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  • Wi-Fi or Bluetooth to USB converter

    - by yerzhik
    Is there a device, that works without a driver, you just connect it as usb, and receive any signal sent to it as if it were COM Port wired connection? For example, such a device that gets data sent to it by Wi-Fi network or Bluetooth and resends it to the USB. Of course it has to be set up once (network name, password etc) and for this purpose you need a driver, but once it is set up, you can use it at any computer without a driver. I have a Bluetooth USB, but I think it can't work without a driver. By just connecting it to any computer you can't find it in device list on another bluetooth device (as phone, etc).

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  • Apache: Stealth 404 the admin area until authenticated via basic auth, then allow access

    - by Kzqai
    Given a administrative area with urls like this: wp-admin/ wp-admin/whatever wp-admin/another-page wp-adminsecretlogin/ A standard basic-auth coverage would provide a username and password prompt on all three urls, and return a 403 on all failed auth attempts. This is a pretty obvious signal that something exists there, and thus is an invitation to script/brute force access. I would like to instead, require basic auth everywhere, but when not authenticated, not prompt for username and password, and instead return a 404 not found error for all urls except a wp-adminsecretlogin/ url. At that individual-to-the-site url, basic auth could go through, and unlock the rest of the administrative functionality (though the standard application login would still be necessary). How would I do that via apache .htaccess or .conf directives?

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  • Not getting my normal internet speed but my other computers can?

    - by Dennis
    I have Comcast Xfinity and I cannot reach anywhere near my promised speed. My family desktop which is hardwired into the router reaches to 60Mbps and so do my parents computers and my brothers. I cannot seem to get anywhere close to it, I know with being wireless I won't reach it, but I should at least get somewhere close. I can only pull 6Mbps and thats terrible for what I should be receiving. Any clue what could be wrong here? Edit: I have 100% signal and I'm not behind any walls

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  • Kill child process when the parent exits

    - by kolypto
    I'm preparing a script for Docker, which allows only one top-level process, which should receive the signals so we can stop it. Therefore, I'm having a script like this: one application writes to syslog (bash script in this sample), and the other one just prints it. #! /usr/bin/env bash set -eu tail -f /var/log/syslog & exec bash -c 'while true ; do logger aaaaaaaaaaaaaaaaaaa ; sleep 1 ; done' Almost solved: when the top-level process bash gets SIGTERM -- it exists, but tail -f continues to run. How do I instruct tail -f to exit when the parent process exits? E.g. it should also get the signal. Note: Can't use bash traps since exec on the last line replaces the process completely.

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  • Viewsonic monitor keeps showing its on-screen menu incessantly

    - by markvgti
    Since yesterday my Viewsonic 22" monitor (VX2255wmb) keeps showing its on-screen menu incessantly, without my touching any of its buttons. The menu comes on in the centre of the screen, stays on for 8-10 seconds, disappears for a second or two, then repeats the cycle. This happens whenever there's a signal being sent to the monitor. I can't actually navigate the menu when it appears on-screen. Pressing the power button, or the Up and Down buttons on its right edge dismiss the menu, only for it to reappear again. These symptoms have appeared before, but earlier they'd stop after 5-10 mins. The power button on the monitor has always been iffy, but now it doesn't seem to be working at all--have to switch off power supply from mains when I leave my desk. Using DVI input on this monitor as my HP desktop has DVI output.

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  • No wireless adapter in msi u200

    - by Mino Marimat
    I have a MSi u200, and the weird thing was that I was using this normally before, then after a few minutes all of a sudden it couldn't find the wifi signal from my house. I did some troubleshooting and a bit of search in the control panel, and it seems like my hardware is missing. :( I can't even turn on the wireless light using Fn+F8, so my suspicions about the missing hardware strengthened. I tried searching for DIY fixes, but I found out that the wireless card is actually built-in deeper, unlike the RAM cards and the hard drive where you can either replace or add more cards. What do I do?? As of the moment, I can get connected to my wifi here at home using a wireless adapter via usb, and it's working. So my guess about the hardware problem seems correct. HELP!!! Thanks!

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  • Internet Connectivity... Help please!

