Wikipedia:Reference desk/Archives/Computing/2016 March 6

= March 6 =

Puzzling extras under HD notes in Disc Utility window
Hi, I tried repairing disk permissions using Disk Utility on my MacBook Pro (10.9.5) to sort an application permissions problem when I noticed some odd figures in the left hand col of Disk ute window. They sit under a partition line (which I didn't make); they look like this, and change every time I open this program (three times):
 * (disk icon) VgkvRe.dmg
 * (disk icon) Installer
 * (disk icon) QWOCx0.dmg
 * (disk icon) Installer

The first group had two variations of this: pfn llb.png The second included a variation and an uninstaller. I don't know where these came from or why. They are unselectable. And of course I assumed they're sinister. I'm computer literate but not tech savvy by the way. What do they mean please? Thanks in advance Manytexts (talk) 03:11, 6 March 2016 (UTC)
 * finally cleared them myself. Still a mystery tho.Manytexts (talk) 22:48, 9 March 2016 (UTC)

self-erasing video clips
I have purchased video clips that I suspect were self-erasing (as I cannot locate them). My questions: 1) Can clips be easily programmed to self erase?  2) would that feature be disabled by conversation to a different format? 3) If not, is there another way to disable the self-erasing feature in such clips? Dmundt96 (talk) 03:48, 6 March 2016 (UTC)
 * Where did you purchase them from? The typical DRM schemes generally work by encrypting the media, and either having the decryption key(s) embedded in the "blessed" media players, or having the player grab the key(s) from a server. Although it's theoretically possible to stick a self-executing payload in files, it's tricky, and such a thing is a frequent malware technique. This means antivirus software and operating systems generally try to prevent such things from being executed. It's extremely unlikely any legitimate company would decide to use such a mechanism. More likely would be requiring you to install some "supervisor" program that monitors your computer to stop you from doing things with the media that the company doesn't want you to do. The coupon printing software used for a lot of online coupons for brick-and-mortar stores works like this, to prevent people from easily forging coupons. But even this I think is unlikely. Per Occam's razor, it's much more likely that you misplaced the files, deleted them (either unintentionally, or you forgot you did it), or a program on your computer, like some disk cleanup program, deleted them inadvertently. --71.119.131.184 (talk) 05:13, 6 March 2016 (UTC)

Solder Pads Lifting Off: Defect, or My Fault?
I bought an electronics project kit to practice my soldering: it came with a PCB and about 30 different components to solder to it. So far, 3 of the copper solder pads have lifted off after I'm done soldering the component to them. I have my iron turned up pretty high--the solder flows in 2-3 seconds after heating the joint--but I haven't left it in contact with the joint for anything more than that. From Googling, it sounds like fixing these pads will be more trouble than it's worth, so this project is a total loss. I just want to know whether the pads lifting off is likely a defect in the PCB, or if I'm doing something wrong. I'm using a Weller soldering stand with an adjustable temperature control, if that matters. Thanks! OldTimeNESter (talk) 13:21, 6 March 2016 (UTC)
 * Your fault for not using any flux 109.207.58.2 (talk) 14:03, 6 March 2016 (UTC)


 * Use solder containing flux, designed for solder assembling electronic devices. There's production solder containing arround 2 % flux and there's repair solder avail, containing up to 3 % flux due the less need from previous solder. Flux can be bought deparately for rapair and hot air soldering applications. When using to small soldering iron, the heat is to less and does not melt the whole pad, causing to tie it to the tool and gets the properties of car chassis repair tools which welds wires to the body for pulling the indented areas of sheet in its previous condition. The other mistake to avoid are unregulated soldering tools burning the glue to the PCB. When soldering multi layer PCBs, warm up first. Cooper is an excellent heat conductor, tieing the soldering irons temerature down. Large multilayers wires and areas are used in power supples, ampilfiers and to handle heat and power on high performance CPUs, operating them on low voltage, high current and heat. Those large layers need to be preheated before soldering. Note, electrolytic capacitors are sesignes as shown on its case to 85°C maximum, some 105°C and 125°C using more expensive fluid for use in automotive or passive cooling and heating applications. Those capacitors may explode! When assembling a PCB 1st time, put a little solder to the iron to make it spead its heat to the pad. Then put some more solder to the iron on the pad. Release to iron when the all solder is on the pad. When the pad is larger, put a little more solder before you remove the iron from it to provide enough flux for a proper solder dot. Using a controlled soldering iron, set it to 307 to 309°C when used lead containing solder to keep the flux the long as possible. Using RoHS specified solder without lead, increase the temerature preset. -- Hans Haase (有问题吗) 14:42, 6 March 2016 (UTC)

