I'm writing a small audio recorder component in Silverlight 4. It works fine, but I've noticed that when I'm recording audio, the light on my webcam turns on indicating that the camera is active.
While I know that I'm not doing anything insidious with the webcam, my users would have every right to be suspicious. Is it possible to tell Silverlight that I'm only interested in microphone access and not activate the webcam?
FWIW here's how I'm accessing the mic:
private CaptureSource _source = new CaptureSource();
private MemoryAudioSink _sink; // Inherits from AudioSink. Doesn't do much more
// than store PCM audio stream in memory
private void Record_Click(object sender, RoutedEventArgs e)
{
if (( CaptureDeviceConfiguration.AllowedDeviceAccess ||
CaptureDeviceConfiguration.RequestDeviceAccess() ) &&
_source.State == CaptureState.Stopped)
{
_sink = new MemoryAudioSink();
_sink.CaptureSource = _source;
_source.Start();
}
}
CaptureSource will frequently grab the default video input device, even if you don't tell it to. Though you aren't using the camera, Silverlight is indeed accessing it. Hopefully, MS will fix this odd behavior in a later version of Silverlight.
In the meantime, just explicitly set VideoCaptureDevice to null:
var _audioCaptureSource = new CaptureSource {VideoCaptureDevice = null};
This would depend on the webcam driver - Silverlight would have no control over this.
I'm guessing its related to your use of CaptureSource. Microsoft's web site claims that:
Silverlight 4 APIs only use
CaptureSource in a video scenario
where audio may not be relevant.
Is there a way to get audio without creating your own CaptureSource?
Related
On the new iOS 11 Safari and MacOS High Sierra Safari, that trick of seeing if window.localStorage.setItem('test', 1); (see https://stackoverflow.com/a/17741714/1330341) throws an error no longer works, because it no longer throws an error, and it also properly sets the localStorage item. Has anyone figured out any other way to check for private browsing mode in the new versions of Safari?
Haven't actually tried it, but from reading Apple's document:
https://support.apple.com/kb/ph21413?locale=en_US
It lists various characteristics of private mode browsing (~snip):
When you use a Private Browsing window:
Each tab in the window is isolated from the others, so websites you
view in one tab can’t track your browsing in other tabs.
Safari doesn’t remember the webpages you visit or your AutoFill
information.
Safari doesn’t store your open webpages in iCloud, so they aren’t
shown when you view all your open tabs from other devices.
Your recent searches aren’t included in the results list when you use
the Smart Search field.
Items you download aren’t included in the downloads list. (The items
do remain on your computer.)
If you use Handoff, Private Browsing windows are not passed to your
iOS devices or other Mac computers.
Safari doesn’t remember changes to your cookies or other website
data. Safari also asks websites and others who provide those sites
with content (including advertisers) not to keep track of your
browsing, although it is up to the websites to honor this request.
Plug-ins that support Private Browsing stop storing cookies and other
tracking information.
From the above, in particular I found interesting that Safari specifically asks websites to "not track" the browsing. This could potentially be a mechanism to look for, to determine if using private browsing.
See this answer for an example:
Implementing Do not track in asp.net mvc
Again, haven't tested and unsure if it will work, but if not the list provides other potential options. HTH.
I find a solution here:
https://gist.github.com/cou929/7973956#gistcomment-2272103
var isPrivate = false;
try {
window.openDatabase(null, null, null, null);
} catch (_) {
isPrivate = true;
}
alert((isPrivate ? 'You\'re' : 'You aren\'t') + ' in private browsing mode');
Hope it helps :)
Quote from apple's website. https://support.apple.com/kb/ph21413?locale=en_US
Websites can’t modify information stored on your device, so services
normally available at such sites may work differently until you turn
off Private Browsing
So, store a test variable, change its value, then read the test variable.
If you get an exception, are unable to find the variable, the value didn't change or you get a null/undefined value back, they are most likely in private mode.
Alternatively, in private browsing, you have no stored search history accessible. So, redirect to a new page in your site on startup and then test if you have any previous history. If not and the fact that you are getting a Do Not Track most likely means your in private mode on safari.
Please note that I have not tested this. This is based off the information provided by Apple in the above link.