    - by James
    Hi. My Laptop is having trouble connecting to my wireless router. Other laptops are using the wireless, but it's not reached capacity. The laptop recognises (with a strong signal) that there is wireless internet, and I can connect via the router with a cable because this happens automatically. My problem is this... When I click "connect" (for example in the network and sharing centre), the dialogue box closes and nothing else happens - as though "connect" is being read as "exit". I am running Vista on a Toshiba Satellite Pro P300. Any help would be very much appreciated, Thanks

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  • Is there an intuitive way to reopen Empathy's contact list?

    - by aef
    Since a short while I'm using Ubuntu Oneiric Ocelot (11.10) with gnome-shell (Gnome 3) and I'm trying to get accustomed to the default Empathy Instant Messaging client. When I hit the close button of Empathy's contact list the window disappears as expected. When I now start Empathy over the Gnome Activities menu the contact list reappears. That's not as easy as clicking a system tray icon back in Psi on Gnome 2 but it works for now. But when I start a conversation first and have an open conversation window, then close the contact list, and try to regain access to it by using Gnome Activities, I only get the conversation window into focus and no contact list appears. I only seem to be able to get the contact list back if I close the conversation window (and thereby signal the conversations to be over) and then use Gnome Activities again to get my contact list back. That's horrible. Is this intended? Is there something I'm missing?

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  • Why do I have inconsistent network issues with my laptop's wireless?

    - by Jason
    I'm having trouble with my laptop Internet connection. It's patchy at best and resets or freezes a lot. The signal strength is also random. I thought it might be a driver issue but now I don't know. Three other computers using the same wireless network run well. I've switched out wireless routers so I don't think it's the router. I thought it might be the laptop's internal wireless card but I just bought an external USB network card and I'm still having problems. Specs Lenovo T-60p Windows 7 Ultimate Edition Patches/drivers are up to date I only use one of the below at a time, disabling the other: Intel PRO/Wireless 3945ABG v. 13.3.0.137 (Internal wireless) Medialink Wireless-N USB 2.0 Adapter (USB wireless) Any ideas on what might be the problem?

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  • TV Card Problem

    - by MladenB
    I have DVB-T card (CE9500B1) and it doesn't work. I've tried everything I knew (but I don't know much). It doesn't show any problem, but shows "No Signal". I used another TV card USB, found channels, put mine card again, and again nothing. I don't think it's broken, when I put USB in my laptop, it recognizes it. Also, these little lights on USB are never turned on. OS is Win 7. Help, please.

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  • Installing WiFi in a church for internet access

    - by Dave Griffiths
    Hi, a colleague at work asked this question: My local church want to get WiFi enabled in the whole of their offices and main church building. The offices and main building are in the same overall structure and so the signal does not need to travel outside to any other buildings outside this main structure. Where would I start on such a project and what kind of repeaters are needed (and how are they set up) given that some of the walls are pretty thick. Do you still have one ADSL line coming in to router or are there some options of having two lines coming in so that they isn't a single point of failure. Am looking at fibre for the broadband for increased speed. Any starting pointers appreciated.

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  • Router Suggestions [closed]

    - by zamN
    Lately I've been having router problems with my Linksys WRT54G when it comes to signal strength. Anyways I am thinking of getting a new router since the linksys is about 5 years old now. I'm just curious what router to get because I want to get the most out of my money. I already have a modem that I will connect to the router. I don't need voIP or any of that. All I simply want is just something that is going to last and will not have any stupid problems.

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  • Issues with new graphics card and drivers

    - by Ortund
    With my onboard graphics card (Intel HD 4000) I was able to use 1680x1050 screen resolution. Using the same screen and an Asus ENGTS250 graphics card with 296.10 drivers installed, I'm not able to use that resolution anymore. Also, I've been having other trouble with driver installations. Using 340.52 or 337.88, I can't boot into Windows 7. I see the Windows Welcome screen and then the screen goes black, loses signal and the computer locks up. I think the drivers issues and the resolution problems go hand-in-hand. I have a feeling I could use a newer driver than 296.10 which would give me access to use the 1680x1050 resolution I want to use, but I'm terrified that if I update or install another driver, that the computer will lock up again. Can anyone recommend a [better] driver for me to use?

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  • Why won't my computer turn off?

    - by kinglime
    I have recently replaced my old Corsair TX650M PSU with a new CoolerMaster Silent Pro Gold 800w PSU. With the old PSU when I turned off my computer from windows it would shut down and everything would turn off. The lights would turn off and the fans would stop turning. With my new power supply when I shut down windows It shows the usual shutting down dialog then my two monitors say "no signal" and turn off. The weird part however is that the lights stay on and the fans continue spinning forever until I manually hold the power button in for 4 seconds then finally everything shuts off. How can I emulate the previous behavior?

