为不同视频的视频帧创建新目录时出错

Question

根据标题，我试图编写代码，循环浏览文件夹中的多个视频以提取它们的帧，然后将每个视频的帧写入它们自己的新文件夹，例如video1到frames\u video1，video2到frames\u video2

这是我的代码：

subclip_video_path = main_path + "\\subclips"
frames_path = main_path + "\\frames"

#loop through videos in file
for subclips in subclip_video_path:
    currentVid = cv2.VideoCapture(subclips)
    success, image = currentVid.read()
    count = 0
    while success:
        
        #create new frames folder for each video
        newFrameFolder = ("frames_" + subclips)
        os.makedirs(newFrameFolder)

我得到这个错误：

[ERROR:0] global C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-k8sx3e60\opencv\modules\videoio\src\cap.cpp (142) cv::VideoCapture::open VIDEOIO(CV_IMAGES): raised OpenCV exception:

OpenCV(4.4.0) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-k8sx3e60\opencv\modules\videoio\src\cap_images.cpp:253: error: (-5:Bad argument) CAP_IMAGES: can't find starting number (in the name of file): P in function 'cv::icvExtractPattern'

这是什么意思？我怎样才能解决这个问题

Answer 1

1. 不能循环使用字符串：for subclips in subclip_video_path:

您需要获取视频列表：

from glob import glob

sub_clip_video_path = glob("sub_clip_video_path/*.mp4")

这意味着获取所有.mp4扩展名视频文件并将其存储在sub_clip_video_path变量中

我的结果是：

['sub_clip_video_path/output.mp4', 'sub_clip_video_path/result.mp4']

因为我确定目录包含两个.mp4扩展文件，现在我可以继续了

1. 您不需要为每个帧重新声明VideoCapture

for count, sub_clips in enumerate(sub_clip_video_path):
    currentVid = cv2.VideoCapture(sub_clips)
    success, image = currentVid.read()
    count = 0

声明VideoCapture后，读取当前视频中的所有帧，然后为下一个视频声明VideoCapture

for count, sub_clips in enumerate(sub_clip_video_path):
    currentVid = cv2.VideoCapture(sub_clips)
    image_counter = 0
    while currentVid.isOpened():
          .
          .

1. 不要使用while success这将创建一个无限循环

如果从视频抓取第一帧，则success变量返回True。当你说：

while success:
    #create new frames folder for each video
    newFrameFolder = ("frames_" + subclips)
    os.makedirs(newFrameFolder)

您将为当前帧创建无限量的文件夹

以下是我的结果：

import os
import cv2
from glob import glob

sub_clip_video_path = glob("sub_clip_video_path/*.mp4")  # Each image extension is `.mp4`

for count, sub_clips in enumerate(sub_clip_video_path):
    currentVid = cv2.VideoCapture(sub_clips)
    image_counter = 0
    while currentVid.isOpened():
        success, image = currentVid.read()

        if success:
            newFrameFolder = "frames_video{}".format(count + 1)

            if not os.path.exists(newFrameFolder):
                os.makedirs(newFrameFolder)
            
            image_name = os.path.join(newFrameFolder, "frame{}.png".format(image_counter + 1))
            cv2.imwrite(image_name, image)
            image_counter += 1
        else:
            break

• 我用glob收集了所有的视频

• 读取当前视频时：

  • for count, sub_clips in enumerate(sub_clip_video_path):
        currentVid = cv2.VideoCapture(sub_clips)
        image_counter = 0
    
        while currentVid.isOpened():
    

• 如果当前帧成功抓取，则声明文件夹名称。如果文件夹不存在，请创建它

  •    if success:
           newFrameFolder = "frames_video{}".format(count + 1)
    
            if not os.path.exists(newFrameFolder):
                os.makedirs(newFrameFolder)
    

• 然后声明图像名称并保存它

  • image_name = os.path.join(newFrameFolder, "frame{}.png".format(image_counter + 1))
    cv2.imwrite(image_name, image)
    image_counter += 1