使用 OpenCV 和 Python 提高视频的捕获和流传输速度 [英] Increase the capture and stream speed of a video using OpenCV and Python

问题描述

我需要拍摄视频并逐帧分析.这是我目前所拥有的:

I need to take a video and analyze it frame-by-frame. This is what I have so far:

'''

cap = cv2.VideoCapture(CAM) # CAM = path to the video
    cap.set(cv2.CAP_PROP_BUFFERSIZE, 1)
    while cap.isOpened():
        ret, capture = cap.read()
        cv2.cvtColor(capture, frame, cv2.COLOR_BGR2GRAY)
        cv2.imshow('frame', capture)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
        analyze_frame(frame)
    cap.release()

'''

这有效，但速度非常慢.有什么办法可以让它更接近实时?

This works, but it's incredibly slow. Is there any way that I can get it closer to real-time?

推荐答案

VideoCapture 之所以这么慢，是因为 VideoCapture 管道在读取和解码上花费的时间最多下一帧.在读取、解码和返回下一帧时，OpenCV 应用程序被完全阻塞.

The reason VideoCapture is so slow because the VideoCapture pipeline spends the most time on the reading and decoding the next frame. While the next frame is being read, decode, and returned the OpenCV application is completely blocked.

所以你可以使用 FileVideoStream 使用队列数据结构并发处理视频.

So you can use FileVideoStream which uses queue data structure to process the video concurrently.

• 您需要安装的软件包:

• 对于虚拟环境:pip install imutils
• 对于anaconda环境:conda install -c conda-forge imutils

  ---

示例代码:

import cv2
import time
from imutils.video import FileVideoStream


fvs = FileVideoStream("test.mp4").start()

time.sleep(1.0)

while fvs.more():
    frame = fvs.read()

    cv2.imshow("Frame", frame)

---

速度测试

您可以使用以下代码使用任何示例视频进行速度测试.下面的代码是为 FileVideoStream 测试而设计的.注释 fvs 变量并取消注释 cap 变量以计算 VideoCapture 速度.到目前为止，fvs 比 cap 变量快.

You can do speed-test using any example video using the below code. below code is designed for FileVideoStream test. Comment fvsvariable and uncomment cap variable to calculate VideoCapture speed. So far fvs more faster than cap variable.

from imutils.video import FileVideoStream
import time
import cv2

print("[INFO] starting video file thread...")
fvs = FileVideoStream("test.mp4").start()
cap = cv2.VideoCapture("test.mp4")
time.sleep(1.0)

start_time = time.time()

while fvs.more():
     # _, frame = cap.read()
     frame = fvs.read()

print("[INFO] elasped time: {:.2f}ms".format(time.time() - start_time))

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