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  • Using a BTHomeHub as a wireless booster

    - by Ploo
    I currently have a BT HomeHub downstairs but the wireless signal isnt strong enough on the second floor. I have an old BT HomeHub from the previous contract that I wanted to set up upstairs. I currently have an ethernet cable leading up into the old router. I then took my laptop and plugged it into the old router in hopes of configuring it but when I cannot reach api.home which is the address of the router. I cannot connect to the router wirelessly either since the password was changed and I'd have to change it through config. At this point I am completely stumped, any ideas?

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  • hdmi output of windows 7 does not stay alive

    - by sjors miltenburg
    I have built a server that is connected to ONLY my tv (with hdmi). If I switch my tv to hdmi and boot my server I get the expected result (windows is displayed on my tv) and I can fully interact with it, no problem. However when "some time" passes the image on my tv dissapears and it seems the server is not outputting any hdmi signal anymore. It does not wake up on mousemove or keyboard presses. I can still interact with my server through a remote desktop session. The only way to get the hdmi output back is to reboot the server. I tried to prevent the computer from "sleeping" but this did not work. I tried upgrading from windows vista to windows 7 but this also did not work. Do you guys have any other ideas?

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  • Which UPS, for home use, which can automatically shutdown the PC when battery is low?

    - by Tony_Henrich
    I am planning to build a single server machine which is highly dependent on data residing in RAM for performance reasons. I am looking for a UPS which can power the PC during a blackout (very rare) and when the battery level is like %20, it sends a signal to Windows 2008 to shutdown. Even if it's only for a few minutes, that's good enough. This is for home use so I am looking for an inexpensive unit ( less than $300? ). Which brand/model is good choice? I prefer one whose battery is easily & cheaply replaced.

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  • Does a HDMI-to-DVI (dual link) adapter exist? I don't care about the price

    - by alex k
    My monitor supports full-resolution display (2560x1440) only when connected to through either the DVI-D dual link port, or the DisplayPort. My laptop, though, has neither of these two kinds of output. Instead, all it's got is a HDMI port (which is version 1.3, and I also read that the laptop's graphics chipset supports 2560x1440 at 60Hz). So I'm wondering whether anyone has ever seen an HDMI-to-DVI dual link adapter, which will carry my ultra-highres signal to the monitor I just bought. So far I haven't seen any, and don't even know whether such an adapter (which I understand would have to be active, USB-powered and expensive (but I don't care)) exists.

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  • Bluetooth RFCOMM / SDP connection to a RS232 adapter in android

