Record last n seconds of picamera in ring buffer and replay with vnc from correct position (all in memory)

main.py

#!/usr/bin/python3 -u
"""
Record last n seconds of picamera in ring buffer and replay with vnc from correct position (all in memory)
"""

import picamera
from time import sleep
import sys
import subprocess


def record_and_replay(n):
    recording_time = n
    
    try:
        # Initialize camera
        camera = picamera.PiCamera()
        camera.resolution = (1600, 1200)
        
        # Start vlc in fullscreen and save piperef
        cmdline = ['vlc', '--demux','h264', '--fullscreen', '-']
        player = subprocess.Popen(cmdline, stdin=subprocess.PIPE)
            
        # Wait till everything is ready and start preview
        sleep(1)
        camera.start_preview()
        
        # Start recording
        ring_buffer = picamera.PiCameraCircularIO(camera, seconds=recording_time+1)
        camera.start_recording(ring_buffer,'h264')
                
        while True:            
            camera.wait_recording(5)
            # Stop recording
            camera.stop_recording()
            # Write to vlc stdin
            ring_buffer.copy_to(player.stdin, seconds=recording_time)
            # Now stop preview
            sleep(1)
            camera.stop_preview()
            # Clear the ring buffer
            ring_buffer.clear()
            # Wait for recording to be played
            sleep(recording_time)
            # Restart recording and preview
            camera.start_preview()
            camera.start_recording(ring_buffer,'h264')
    except:
        camera.stop_recording()
        camera.stop_preview()
        player.kill()
        

if __name__ == "__main__":
    record_and_replay(3)