Wikipedia:Reference desk/Archives/Computing/2013 June 2

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June 2

MacBook Pro Keyboard Issue

Hi. I run Mountain Lion on my MacBook Pro and I have recently been experiencing some very frustrating behaviour with my keyboard. Basically, for quite a while, after waking the computer up from sleep, and trying to enter my password to log in, the computer would take several seconds to register that I had typed anything and then, all of a sudden, would display the process of (most of) the characters being displayed on screen. It has now got to the point where, if there is a brief interlude (which needn't be longer than a few minutes) where I'm not typing (though I can stil be using the computer in other ways, eg using the mouse or switching from one screen to another), the computer will take several seconds to respond to my initial typing once I begin. At its worst, the computer hasn't registered that I've been typing anything and I have had to restart the whole thing.

I have tried this with an external keyboard and I have the same problem. Interestingly though, when I have opened up the built-in on-screen keyboard, I have been able to type a few characters on that with immediate response but, when I immediately follow that with the physical keyboard, the behaviour I described above re-appears. This is extremely frustrating.

Clearly, the problem lies in how the process of information from a key depression being transferred to the internals of the computer differs between a physical keyboard and an on-screen one. I don't know enough about computers to be able to trouble shoot this though. Does anyone have any suggestions? Thanks. meromorphic [talk to me] 15:50, 2 June 2013 (UTC)

Unfortunately, I'm no expert when it comes to Macs; but if you want, you can report this bug to Apple here. Though hopefully a Mac user here will be able to give a better suggestion than me. --Yellow1996 (talk) 17:28, 2 June 2013 (UTC)

Apparently there is a bug in the SystemUIServer (or some of the applets it manages). This can cause the process to hog system resources, and I have experienced symptoms similar to the one described by the OP. To fix it, simply kill the SystemUIServer process. The system will restart it in a sane state, and the symptoms will be gone. Repeat as needed (so far, for me it has happend twice in 11 years ;-). To kill it, open a terminal, type "top -u", note the PID of the offending process, hit "q" to get out of top, and then "kill PID" (where PID is, of course, the PID you noted). --Stephan Schulz (talk) 20:01, 2 June 2013 (UTC)

Thanks, Stephan! Preliminary results are good. I haven't noticed the problem at all since I did as you said last night (and, given the frequency with which it was occurring before, I would definitely expect to have seen something by now if it were still present). Definitely something to remember for next time it happens. Thanks again and happy editing! meromorphic [talk to me] 12:32, 3 June 2013 (UTC)

You're welcome. --Stephan Schulz (talk) 19:34, 3 June 2013 (UTC)

Cracking a facial recognition system login

Do those laptops with facial recognition login get tricked by putting a simple video of the user in front of the camera? Or do they have a more sophisticated approach to tell apart real people from pictures of real people? OsmanRF34 (talk) 17:01, 2 June 2013 (UTC)

Well, I would think that the recognition software would take things such as depth and/or lighting into account; factors which a picture or video held up could not emulate well, though less accurate systems may be fooled. --Yellow1996 (talk) 19:27, 2 June 2013 (UTC)

As of 2009, the laptops could be fooled by a still image ([1]). Android Jelly Bean's face unlock checks for blinking, but can be fooled by a video that alternately shows a photograph and the same photograph with the eyes painted out ([2]). It's possible to do better with active illumination, as mentioned in the facial recognition system article, but that would probably require extra hardware which would affect the price of the laptop. -- BenRG 20:09, 2 June 2013 (UTC)

Yes, active lighting could kind of guess if the image in front of the camera lens is at least 3d. But does any laptop incorporates it? Otherwise, it looks like a huge security weak point. It's even easier than cloning fingerprints (which can also be done). OsmanRF34 (talk) 20:27, 2 June 2013 (UTC)

Gadgets

So I've heard that desktop gadgets (like clocks, local weather, sticky notes etc) can slow down your system (I've heard just startup but also overall performance.) Is there any truth to this? If so, how much difference does it make? Thanks! --Yellow1996 (talk) 17:12, 2 June 2013 (UTC)

From my experience on this slow computer, I'd say that gadgets certainly delay startup, but make only a slight difference to perceived performance. Perhaps someone can find some published timings for comparison? Dbfirs 22:16, 3 June 2013 (UTC)

If you manage to use up all available RAM, the system will start thrashing and there will be a severe performance degradation. Otherwise, it depends on the nature of the things you are installing. Bobmath (talk) 22:40, 3 June 2013 (UTC)

Well, in my case I've got like 10 different-styled clocks. Seemed like a good idea back in 2008! :) Sometime soon I'll do a test without and see if I notice any speed change. Thanks, guys! :) --Yellow1996 (talk) 00:01, 4 June 2013 (UTC)

Illogical Colour Cast - Help Please

My Relisys monitor has what seem to be light sensitive control buttons on the base - the control choices come up if you so much as drop a piece of paper over one of them. Today I leant forward, covering them all with my sleeve and when I leant back I had a heavy yellow cast to my screen. I opened the controls again and tried to see how I could correct the colour balance but had no luck (this is not an area in which I have much experience). I then opened the Nvidia control panel to see if I could adjust the colour from there but didn't have much luck there either.

