- 1 year ago
How to get the default, max, min value of Video Proc Amp/Camera Control parameters from UVC camera?
To retrieve the default, maximum, and minimum values of Video Proc Amp and Camera Control parameters from a UVC camera, you can use the Windows API functions and structures related to DirectShow and video capture. Here's an example of how you can achieve this in C++:
Include the necessary headers:
cpp#include <dshow.h>
Initialize COM:
cppCoInitialize(NULL);
Create an instance of the Filter Graph Manager:
cppIGraphBuilder* pGraph = NULL;
CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&pGraph);
Create the camera capture filter:
cppICaptureGraphBuilder2* pCaptureGraphBuilder = NULL;
CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&pCaptureGraphBuilder);
IBaseFilter* pCameraFilter = NULL;
pCaptureGraphBuilder->SetFiltergraph(pGraph);
pCaptureGraphBuilder->FindInterface(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video, pCameraFilter, IID_IBaseFilter, (void**)&pCameraFilter);
Get the IAMVideoProcAmp and IAMCameraControl interfaces:
cppIAMVideoProcAmp* pVideoProcAmp = NULL;
pCameraFilter->QueryInterface(IID_IAMVideoProcAmp, (void**)&pVideoProcAmp);
IAMCameraControl* pCameraControl = NULL;
pCameraFilter->QueryInterface(IID_IAMCameraControl, (void**)&pCameraControl);
Retrieve the parameter ranges:
cpplong defaultValue, minValue, maxValue, stepSize, flags;
// Video Proc Amp parameters
pVideoProcAmp->GetRange(VideoProcAmp_Brightness, &minValue, &maxValue, &stepSize, &defaultValue, &flags);
pVideoProcAmp->GetRange(VideoProcAmp_Contrast, &minValue, &maxValue, &stepSize, &defaultValue, &flags);
// Add more Video Proc Amp parameters as needed
// Camera Control parameters
pCameraControl->GetRange(CameraControl_Pan, &minValue, &maxValue, &stepSize, &defaultValue, &flags);
pCameraControl->GetRange(CameraControl_Tilt, &minValue, &maxValue, &stepSize, &defaultValue, &flags);
// Add more Camera Control parameters as needed
Clean up:
cpppVideoProcAmp->Release();
pCameraControl->Release();
pCameraFilter->Release();
pCaptureGraphBuilder->Release();
pGraph->Release();
CoUninitialize();
Make sure to handle any potential errors and check the return values of function calls for success or failure.
The above code snippet demonstrates how to retrieve the parameter ranges for Video Proc Amp (brightness, contrast, etc.) and Camera Control (pan, tilt, etc.) using the IAMVideoProcAmp and IAMCameraControl interfaces, respectively. Adjust the code as per your specific requirements and add more parameters as needed.
Remember to link against the appropriate libraries (strmiids.lib
, uuid.lib
) and include the required header files (dshow.h
) in your project.
Please note that the above code uses the DirectShow API, which is a deprecated technology. It is recommended to consider using newer APIs like Media Foundation or Windows.Media.Capture for