    - by ThePosey
    Hello All, I am trying to use the Bluetooth Chat sample API app that google provides to connect to a bluetooth RS232 adapter hooked up to another device. Here is the app for reference: http://developer.android.com/resources/samples/BluetoothChat/index.html And here is the spec sheet for the RS232 connector just for reference: http://serialio.com/download/Docs/BlueSnap-guide-4.77_Commands.pdf Well the problem is that when I go to connect to the device with: mmSocket.connect(); (BluetoothSocket::connect()) I always get an IOException error thrown by the connect() method. When I do a toString on the exception I get "Service discovery failed". My question is mostly what are the cases that would cause an IOException to get thrown in the connect method? I know those are in the source somewhere but I don't know exactly how the java layer that you write apps in and the C/C++ layer that contains the actual stacks interface. I know that it uses the bluez bluetooth stack which is written in C/C++ but not sure how that ties into the java layer which is what I would think is throwing the exception. Any help on pointing me to where I can try to dissect this issue would be incredible. Also just to note I am able to pair with the RS232 adapter just fine but I am never able to actually connect. Here is the logcat output for more reference: I/ActivityManager( 1018): Displayed activity com.example.android.BluetoothChat/.DeviceListActivity: 326 ms (total 326 ms) E/BluetoothService.cpp( 1018): stopDiscoveryNative: D-Bus error in StopDiscovery: org.bluez.Error.Failed (Invalid discovery session) D/BluetoothChat( 1729): onActivityResult -1 D/BluetoothChatService( 1729): connect to: 00:06:66:03:0C:51 D/BluetoothChatService( 1729): setState() STATE_LISTEN - STATE_CONNECTING E/BluetoothChat( 1729): + ON RESUME + I/BluetoothChat( 1729): MESSAGE_STATE_CHANGE: STATE_CONNECTING I/BluetoothChatService( 1729): BEGIN mConnectThread E/BluetoothService.cpp( 1018): stopDiscoveryNative: D-Bus error in StopDiscovery: org.bluez.Error.Failed (Invalid discovery session) E/BluetoothEventLoop.cpp( 1018): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/1498/hci0/dev_00_06_66_03_0C_51 I/BluetoothChatService( 1729): CONNECTION FAIL TOSTRING: java.io.IOException: Service discovery failed D/BluetoothChatService( 1729): setState() STATE_CONNECTING - STATE_LISTEN D/BluetoothChatService( 1729): start D/BluetoothChatService( 1729): setState() STATE_LISTEN - STATE_LISTEN I/BluetoothChat( 1729): MESSAGE_STATE_CHANGE: STATE_LISTEN V/BluetoothEventRedirector( 1080): Received android.bleutooth.device.action.UUID I/NotificationService( 1018): enqueueToast pkg=com.example.android.BluetoothChat callback=android.app.ITransientNotification$Stub$Proxy@446327c8 duration=0 I/BluetoothChat( 1729): MESSAGE_STATE_CHANGE: STATE_LISTEN E/BluetoothEventLoop.cpp( 1018): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/1498/hci0/dev_00_06_66_03_0C_51 V/BluetoothEventRedirector( 1080): Received android.bleutooth.device.action.UUID The device I'm trying to connect to is the 00:06:66:03:0C:51 which I can scan for and apparently pair with just fine. The below is merged from a similar question which was successfully resolved by the selected answer here: How can one connect to an rfcomm device other than another phone in Android? The Android API provides examples of using listenUsingRfcommWithServiceRecord() to set up a socket and createRfcommSocketToServiceRecord() to connect to that socket. I'm trying to connect to an embedded device with a BlueSMiRF Gold chip. My working Python code (using the PyBluez library), which I'd like to port to Android, is as follows: sock = bluetooth.BluetoothSocket(proto=bluetooth.RFCOMM) sock.connect((device_addr, 1)) return sock.makefile() ...so the service to connect to is simply defined as channel 1, without any SDP lookup. As the only documented mechanism I see in the Android API does SDP lookup of a UUID, I'm slightly at a loss. Using "sdptool browse" from my Linux host comes up empty, so I surmise that the chip in question simply lacks SDP support.

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  • Application stopped unexpectedly at launch