Well, it seemed to me that it had to be a problem with the screen hardware as that is what had been altered when I leant across the buttons. So I physically switched screens and plugged in a Viewsonic that I use on my other PC. The colour cast was still there. This seems weird since it had to be a hardware problem. But since the Viewsonic showed perfect colour before I unhooked it, but 'inherited' the colour cast, that suggested that my problem was with the monitor driver/software. I reinstalled the Nvidia software using a "clean" instal so any settings or preferences would be overwritten with the defaults.

I still have the yellow colour cast! So it seems that it is neither hardware nor software . . . HELP!!!!

Gurumaister (talk) 19:19, 2 June 2013 (UTC)

If your computer is using an analog video signal, it has separate pins for red, green, and blue signals. If the blue signal isn't getting to the monitor, then the screen will have a yellow tint. Take a look at this image: File:AdditiveColor.svg. Do you see three circles for red, green, and blue? Or just two circles for red and green?

If the blue signal is missing, then you might try the following: If your monitors have a built-in video cable, make sure you securely connect the cable to the computer's video port. If your monitors have their own video port, then try replacing the video cable with another one. --Bavi H (talk) 20:44, 2 June 2013 (UTC)

Bavi H, Thank you. I have now switched the cable with one that I know is OK and the problem has disappeared. Thank you so much for your valuable help. Gurumaister (talk) 17:15, 3 June 2013 (UTC)

How to log out of facebook when it's unresponsive

I'm logged in to facebook. I dialog box says "The following pages have become unresponsive: You can wait for them to become responsive or kill them." Then it lists facebook. Two buttons are there: "Wait" and "Kill". I "killed" it, and opened a new window and looked at facebook. Same thing. I can't move the scroll bar or look at my nofitifications. Nor log out. This has persisted for an hour and a whole bunch of new windows----never more than one window open at a time. Is there any way for me to log out of facebook? No such problem affects other web sites with the same browser on the same machine. Michael Hardy (talk) 22:10, 2 June 2013 (UTC)

I'm not sure how you would go about logging out, but try closing the window, clearing your cache and going back - see if the problem persists. I'd also be curious as to whether it happens in another browser. Which one are you using? --Yellow1996 (talk) 01:15, 3 June 2013 (UTC)

I solved this by rebooting twice. It hasn't recurred. But I found out by googling that several others have seen this happen. Michael Hardy (talk) 17:05, 3 June 2013 (UTC)

Okay, that's good. I'm glad you managed to fix it! :) --Yellow1996 (talk) 00:03, 4 June 2013 (UTC)

Modified MP3

Do you know of any software capable to edit an MP3 file and make it sound as it had a higher pitched voice? Take for example this song, a parody of the Gangnam Style as if it was singed by Alvin and the Chipmunks (in case someone doesn't know the original song for comparison, it's here). How did they do that? Cambalachero (talk) 22:24, 2 June 2013 (UTC)

That clip may just have been sped up, which also raises the pitch (for example, playing it at 4/3 speed raises the pitch by a perfect fourth). Any audio editing tool can do this (Audacity is popular). It is possible to change pitch without changing tempo—audio time-scale/pitch modification is the article. It appears Audacity can do this too, and there are other free tools, but I'm not sure which to recommend. -- BenRG 00:26, 3 June 2013 (UTC)

As BenRG says, you can alter pitch without changing tempo, and you can alter tempo without changing pitch. However, if you wanted to alter the pitch or tempo of just one part of the audio (i.e. just the vocal) then the short answer is it's not really possible. To do that you'd have to somehow separate the vocal from the music. An analogy I often use is baking a cake—once it's out the oven, try to remove the egg yolk. The baking process is similar to mixing and exporting in audio; everything gets "flattened". In reality, most remixes or parodies like this (I'm working on assumption, because I've not watched the clip) will be done either by re-recording the parts to alter, or by using the original stems. matt (talk) 19:44, 5 June 2013 (UTC)