Wikipedia:Reference desk/Archives/Computing/2012 August 4

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August 4

which dac is the better one

CS5381 or CS4398 ???

THANX!!! — Preceding unsigned comment added by 77.35.7.43 (talk) 12:00, 4 August 2012 (UTC)

CS5381 is an analog to digital converter, while CS4398 is a digital to analog converter. They do opposite tasks. A quick glance at their specifications indicate that they're both designed for 24-bit, 192 kHz systems - well beyond the average consumer audio application's needs. Nimur (talk) 16:39, 4 August 2012 (UTC)

yeah sorry i got it mixed up the one i meant was

PCM1792A vs CS4398

so which is the better in terms of audiophile merits? — Preceding unsigned comment added by 77.35.26.85 (talk) 00:06, 5 August 2012 (UTC)

I've used the TI part, and it puts out nice clean signals. Right now all I've pushed through it is sawtooth waves, but the transition looks beautiful. I have no reason to suspect that the other part will be worse. As Nimur said they're both more than enough for audio - one isn't really better than the other for those needs. Any noise in the system is going to be at such a ridiculously high frequency and low amplitude that it simply doesn't matter and will probably be filtered out by minor capacitances or the mechanics of your speakers. 209.131.76.183 (talk) 12:51, 6 August 2012 (UTC)

IRC always timing out

I'm unable to get onto IRC. I can connect to Steam, the Internet, etc. just fine, but eery time I try to get onto IRC it times out. What exactly's wrong? —Jeremy v^_^v ^Bori! 17:39, 4 August 2012 (UTC)

Do you have a firewall enabled? You might try disabling it and trying to connect — just to try and isolate the problem. --Mr.98 (talk) 17:52, 4 August 2012 (UTC)

I do, and disabling it doesn't help. —Jeremy v^_^v ^Bori! 17:58, 4 August 2012 (UTC)

Update: I managed to get on - for all of half an hour, and only on one network. One user suggested I use a bouncer, but he didn't give me a reply when I asked him to clarify. Reading up on it, I don't think a bouncer will help, but I'm not tech-savvy enough to know. —Jeremy v^_^v ^Bori! 19:06, 4 August 2012 (UTC)

Any other suggestions? —Jeremy v^_^v ^Bori! 07:12, 5 August 2012 (UTC)

Since you are able to use the internet and everything else ok, it seems like something is blocking the specific IRC ports (usually 6667). Check on their websites to see if the networks you're connecting to have alternative ports available and try using those. Also many IRC servers support SSL connections, try setting that in your IRC client and see if it works. The only other thing I can think of is that your other programs connect via a proxy server (perhaps a company or ISP cache/filter system) and that you need to set the IRC client to use this as well. 92.233.64.26 (talk) 10:51, 5 August 2012 (UTC)

What does it mean to open a file?

I understand that from a user perspective. But, it seems like a poor metaphor, since it's not like a book or folder that can be physically opened. What does the computer do to the file when I run a open("myfile.txt") method? In some cases it blocks other programs from changing it, however, that's not always the case. Comploose (talk) 17:44, 4 August 2012 (UTC)

When you say, "open a file," in most cases the computer program interprets this as, "look at the sectors of the hard drive that are indicated as being part of a given file and load them into some kind of random-access memory." The ones that "lock" the file usually (but not always) aren't loading the whole thing into RAM. But basically the issue is that the program is accessing the hard disk in the places that correspond to the file, and interpreting the data it finds there. The verbs often used in the computer languages themselves are "read" or "get" as opposed to "open." In high level languages (and with straightforward files) you don't usually have to worry about all of the physical backend. --Mr.98 (talk) 17:54, 4 August 2012 (UTC)

Mr.98 and I have interpreted what you mean by "open a file" at quite different layers of abstraction. If you mean "open a file in Microsoft Word" then Mr.98's answer about open really meaning "find and read the file" pertains. If you meant simply the low-level open(2) call (or its equivalents on other OSes, which work very much the same) then mine is all that happens. -- Finlay McWalterჷTalk 18:07, 4 August 2012 (UTC)

