Wikipedia:Reference desk/Archives/Computing/2011 September 21

= September 21 =

cable modem problems
I've been having problems with the cable modem dropping for a week. There are four green lights: power, receive, send, and online. when it drops, I get the first two lights solid, but the third one (send) is flashing. If I cycle the modem (unplug the power and plug it back in), it doesn't come back. If I also unplug the coax, sometimes it will come back (it takes up to four tries of this). Four days ago the cable tech support thought it was the modem, and had me replace it. It didn't fix the problem. They think the problem is at my house, and are sending a truck here in a few days.

With it dropping several times per day, then giving only the first two lights solid, until I unplug both power and coax - where is the problem likely to be (at my house or before it gets here)? Bubba73 You talkin' to me? 04:34, 21 September 2011 (UTC)
 * You can probably log into the modem to find out: . Check the signal levels: . That will tell you if the modem is OK.--Best Dog Ever (talk) 06:15, 21 September 2011 (UTC)

I'm having trouble with the "send" light. Is that due to the low upstream power? Where is the problem likely to be? Bubba73 You talkin' to me? 06:25, 21 September 2011 (UTC)
 * Right now, my down S/N is 37.1 (>30 is good).
 * down power is -10.9 (should be -15 to 16, but -8 to 8 is better)
 * upstream power is low: 51.7 (should be >55).


 * If you have low upstream power, that is a clue that they may have given you a defective modem. But the connections at utility boxes often come loose. And if your neighbors aren't experiencing any issues, and if you haven't been doing any landscaping work, then I would guess probably either the modem or the utility box. You also probably have different cable outlets in your house. So, you could also try plugging the modem into different outlets.--Best Dog Ever (talk) 06:31, 21 September 2011 (UTC)


 * I was having this same problem before I swapped out the modem last Friday. About two months ago I had a different problem - it would drop frequently, but it would come back up by itself quickly.  They came out and replaced all of the connections and that fixed that problem.


 * I have a two-way splitter in the attic. One side goes to the outlet with the cable modem.  The other goes to a four-way amplified splitter for the TV (three of the outputs are in use).  I could take out the two-way splitter and put this on the other splitter, but I don't know if that would help.  Bubba73 You talkin' to me? 15:00, 21 September 2011 (UTC)

Administrator rights at my own PC
Yesterday and today I've tried to install updates (Acrobat Reader + VLC) and have been told by the install software that I couldn't use all of the program, or the program couldn't be installed at all, respectively, because I wasn't having administrator rights or didn't have a password as "Administrator", respectively. I tried to argue: I've awarded myself all the rights and privileges of using my own PC, it's not fair, etc., but well, the install software just wouldn't listen...

So what's going on? First, why is this happening? And second, how can I get back to peacefully installing and using updates? Thanks for your help, Ibn Battuta (talk) 06:13, 21 September 2011 (UTC)


 * Yes, I've had the same problem, though the system eventually listened. I suppose the "correct" procedure is simply to log on as administrator (the original account) whenever installing software.  This is a security measure to prevent rogue software from installing itself, and we shouldn't really be using an account with full admin rights for everyday use.    D b f i r s   08:21, 21 September 2011 (UTC)


 * Note that at least some versions of Windows have the account named "Administrator" hidden and disabled. You can enable it (if logged in with administrator privileges): use your favourite search engine to search for "enable Windows administrator account" - there are many web sites that will explain how. Mitch Ames (talk) 11:48, 21 September 2011 (UTC)

Google's new option
Is there any way to get rid of that annoying blue arrow which has appeared on Google in the last day or so, and to move the +You option from the left hand side. It's a bit confusing and irritating as it occupies the space where the Web option used to be, and now everything has moved along one space I keep forgetting and accidentally clicking on it. TheRetroGuy (talk) 10:09, 21 September 2011 (UTC)


 * You can install Adblock Plus or a similar advertisement/content filter tool for the browser of your choice. In Firefox, you can install the extension, and then right-click the arrow image on Google's main page, and add it to your list of filtered advertisements.  I added this block-filter (in AdBlock+ syntax):

||google.com/logos/*
 * This blocks all Google logos on all Google domains. You may prefer the more selective filter only for the single image,

|http://www.google.com/logos/2011/gplus11-hp.gif
 * Note that Google uses a lot of active content and may change the URL for this particular arrow, based on your region, browser, or other variations - so this may be one of many similar images you need to block. Nimur (talk) 15:46, 21 September 2011 (UTC)
 * That's fantastic, thank you. I just installed it with Chrome and the annoying thing has gone. Now I'll go get the versions for the other browsers I use. Cheers TheRetroGuy (talk) 20:03, 21 September 2011 (UTC)
 * Just found out the thing's called Google+. :) TheRetroGuy (talk) 20:30, 21 September 2011 (UTC)
 * Google+ is actually quite a popular and famous service. But, as far as I'm concerned, it's just another spammy commercial internet-site with a flashing animated GIF banner-ad.  Nimur (talk) 22:49, 21 September 2011 (UTC)
 * Couldn't agree with you more. I just don't know why they have to keep messing with it. If you want these new features, then that's great, but if they're forced on you it becomes a real pain. They should tell people about it and let them make up their own minds. TheRetroGuy (talk) 10:10, 22 September 2011 (UTC)

