在Raspberry Pi上使用Python和OpenCV实现低FPS

Question

I'm trying to do some image processing on a Raspberry Pi with Python and OpenCV. It works well so far except a low FPS rate. Even without any image processing and just with the code below I get only 10 FPS with 640x480 resolution. Is there a faster way to capture the video stream? Do I something wrong here?

import numpy as np
import cv2
import time
from picamera.array import PiRGBArray
from picamera import PiCamera

# initialize the camera and grab a reference to the raw camera capture
camera = PiCamera()
camera.resolution = (640, 480)
camera.framerate = 32
rawCapture = PiRGBArray(camera, size=(640, 480))
# allow the camera to warmup
time.sleep(0.1)
start = time.time()

for img in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True):

    frame = img.array
    rawCapture.truncate(0)
    end = time.time()
    print 'fps:', int(round(1 / (end - start)))
    start = time.time()

Thank you so far.

regards

Answer 1

From the best of my knowledge, the hardware always produces YUV (I420) and conversion to BGR or RGB is done as an extra vector sw stage, thus reducing your frames per second.

I would suggest creating a thread dedicated solely to your IO pipeline, reducing latency and potentially increasing your fps, however I highly doubt you will be able to achieve the glorious 90fps (at 640x480) with the BGR model.

Check these two posts for a more detailed explanation: limited framerate picamera v2

https://raspberrypi.stackexchange.com/questions/22040/take-images-in-a-short-time-using-the-raspberry-pi-camera-module