Firstly it takes than name "myfile.txt" and adds to it the current or default path (usually the current working directory of your process) to make a fully qualified name "/mnt/mydisk/foo/bar/myfile.txt". Then it looks that name up to see if the file exists, and if you have permissions to access it. Most OS filesystem layers cache some, but not all, of the files they know about - so it may have to go to the disk and read from it the requisite directory information (or it may have a cached version of that, in which case it won't). That tells it that the file exists, its owner and permission info, and where the file's data is physically located on the disk. Then the OS constructs a software object that corresponds with that info, stores that in a table, and returns the ID of that object to the calling program. That ID is usually completely opaque (on unix it's just an integer, usually 3,4,5,etc.) which the program has to remember and pass back to the OS when it wants to do other things to do with that file. And that's often that. In some OSes the open call can include an optional request for an exclusive lock, in others a lock, if a program wants one, has to be acquired by separate calls. At this time an filesystem driver might elect to optimistically start preloading the file (into its own data cache), as reading from files one has just opening for reading is a common pattern - but it might chose not to. -- Finlay McWalterჷTalk 18:03, 4 August 2012 (UTC)

What article ought to describe this, especially for people who have no idea how "cache" or "software object" or "preload" might be relevant and just seek an elementary notion of what ought to happen when they double-click a file? Jim.henderson (talk) 18:31, 4 August 2012 (UTC)

For the basic "open file" system call, file system, cache (computing), and page cache might help. "Object" doesn't mean anything specific (it might be a Object (computer science), but probably isn't) - "software thingmabob" would be just as good. I don't think we have much about anticipatory caching ("preloading"), although prefetching lists other circumstances under which an analogous load-incase-we-need-it strategy might be found. But the full "what happens when I double click" is an order of magnitude more stuff. -- Finlay McWalterჷTalk 19:13, 4 August 2012 (UTC)

Full story? Does someone want that? Should History of France give the full story of its topic? I seem to have expressed my concern poorly. What I'm hoping for is a broad view, taking a paragraph or two or perhaps three as part of another article, or a dozen or two in their own article. If these questions are vital to a superficial understanding what happens when someone as ignorant as me (or more so) double-clicks, then they should be mentioned, otherwise not. Jim.henderson (talk) 19:53, 4 August 2012 (UTC)

At least for technological things, Wikipedia does not seem inclined toward such vertically integrated How Stuff Works type articles. For example we don't have (that I can find) an article about the full story of what happens when you flip a lightswitch - there's plenty of articles about the elements involved, from lightswitches to generators to power transmission to voltage. Maybe we should, I don't know. -- Finlay McWalterჷTalk 20:56, 4 August 2012 (UTC)

Drat; failed again. Rather than fully describe the sequence of events that are performed to accomplish the desirable goal of opening the file, the question "What does it mean" suggests, or at least I suggest, that Wikipedia ought to define or describe that goal. When we have "opened a file" what important condition, circumstance or happy result have we achieved? Jim.henderson (talk) 21:04, 4 August 2012 (UTC)

I don't think "opening a file" makes much sense as a concept. It combines a bunch of things that are conceptually unrelated: looking up a file name to find the file it corresponds to at that moment, locking the file (e.g., to prevent multiple simultaneous writers), doing a security check and returning a capability, among other things. There's no reason for these to be lumped together and in many ways it's bad—a lot of security bugs are caused by having to open a file more than once for some silly reason, and thus incidentally redoing the lookup of the file name, even though it may not refer to the same file any more. Higher-level "opening" and "saving" in word processors and such is kind of arbitrary too. It's like a very limited version control system where you only have two versions of the file, the "open" one and the one on disk since the last time you "saved". It made more sense in the old days when disks were very very slow and it was useful to control when you'd have to wait. -- BenRG (talk) 23:04, 4 August 2012 (UTC)

