Synchronize video and audio [closed]

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I am trying to create a system that gets broadcasts from clients, improve the quality of the frames with OpenCV and then rebroadcast to some external servers.

My problem is that I am getting the broadcast from an RTMP, with video and audio, when I want to rebroadcast, how can I synchronize video and audio again ?

I thought of using Ffmpeg to do the audio and OpenCV to do the video but If I get 2 RTMP streaming from clients that is goint to take much more bandwidth from them.

Any suggestions ? Thank you !