Python-OpenCV 处理视频（一）：输入输出

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视频的处理和图片的处理类似，只不过视频处理需要连续处理一系列图片。

一般有两种视频源，一种是直接从硬盘加载视频，另一种是获取摄像头视频。

0x00. 本地读取视频

核心函数:

cv.CaptureFromFile()

代码示例：

import cv2.cv as cv

capture = cv.CaptureFromFile('myvideo.avi')

nbFrames = int(cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FRAME_COUNT))

#CV_CAP_PROP_FRAME_WIDTH Width of the frames in the video stream

#CV_CAP_PROP_FRAME_HEIGHT Height of the frames in the video stream

fps = cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FPS)

wait = int(1/fps * 1000/1)

duration = (nbFrames * fps) / 1000

print 'Num. Frames = ', nbFrames

print 'Frame Rate = ', fps, 'fps'

print 'Duration = ', duration, 'sec'

for f in xrange( nbFrames ):

frameImg = cv.QueryFrame(capture)

print cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_POS_FRAMES)

cv.ShowImage("The Video", frameImg)

cv.WaitKey(wait)

cv2

import numpy as np

import cv2

cap = cv2.VideoCapture('vtest.avi')

while(cap.isOpened()):

ret, frame = cap.read()

gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

cv2.imshow('frame',gray)

if cv2.waitKey(1) & 0xFF == ord('q'):

break

cap.release()

cv2.destroyAllWindows()

0x01. 摄像头视频读取

核心函数：

cv.CaptureFromCAM()

示例代码：

import cv2.cv as cv

capture = cv.CaptureFromCAM(0)

while True:

frame = cv.QueryFrame(capture)

cv.ShowImage("Webcam", frame)

c = cv.WaitKey(1)

if c == 27: #Esc on Windows

break

cv2

import numpy as np

import cv2

cap = cv2.VideoCapture/span>cv2

cap = cv2.VideoCapture="crayon-5812a37a11732965027020" class="crayon-syntax crayon-theme-github crayon-font-monaco crayon-os-pc print-yes notranslate" data-settings=" minimize scroll-always" style=" margin-top: 12px; margin-bottom: 12px; font-size: 13px !important; line-height: 15px !important;">

import cv2.cv as cv

capture = cv.CaptureFromFile('myvideo.avi')

nbFrames = int(cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FRAME_COUNT))

#CV_CAP_PROP_FRAME_WIDTH Width of the frames in the video stream

#CV_CAP_PROP_FRAME_HEIGHT Height of the frames in the video stream

fps = cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FPS)

wait = int(1/fps * 1000/1)

duration = (nbFrames * fps) / 1000

print 'Num. Frames = ', nbFrames

print 'Frame Rate = ', fps, 'fps'

print 'Duration = ', duration, 'sec'

for f in xrange( nbFrames ):

frameImg = cv.QueryFrame(capture)

print cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_POS_FRAMES)

cv.ShowImage("The Video", frameImg)

cv.WaitKey(wait)

cv2

import numpy as np

import cv2

cap = cv2.VideoCapture('vtest.avi')

while(cap.isOpened()):

ret, frame = cap.read()

gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

cv2.imshow('frame',gray)

if cv2.waitKey(1) & 0xFF == ord('q'):

break

cap.release()

cv2.destroyAllWindows()

0x01. 摄像头视频读取

核心函数：

cv.CaptureFromCAM()

示例代码：

import cv2.cv as cv

capture = cv.CaptureFromCAM(0)

while True:

frame = cv.QueryFrame(capture)

cv.ShowImage("Webcam", frame)

c = cv.WaitKey(1)

if c == 27: #Esc on Windows

break

cv2

import numpy as np

import cv2

cap =