Wikipedia:Reference desk/Archives/Computing/2013 August 25

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August 25

mplayer

i have smplayer installed on windows 7, and i can't find mencoder. please help. (mplayer.exe is in c:/Program /Files (x86)/SMplayer/mplayer.) thank you, 70.114.248.114 (talk) 00:00, 25 August 2013 (UTC)

Mencoder is command-line based, so you have to open up a cmd window. See this helpful wikibook on mplayer, mencoder etc. --.Yellow1996.^(ЬMИED¡) 16:16, 25 August 2013 (UTC)

four-channel internet

My internet provider offers a four-channel internet access. I know that will make the transfer of large files much faster, but what about regular browsing, like downloading a Wikipedia page? Bubba73 ^{You talkin' to me?} 02:20, 25 August 2013 (UTC)

For most browsing, if your downstream is sufficient e.g. 1mbps or so, the downstream speed isn't particularly important. Latency of course always is but it's unlikely there is any improvement and if there is even for many home broadband connections it's getting to the level where it doesn't make that much of a difference (particularly considering the proportion which comes from your connection compared to the backbone connection to the server). However many home connections are fairly limited in the upstream, and many home users have no or poor QoS on their routers or setups and of course for browsing which is generally primarily TCP traffic, upstream does matter, e.g. to get the the ACKs out as quickly as possible as well as the requests for files. Their ISPs may have their own QoS but considering the importance of latency and the QoS usually coming after the bottleneck, it's far less effective. So while a 256kbps or so upstream may be enough under simple browsing conditions or with very good QoS (depending on the concurrent downstream usage and QoS setup), it's unlikely to be enough if you are uploading e.g. a file to a server (e.g. Email, cloud computing), P2P etc. If you notice a significant difference in your connection' browsing performance depending on wheter other stuff is happening (i.e. turn off all other devices which may use the connection and any background stuff which may have an effect), then you know something will help, a better connection or better QoS. Of course, it also depends on other factors like what you're browsing. In other words, without knowing your current connect, setup and what your ISP is offering it's difficult to say although I expect for a wired connection in the US, the answer is probably 'not much'. Nil Einne (talk) 14:43, 25 August 2013 (UTC)

I was on a 6Mb/s cable internet and had my own modem. About a month ago I replaced the modem with a modern one and all of a sudden I was getting four channels. I tested it on two sites (DSL Reports, etc) and I do get about 4x on file transfers. Now yesterday I got a bill from the cable company for the new service that I requested. I didn't request any new service. I don't transfer a lot of big files. Much of the time I see "waiting for wikipedia.org", etc. So I don't think it is really worth it to me. Bubba73 ^{You talkin' to me?} 14:51, 25 August 2013 (UTC)

Adding a space before "/>" in tags

I was just curious what the wisdom is in adding a space before /> in tags. Is there some software interpretation, human eye helping or machine-readable purpose served by placing the space? I generally use the space because I take my cue on it from what other, more code-savvy people do, but I also see people fixing this all over, such as changing <br/> to <br />, <ref name="Name"/> to <ref name="Name" /> and so on, without knowing the purpose.--Fuhghettaboutit (talk) 16:59, 25 August 2013 (UTC)

It's just a coding style choice, similar to using if ( $blah ) instead of if ($blah). but everyone knows that the second one is better :) →Σσς. (Sigma) 20:04, 25 August 2013 (UTC)

Yes, you can certainly pick up strange programming styles depending on your situation. I for instance triple-quote every string (Python); simply because my IDE highlights triple-quoted strings in purple, rather than musty green for single- and double-quoted strings. I know I could change the colours in preferences, but the habit has stuck; so I don't bother. ;) --.Yellow1996.^(ЬMИED¡) 01:20, 26 August 2013 (UTC)

