On windows when opening up RTSP streams with VideoCapture::open() and the FFMPEG back end, there is normally a delay, say 2000ms while the stream is setup, which is to be expected.
While this is happening any additional calls to VideoCapture::open() and VideoWriter.open() in other threads are blocked.
Is this blocking/queuing part of OpenCV or FFMPEG and can it be removed?

System information (version)

• OpenCV => 4.5.2
• Operating System / Platform => Windows 64 Bit
• Compiler => Visual Studio 2019

Steps to reproduce

Issue submission checklist

• [* ] I report the issue, it's not a question
• [ *] I checked the problem with documentation, FAQ, open issues,
  forum.opencv.org, Stack Overflow, etc and have not found solution
• I updated to latest OpenCV version and the issue is still there
• There is reproducer code and related data files: videos, images, onnx, etc