The Producer thread receives data from Source and passes to queue A that is shared with Consumer. Consumer process data, i.e., resize and apply median filter and then pass to another queue B. From queue B, thread SavePicture take data and save it to a png file.
This architecture has 3 levels, where the middle one is both producer and consumer.
All threads run simultaneously, and join() is executed after starting all threads. This speeds up work and data are continuously taken from pipelines. However, it complicates the condition to stop threads of the consumer.
Here, information about the amount of data (variable named frame_count) is explicitly passed to all threads. It must be assured that all threads take the same values.