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c++opencvbuffercircular-buffer
Alexey
Alexey

Reputation: 5978

How to implement a circular buffer of cv::Mat objects (OpenCV)?

I'm trying to implement a circular buffer for my program. The buffer is used to share data between two threads as shown below. I use OpenCV to grab video frames from camera (Thread 1). Then I would like to store this data in a circular buffer, so that Thread 2 can get the data from the buffer.

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How can I implement a circular buffer for cv::Mat objects in C++? I know how to create circular buffer for standard C++ objects (like int or char) but I can't make it work with objects of type cv::Mat.

Any suggestions?

Upvotes: 5

Views: 7274

Answers (3)

Alexey
Alexey

Reputation: 5978

Solved, see Thread safe implementation of circular buffer

Upvotes: 5

Mark Ransom
Mark Ransom

Reputation: 308206

A circular buffer is thread-safe when only the writing thread updates the end pointer and only the reading thread updates the start pointer, and accesses to those pointers are atomic. You have a spot in cbWrite that updates start which will lead to a race condition.

Upvotes: 1

Martin Beckett
Martin Beckett

Reputation: 96109

Whats wrong with just a vector and an index to the next slot to write to and the next one to process?

All you have to handle is the wrap around when you get to the end, and if you use a power of 2 in the vector size you can use a simple mask for that.

Upvotes: 3

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