Always push the devices to be soldered down to the PCB to safe the single layer solder pad. When the device is required cooling and spaced from the PCB, make its pins to to force the pad. A TO-220 case supports screwmount and two different sizes per pin which can be used when no heat sink is used. With the solder iron, do not rubb the pads. if the PCB does not like the solder or is corroded, clean it first. The use of kitchen cleaner can remove grease. Its acid removes corroded cooper and protective films, You need to restore with plasic spray or cover it with solder, depending on the use of the curcuit You are assemling. Brake cleaner, which is explosive burnable, but a cheaper way to but in from the automotive part dealers as the degrease spray from the electronic distributor can remove grease form the PCB. Use outdoor only! Don't smoke and keep the soldering iron far from it. Don't breath it! Never apply it to rubber parts, electrolytic capacitors has installed on the bottom! Citric acid can remove coorded cooper, but the PCD needes to be washed after this application. -- Hans Haase (有问题吗) 21:20, 6 March 2016 (UTC)


 * Well, I did use flux--the solder has flux in it--but it sounds like my iron was too hot. Drat! Oh well, live and learn.OldTimeNESter (talk) 00:58, 7 March 2016 (UTC)

Android packages
can deleting "update_package" on android be dangerous? — Preceding unsigned comment added by 188.29.165.20 (talk) 14:04, 6 March 2016‎ (UTC)


 * It appears that you are referring to vendor-installed packages that give you the option to update or delete the updates, but not remove. Deleting the updates might delete a security update. If you don't want the application, you should delete the updates and related data and then disable it. If you want to use the app, it is probably best to keep the updates as they might contain a security update. 209.149.113.194 (talk) 12:13, 7 March 2016 (UTC)

SaaS vs Web Services vs Web application
May I ask how would you define the difference between these 3 "Categories" of software? I must say I don't find any major difference between them, do you recognize it ? 79.182.232.172 (talk) 18:55, 6 March 2016 (UTC)
 * As usual, buzzwords often have a "flexible" and overlapping meanings. But in general, "Software as a Service" is a business model (you buy  access to centrally hosted software). Web services are really just interfaces to a backend service. And a web application typically is  client software running in the browser, which may or may not have a backend component. --Stephan Schulz (talk) 19:06, 6 March 2016 (UTC)
 * Thanks Stefan ! Much thanks ! I guess we can say that any SaaS is a both a web service and a web app (but not all web services or apps are SaaS) 79.182.232.172 (talk) 03:51, 7 March 2016 (UTC)
 * Not quite: as Stephan says, Web service has a specific technical meaning (which is not "a service provided over the Web") so it would be rather loose to describe an SaaS product as a Web service. SaaS is (probably) usually delivered these days as a web app, but not necessarily so - it could use its own client-side software instead of a browser, and/or network protocols other than HTTP/HTTPS (maybe even not TCP/IP). AndrewWTaylor (talk) 12:47, 7 March 2016 (UTC)

Duplicated filenames in photographs
I recently asked about finding duplicated filenames in my photograph directory structure and got quite a nice Python program as an answer. My Olympus E-620 camera names its filenames in the format  where m is the month from 1 to c (in hexadecimal to fit in a single digit), dd is the day and nnnn is a running number from 1 to 9999.

I found out that by far the most of the duplicates were from the Helsinki Burlesque Festival in February-March and from the World Bodypainting Festival in July (along with quite a few from the recent World Gymnaestrada in middle July, but the next one won't come along until 2019). Duplicates from periods where I usually take only a few photographs were pretty much non-existent.

Because of the way the camera names the files, if I order the list of duplicated filenames alphabetically, wouldn't there pretty much always be consecutive stretches of duplicates where the stretch starts from the first photograph in the morning on one of the duplicated days, and ends with the last photograph in the evening on the other day? J I P &#124; Talk 19:18, 6 March 2016 (UTC)


 * A digital photo camera uses filesystems on flash memory to store the taken pictures. But the camera is not and whole computer and does not support al file systems the computer supports. And the camera creates its own files for indexing and folder structures. To prevent furter date lost, backup the cameras flash device to Your computer. Use the computer to test performance to the flash device. Fakes on flash memory devices have half of the specified memory, only. D data lost occures when a data block or sector of the 2nd half is beeing written. Malfunction occurs when the preformance is being faked. Such flash devices can not write the buffer in time. A data lost occurs when the data rate to be written exceeds over time. SSDs using write amplification drop performance when the cache is filled due mpeg and jpg, a digital camera writes to the memory, is already compressed and can not be compressed again to save memory. In case of doubt, use a new flash memory in the camera. Format it inside the camera before taking a picture. Formatting deletes all data of the flash memory and initiatizes a new file system. Doing this with the camera, the camera will support its own file system. Doing tihs on the computer, the camera may cause a lost of data due missing support of the other file system version. When changeing multible flash memory cards/devices, each has its own index and the camera might reset its counter, used for naming the new files of the new taken pictures. When transfering files form the camera, just keep the last file and folder on the camera. Never modify or toch the camers indexing files and folders. On the flash memory, only delete empty folders of pictures, when the newer folder exists an contains least one picture. On the computer, bulkrename (ren ????*.JPG=TEST*.JPG ←not verified exsample, try after backup, only!) the transfered files to prevent acciential overwriting different pictures having an identical filename. -- Hans Haase (有问题吗) 20:36, 6 March 2016 (UTC)


