How to set exposure for Still Image capture when using DirectShow API on Windows?

Question

How to set exposure for Still Image capture when using DirectShow API on Windows?

Alok Chander 30

I am trying to use the Windows Directshow API to capture still images using a UVC camera. I am using this article from Microsof(https://learn.microsoft.com/en-us/windows/win32/directshow/capturing-an-image-from-a-still-image-pin) to implement this. I want to be able to capture still images at different exposures so I can later use OpenCV to create an HDR image with them. I am aware that Directshow is a legacy feature. I ended up using it as it was the only API that had an example of how to implement still image capture for uvc cameras.

I tried setting the camera exposure before the still image trigger(pAMVidControl->SetMode(pPin, VideoControlFlag_Trigger) using the IAMCameraControl interface(https://learn.microsoft.com/en-us/windows/win32/api/strmif/nn-strmif-iamcameracontrol). I can see the exposure change in the preview feed but the still image captured has a different exposure to what I set it to. Is there a different interface for setting the camera exposure for still image capture?

Xiaopo Yang - MSFT 12,736 Reputation points Microsoft External Staff

2023-12-07T03:12:59.35+00:00

Where is your IAMCameraControl instance queried from? Did you try to query it from the camera device (IMFMediaSource)? Could you please provide a minimal sample?
Alok Chander 30 Reputation points

2023-12-10T22:29:15.0266667+00:00

I am quite new to this stuff so I may get a few thing wrong.
I query the IBaseFilter *pCap for the IAMCameraControl interface.

I then set the exposure as shown below:

I haven't tried query it from IMFMediaSource as I am using the Directshow API. Should I try to use this?

I will try creating a minimal sample and share it with you. Something else I would like to clarify is that changing the exposure does change it and I can see that in the video feed. However once it hits the SetMode still image trigger command the exposure gets reset to some value. Do you know if this is the expected behaviour for still image capture? Unfortunately I could not find much info on this on the internet and the UVC spec also doesn't mention what happens to the camera exposure while using still image capture.
Xiaopo Yang - MSFT 12,736 Reputation points Microsoft External Staff

2023-12-11T06:56:50.73+00:00

A still image pin has a separate Pin category, PIN_CATEGORY_STILL. I doubt if the still category pin supports the output image reacting to such controls. Anyway, a minimal sample is helpful.
Alok Chander 30 Reputation points

2023-12-13T23:42:50.74+00:00

Here is an sample. Its not very minimal though there is a lot of additional stuff I had to add on to get this to work. still.txt
Xiaopo Yang - MSFT 12,736 Reputation points Microsoft External Staff

2023-12-14T03:15:20.1433333+00:00

I'm sorry that I haven't found a usable device.

As this issue is complex, please open an incident at https://developer.microsoft.com/en-us/windows/support/ so that our engineer can work with you closely and please choose the Graphics and Multimedia development - DirectShow API for Windows SDK for this issue. In-addition, if the support engineer determines that the issue is the result of a bug the service request will be a no-charge case and you won't be charged.

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Xiaopo Yang - MSFT 12,736 Reputation points Microsoft External Staff

2023-12-07T03:12:59.35+00:00

Where is your IAMCameraControl instance queried from? Did you try to query it from the camera device (IMFMediaSource)? Could you please provide a minimal sample?
Alok Chander 30 Reputation points

2023-12-10T22:29:15.0266667+00:00

I am quite new to this stuff so I may get a few thing wrong.
I query the IBaseFilter *pCap for the IAMCameraControl interface.

I then set the exposure as shown below:

I haven't tried query it from IMFMediaSource as I am using the Directshow API. Should I try to use this?

I will try creating a minimal sample and share it with you. Something else I would like to clarify is that changing the exposure does change it and I can see that in the video feed. However once it hits the SetMode still image trigger command the exposure gets reset to some value. Do you know if this is the expected behaviour for still image capture? Unfortunately I could not find much info on this on the internet and the UVC spec also doesn't mention what happens to the camera exposure while using still image capture.
Xiaopo Yang - MSFT 12,736 Reputation points Microsoft External Staff

2023-12-11T06:56:50.73+00:00

A still image pin has a separate Pin category, PIN_CATEGORY_STILL. I doubt if the still category pin supports the output image reacting to such controls. Anyway, a minimal sample is helpful.
Alok Chander 30 Reputation points

2023-12-13T23:42:50.74+00:00

Here is an sample. Its not very minimal though there is a lot of additional stuff I had to add on to get this to work. still.txt
Xiaopo Yang - MSFT 12,736 Reputation points Microsoft External Staff

2023-12-14T03:15:20.1433333+00:00

I'm sorry that I haven't found a usable device.

As this issue is complex, please open an incident at https://developer.microsoft.com/en-us/windows/support/ so that our engineer can work with you closely and please choose the Graphics and Multimedia development - DirectShow API for Windows SDK for this issue. In-addition, if the support engineer determines that the issue is the result of a bug the service request will be a no-charge case and you won't be charged.

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How to set exposure for Still Image capture when using DirectShow API on Windows?

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