You could use Lynx until Google stops promoting their new product. Also, if you type https://www.google.com you won't see the arrow. It also happens to be more secure.20.137.18.50 (talk) 13:31, 22 September 2011 (UTC)
 * Lynx doesn't seem to work with my computer. I downloaded it, but Windows wouldn't or couldn't open it, so had to delete it again. I like the secure Google though. Looks much better. TheRetroGuy (talk) 21:11, 22 September 2011 (UTC)

best way to create 1080p videos in iMovie
Over the next few weeks I'll be creating a lot of 'videos' on iMovie which comprise of maybe a few images blending into each other with an audio soundtrack and uploading to youtube. Which settings should I choose when exporting to make the rendering and uploading process more efficient? My test runs seem to be creating 5 minute videos around 400-500 mb, seems a bit excessive to me. Thanks, doom gaze   (talk)  11:30, 21 September 2011 (UTC)
 * Nobody has answered yet - so I'll fire off my very long response...
 * That file size sounds very reasonable for a 1080p movie. It's around 10 megabits per second, which is actually quite well compressed.  1080p video (rather, 1920x1080 at 30 frames per second, 8-bits-per-channel RGB) is around a gigabit of data per second (or, about 50 gigabytes for your five-minute video)  High-quality H.264 encoders, such as the video codec used by iMovie, shrink that data rate to around a ballpark of 10 megabits per second (right where your video is at, a compression factor of about 100x - a ratio unheard of in any domain of computer science other than video compression).  Even still - you started with tens of gigabytes of uncompressed data - so a 100x compression still creates a large file!  If you haven't worked extensively with 1080p video, these file sizes seem surprising.  When I started playing with video more than a decade ago, with toy computer hardware, I recall 50 kbps QVGA video files that were about 3 or 5 megabytes for a few minutes of footage - but let's say that the image quality was "marginal."  A 1080p video I processed in iMovie last week was around 500 MB for 4 minutes of footage and audio at 1080p (the same video was only 50 megabytes when exported as a still-usable VGA-sized file).  500-MB file-sizes are normal for five minutes of 1080p - there's a lot of pixel data in there.
 * "Optimal" settings are going to depend on many factors: the content of your video affects its compressibility. Your preferred quality, and your personal ability to notice video perfections/imperfections, affects the bit-rate that you consider "reasonable."  The type of noise you anticipate affects the best type of coding for the data.  Your computer's hardware capabilities - specifically, the exact type of CPU and GPU, affect the encoding time (and some other minor details of the codec).  The version of OS X and iMovie that you are running affect the features that are supported.
 * If you want to upload a 1080p video to YouTube from the most recent version of iMovie, there is a one-click button that takes care of everything (and picks "optimal" settings for you); you can actually click on the Help Menu in iMovie and watch a tutorial demonstrating how to go through this process.
 * If you want finer-grained control over your video performance and quality, I always recommend the free software utility ffmpeg, which will allow you rescale, reprocess, and re-encode your video with much more technical detail exposed, compared to iMovie. This will let you specify individual codec parameters (far more configurable quality/performance options than you even realized were possible).  Still, I recommend using libx264 presets, for most purposes.  With FFmpeg, you can also request a specific output file-size, and the utility will encode with whatever quality-setting will generate that file-size.  H.264 provides a sort of "quality" slider that directly relates to output file-size.  "In general," you will not get better quality-to-file-size than H.264 codec provided by libx264 - so this is the only knob you should really spend time playing with.  If you are a professional video technician or a video research engineer, or a well-qualified hobbyist, you already know what you need to do to get better performance by playing with codec parameters, maybe using a different codec for your video, but this is not easy, it requires fairly advanced knowledge, and you'll rarely beat the performance of H.264 anyway.  More probably, you'll dork up the processing and get ugly video glitches.  Because these advanced settings are not very easy to use, such advanced settings are not exposed through iMovie's user-interface - you can only select preset resolution/quality "packs" that are guaranteed to give good quality results.  Nimur (talk) 17:52, 21 September 2011 (UTC)