 * This does not answer my question at all. J I P  &#124; Talk 20:43, 6 March 2016 (UTC)


 * My mobile uses the system date and time for filenaming. Did You adjust the cameras clock on current date/time? When the camera is equipped with GPS, it might set its system clock to the received time from satellite. Some cameras with GPS might not support to adjust the time by the user. Do You really take 10.000 picures on one day without transfering the pictures to the computer? -- Hans Haase (有问题吗) 20:53, 6 March 2016 (UTC)


 * You are talking about completely different things than I am. I don't take 10.000 pictures per day. On some days I take 2000, but on most days I take about 20. The running numbers (nnnn) continue from one day to the next one, so if I take for example picture  as the last picture of March 6, the first picture of March 7 will be  . The technology in the camera (or indeed, the existence of the camera in the first place) does not factor into this. I'm just asking about filenames. Duplicated filenames don't overwrite each other either on the camera or on the computer as they go to different folders. I make a new folder every time the running number resets.  J I P  &#124; Talk 06:04, 7 March 2016 (UTC)


 * To answer, it's not guaranteed. You could have two days that overlap the same ranges, e.g. p7042000-p7043000 taken in 2014, and p7042500-p7043500 taken in 2015, and you'd have 500 pictures with the same name. Easiest way to handle it is to rename your pictures so that it either includes the year, the folder, or better yet, both. Using just the folder may not work, if the folders reset back to 001 or whatever it starts at.
 * Using the folder in there is ideal, so you know the order when it rolls over, e.g. p0013069999.jpg rolls over to p0023060001.jpg. Hope that's what you're asking. --Wirbelwind( ヴィルヴェルヴィント ) 07:33, 7 March 2016 (UTC)


 * What the camera does may be not known can be tired only. A way to do this is, to make the camera create the many pictures as possible. Set it to lowest resolution, highes compression, lowest JPG quality, longest exposure and widest iris. Take pictures of a clear lightbox using the biggest memory device. This test is to verify the camera file operation only by creating many small files on a large flash memory to enforce that happens when the snake mouth hits its tail. Only the noise in the picture enlarges the file sizes. Maybe camera by camera, it is a bug which has been not evaluated due avail flash memory capacities when the camera came on the market.
 * My recomendation is to prevent occuring the results of any possible bug by moving the files in time to the computers hard drive and further backup media. If possible and wanted, move all files completely to the computer and reformat to reset the indexing on the flash device by the camera. Only have the camera creating, modifing and naming files on the flash device.
 * Conflicts and overwriting on the computer can be solved by renaming software or such pariticial automated tasks like these: Using Spreadsheets to prepare renaming, update: Using dir /b. This allows much more individual changes and documentation to the stored file inside the file names, but rename files before folders! The Spreadsheet methode is also recommended if don't trust renaming software, but it is not save to apply changes accidentially a second time. -- Hans Haase (有问题吗) 12:26, 8 March 2016 (UTC)


 * This still doesn't have very much to do with my question. My question is about storing the files only. Where they come from is irrelevant. And there is no danger of overwriting, as I never put all the files in the same directory. I make a new directory every time the running counter resets. I already know I have loads of duplicated filenames, but that's not a problem, as they are in different directories. I have no need to rename any files. I still think what I originally guessed stands, i.e. the ranges with duplicated filenames (not duplicated files) begin at the first photograph in the morning on one year and end at the last photograph in the evening on the other. Can this be verified or disproved? J I P  &#124; Talk 20:13, 8 March 2016 (UTC)


 * I've already disproved it in my answer above. If you're asking anything different that what I've answered, it's hard to understand. How do you have duplicate filename blocks if they're not going to be in the same folder? And if you have two folders of 10000 photos each, how do you have non-duplicate filenames? And if the year spans multiple folders (like I stated in my original answer), how do you have a continuous block from the first of the year to the last, when they're in different folders? --Wirbelwind( ヴィルヴェルヴィント ) 15:53, 9 March 2016 (UTC)


 * The way I can have duplicate filenames in different directories is, for example, to have both  and  . Note: same filename, different files. The way I can have non-duplicate filenames is because the date and running number part rarely correlate. For example, in the above,   is the date (March 9) and   is the running number. I might take a picture nowhere near 1682 on March 9 the next year, or take picture number 1682 nowhere near March 9 after the counter resets. By "continuous block" I mean a range of filenames that represent consecutive pictures that are duplicated across directories like in my example at the start of this reply. Such a block is going to span nowhere near 10000 pictures, let alone a year. At the best it spans a couple of days or a few hundred pictures.  J I P  &#124; Talk 18:48, 9 March 2016 (UTC)