Video Capture on recent Windows 8.1 Tablets shows very dark video

Question

Hello,
I switched from direct show to media foundation to capture video from webcams. It is a desktop application and works well with both direct show and media foundation on Windows 7 and Windows 8.1 desktop computers for a lot of different webcams.
Trying the same application on a Windows 8.1 Atom based tablet, the video is very dark and green.
I tried it on the following tablets (all of them show the above described behavior):
-Acer T100A (camera sensor MT9M114, Atom 3740)
-Dell Venue Pro 11 (camera sensor OV2722 front, IMX175 back - Atom 3770)
-HP Omni 10 5600 (camera sensor OV2722, IMX175 - Atom 3770)
I capture using IMFMediaSession, building a simple topology with a media source and the EVR.
TopoEdit shows the same strange behavior
MFTrace does not show any errors (at least I do not see any errors)
In case an external usb camera is used on all these tablets, the video is fine.
The SDK Sample MFCapture3d3 works fine, it uses the source reader for capturing - I verified the media type of the source used there, it is the same I use in my application (same
stream descriptor, same media type, verified with mftrace)
The "CaptureEngine" video capture sample from the SDK also works as expected, however, I need Windows 7 compatibility and would like to use the same source on both platforms
When using direct show, all the above mentioned tablets show only a fraction of the sensor image when capturing with lower resolutions (e.g. 640x360), the colors of the video are
fine. I tried it with the desktop app of Skype and GraphEdit, same behavior (only a fraction of the video is shown, colors are fine) - Skype for destkop apparently uses a DirectShow source filter.
Has anyone tried capturing the camera of an Atom z3700 series tablet with media foundation using the media session? If so, is special handling of the media source required on these tablets?
If required, I will post some code or mftrace logs.
Thanks a lot,
Karl
Bluemlinger

Answer 1

On the contrary of my previous post, the MFTrace file shows an error:
"COle32ExportDetours::CoCreateInstance @ Failed to create {FEB9695C-C7DF-4D40-8019-00FA047288FF} KSPlugin Class (C:\Windows\system32\IntelCameraPlugin.dll) hr=0x80004005 E_FAIL"
This dll contains the Intel Camera MFT. While it is on the specified location, it cannot be loaded. According to the Windows Driver Kit documentation, a camera MFT is used in windows store device app.
My assumption is that this MFT is responsible for doing post processing of the video stream from the camera. Since it cannot be loaded, the video stream is dark with a green color fault.
By the way, setting brightness or exposure via IAMVideoProcAmp and IAMCameraControl has no effect, Setting/reading these properties returns S_OK, the properties are stored correctly but obviously ignored.
Bluemlinger