You need to have the camera process running all the time.
This is the only way I could acheive results of (on average) 50ms. I looked everywhere for a solution. 1 second was just too slow for my motion sensor project.
@Dave Jones 's project helped me figure out how to do it.
Just 2 files:
a daemon, running all the time and a client.
The daemon is where you set all the camera settings.
picam-daemon.py
picam-client.py
python picam-daemon.py
import threading import os, io, base64, time, socket, picamera, daemon import daemon.runner MAX_LENGTH = 50 # max length of any possible entry from "client" serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # setup socket PORT = 10000 # port 10000 HOST = '127.0.0.1' # runs on local host serversocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) # this allows us to override port, prevents error serversocket.bind((HOST, PORT)) # lock server to this port and host serversocket.listen(10) # max 10 clients # Waits for commands, such as "snap" and "ack" # Runs over "sockets" def handle(clientsocket): while 1: buf = clientsocket.recv(MAX_LENGTH) # Receive the SNAP command. Take a picture with PiCam. if buf == 'snap': start = time.time() camera.capture('/home/pi/ir/picam-latest-snap.jpg') finish = start - time.time() print finish print 'Picture Taken!' if buf == 'ack': print 'Ping: Hello!' if len(buf) == 0: break # Camera is always loaded here # The "magic" is in the camThread, this allows a picture to be captured, then it gracefully closed the camera connection and reopens it. This produces very fast captures (54ms vs 1.5s!) while 1: # setup camera camera = picamera.PiCamera() camera.resolution = (640, 480) #camera.zoom = (0.2, 0.2, 1.0, 1.0) camera.exposure_mode = 'sports' print('Camera server running') # accept connections from outside, in order to receive commands (clientsocket, address) = serversocket.accept() ct = threading.Thread(target=handle, args=(clientsocket,)) ct.run() # this can be run(), because it can be scaled. print 'Camera thread starting.' camThread = threading.Thread() while camThread.is_alive(): camThread.join(1) camThread.run() # this must be start(), otherwise PiCam will crash. This is because PiCam cannot receive more than 1 connection. print 'Camera thread ended' camera.close() # Gracefully close PiCam if client disconnects
(in a second terminal) python picam-client.py
import socket import sys HOST = '127.0.0.1' PORT = 10000 s = socket.socket() s.connect((HOST, PORT)) print s while 1: msg = raw_input("Command To Send: ") if msg == "close": s.close() sys.exit(0) s.send(msg)
I'm posting this answer because I found this in Google, trying to find an answer myself. I couldn't find one, so I had to dig around some projects and come up with something myself.