I've had problems with some XML parsers which in certain circumstances aren't able to correctly parse the closing /> if it's snugged up against other text. That's probably not strictly standards-conforming, but in reality people often have to work around such things. Adding a space to separate won't change the parsing for standards conforming parsers, but might help non-conforming parsers. It could therefore be a habit that's been picked up and passed on by people who had to work with such a beast. Additionally, as Σ alludes to, adding the space helps to separate out the closing slash, so the meat-based parser in your skull has an easier time recognizing that the slash is there in situations where it might be optional. -- 205.175.124.72 (talk) 20:34, 25 August 2013 (UTC)

The space in <br /> and other empty elements was a compatibility guideline for getting XHTML documents to render on existing HTML user agents. See

• Stack Overflow - HTML 5: Is it <br> <br/> or <br />? - Answer 2

The page this answer quotes from seems to have been revised and no longer contains the quoted text, but the end of the quote helps explain why some people use the space: Some authors also choose to include whitespace before the slash, however this is not necessary. (Using whitespace in that fashion is a convention inherited from the compatibility guidelines in XHTML 1.0, Appendix C.)

• Here's the compatibility guideline that quote mentioned: XHTML 1.0 - HTML Compatibility Guidelines - Empty Elements

--Bavi H (talk) 21:06, 25 August 2013 (UTC)

Also, I believe AutoEd always adds the space to tags that don't have it. --.Yellow1996.^(ЬMИED¡) 01:20, 26 August 2013 (UTC)

I recall being told it was some bug in the Media-Wiki software that Wikipedia uses. Sometimes it wouldn't parse the /> without a space in front. Maybe that bug is fixed now. Astronaut (talk) 18:37, 26 August 2013 (UTC)

It's certainly possible since AutoEd has been around for several years now, that it was a MediaWiki bug, so that feature was added to the script; though if said bug is no longer present, the script hasn't been modified to reflect that. --.Yellow1996.^(ЬMИED¡) 20:02, 26 August 2013 (UTC)

Windows will not start up

I have a back-up computer for work, and as a back-up for this back-up, I decided to install Linux Mint on it as a dual-boot. However, now, Windows will not start-up. In fact, I don't even get the option to choose either Mint or Windows, it just automatically goes into startup repair, which I cannot cancel. To make matters worse, the computer is in Hungarian, so I have no idea what it is doing. I can press ESC and get to the recovery menu, and I am performing the Startup Repair option now, but it has been doing this for almost an hour - just a little blue bar going left to right in the dialogue box. Is there anything else I can do? The computer has no recovery disks with it, and does not have a CD drive, only a USB port. I have a 5GB flash drive. can anyone help? KägeTorä - (影虎) (TALK) 19:20, 25 August 2013 (UTC)

What kind of computer is it? What was your process for installing Mint? What version of Windows is it? Can you access the BIOS during startup? Looie496 (talk) 20:27, 25 August 2013 (UTC)

It is a Dell Inspiron duo. I used Unetbootin to install Mint from my 5GB flash drive, and had to partition the computer myself - I partitioned 50GB of the 300GB 'free space' I had. It is a Win7 laptop. I can get into the BIOS. However, pressing F8 does not do anything. If I press Fn+F8 (or F2), I get this blue testing screen which I have never seen before on any other computer. KägeTorä - (影虎) (TALK) 20:35, 25 August 2013 (UTC)

[EDIT] I also have a 1TB external HDD. If I need a recovery disk, would I be able to put it on there and boot from that? KägeTorä - (影虎) (TALK) 20:47, 25 August 2013 (UTC)

Here is a screenshot of what the partitions currently look like. I think by changing the last partition to 'free space' I may have basically destroyed Windows. What can I do to remedy this? --KägeTorä - (影虎) (TALK) 21:17, 25 August 2013 (UTC)

I'm not an expert, but I would assume that if that is the case (and you have the installation disk...) then you should probably reinstall Windows into that empty partition. --.Yellow1996.^(ЬMИED¡) 01:24, 26 August 2013 (UTC)

Linux Mint. A link for those like me who were wondering. :-| --220 of ^Borg 02:14, 26 August 2013 (UTC)

os-prober is a tool that lists the operating systems installed on a computer, used by grub to add entries to the boot menu. Usage example:

$ sudo os-prober
/dev/sda1:Windows Recovery Environment (loader):Windows:chain

It does not display the current OS, only other available ones. Hopefully, Windows comes up when you use it. →Σσς. (Sigma) 03:13, 26 August 2013 (UTC)

Only a couple of weeks ago I did something similar with my Dell laptop, installing Mint as a dual boot with Windows (Vista). Here is my experience: I installed Windows first, limiting it to a single 120GB ntfs partition and making sure I got a stable, bootable system. I then installed Mint from a USB stick, adding a swap partition and formatting the rest of the disk as a single ~600GB ext4 partition. The Mint installation overwrote the boot sector so it starts with Grub, and grub then detects both Mint and Windows. When I rebooted, I got a Grub menu showing Mint, Windows and a couple of other things, but it is only about 10 seconds before it chooses the default option - Mint.

I'm a little unclear how you did the installation... did you try to shrink an existing Windows 7 installation, because I notice your Windows partition is quite small? I wouldn't imagine my Vista setup being happy with ~1.5GB spare on its disk and I doubt it would be any different with Win 7. Is the "startup repair" a Windows/Microsoft thing, a linux thing, or a Grub thing? Do you see any sign of the Grub menu at all? Can you still hit F12 towards the end of the POST (assuming it has a similar BIOS as mine), and then boot off your USB stick again (entering live-CD version of Mint)?

The worry is that if you shrank the Windows partition, you might have 'lost' a bit of Windows. Unfortunatly, that probably isn't recoverable. I might be tempted to suggest you wipe the disk entirely and reinstall Windows and Mint, but am I right in assuming that because you don't have a DVD drive, you can't reinstall Windows 7?

Astronaut (talk) 18:27, 26 August 2013 (UTC)

Actually, what I had done was install Mint from the USB stick, and in choosing 50GB as a partition for it, I accidentally set the remaining 250GB to 'free space' - essentially wiping Windows 7 off, but leaving the Recovery partition (hence the 8GB partition). This was an honest mistake - I've installed Ubuntu on other laptops before and never made this mistake in the past. I don't know why I did it this time. In any case, problem solved: I did indeed manage to reinstall Windows 7 from a USB stick using something called 'Windows 7 USB DVD Download Tool', which I got from the PC World website, and a USB-bootable .iso for Win7 HP 32-bit from the same website. This installed fine, and did not wipe the Mint partition(s). I then had to use the Mint Live USB to get back into Mint and rebuild the GRUB menu, and then go back to Windows to install all the Windows drivers specific to my Dell machine. This was a pain in the backside, because the driver for the wi-fi card was missing (and the one on the Dell website was the wrong one), so I had to download them all on another machine and transfer them across. I am still waiting for Dell to reply to me with the drivers I need for the wi-fi card - this is the only one which is currently missing. It's basically fixed. Luckily there was no loss of essential data, in the sense that everything is backed up daily on an external HDD and multiple other devices. I just have to reinstall a lot of software now..... [sigh]. Thanks for the detailed explanation. I shall keep that as a reference for next time. KägeTorä - (影虎) (TALK) 09:24, 28 August 2013 (UTC)

Internet Download Rate Control

For reasons I am still trying to determine my hourly internet download last night were way above my low average of ≈10+ Mb per hour when I am just browsing and editing WP. I hit 248.8Mb (at 21-22.00) and a very high 294.1Mb (22-23.00). These levels are what I expect to use on a busy day of over 12 hours online. Before and after it was under 50 Mb, which is still rather high (over 600 Mb for a 4 hour period). I would expect this if I was downloading from YouTube or similar video sites, but I was not. (This is also 2 & 1/2 days data allowance in 2 hours as I average about 200 MB a day, and I am left with only ≈600 Mb for 6 days to the 31st.)

I have software called NetWorx from www.softperfect.com that is supposed to warn me if I hit over 1 Mb per minute, and it has done so in the past but it didn't seem to work his time.

