How fast can you take pics?

ShreddinPB · July 8, 2022, 6:54pm

Hey guys, I got the camarray hat and 4 64mp camera bundle. I misread the description thinking it could take all 4 at 64mp at once, my bad
My question is, how fast can you shoot all 4 individually? How much lag is there between shots? What if you shoot 2 at 32mp, is it the same lag between shots?
Thanks!

lvbin · July 11, 2022, 1:19am

Hello,
The four camera clocks are fully synchronized.

amdreallyfast · July 11, 2022, 1:47pm

Chiming in here. A raw file can be captured pretty fast. I haven’t figured out how to actually convert the raw image yet, but since libcamera-raw can quickly capture multiple raw images in a single second and libcamera-still takes 2-3sec for a single image, that tells me that most of the lag is due to post-processing and not IO. Have you tried using python with Popen to launch a new process that will call libcamera-still? If you can do that 4 times in a row (one for each camera) and then call <process object>.wait() on all the process objects that were just created, then maybe you get the images taken as fast as possible.

Or maybe the libcamera-apps software isn’t designed to wait and will just blow up if more than one attempt is made to use the camera interface at one time. Not sure. If it does blow up, you might have to experiment with sleeping for a hard-coded magic number of milliseconds between calls.

Note: Just to be clear, I’m talking about multiprocessing here, which is useful when processing power is the bottleneck (as it is when post-processing the images), not multithreading, which is useful when IO is the bottleneck and the CPU is mostly twiddling its thumbs waiting for it to finish.

ShreddinPB · July 11, 2022, 9:31pm

Right, when taking 4 16mp images as one 64mp image. I looking to take 4 64mp images one from each camera in quick succession.

ShreddinPB · July 11, 2022, 9:32pm

I havnt got that far yet, was just looking to see if people have done it. Fantastic response tho, I will def look into it!

lvbin · May 4, 2023, 1:15am

The current processing method does not support a single camera to take four consecutive shots, unless only single-channel mode is used

ShreddinPB · May 4, 2023, 1:44am

I wasnt asking about a single camera taking 4 consecutive shots, I was asking about shooting 1 64mp image from each camera. so how quickly could cam1 then cam2 then 3 then 4 shoot.

Edward · May 5, 2023, 2:04am

@ShreddinPB

You can test it yourself. I have two examples for your reference. One is to test the image saving speed of a single camera, and the other is to switch cameras. The logic is to remove the time when the camera is turned on, read the time stamp before and after saving the image, and use the difference to calculate the time.

github.com

ArduCAM/picamera2_examples/blob/main/64mp_speed_test.py

#!/usr/bin/python3

import time

from picamera2 import Picamera2, Preview

i = 0
FrameRate = 2.7
frame_time = 1000000 // FrameRate 

start = time.time()

picam2 = Picamera2()
# picam2.start_preview(Preview.QTGL)

capture_config = picam2.create_still_configuration(main={"format": 'RGB888', "size": (9152, 6944)})
picam2.configure(capture_config)

# picam2.set_controls({"FrameDurationLimits":(frame_time, frame_time)})
picam2.start()

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github.com

ArduCAM/picamera2_examples/blob/main/hat_switch_camera_to_take_pictures.py

#!/usr/bin/python3

import cv2
import sys
import argparse
from picamera2 import Picamera2
import subprocess
import time

def run_cmd(cmd):
    print(f'{cmd}')
    try:
        subprocess.run(cmd, universal_newlines=True, check=False, shell=True,
                        stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    except RuntimeError as e:
        print(f'Error: {e}')
    except:
        print("Set up error!")

argv = sys.argv[:]

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