    - by Chris Stryker
    I've run this on a device and on the emulator. The app stops unexpectedly on both. I have not a clue what is wrong currently. It uses Google API Maps I compiled with Google Api 7. I followed this tutorial http://developer.android.com/guide/tutorials/views/hello-mapview.html (made some alterations clearly) I did use the correct API Key That the final apk is signed with This is the source(If you compile it shouldn't work as it is unsigned) This is the compiled signed apk Log 03-21 00:30:38.912: INFO/ActivityManager(54): Starting activity: Intent { act=android.intent.action.MAIN flg=0x10000000 cmp=com.chris.stryker.worldly/.com.poppoob.WorldlyMap } 03-21 00:30:39.173: INFO/ActivityManager(54): Start proc com.chris.stryker.worldly for activity com.chris.stryker.worldly/.com.poppoob.WorldlyMap: pid=287 uid=10031 gids={3003, 1015} 03-21 00:30:39.532: DEBUG/ddm-heap(287): Got feature list request 03-21 00:30:40.185: WARN/dalvikvm(287): Unable to resolve superclass of Lcom/chris/stryker/worldly/com/poppoob/WorldlyMap; (17) 03-21 00:30:40.193: WARN/dalvikvm(287): Link of class 'Lcom/chris/stryker/worldly/com/poppoob/WorldlyMap;' failed 03-21 00:30:40.205: DEBUG/AndroidRuntime(287): Shutting down VM 03-21 00:30:40.223: WARN/dalvikvm(287): threadid=3: thread exiting with uncaught exception (group=0x4001b188) 03-21 00:30:40.223: ERROR/AndroidRuntime(287): Uncaught handler: thread main exiting due to uncaught exception 03-21 00:30:40.252: ERROR/AndroidRuntime(287): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.chris.stryker.worldly/com.chris.stryker.worldly.com.poppoob.WorldlyMap}: java.lang.ClassNotFoundException: com.chris.stryker.worldly.com.poppoob.WorldlyMap in loader dalvik.system.PathClassLoader@45a13938 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at android.app.ActivityThread.access$2200(ActivityThread.java:119) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at android.os.Handler.dispatchMessage(Handler.java:99) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at android.os.Looper.loop(Looper.java:123) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at android.app.ActivityThread.main(ActivityThread.java:4363) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at java.lang.reflect.Method.invokeNative(Native Method) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at java.lang.reflect.Method.invoke(Method.java:521) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at dalvik.system.NativeStart.main(Native Method) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): Caused by: java.lang.ClassNotFoundException: com.chris.stryker.worldly.com.poppoob.WorldlyMap in loader dalvik.system.PathClassLoader@45a13938 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:243) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at java.lang.ClassLoader.loadClass(ClassLoader.java:573) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at java.lang.ClassLoader.loadClass(ClassLoader.java:532) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2409) 03-21 00:30:40.252: ERROR/AndroidRuntime(287): ... 11 more 03-21 00:30:40.300: INFO/Process(54): Sending signal. PID: 287 SIG: 3 03-21 00:30:40.312: INFO/dalvikvm(287): threadid=7: reacting to signal 3 03-21 00:30:40.396: INFO/dalvikvm(287): Wrote stack trace to '/data/anr/traces.txt' 03-21 00:30:49.002: WARN/ActivityManager(54): Launch timeout has expired, giving up wake lock! 03-21 00:30:49.685: WARN/ActivityManager(54): Activity idle timeout for HistoryRecord{458ab6d0 com.chris.stryker.worldly/.com.poppoob.WorldlyMap}

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  • Qt 4.6 Adding objects and sub-objects to QWebView window object (C++ & Javascript)

    - by Cor
    I am working with Qt's QWebView, and have been finding lots of great uses for adding to the webkit window object. One thing I would like to do is nested objects... for instance: in Javascript I can... var api = new Object; api.os = new Object; api.os.foo = function(){} api.window = new Object(); api.window.bar = function(){} obviously in most cases this would be done through a more OO js-framework. This results in a tidy structure of: >>>api ------------------------------------------------------- - api Object {os=Object, more... } - os Object {} foo function() - win Object {} bar function() ------------------------------------------------------- Right now I'm able to extend the window object with all of the qtC++ methods and signals I need, but they all have 'seem' to have to be in a root child of "window". This is forcing me to write a js wrapper object to get the hierarchy that I want in the DOM. >>>api ------------------------------------------------------- - api Object {os=function, more... } - os_foo function() - win_bar function() ------------------------------------------------------- This is a pretty simplified example... I want objects for parameters, etc... Does anyone know of a way to pass an child object with the object that extends the WebFrame's window object? Here's some example code of how I'm adding the object: mainwindow.h #ifndef MAINWINDOW_H #define MAINWINDOW_H #include <QtGui/QMainWindow> #include <QWebFrame> #include "mainwindow.h" #include "happyapi.h" class QWebView; class QWebFrame; QT_BEGIN_NAMESPACE class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent = 0); private slots: void attachWindowObject(); void bluesBros(); private: QWebView *view; HappyApi *api; QWebFrame *frame; }; #endif // MAINWINDOW_H mainwindow.cpp #include <QDebug> #include <QtGui> #include <QWebView> #include <QWebPage> #include "mainwindow.h" #include "happyapi.h" MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { view = new QWebView(this); view->load(QUrl("file:///Q:/example.htm")); api = new HappyApi(this); QWebPage *page = view->page(); frame = page->mainFrame(); attachWindowObject(); connect(frame, SIGNAL(javaScriptWindowObjectCleared()), this, SLOT(attachWindowObject())); connect(api, SIGNAL(win_bar()), this, SLOT(bluesBros())); setCentralWidget(view); }; void MainWindow::attachWindowObject() { frame->addToJavaScriptWindowObject(QString("api"), api); }; void MainWindow::bluesBros() { qDebug() << "foo and bar are getting the band back together!"; }; happyapi.h #ifndef HAPPYAPI_H #define HAPPYAPI_H #include <QObject> class HappyApi : public QObject { Q_OBJECT public: HappyApi(QObject *parent); public slots: void os_foo(); signals: void win_bar(); }; #endif // HAPPYAPI_H happyapi.cpp #include <QDebug> #include "happyapi.h" HappyApi::HappyApi(QObject *parent) : QObject(parent) { }; void HappyApi::os_foo() { qDebug() << "foo called, it want's it's bar back"; }; I'm reasonably new to C++ programming (coming from a web and python background). Hopefully this example will serve to not only help other new users, but be something interesting for a more experienced c++ programmer to elaborate on. Thanks for any assistance that can be provided. :)