Is there any way to control the maximum rate of download? Any settings in Windows 7, or any software anyone can suggest/recommend that can do this? -- 220 of ^Borg 20:23, 25 August 2013 (UTC)

Found this page, which has some reviews for different programs. Hope this helps, --.Yellow1996.^(ЬMИED¡) 01:36, 26 August 2013 (UTC)

Thanks, Yellow1996 I'll take look. I am using Windows 7 Home Premium (version 6.1 Build 7600) if it's of any relevance.

• I had a suspicion that perhaps it was because Chrome has 'updated itself', it is now at version 29 (was 27) though I never told it to do so as far as I recall. Could that be it? But it seems to be a very large download for an update. (Does Chrome update automatically without asking 'permission'?)
• Then again I was browsing around looking at tablet prices, like at JB Hi-Fi, Cnet.com and Dick Smith and those sites having a lot of graphics may be the reason. Even then it seems very high as these are my 2nd & 3rd highest hourly usages for July &August.

Anyone else with ideas or suggestions please chime in. --220 of ^Borg 03:12, 26 August 2013 (UTC)

Apparently, it does. And here's how to disable it. --.Yellow1996.^(ЬMИED¡) 16:34, 26 August 2013 (UTC)

Thank you Yellow 1996, I'll look into those links. I have now doubled my Internet allowance to 12 Gb a month, so there is far less urgency in preventing 'spurious' downloads. Interesting though, that when I wanted to use a lot of bandwidth before the end of the month I was unable to get it to download very fast (from Steam, at least) and only used about 9.9 Gb . --220 of ^Borg 16:30, 31 August 2013 (UTC)

No trouble at all - I'm glad your problem got solved in the end. :) And yeah as I've always said, trying to figure out how these things happen/work is a fast path to insanity. ;) --.Yellow1996.^(ЬMИED¡) 17:48, 31 August 2013 (UTC)

Question on hacking a smartphone's G.P.S. data.

Greetings!

This is probably one of the silliest questions I've ever asked on here, and, if so, then I apologize in advance. But a woman today asked me whether one could check the G.P.S. on a MetroPCS® smartphone to see where said phone was while she was away from it.

She told me that she believes that her significant other has been cheating on her, and that she'd like to find out (by way of GPS coordinates) where he has been taking her smartphone. Regrettably, however, she couldn't tell me anything other than it's a phone running a G.P.S. application downloaded from the MetroPCS® store. Also, that she tried calling their tech support staff, but they told her that they don't know anything about hacking a downloaded application (go figure)!

Specifically, she would like to read a recorded display of G.P.S. coordinates—assuming that the phone even stores them in the first place, I shouldn't know—on her desktop P.C. Perhaps, by means of a USB-to-powersocket adapter. I told her that this falls very far outside my area of expertise, but that I'd ask people who would know.

Please, venerable experts, help a modern-day damsel-in-distress, at your earliest convenience, if you can. Thank You. Pine (talk) 22:51, 25 August 2013 (UTC)

If she has an android smartphone you just have to install this: find my phone. There is a equvalent app on the iphone too. No hacking necessary, but I believe it only works from the time you intall the app. If she needs access to the data in the past, I doubt you can get it without being a law enforcement agency. Vespine (talk) 03:47, 26 August 2013 (UTC)

Actually, both iOS and Android keep a GPS cache. This is done to improve performance (GPS works faster if you have some 'best guesses' to try.), but you can imagine that it made people unhappy when it came to light.

However, this article claims that you'd need root access and/or physical access to the phone to extract that data. APL (talk) 14:33, 26 August 2013 (UTC)

... and the cache built into the GPS receiver just stores the single last location at which a coherent signal was received. (That's not the same as the cell tower location database that some phones store.) What you need is an app that stores a GPS "track" which can easily be downloaded from the phone and displayed on a map. It is possible to get the app to e-mail the track as a series of gpx files (see GPS eXchange Format) so that the position can be continuously displayed on a monitoring computer. This app seems to use that method. Dbfirs 17:29, 27 August 2013 (UTC)