Media Foundation屏幕截图钩

Question

It is required to take at the right time a screenshot from the application (it can be blocked, collapsed or even in a different session). The application plays a video stream through the Media Foundation:

As I understand it is necessary to intercept MFCreateMediaSession , what to receive IMFMediaSession , only here what further with this object to do? And can it be accessed from another thread?

Answer 1

I see that you wrote application on base of Media Foundation for playing of video -and you need take video images as a separated decoded frames. So, you have two opportunities:

1. take video frames from renderer: the regular Media Foundation renderer has IMFVideoDisplayControl interface - on MSDN IMFVideoDisplayControl - it has command GetCurrentImage - retrieves a copy of the current image being displayed by the video renderer - on MSDN GetCurrentImage .
2. The second way - attach sample grabber sink to the video pipeline - Media Foundation function MFCreateSampleGrabberSinkActivate allows create sink from sample grabber object with IMFSampleGrabberSinkCallback interface - it allows get decoded video images in format of Bitmap images in System Memory. Using of sample grabber is more difficult, and I can recommend my project Capturing Video from Web-camera on Windows 7 and 8 by using Media Foundation for researching of the such way.

Regards.