python - 为不同视频的视频帧创建新目录时出错

Question

对于每个标题，我正在尝试编写代码以循环浏览文件夹中的多个视频以提取其帧，然后将每个视频的帧写入到自己的新文件夹中，例如video1到frames_video1，video2到frames_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)

我收到此错误:

[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

您不能循环访问字符串: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:

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

由于我确定目录中包含两个.mp4扩展文件，因此我现在可以继续。

您无需为每个帧重新声明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():
          .
          .

不要使用while success这将创建一个无限循环。

如果从视频中获取了第一帧，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)

您将为当前框架创建无限数量的文件夹。
这是我的结果:

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

我使用glob收集了所有视频

在读取当前视频时:

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

    while currentVid.isOpened():

如果成功捕获了当前帧，则声明文件夹名称。如果该文件夹不存在，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。

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