So, now it seems the question is understood. Perhaps I have come across as angry, and must confess to being miffed out of proportion at the repetition of "full story" after thinking I had explained that's exactly what I'm not after. Anyway, that bit having been straightened out, what, if anything, should be done about the use of this term in Wikipedia? When a menu on a window offers the choice "File" ... "Open" should the encyclopedia be silent about it because the term is nonsensical? For the same reason should file association not say "Some of the common verbs are: *open to open a file"? Or should the term be defined as far as necessary to each appearance? And should other articles have such material censored, umm, edited out as unfit to be said? Or should there be a disambiguator covering most of those possible meanings? Or a small article explaining that this unpleasant or misleading or very limited term may refer to various combinations of the above? Jim.henderson (talk) 00:28, 5 August 2012 (UTC)

If you want to discuss the content of articles, take it to the article talk pages or some other appropriate place. One of the reasons you aren't getting a good response is because you're at the wrong place. Nil Einne (talk) 05:01, 5 August 2012 (UTC)

Yes, it is disappointing. Someone asks what a phrase means, and one expert says we can't define it without telling the whole story, and the whole story is too long, and we can't answer without telling the whole story (yes, redundantly). Another expert says we can't say what it means because the concept doesn't make sense, and a third says this isn't the department of saying what anything means. Obviously all these answers are rooted in a technical understanding deeper than mine, but it makes me wonder who could possibly be helped by any of them. Perhaps the talk page for Computer file or another one can find a more useful expert. Jim.henderson (talk) 00:45, 6 August 2012 (UTC)

So far, the OP hasn't complained about any of the responses. If the OP does have problems, they're welcome to seek clarification as with all OPs. In the mean time, people have tried to help you with your followups despite the fact your questions appear to be largely OT and your manner of asking leaves much to be desired. If the OP does have something to be disappointed about, it's not those who have tried to help them. Nil Einne (talk) 16:16, 6 August 2012 (UTC)

So you mean the philosophical/literal meaning of opening a file?, Like the meaning itself of opening a file? It means, accessing to it. 65.49.68.173 (talk) 17:17, 6 August 2012 (UTC)

3D Bluray Ripping

Hello, I have a sudden need to rip 3D blurays for a client. I have looked at DVDFab, but I've only found one review that seems to be mixed. I'm willing to spend money (as I can just bill the client for it), but would prefer if it could deal with regular blurays and DVDs as well. The client is fairly tech-savvy, so might want specific formats and settings. So, two questions: 1) Could someone point me to a breakdown of the various options in ripping 3D content (e.g. Anaglyph vs side by side 3d?), and 2) any recommendations for a good 3d bluray ripper?

Thanks, 64.134.179.102 (talk) 22:42, 4 August 2012 (UTC)

USB Flash Drive vs USB External Hard Drive

Hello, Would a device designed to accomodate a USB flash drive work with an external USB hard drive? Specifically, I'm looking at turntables that can rip vinyl to a USB stick, but I'd prefer if it was possible to rip it directly to an external drive. Can the device tell the difference? Is there a technical difference (other than the obvious magnetic HDD vs flash memory one)? Does it matter? Thanks, 64.134.179.102 (talk) 22:58, 4 August 2012 (UTC)

The type of hardware doesn't matter, at least to Microsoft Windows and I assume to other operating systems. Regards, SunCreator ^(talk) 23:48, 4 August 2012 (UTC)

It really depends on how forward thinking the manufacturer of the particular device was when designing it. One potential issue might be capacity. The turntable device may only be able to cope with small capacities, perhaps limited to as low as just 2GB, while a typical external hard drive can be several TBs in size. On the other hand it may have no problem with huge capacities at all. Without knowing the exact device there isn't any way to answer this definitively 92.233.64.26 (talk) 00:09, 5 August 2012 (UTC)

Electrical power might be an issue. Does a USB-powered HDD use more power than a USB-powered flash disk? Eg if the host expects a lower power device (1 unit load) but the HDD is a high-power device, it might fail. Of course this problem is probably easily solved by using an HDD with a separate power supply, rather then one powered from the USB. Mitch Ames (talk) 01:41, 5 August 2012 (UTC)