Limiting memory usage
On Linux (CentOS 5.6), what is the best way to limit the memory allocation to a process or group of processes? I have some software where the memory demands are hard to predict in advance. Sometimes it grabs so much memory that everything else starts swapping and the system is thrashed and unusable. I'd like to set a limit so that this software can use no more than ~90% of physical RAM, in order to help ensure the stability of the rest of the system. I don't mind if the program crashes when it hits that limit. There doesn't seem to be any way to set such a limit within the software itself, so I'm looking for some way to do it at the system level. Dragons flight (talk) 19:45, 21 September 2011 (UTC)


 * There are lots and lots and lots of ways to do this. In my opinion, the best and safest way is to create a user account for the specific process; and then limit that user account to a maximum amount of physical ram; this avoids any weirdness or corner-cases with forking, pid changing, executable name changing due to spawning new processes, and so forth.  Basically, you "sandbox" the entire program inside a login-session, and then restrict the rights of that login-session.
 * You (rather, root) can modify limits.conf to limit a user's CPU, RAM, files, PIDs, and so on. You can also restrict individual PIDs, if you opt not to sandbox your process in its own login-account, but beware the corner-cases I mentioned above.  You should also make sure that you have pam_limits (usually you do - make sure you have libpam enabled in your kernel and pam_limits.so - these are in and enabled by default, in new Linux including CentOS 5.6.  Nimur (talk) 21:33, 21 September 2011 (UTC)

Visual Basic Express & AVG
I'm currently playing around with Visual Basic Express to see if I can get something out of learning some simple programming. Anyway, every time I make anything (following the tutorials provided), AVG tells me what I've made is a virus and won't let me acess it, even though I have pressed the 'ignore' button. How can I stop this from happening? -- KägeTorä - (影虎) (TALK) 20:34, 21 September 2011 (UTC)

Printing is a disaster
I have a rather big .Net application that is used by a couple of hundred users who all have their own printers. All I want is to be able to print either an HTML file or a bitmap to a printer and to be able to tell if it should use tray 1 or 2. "In the old days", I could manage any matrix printer. I just needed to know LPT1 or LPT2 and practically all printers understood what they were supposed to do (or I could fix it myself). The main problem now is that people log on to different terminal services, expecting their local printer to print. In one set up this means we have to install 17 (different!) printer drivers, creating IP-ports for them, etc. Our helpdesk is spending 70% of its time solving printer problems (not counting the fact that our program seems to say "I want to print on A4" and the printer starts whining that it only has Letter available, which we also must have wasted a few thousand hours on). A printer should print, not think its smarter than we are.

Is there a "Generic printer" for laser printers in Windows? I can't find it anywhere. I'd be happy to implement both a "Generic PostScript" printer or a "Generic PCL printer" once. Now we have about 5 GB of drivers, most of which we cannot even install without attaching the printer physically. It's hell, really. Somewhere out there someone must have solved all this with this magical printer driver that translates my bitmap or HTML file to any possible printer on any port. The configuration should consist of 3 settings: 1) PCL or PostScript (or "cheap printer brand X"); 2) Tray 1 or Tray 2 and 3) the IP. Anyone? Joepnl (talk) 21:06, 21 September 2011 (UTC)


 * Is there a reason you are trying to send data directly to the printer rather than using a printer API to do so? The latter seems like an infinitely easier option, and would allow the Windows OS to handle the actual nuts and bolts of it. E.g. the .NET PrintDocument class. --Mr.98 (talk) 22:45, 21 September 2011 (UTC)
 * That is precisely the problem. I am using PrintDocument. Which needs Windows. Which needs drivers. Which needs personnel. And a awful lot of them. I need an API that doesn't rely on Windows having a printer installed. I want to bypass Windows, the drivers, etc and just tell to my uberAPI: please print this bitmap at IP 172.26.10.101 from tray 2, my guess is that the printer understands PCL. Without having to install a driver at all. Without having to refer to a printer as "Printer 18 (from session 37) (used by Pete) (who's also in session 39) (since 18:31 ECT) (which is 12:11 ABC) (and he'd like Letter instead of A4) (And did you know the Yellow cartridge is almost empty?)". Microsoft and all printer manufacturers are just too helpful. All I want is to print. Joepnl (talk) 23:53, 21 September 2011 (UTC)


 * I feel for you. It was (part of) my job to manage printers at Chrysler some 15 years ago.  They were not all created equal.  At that time, QMS laser printers were best, since you could log on remotely to check them, change settings, etc.  I'm not sure which printers are best these days, but I bet there's still a big difference. StuRat (talk) 22:57, 21 September 2011 (UTC)