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  • Synchronizing issue: I want the main thread to be run before another thread but it sometimes doesn´t

    - by Rox
    I have done my own small concurrency framework (just for learning purposes) inspired by the java.util.concurrency package. This is about the Callable/Future mechanism. My code below is the whole one and is compilable and very easy to understand. My problem is that sometimes I run into a deadlock where the first thread (the main thread) awaits for a signal from the other thread. But then the other thread has already notified the main thread before the main thread went into waiting state, so the main thread cannot wake up. FutureTask.get() should always be run before FutureTask.run() but sometimes the run() method (which is called by new thread) runs before the get() method (which is called by main thread). I don´t know how I can prevent that. This is a pseudo code of how I want the two threads to be run. //From main thread: Executor.submit().get() (in get() the main thread waits for new thread to notify) ->submit() calls Executor.execute(FutureTask object) -> execute() starts new thread -> new thread shall notify `main thread` I cannot understand how the new thread can start up and run faster than the main thread that actually starts the new thread. Main.java: public class Main { public static void main(String[] args) { new ExecutorServiceExample(); } public Main() { ThreadExecutor executor = new ThreadExecutor(); Integer i = executor.submit(new Callable<Integer>() { @Override public Integer call() { return 10; } }).get(); System.err.println("Value: "+i); } } ThreadExecutor.java: public class ThreadExecutor { public ThreadExecutor() {} protected <V> RunnableFuture<V> newTaskFor(Callable c) { return new FutureTask<V>(c); } public <V> Future<V> submit(Callable<V> task) { if (task == null) throw new NullPointerException(); RunnableFuture<V> ftask = newTaskFor(task); execute(ftask); return ftask; } public void execute(Runnable r) { new Thread(r).start(); } } FutureTask.java: import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.ReentrantLock; import java.util.logging.Level; import java.util.logging.Logger; public class FutureTask<V> implements RunnableFuture<V> { private Callable<V> callable; private volatile V result; private ReentrantLock lock = new ReentrantLock(); private Condition condition = lock.newCondition(); public FutureTask(Callable callable) { if (callable == null) throw new NullPointerException(); this.callable = callable; } @Override public void run() { acquireLock(); System.err.println("RUN"+Thread.currentThread().getName()); V v = this.callable.call(); set(v); condition.signal(); releaseLock(); } @Override public V get() { acquireLock(); System.err.println("GET "+Thread.currentThread().getName()); try { condition.await(); } catch (InterruptedException ex) { Logger.getLogger(FutureTask.class.getName()).log(Level.SEVERE, null, ex); } releaseLock(); return this.result; } public void set(V v) { this.result = v; } private void acquireLock() { lock.lock(); } private void releaseLock() { lock.unlock(); } } And the interfaces: public interface RunnableFuture<V> extends Runnable, Future<V> { @Override void run(); } public interface Future<V> { V get(); } public interface Callable<V> { V call(); }

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  • image processing algorithm in MATLAB