(ec) I think the above responses are incorrect. If you have a turntable that is designed to allow you to plug a USB stick directly into the turntable, it probably won't work with any other type of USB device. In order to do so, it would need a different type of driver, and if it had one, the advertising for it would probably say so. Note, however, that turntables of that sort are much less common than USB turntables, which are designed to connect via a USB cable to your computer. If you have one of those, you can use your computer to store the data to any sort of device you please. Looie496 (talk) 01:47, 5 August 2012 (UTC)

OP here. Thanks for the responses: the HDD I have is externally powered, so that shouldn't be a problem. Am I correct in thinking that the only way to tell will be to try it and see if it works? Also, I'd like to throw in a cheap plug for help on my question above this one (is that allowed? cross-promotion?). Thanks again, 64.134.179.102 (talk) 03:15, 5 August 2012 (UTC)

Be very careful with cheap plugs as the error rate can be unacceptably high. Email me your banking details and I well send you a high quality gold-coated plug. ;) Franamax (talk) 03:59, 5 August 2012 (UTC)

Surprisingly no one mentioned this until now but you should consider file system issues. Most memory sticks tends to be factory formatted with the FAT file system, with what would be tiny ones nowadays FAT16 and most others FAT32. You may occasionally find them formatted with NTFS or exFAT and of course you yourself can format them with whatever you want, this is rare. However external hard disks tend to be factory formatted with NTFS, while it is possible to make large partitions with FAT32 albeit not with Windows, this is rarely done unless really needed for compatibility purposes, I would say this is rarely done because of the various disadvantages of FAT. (Those using *nix, Mac OS X are likely to use some modern file system their OS supports when they don't need Windows compatibility, e.g. some variant of UFS2, zFS, extFS, HFS Plus.) I think there's a very good chance your turntable will not support anything besides FAT16 and FAT32 (well probably FAT12 as well), i.e. NTFS, exFAT etc are all out. You could try making one small FAT partition for the external HDD but speaking of partitions, I wonder whether there's a risk the turntable won't work at all if your device has a partition table which is the norm for HDDs (even when they only have one partition) but AFAIK not for memory sticks. As already mention, regardless of all the other things, the turntable may have problems coping with something too large. There are likely other complications which may make the HDD not work, but I'm not sure whether generic driver issues are one of them. AFAIK, both memory sticks and external HDDs usually just expose themselves as USB mass-storage device class so theoretically at least, the drivers themselves should nominally work on both ignoring all the other possible complications (some of which e.g. the space issue may work at the driver level). Nil Einne (talk) 04:45, 5 August 2012 (UTC)

> Surprisingly no one mentioned this until now but you should consider file system issues ...

I have seen this problem. I wanted to transfer the channel settings from my TV to my video recorder, both Samsung, and both of which included the capability to save/load the settings to/from a USB storage device. When I tried it, the TV knew I had plugged something in, but refused to write to it. It turned out that the USB flash drive was formatted as NTFS, and the TV could only handle FAT. I reformatted it from my PC, and it worked fine. Mitch Ames (talk) 09:55, 7 August 2012 (UTC)

I will tell you from experince get the Hard Drive external its great they are fast and hold tons you can get one off of newegg for under $100 and its 1 Tb.

Case-sensitive searches?

How do I do a case sensitive search of Wikipedia? Seems that Wikipedia search is case insensitive and Google is also. Any ideas? Regards, SunCreator ^(talk) 23:10, 4 August 2012 (UTC)

Download the Wikipedia database, run your own search queries on it? --Mr.98 (talk) 03:18, 5 August 2012 (UTC)

That seems overkill. You could simply use the case-insensitive search, provided by Wikipedia; and then search the results with a custom case-sensitive search. Because the case-sensitive results are a strict subset of case-insensitive results, you can guarantee that you haven't missed a match. If you need help doing this programmatically, there is a web services API: the complete documentation is available online: Full Text search; and the title-completion-tool OpenSearch, among many many other ways to perform programmatic searches using the web service API. Nimur (talk) 05:34, 5 August 2012 (UTC)