Introduce libavdevice to make v4l2 available to the ffmpeg backend
* introduce libavdevice to make v4l2 available to the ffmpeg backend
* downgrade the min required libavdevice version to 53.2.0
* make libavdevice optional
* create OCV_OPTION OPENCV_FFMPEG_ENABLE_LIBAVDEVICE and add definition through ocv_add_external_target
* move OCV_OPTION 'OPENCV_FFMPEG_ENABLE_LIBAVDEVICE' to detect_ffmpeg.cmake
Setting CAP_PROP_AUTO_EXPOSURE on VideoCapture with backend DSHOW does not change anything. Now with this implementation the property can be used with value 1 for availability.
* Allow the number of threads FFMpeg uses to be selected during VideoCapture::open().
Reset interupt timer in grab if
err = avformat_find_stream_info(ic, NULL);
is interupted but open is successful.
* Correct the returned number of threads and amend test cases.
* Update container test case.
* Reverse changes added to existing videoio_container test case and include test combining thread change and raw read in the newly added videoio_read test case.
This fixes the following error with mingw toolchain:
opencv/modules/videoio/src/cap_msmf.cpp:1020: error: 'wstring_convert' is not a member of 'std'
1020 | std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> conv;
| ^~~~~~~~~~~~~~~
opencv/modules/videoio/src/cap_ffmpeg_hw.hpp:230:26: error: 'wstring_convert' is not a member of 'std'
230 | std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> conv;
| ^~~~~~~~~~~~~~~
The locale header is required according to C++ standard.
See https://en.cppreference.com/w/cpp/locale/wstring_convert
This fixes the following error with mingw toolchain:
opencv/modules/videoio/src/cap_obsensor/obsensor_stream_channel_msmf.hpp:160:10: error: 'condition_variable' in namespace 'std' does not name a type
160 | std::condition_variable streamStateCv_;
| ^~~~~~~~~~~~~~~~~~
libstdc++ that comes with gcc 4.8 doesn't
define `getline(basic_istream<char>&&, std::string&)`
even if it's part of the c++11 standard.
However we can still use the following:
`getline(basic_istream<char>&, std::string&)`.
* videoio: add support for obsensor (Orbbec RGB-D Camera )
* obsensor: code format issues fixed and some code optimized
* obsensor: fix typo and format issues
* obsensor: fix crosses initialization error
