python 视频处理，提取视频相关帧，读取Excel

Posted 2020-09-06

一共这几个模块：

class videoReader 读取视频

class videoFramesExtractor(videoReader):继承了读取视频，主要是用来限制读取视频中的哪些帧，并保存。

read_excel_single(excel_path,event_instance): 处理Excel中的数组，找到事件的帧数范围：

Excel内容是这样的，需要的只是第二列的帧范围，另外第二列中的这些值还有重复的所以需要去除重复：

每一个范围，例如:23450:23461之内的帧要存放在一个文件夹里。

 

 

[python] view plain copy

 

1. </pre><pre name="code" class="python"># -*- coding: cp936 -*-  
2.   
3. import cv2.cv as cv  
4. import os  
5. import cv2  
6. import numpy  
7. import Image  
8. import xlrd  
9.   
10. class videoReader:  
11.     frame_count=0  
12.     def __init__(self,videoPath):  
13.         self.videoPath=videoPath  
14.     def video_init(self):  
15.         self.capture = cv.CaptureFromFile(self.videoPath)  
16.         self.win_name = "test"  
17.         cv.NamedWindow(self.win_name, cv.CV_WINDOW_AUTOSIZE)  
18.           
19.     def read(self):  
20.         self.video_init()  
21.         while 1:  
22.             self.frame_count+=1  
23.             image = cv.QueryFrame(self.capture )  
24.              
25.             cv.ShowImage(self.win_name, image)  
26.             print self.frame_count  
27.             c = cv.WaitKey(10)  
28.             if c == 27:  
29.                 break  
30.               
31.         cv.DestroyWindow(self.win_name)  
32.   
33.   
34. class videoFramesExtractor(videoReader):  
35.     save_path=‘d:/‘  
36.     def __init__(self,videoPath,frameSpan,image_prefix):#image_prefix=event_name  
37.         videoReader.__init__(self,videoPath)  
38.         self.frameSpan=frameSpan  
39.         self.image_prefix=image_prefix  
40.           
41.     def read(self):  
42.         capture = cv2.VideoCapture(self.videoPath)  
43.         win_name = "test"  
44.         cv.NamedWindow(win_name, cv.CV_WINDOW_AUTOSIZE)  
45.         success,frame = capture.read()  
46.           
47.         init_row=0  
48.         while success:  
49.               
50.             self.frame_count+=1  
51.             success,frame = capture.read()  
52.             #cv2.imshow(win_name,frame) #显示照片浪费时间  
53.             time_duration=self.frameSpan[init_row][1]-self.frameSpan[init_row][0]+1  
54.             if self.frame_count>=self.frameSpan[init_row][0] and \  
55.               self.frame_count<=self.frameSpan[init_row][1] :  
56.                   
57.                                          
58.                 self.image_save(frame,init_row,time_duration)  
59.                       
60.                   
61.                 if self.frame_count==self.frameSpan[init_row][1]:  
62.                     init_row+=1  
63.                 if init_row==len(self.frameSpan):  
64.                     cv.DestroyWindow(win_name)  
65.                     return 0  
66.                   
67.             c = cv.WaitKey(10)  
68.             if c == 27:  
69.                 break  
70.               
71.         cv.DestroyWindow(win_name)  
72.     def image_save(self,frame,init_row,time_duration):  
73.         save_path=self.make_folder(init_row,time_duration)  
74.       
75.         #frame=Image.fromarray(frame)  
76.         #frame.resize((300,300))  
77.         #frame.save(‘%s//%s.jpg‘ % (save_path,self.frame_count))  
78.         frame=cv2.resize(frame,(300,300))#  
79.         cv2.imwrite( ‘%s//%s.jpg‘ % (save_path,self.frame_count), frame)  
80.   
81.           
82.     def make_folder(self,init_row,time_duration):  
83.         temp= self.image_prefix+‘_‘+str(init_row)+‘_‘+str(time_duration)#事件名称_事件顺序_  
84.         new_path = os.path.join(self.save_path,temp)  
85.         if not os.path.isdir(new_path):  
86.             os.makedirs(new_path)  
87.         return new_path  
88.       
89.   
90.       
91. def read_excel_single(excel_path,event_instance):  
92.           
93.         data=[]  
94.         data=xlrd.open_workbook(excel_path)  
95.         #read the first sheets  
96.         table = data.sheets()[0]  
97.         #read the num fo cols  
98.         nrows = table.nrows  
99.         rowmsg=[]#用来存储帧的范围，及事件的类别，描述。  
100.   
101.         for i in xrange(nrows):  
102.             start_frame,end_frame=table.row_values(i)[1].split(‘:‘)  
103.             rowmsg.append([int(start_frame),int(end_frame),table.row_values(i)[3]])  
104.   
105.         rowmsg.sort(lambda x,y:cmp(x[0],y[0]))#按照数字大小排序~  
106.           
107.         event_id=[]  
108.         event_id=event_instance  
109.         #print event_id  
110.   
111.               
112.         event=[]  
113.         for item in xrange(len(rowmsg)):  
114.             if rowmsg[item][2]==event_id:#  
115.                 event.append(rowmsg[item])  
116.         if event==[]:  
117.             print ("there is no %s occurs" % event_instance)  
118.             return 0  
119.         #去除重复  
120.                         
121.         cur_pos=1  
122.         new_rowmsg=[]  
123.         pre_s=event[0][0]  
124.         pre_e=event[0][1]  
125.         cur_s=event[cur_pos][0]  
126.         cur_e=event[cur_pos][1]  
127.   
128.         while cur_pos<len(event)-1:   
129.             while not (cur_s>pre_e):  
130.                 if cur_s>pre_s:  
131.                     cur_s=pre_s  
132.                 if cur_e<pre_e:  
133.                     cur_e=pre_e  
134.                 still_pos=[cur_s,cur_e,event_id]  
135.                 cur_pos+=1  
136.                 if cur_pos==len(event)-1:  
137.                     break  
138.                               
139.                 pre_s=cur_s  
140.                 pre_e=cur_e  
141.                 cur_s=event[cur_pos][0]  
142.                 cur_e=event[cur_pos][1]  
143.             new_rowmsg.append(still_pos)  
144.             if cur_pos==len(event)-1:  
145.                 break  
146.       
147.             cur_pos+=1  
148.             pre_s=cur_s  
149.             pre_e=cur_e  
150.             cur_s=event[cur_pos][0]  
151.             cur_e=event[cur_pos][1]  
152.   
153.           
154.         return new_rowmsg  
155.           
156.       
157.        
158. excel_source=‘E:/08ann/dev_20071101/LGW_20071101_E1_CAM1.mpeg.xlsx‘  
159. event_instance=‘CellToEar‘  
160.   
161. row_msg=read_excel_single(excel_source,event_instance)  
162. new_row=[ item[0:2] for item in row_msg ]   
163.   
164. filename = "G:/TrecvidData/08/DEV/LGW_20071101_E1_CAM1.mpg"  
165.   
166.   
167.               
168. videoread=videoFramesExtractor(filename,new_row,‘CellToEar‘)  
169. videoread.read()  

 

 

有几点发现：

cv2.的函数输出的数据类型基本都是numpy，而cv.不行。所以尽量在Python中使用cv2.的函数。

通过numpy转换后的图片会在颜色上有些失真，不过影响不大，如果是灰度图的话则完全没有影响。