Is there a way for my Windows program to get notifications when a video device is in use. I know how to enumerate the devices using http://msdn.microsoft.com/en-us/library/dd377566(v=vs.85).aspx
I can also use ffmpeg to open the video device to check if it is available but it opens up the camera for that fraction of a time which I don't want.
Any help will be appreciated. Thanks.
you can use physical device object name of camera and use sysinternals handle utility to search for handle usage of camera
http://technet.microsoft.com/en-in/sysinternals/
to downlaod handle utility
Related
The task:
OS: Mac OS X 10.9 +
Description:
There is web-camera connected to a Mac via USB. I need to discover a way of getting access to its' brightness, pan, color temperature, focus, etc.
I also need a way to apply image filters against camera's video stream.
I need to be able to control the camera while it is being used by other programs like Skype, so I can transmit for example video stream with increased contrast at Skype video call.
Reference app: https://itunes.apple.com/app/webcam-settings/id533696630?mt=12
Solution:
This is the question.
As far as I understood I must to find custom kext (driver) in order to perform all this magic.
Could you please show me right direction, libraries, drivers, etc.
You can use opencv library to capture camera frames, apply filters, etc.
http://docs.opencv.org/2.4/doc/tutorials/introduction/display_image/display_image.html
Then you can feed a virtual cam that can feed into Skype, etc.
http://download.cnet.com/Virtual-Webcam/3000-2348_4-75754338.html
There also many open source virtual webcam available.
I hope this helps.
Is there way in Windows API to be notified when audio device gets enabled or disabled?
I have source code with RegisterDeviceNotification() and WM_DEVICECHANGE; it tracks USB device insertion/removing good. But it does not track laptop's internal audio device enabling or disabling.
Of course I can make timer and use waveInGetNumDevs/waveOutGetNumDevs.
But it is more interest to find way to force OS to send notifications :)
Thank you :)
waveIn/waveOut is legacy API you don't have notifications with. Yes you can poll with timer, of course, as you mentioned. In Vista+ the newer API does have notifications via IMMNotificationClient interface, see also this related answer: Get automatically notified on audio device connection/disconnection?
As my company has a special need of installing a third camera on a Windows Phone Mango, do you think this is possible to access to the camera using Mango's Camera API?
As far as I can see the PhotoCamera only has two constructures: PhotoCamera() and PhotoCamera(CameraType type). The "type" here can only Primary or FrontFacing so I guess we cannot do anything else here.
We don't get this issue on Android, as they have the interface of Camera.open(int cameraId), and the cameraId can be any id between 0 and Camera.getNumberOfCameras() - 1.
I'm a bit confused, as there's no way to "install" another camera. There is no USB host port on the device, nor is there any other harcware interface, so how would you connect the camera physically?
Even if you could connect physically, there's no way for anyone other than a phone OEM to create and install the drivers for said camera, so how would the OS enumerate it to the platform?
If you're an OEM, you've undoubtedly got a support channel directly with Microsoft where you could ask this, as no one outside that channel is going to have any idea. If you're not an OEM, there's simply no way to add a camera or any other (non-bluetooth) peripheral to the phone.
i am looking for differnt solutions to capture video stream from monitor screen and send it to vidoestreaming server to broadcast in web. it must occuring in "live".
i'd not like to use external services like "procaster" for broad.
OS: Windows.
it will be great to know the ideas and expirience people have to accomplish that.
Thanks all.
Recently, I build a GoLang project called ScreenStreamer, is a tool to stream current active window or full screen (Linux's or Windows's) to other device, like phone or another PC, as MJPEG over http or FLV over rtmp, it's very realtime (delay < 100ms). It works on Windows and Linux.
After building it, you can run it as:
# enter the project root directory
cd ./src/ScreenStreamer
# run it
./mjpeg or .\mjpeg.exe
# use a web browser or other video player, open http://host:port/mjpeg
./rtmp or .\rtmp.exe
# use a video player, open rtmp://host:port/live/screen
Screenshot:
Windows SDK includes Push Source Filters Sample, which in turn contains CPushSourceDesktop filter/class.
CPushSourceDesktop: Copy of current desktop image (GDI only)
It captures desktop image and pushes it into DirectShow pipeline. From there on you can process it using video compression codec and stream it to remote location. A decent screen image compression codec is included with Windows Media subsystem, network streaming will have to be a custom or third party component. Alternatively, it is possible to make the capture class a virtual camera and have Windows Media Encoder broadcast it (or, it already has a simila feature built in).
Alternatively, you can check VNC (or one of the clones) source code and see how it hooks windows and captures image updates, then compresses them and makes it available for remote applications.
Note that you will have to specifically capture non-GDI images (such as coming from video/gaming applications, which use hardware acceleration and non-RGB surffaces).
I'm looking for writing virtual camera drivers. Does anybody has idea?
Any book that would be helpful or any link.
Adding more details:
I have developed a device driver which saves the image to disk and the display uses the device driver to display the image. The performance does not seem good.
The fns. that I have used are:
//to capture
GetDesktopWindow()
CreateCompatibleBitmap()
Save()
//to display
WM_MOUSEMOVE
giving a call to capture and display every time
but the display is not continuous and appears only after window goes out of focus and comes in focus again
Should I use some other technique to record or display images, what will give fruitful results, please help.
Thanks,
-mitesh
What do you mean by virtual camera driver?
It is possible to write a virtual capture device using DirectShow. Such a virtual capture device can then be used by applications such as skype, etc. If that suffices for your needs, you can download vcam from http://tmhare.mvps.org/downloads.htm under the "Capture Source Filter" link.
Edit:
In order to use that capture device in the link I posted you need to download the Windows SDK. The Windows SDK has a tool called "GraphEdit" If you search online, I'm sure you can find a quick GraphEdit tutorial. Basically GraphEdit allows you to construct a multimedia pipeline by connecting a bunch of filters. (This is what happens in the background for instance when you play a movie on your computer. ) This could be something like
web cam -> renderer
or
file source -> some decoder -> renderer
and would result in you seeing the video captured by the web cam or the content of the file. The example download shows how you can construct a virtual capture device i.e. it looks like media is coming from a 'real' capture device, but actually you can generate any video you want if you adapt the code to your specific means i.e. take a screengrab and output that. Applications like skype can pick up you virtual capture device if it is registered correctly.
The easiest way to find out if this is sufficient for your needs is to download the capture source filter, register it with the regsvr32 command, and then to use GraphEdit to insert the capture source into a graph, connect the source to a video renderer and hit the play button. A lot of the above mentioned concepts/keywords might seem new to you, but you can do some reading on each topic, and perhaps this will give you a point to get started.
Edit 2:
Is the capture source filter approach not sufficient for your requirements?
1) AFAIR you stated in your (now deleted) answer that you would like to take a screen grab, and use that as a virtual camera device for use in applications such as skype.
If that is all you require, you do NOT have to write a device driver. DirectShow can do that perfectly well by means of the capture source filter. You would then need to
learn some basic DirectShow
modify the source code of the capture filter to take screen grabs etc.
As far as books are concerned to write device driver to accomplish the same, I have no idea. The point I'm trying to make, is that you need to determine whether you actually need to write a device driver or whether simply modifying the open source capture filter is sufficient.