    - by user261002
    I am trying to reconstruct an algorithm belong to this paper: Decomposition of biospeckle images in temporary spectral bands Here is an explanation of the algorithm: We recorded a sequence of N successive speckle images with a sampling frequency fs. In this way it was possible to observe how a pixel evolves through the N images. That evolution can be treated as a time series and can be processed in the following way: Each signal corresponding to the evolution of every pixel was used as input to a bank of filters. The intensity values were previously divided by their temporal mean value to minimize local differences in reflectivity or illumination of the object. The maximum frequency that can be adequately analyzed is determined by the sampling theorem and s half of sampling frequency fs. The latter is set by the CCD camera, the size of the image, and the frame grabber. The bank of filters is outlined in Fig. 1. In our case, ten 5° order Butterworth11 filters were used, but this number can be varied according to the required discrimination. The bank was implemented in a computer using MATLAB software. We chose the Butter-worth filter because, in addition to its simplicity, it is maximally flat. Other filters, an infinite impulse response, or a finite impulse response could be used. By means of this bank of filters, ten corresponding signals of each filter of each temporary pixel evolution were obtained as output. Average energy Eb in each signal was then calculated: where pb(n) is the intensity of the filtered pixel in the nth image for filter b divided by its mean value and N is the total number of images. In this way, en values of energy for each pixel were obtained, each of hem belonging to one of the frequency bands in Fig. 1. With these values it is possible to build ten images of the active object, each one of which shows how much energy of time-varying speckle there is in a certain frequency band. False color assignment to the gray levels in the results would help in discrimination. and here is my MATLAB code base on that : clear all for i=0:39 str = num2str(i); str1 = strcat(str,'.mat'); load(str1); D{i+1}=A; end new_max = max(max(A)); new_min = min(min(A)); for i=20:180 for j=20:140 ts = []; for k=1:40 ts = [ts D{k}(i,j)]; %%% kth image pixel i,j --- ts is time series end ts = double(ts); temp = mean(ts); ts = ts-temp; ts = ts/temp; N = 5; % filter order W = [0.00001 0.05;0.05 0.1;0.1 0.15;0.15 0.20;0.20 0.25;0.25 0.30;0.30 0.35;0.35 0.40;0.40 0.45;0.45 0.50]; N1 = 5; for ind = 1:10 Wn = W(ind,:); [B,A] = butter(N1,Wn); ts_f(ind,:) = filter(B,A,ts); end for ind=1:10 imag_test1{ind}(i,j) =sum((ts_f(ind,:)./mean(ts_f(ind,:))).^2); end end end for i=1:10 temp_imag = imag_test1{i}(:,:); x=isnan(temp_imag); temp_imag(x)=0; temp_imag=medfilt2(temp_imag); t_max = max(max(temp_imag)); t_min = min(min(temp_imag)); temp_imag = (temp_imag-t_min).*(double(new_max-new_min)/double(t_max-t_min))+double(new_min); imag_test2{i}(:,:) = temp_imag; end for i=1:10 A=imag_test2{i}(:,:); B=A/max(max(A)); B=histeq(B); figure,imshow(B) colorbar end but I am not getting the same result as paper. has anybody has aby idea why? or where I have gone wrong? Refrence Link to the paper

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  • How do I handle calls to AudioTrack from jni without crashing?

    - by icecream
    I was trying to write to an AudioTrack from a jni callback, and I get a signal 7 (SIGBUS), fault addr 00000000. I have looked at the Wolf3D example for odroid and they seem to use a android.os.Handler to post a Runnable that will do an update in the correct thread context. I have also tried AttachCurrentThread, but I fail in this case also. It works to play the sound when running from the constructor even if I wrap it in a thread and then post it to the handler. When I do the "same" via a callback from jni it fails. I assume I am braeaking some rules, but I haven't been able to figure out what they are. So far, I haven't found the answer here on SO. So I wonder if anyone knows how this should be done. EDIT: Answered below. The following code is to illustrate the problem. Java: package com.example.jniaudiotrack; import android.app.Activity; import android.media.AudioFormat; import android.media.AudioManager; import android.media.AudioTrack; import android.os.Bundle; import android.os.Handler; import android.util.Log; public class JniAudioTrackActivity extends Activity { AudioTrack mAudioTrack; byte[] mArr; public static final Handler mHandler = new Handler(); /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mArr = new byte[2048]; for (int i = 0; i < 2048; i++) { mArr[i] = (byte) (Math.sin(i) * 128); } mAudioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, 11025, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_8BIT, 2048, AudioTrack.MODE_STREAM); mAudioTrack.play(); new Thread(new Runnable() { public void run() { mHandler.post(new Runnable() { public void run() { mAudioTrack.write(mArr, 0, 2048); Log.i(TAG, "*** Handler from constructor ***"); } }); } }).start(); new Thread(new Runnable() { public void run() { audioFunc(); } }).start(); } public native void audioFunc(); @SuppressWarnings("unused") private void audioCB() { mHandler.post(new Runnable() { public void run() { mAudioTrack.write(mArr, 0, 2048); Log.i(TAG, "*** audioCB called ***"); } }); } private static final String TAG = "JniAudioTrackActivity"; static { System.loadLibrary("jni_audiotrack"); } } cpp: #include <jni.h> extern "C" { JNIEXPORT void Java_com_example_jniaudiotrack_JniAudioTrackActivity_audioFunc(JNIEnv* env, jobject obj); } JNIEXPORT void Java_com_example_jniaudiotrack_JniAudioTrackActivity_audioFunc(JNIEnv* env, jobject obj) { JNIEnv* jniEnv; JavaVM* vm; env->GetJavaVM(&vm); vm->AttachCurrentThread(&jniEnv, 0); jclass cls = env->GetObjectClass(obj); jmethodID audioCBID = env->GetMethodID(cls, "audioCB", "()V"); if (!audioCBID) { return; } env->CallVoidMethod(cls, audioCBID); } Trace snippet: I/DEBUG ( 1653): pid: 9811, tid: 9811 >>> com.example.jniaudiotrack <<< I/DEBUG ( 1653): signal 7 (SIGBUS), fault addr 00000000 I/DEBUG ( 1653): r0 00000800 r1 00000026 r2 00000001 r3 00000000 I/DEBUG ( 1653): r4 42385726 r5 41049e54 r6 bee25570 r7 ad00e540 I/DEBUG ( 1653): r8 000040f8 r9 41048200 10 41049e44 fp 00000000 I/DEBUG ( 1653): ip 000000f8 sp bee25530 lr ad02dbb5 pc ad012358 cpsr 20000010 I/DEBUG ( 1653): #00 pc 00012358 /system/lib/libdvm.so

