thing when i go to safe mode and the boot screen where the drivers are loaded,i realized the last device loaded is deep freeze and its in my c folder inside system 32.do i need to run xp again?my system restore has also been killed.how do i force unistall a program that regenerates itself. —Preceding unsigned comment added by 41.220.113.117 (talk) 14:30, 3 March 2008 (UTC)

i just want to remove the vista inspirant.its my major headache —Preceding unsigned comment added by 41.220.113.117 (talk) 14:32, 3 March 2008 (UTC)

Can no one help this person? I am aware that Deep Freeze has a feature where you can set "Thaw Zones" where files are not reset. Maybe you can set one on the Windows themes folder and then freeze it again? 206.252.74.48 (talk) 17:14, 7 March 2008 (UTC)

iTunes "Not Responding"

I need some help getting my iTunes to work again. I have a Dell and am using Windows XP. I was downloading some Podcasts in iTunes and all the sudden the program froze and crashed. The error reporting dialog box came up and that was it. I restarted my computer, reinstalled the program. But iTunes still won't work. All it does when i double click on it is open to the minimized size player. It won't maximize, play or even close when i hit the X button. Windows task manager says that it isn't responding and the only way to close the program is to end the iTunes process. I tried the tips given here:

[[1]]

iTunes DOES work on other user profiles. So it is not a system problem, it is just a user-specific problem. I have been using iTunes for years and have never had a problem like this. Any info or tips would be greatly appreciated. Thank you for your time! —Preceding unsigned comment added by 68.7.130.43 (talk) 21:12, 3 March 2008 (UTC)

LateX: referring to a list item

I'm trying to make a reference to a list item that's nested in another list, in LaTeX. For instance, given the list: 1. item one

(a) item one, subitem one

(b) item one, subitem two

i. item one, subitem one, subsubitem one

ii. item one, subitem one, subsubitem two

2. item two

I'd like to make a reference in the text to subsubitem two, but only by it's deepest label. Now, when I place a \label{labelone} in the list item, and refer to it as "... item \ref{labelone} shows ...", it shows up rendered as "...item 1(a)ii. shows ...". I'd like it to say "... item ii. shows ...", as this text is actually inside item 1(a). Any ideas?84.245.33.163 (talk) 21:32, 3 March 2008 (UTC)

starting a wiki

Hi

I wanted to know how I would go about starting my own wiki if I did not want to harm my computer doing it or risk the possibilty of overloading or crashing my computer in the process.

Also, is this the same as just starting a website? What are the differences and similarities?

And I was wondering what are the costs, if any, involved with each.

Thanks 75.23.79.223 (talk) 22:41, 3 March 2008 (UTC)

There are two ways you can start a wiki:

1. You can install MediaWiki (which Wikipedia runs on) or other wiki software on your own server. For MediaWiki, you will need PHP, a database server (either MySQL, PostgreSQL, or Ingres) and of course a web server. See the official MediaWiki site for more.
2. You can also register at Wikia (or another wiki farm), which hosts your wiki for you. Xenon⁵⁴ 23:01, 3 March 2008 (UTC)

If you make that wiki available online, and you get a lot of visitors at one time you might overload your internet connection- but this won't harm your computer in the long term.

It is similar to starting your own website - the main difference is that you are using a special program to present the info. the terms of use of the software might be different from program to program87.102.44.156 (talk) 09:35, 4 March 2008 (UTC)

A little side question from me, if no one minds. Is there a way to make an offline Wiki that behaves like a stored website and never needs to go online? I've been wanting to do something like that for a while. Never mind, I found my answer above 206.252.74.48 (talk) 16:51, 4 March 2008 (UTC)