[Libav-user] Handling a large number of rtsp cameras ( > 100) - image processing

[Francesco Taioli]

Hi all,
I have a performance problem regarding image acquisition from a
large number of cameras (they are greater than 100) in a *python* program.
Currently, I use cv2 with a ffmpeg pipeline.

*What I want to do*
I want to do some image processing on those cameras multiple times in a
minute.

*Current solution - pseudocode*

while True:
    for every rtsp_cameras_connection_params:
        *open_connection*
        read_current_frame # the real time frame
        process_frame
        close connection

This solution works, but opening the connection takes a lot of time.

*Why do you open the connection inside the loop, you may ask?*
As far as I know and I have tried, this is the only solution that allows me
to fetch the LAST frame from a camera (the real time frame, no buffer)
without
giving  performance issues for the powerful high-end server that this code
runs on.

*What do I want?*
Ideally, this

open_all_the_cameras

while True:
    for every rtsp_camera_already_opened:
        read_current_frame # the real time frame
        process_frame

As you can see, the ideal solution is to open *once* all the cameras
and save them into an array. Then, at every loop, read the last frame.

*What have I tried?*

Basically every solution. *Multithreading*, *multiprocessing,* and every
stackoverflow answers. These solutions work only for a limited amount of
cameras (10-15),
then the CPU will be 100% on usage (because the threads, in the background,
are
always reading the last frame and discarding it if I am not asking the
last).

There is a way to open the connection, and read the last frame (the real
time one),
not the one that I was before (the buffered one)?

Thanks to all. Hope it's clear.
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