Thing that I realized is Safari throws a "Quota Exceeded" error in the Private mode. So here is what I did!
isPrivateMode: function () {
if (localStorage.length === 0) {
try {
localStorage.setItem('isLocalStorageAvaialble', 'That is being tested!');
localStorage.removeItem('isLocalStorageAvaialble');
return false;
} catch (e) {
return true;
}
}
}
Checking the length of localStorage is important for the fact that, if you are trying this method on a browser that supports localStorage, but is full, you still will get the "Quota Exceeded" error.
In private mode, the length of localStorage is always 0.
Hope this helps!
I'm currently developing an application on 10.6.7 which should receive notifications when a new usb device is plugged in. I found out that there is a IOKit function which handles such stuff 'IOServiceAddMatchingNotification'. Because the return value from this specific function is 0, I think that the problem perhaps is in my matching Dictionary, which is given into this function. I declare the Dictionary that way:
CFMutableDictionaryRef matchingDict = IOServiceMatching(kIOUSBDeviceClassName);
Because I wan't to receive a notification for each device, I don't know if this is the right way to create this particular dictionary.
My complete code look like this:
ioKitNotificationPort = IONotificationPortCreate(kIOMasterPortDefault);
notificationRunLoopSource = IONotificationPortGetRunLoopSource(ioKitNotificationPort);
CFRunLoopAddSource(CFRunLoopGetCurrent(), notificationRunLoopSource, kCFRunLoopDefaultMode);
CFMutableDictionaryRef matchingDict = IOServiceMatching(kIOUSBDeviceClassName);
addMatchingNotificationResult = IOServiceAddMatchingNotification(ioKitNotificationPort,
kIOPublishNotification,
matchingDict,
deviceAdded,
NULL,
Does anyone has a idea why this won't work?
(Note: The Callback function is a static void c function and the rest is wrapped ins
ide a Obj-C class).
Thanks
Xcode 4, 10.6.7
Weirdly, you must empty the iterator returned by IOServiceAddMatchingNotification before the notification will be armed. I don't see that in the code provided, so that could be in the issue. That iterator is actually what you need to keep around to keep the notification running.
io_iterator_t ioNotification;
addMatchingNotificationResult = IOServiceAddMatchingNotification(ioKitNotificationPort,
kIOPublishNotification,
matchingDict,
deviceAdded,
NULL,
&ioNotification);
while ((service = IOIteratorNext(ioNotification)))
{
NSLog(#"Hey, I found a service!");
IOObjectRelease(service); // yes, you have to release this
}
In my opinion, u should download the source code form IOUSBFamily on opensource.apple.com, and then find the code for USB Prober, this application does exactly the same thing as u described, listening the USB Device attachment.(Further, USB Prober also get the general device and configuration descriptor, maybe it is also the things u need.)
Did you add the VID and PID of the device you wish to look for to your matching dictionary? For the dictionary you have, and VID= yourVid, PID= yourPid, it would be:
CFDictionaryAddValue(matchingDict, usbVendorId, yourVid);
CFDictionaryAddValue(matchingDict, usbProductId, yourPid);
Another thing - after the call to IOServiceAddMatchingNotification succeeds, you need to call your device-added handler with the iterator that was set in the call. That will arm the notification and check for existing devices.
the easiest way to do what i think you are describing is to hook into the DiskArbitration Framework. DA is relatively new to OSX and allows userland applications to examine devices as they get attached. it is what is used to open iTunes when an iPod is attached, launch iPhoto when a camera is attached, etc... if the USB device you are looking for is a storage device then this will work for you. otherwise you will need to go the matching dictionary route...
I'm porting an archaic C++/Carbon program to Obj-C and Cocoa. The current version uses asynchronous usb reads and GetNextEvent to read the data.
When I try to compile this in Objective C, GetNextEvent isn't found because it's in the Carbon framework.
Searching Apple support yields nothing of use.
EDIT TO ADD:
Ok, so what I'm trying to do is run a document scanner through USB. I have set up the USBDeviceInterface and the USBInterfaceInterface (who came up with THAT name???) and I call (*usbInterfaceInterface)->WritePipeTO() to ask the scanner to scan. I believe this works. AT least the flatbed light moves across the page...
Then I try to use *(usbInterfaceInterface))->ReadPipeAsyncTO() to read data. I give this function a callback function, USBDoneProc().
