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Merge pull request #21064 from alalek:doc_videoio_api_preference_3.4

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Alexander Alekhin 2021-11-16 20:05:59 +00:00
commit 49432009fe
1 changed files with 7 additions and 8 deletions
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modules/videoio/doc/videoio_overview.markdown
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@ -32,27 +32,26 @@ Select the backend at runtime
OpenCV automatically selects and uses first available backend (`apiPreference=cv::CAP_ANY`). OpenCV automatically selects and uses first available backend (`apiPreference=cv::CAP_ANY`).
As advanced usage you can select the backend to use at runtime. Currently this option is As advanced usage you can select the backend to use at runtime.
available only with %VideoCapture.
For example to grab from default camera using Direct Show as backend For example to grab from default camera using Microsoft Media Foundation (MSMF) as backend
```cpp ```cpp
//declare a capture object //declare a capture object
cv::VideoCapture cap(0, cv::CAP_DSHOW); cv::VideoCapture cap(0, cv::CAP_MSMF);
//or specify the apiPreference with open //or specify the apiPreference with open
cap.open(0, cv::CAP_DSHOW); cap.open(0, cv::CAP_MSMF);
``` ```
If you want to grab from a file using the Direct Show as backend: If you want to grab from a file using the Microsoft Media Foundation (MSMF) as backend:
```cpp ```cpp
//declare a capture object //declare a capture object
cv::VideoCapture cap(filename, cv::CAP_DSHOW); cv::VideoCapture cap(filename, cv::CAP_MSMF);
//or specify the apiPreference with open //or specify the apiPreference with open
cap.open(filename, cv::CAP_DSHOW); cap.open(filename, cv::CAP_MSMF);
``` ```
@sa cv::VideoCapture::open() , cv::VideoCapture::VideoCapture() @sa cv::VideoCapture::open() , cv::VideoCapture::VideoCapture()