 * That's part of the problem. If I were to choose the printers every customer would have exactly the same one and there would be no problem. We wouldn't even want to check them remotely because if one was broke (or had paper stuck somewhere) we'd just replace it and it would still work. But I'm glad and should congratulate you that you seemed to have worked your way out of this mess. Joepnl (talk) 23:53, 21 September 2011 (UTC)


 * And I supported a lot of printers for GM and Chrysler. This just the sort of thing I did in my 15 years are GENICOM. Have to know more about the printer types. And QMS is now Konica Minolta. ---— Gadget850 (Ed)  talk 23:37, 21 September 2011 (UTC)


 * When we install our software, the printers are already there and we simply have to deal with it. Our customers don't and won't understand that getting their $150 printer to work costs us more than replacing it with a network printer, and will not pay for us to get it to work. (we also have to deal with this "it's your hobby isn't it" syndrome, but "professionalizing" on that would cost us their business) Joepnl (talk) 23:53, 21 September 2011 (UTC)


 * Well, if it really does cost more to manage their printer than supply your own, then you should supply a dedicated printer along with the app (maybe one price for a view-only, non-printing version of app, and another which includes the printer). I'm a bit skeptical that this is really the case, though.  StuRat (talk) 00:13, 22 September 2011 (UTC)


 * Problem is that a lot of low end printers are GDI and do not have PCL or PostScript. If these are your customer printers, then a universal is very unlikely. Some vendors like Samsung have universal drivers for newer products. ---— Gadget850 (Ed)  talk 00:14, 22 September 2011 (UTC)
 * Most printers are not low end, there are just to many different drivers needed. If there would be a driver called "General PCL Printer" we'd have handled most (if not all) HP printers. Joepnl (talk) 00:37, 22 September 2011 (UTC)


 * Haven't dealt with HP in a while, but I though they were doing something in this area. HP Universal Print Driver - Direct IP Printing ---— Gadget850 (Ed)  talk 01:14, 22 September 2011 (UTC)


 * What do you mean by 'not low end'? Many $150 (which you mentioned)-$200 inkjet printers don't support PCL or PostScript. Or to put things a different way, it may be advisable to do a survey and see whether the majority of the printers really do support PCL or PostScript. Nil Einne (talk) 04:18, 22 September 2011 (UTC)


 * A few years ago, faced by the problem of a company that did a lot of shipping and other weird print jobs, with a lot of people wanting to do different odd things at once, a colleague and I figured out a pooled-printer solution, which I always thought was kind of neat. All the printers hung off a single print server (but had the need arisen that could have become a single dispatcher for many print servers). It exported a single postscript network printer. Jobs sent to it (it was implemented in CUPS on RHEL) were turned into PostScript files, and an entry was written on a little database on the print server. All the Windows PCs in the office ran a single abstract PostScript printer driver (written by my colleague, mostly from an adaptation of whatever sample he found in the DDK). The custom dialog for it had all the different options (the different kinds of labels, plain A4, letterhead, colour, A3) which were packaged up in the print job (I think in DSCs). The server would read the job details from the DSC and route it to the appropriate actual printer. This was a bunch of work, but once it was done it was very flexible - if you needed to add another printer (there was always more demand for the label printers than they could comfortably accommodate) you just added another and told the print server about it. The only problem was people finding their job (because they didn't know which printer would generate it); I did have a little visible log somewhere, but I think they had such traffic that they eventually employed an unfortunate person to stand amid the printer cloud and sort print jobs into trays.  I don't know of an off-the-shelf solution that does the same job, unfortunately. -- Finlay McWalterჷTalk 01:41, 22 September 2011 (UTC)
 * I think we are going to do something similar. Some wheels apparently just need to be invented thousands of times. Still I wonder, why didn't Microsoft just tell the printer manufacturers: this is what Windows will understand and if you do it otherwise you'll have to provide your own drivers. No one needs a special driver for their speakers, mouse or keyboard. It seems that printer manufacturers think that they have a product that's very special. It was, in 1990, when you needed a special memory card for your favorite font. Now a printer should just print a bitmap exactly as Windows tells it to. A label "Microsoft Printing Protocol Approved", similar to MSX, "PC-Compatible" or TWAIN would really help us here. It might not save world economy, but it would save at least a few billion dollars in lost productivity. Joepnl (talk) 00:16, 23 September 2011 (UTC)
 * I believe Microsoft did try to convince printer manufacturers to use XPS but it didn't work very well. Of course this was fairly late in the game (the Vista era) Nil Einne (talk) 03:20, 25 September 2011 (UTC)