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  • DSP - Problems using the inverse Fast Fourier Transform

    - by Trap
    I've been playing around a little with the Exocortex implementation of the FFT, but I'm having some problems. First, after calculating the inverse FFT of an unchanged frequency spectrum obtained by a previous forward FFT, one would expect to get the original signal back, but this is not the case. I had to figure out that I needed to scale the FFT output to about 1 / fftLength to get the amplitudes ok. Why is this? Second, whenever I modify the amplitudes of the frequency bins before calling the iFFT the signal gets distorted at low frequencies. However, this does not happen if I attenuate all the bins by the same factor. Let me put a very simplified example of the output buffer of a 4-sample FFT: // Bin 0 (DC) FFTOut[0] = 0.0000610351563 FFTOut[1] = 0.0 // Bin 1 FFTOut[2] = 0.000331878662 FFTOut[3] = 0.000629425049 // Central bin FFTOut[4] = -0.0000381469727 FFTOut[5] = 0.0 // Bin 3, this is a negative frequency bin. FFTOut[6] = 0.000331878662 FFTOut[7] = -0.000629425049 The output is composed of pairs of floats, each representing the real and imaginay parts of a single bin. So, bin 0 (array indexes 0, 1) would represent the real and imaginary parts of the DC frequency. As you can see, bins 1 and 3 both have the same values, (except for the sign of the Im part), so I guess these are the negative frequency values, and finally indexes (4, 5) would be the central frequency bin. To attenuate the frequency bin 1 this is what I do: // Attenuate the 'positive' bin FFTOut[2] *= 0.5; FFTOut[3] *= 0.5; // Attenuate its corresponding negative bin. FFTOut[6] *= 0.5; FFTOut[7] *= 0.5; For the actual tests I'm using a 1024-length FFT and I always provide all the samples so no 0-padding is needed. // Attenuate var halfSize = fftWindowLength / 2; float leftFreq = 0f; float rightFreq = 22050f; for( var c = 1; c < halfSize; c++ ) { var freq = c * (44100d / halfSize); // Calc. positive and negative frequency locations. var k = c * 2; var nk = (fftWindowLength - c) * 2; // This kind of attenuation corresponds to a high-pass filter. // The attenuation at the transition band is linearly applied, could // this be the cause of the distortion of low frequencies? var attn = (freq < leftFreq) ? 0 : (freq < rightFreq) ? ((freq - leftFreq) / (rightFreq - leftFreq)) : 1; mFFTOut[ k ] *= (float)attn; mFFTOut[ k + 1 ] *= (float)attn; mFFTOut[ nk ] *= (float)attn; mFFTOut[ nk + 1 ] *= (float)attn; } Obviously I'm doing something wrong but can't figure out what or where.

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