Python Opencv实践 - 视频文件操作

参考资料：

视频处理VideoCapture类---OpenCV-Python开发指南（38）_python opencv videocapture_李元静的博客-CSDN博客

OpenCV VideoCapture.get()参数详解 - 简书
FOURCC四字符码对照表_4fvcc_Kellybook的博客-CSDN博客

import cv2 as cv
import numpy as np

#1.创建VideoCapture对象
#  video = cv.VideoCapture(filePath)
#  filePath： 视频文件路径
# 参考资料：https://blog.csdn.net/liyuanjinglyj/article/details/114374223
video = cv.VideoCapture("../SampleVideos/Unity2D.mp4")
print("Video Opened?", video.isOpened())

#2.获得视频属性
#  video.get(propId)
#  propId: 属性ID
#          cv.CAP_PROP_POS_MSEC - 视频文件的当前位置（ms）
#          cv.CAP_PROP_POS_FRAMES - 当前帧序号(从0开始)
#          cv.CAP_PROP_POS_AVI_RATIO - 视频文件相对位置（0表示开始，1表示结束）
#          cv.CAP_PROP_FRAME_WIDTH - 视频的帧宽度
#          cv.CAP_PROP_FRAME_HEIGHT - 视频的帧高度
#          cv.CAP_PROP_FPS - 帧率
#          cv.CAP_PROP_FOURCC - 视频编码的四字节编码
#          cv.CAP_PROP_FRAME_COUNT - 视频文件的帧的数量
#          cv.CAP_PROP_FORMAT - 对象的格式
#  参考资料：https://www.jianshu.com/p/676bef32e655
#           https://blog.csdn.net/qq_30622831/article/details/82082122
width = video.get(cv.CAP_PROP_FRAME_WIDTH)
height = video.get(cv.CAP_PROP_FRAME_HEIGHT)
fps = video.get(cv.CAP_PROP_FPS)
fourcc = int(video.get(cv.CAP_PROP_FOURCC))
totalFrames = video.get(cv.CAP_PROP_FRAME_COUNT)
print("Video Properties: resolution - (", width, height, ") FPS - "
      , fps, " FOURCC - "
      , chr(fourcc&0xFF), chr((fourcc>>8)&0xFF), chr((fourcc>>16)&0xFF),chr((fourcc>>24)&0xFF)
      , " Frame Count - ", totalFrames)

#3. 读取视频的一帧图像
#    ret,frame = video.read()
#    read()按帧读取视频，ret,frame是获cap.read()方法的两个返回值
#          其中ret读取帧是正确的话则返回True，如果文件读取到结尾，它的返回值就为False
frame_delay = int(1000 / fps)
while True:
    ret,frame = video.read()
    cv.imshow('Opencv Video Play', frame)
    key = cv.waitKey(frame_delay)
    if key == 27: #检测ESC键
        break
#4. 释放视频对象
video.release()
cv.destroyAllWindows()