Make cv::VideoCapture::get return cv::CAP_PROP_UNKNOWN (-1) for unsupported properties #21337
The return value indicating an unsupported property is not consistent across backends.
I stumbled on this issue because my code was determining if a property value is valid if it's non-zero (like the documentation says), which worked fine on macOS, but not on Android.
For example, auto-exposure is not supported on macOS, so get() returns 0. But it is supported on Android and 0 means auto-exposure is off.
I think -1 is the better return value to indicate unsupported properties.
I made changes to all the backends. I think I got every case. This breaks API compatibility for some backends, so I based this on branch 3.4.
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or other license that is incompatible with OpenCV
- [x] The PR is proposed to proper branch
- [ ] There is reference to original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake
* Added exposure and gain props, maximized pixel clk
* removed pixel clock maximization
pixel clock maximization is not suitable for all use cases, so I removed it from PR.
Add CV_16UC1/GRAY16_LE support to GStreamer backend for VideoWriter
* videoio(backend): add Writer_open_with_params to plugin API
This will allow arbitrary parameters to be passed to plugin backends
* videoio(gstreamer): add GRAY16_LE/CV_16UC1 writing support to GStreamer
This introduces a new property VIDEOWRITER_PROP_DEPTH, which defaults to
CV_8U, but for GStreamer can be set to CV_16U.
Also, fix another test to not fail if plugin isn't found, copying logic
from the read_write test.
* videoio(plugin): fix handling plugins with previous API level
* videoio: coding style
* fix warning
uEye are cameras from IDS, c.f. https://en.ids-imaging.com/
Supports driver version 4.94 and up currently, since the event system was overhauled there.
Supports setting/getting the properties: fps,width,height
Mansour Moufid
Nicolai Behmann
Alexander Alekhin
joshdoe
Andreas Franek