The general structure is:
StartScan()
WaitForScan()
StartScan() calls the WritePipeTO and the ReadPipeAsyncTO
WaitForScan() has this:
while (deviceActive) {
EventRecord event;
GetNextEvent(0,&event);
if (gDataPtr != saveDataPtr) { // more data up the timeout
timeoutTicks = TickCount() + 60 * 60;
saveDataPtr = gDataPtr;
}
if (TickCount() > timeoutTicks) {
deviceActive = false;
}
}
Meanwhile, USBDoneProc incrementing gDataPtr to be the end of the data that we've read so far. It gets called several times during the asynchronous read, called automatically by the callback, as far as I can tell.
If I cake out the GetNextEvent() call in the WORKING code the USBDoneProc doesn't get called until the asynchronous readpipe timesout.
So it looks to me that I need something to give control back to the event handler so that the USBRead interrupts can actually interrupt and make the USBDoneProcget called...
Does that make any sense?
thanks.
I suppose the nearest thing to a Cocoa equivalent would be -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:]. But bear in mind that GetNextEvent is archaic even for Carbon. The preferred way of handing events is the "don't call us, we'll call you" scheme, where the app calls NSApplicationMain or RunApplicationEventLoop and events are dispatched to you.
EDIT to add: Does you app have a normal event loop? If so, maybe WaitForScan could start a Carbon timer and return to the event loop. Each time the timer fires, do what you did in the WaitForScan loop.
there is a USB hidapi that works for mac on windows.
http://www.signal11.us/oss/hidapi/
may this could be of help to you?
It works fine (I can list the connected USB devices and connect/write/read to a device);
however, if i USB device is connected/disconnected during the runtime of the application, I don't see the new connected/disconnected devices.
See: https://github.com/signal11/hidapi/issues/14
If I add the following code to hidapi, then hidapi detects the new USB devices.
#include <Carbon/Carbon.h>
void check_apple_events() {
printf("check_apple_events\n");
RgnHandle cursorRgn = NULL;
Boolean gotEvent=TRUE;
EventRecord event;
while (gotEvent) {
gotEvent = WaitNextEvent(everyEvent, &event, 0L, cursorRgn);
}
}
I need to compile this on OSX10.5 because it uses Carbon instead of Cocoa.
I am currently looking how to transform this to Cocoa.
you are also trying to move your code to cocoa, right?
let me know if you find out; I'll post it here if I get it.
regards,
David
Have you considered throwing the whole thing out and using Image Kit's new-in-10.6 scanner support instead? Even if it's custom, writing a TWAIN driver for it might be easier (and is certainly better) than trying to twist Cocoa into a GetNextEvent shape.
I would like to be able to gather info like how often certain windows are opened, what types of user data are accessed, how often menu items are clicked, etc. Does anyone know of a 3rd party (open source or commercial) Cocoa/Obj-C library or plugin that would allow me to gather this info?
I have used pinch media in the past, and they merged with Flurry. Library was simple to use and was setup in around 40 minutes.
I don't know any library for that but at least to get informed about when the user switches the front application you can install an event handler like this:
EventTypeSpec eventType;
eventType.eventClass = kEventClassApplication;
eventType.eventKind = kEventAppFrontSwitched;
EventHandlerUPP handlerUPP = NewEventHandlerUPP(FrontAppSwitchedDetector_callback);
OSStatus status=InstallApplicationEventHandler(handlerUPP,1,&eventType,self,&_eventHandlerRef);
... and when receiving an callback you may get the current front application process:
pascal OSStatus FrontAppSwitchedDetector_callback(EventHandlerCallRef nextHandler,EventRef theEvent,void* userData)
{
ProcessSerialNumber newSerial;
GetFrontProcess(&newSerial);
//to something with that ....
return (CallNextEventHandler(nextHandler, theEvent));
}
In a .NET Compact Framework application we are using ocx media player component written by coppercoins.
The media player launches on a new screen when ever user clicks a button. The media player works well on the first time. When we close the media player form and launch it once again on click of the button, it breaks with the following exception
ExceptionCode: 0xc0000005
ExceptionAddress: <address location>
Can someone tell me how to resolve this issue?
Note: we are disposing the media player form as well as the media player activeX wrapper control when the form is closed. The media player is disposed inside the designer code( using as shown below
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
if (disposing)
{
_axPlayer.Dispose();
_axPlayer = null;
}
base.Dispose(disposing);
}
That probably isn't going to be something you'll be able to fix your side and is an issue for forward to the component designer.
As a work around I would suggest retaining the object reference for the duration of the application and not disposing it. Obviously this blows if it occupies a lot of memory.
this solution helped me to fix the issue Media Player Control for .NET Compact Framework