Repository: opencv
Issue: OpenCV 4.4 VideoCapture Memory Leak with Gstreamer
Labels: category: videoio,category: videoio(camera),incomplete,platform: win32,needs reproducer

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##### System information (version)
<!-- Example
- OpenCV => 4.2
- Operating System / Platform => Windows 64 Bit
- Compiler => Visual Studio 2017
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- OpenCV => 4.4.0
- Operating System / Platform => Windows 10
- Compiler => Visual Studio 2017

##### Detailed description
When using OpenCV with gstreamer support, VideoCapture API appears to have a memory leak. 
Observed behavior was a complete program shutdown after a long period of time. 
Ran through Visual Studio debugger, and memory heap profiling shows consistent growth. 

VideoCapture is initialized with a gstreamer pipeline, reading an encoded video stream over UDP. 
Issue exists with H265, H264, UDP multicast, RTP or MPEGTS 

Pipeline example:
"udpsrc address=225.1.1.1 port=5555 ! queue ! tsdemux ! h265parse ! video/x-h265, stream-format=byte-stream, alignment=au ! queue ! avdec_h265 ! videoconvert ! queue ! appsink"  

Memory issue appears to go away if I switch the backend to using FFMPEG

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##### Steps to reproduce

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 - [ ] I updated to latest OpenCV version and the issue is still there
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 - [ ] There is reproducer code and related data files: videos, images, onnx, etc
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