如何从 mp4 视频文件夹中提取帧并将它们传输到另一个文件夹？

Question

我有一个装满 mp4 剪辑的文件夹（超过 200 个）。我想拍摄所有这些剪辑，提取它们的帧并将它们发送到另一个文件夹以存储所有帧。这就是我到目前为止所拥有的（部分代码）但它只有在我有一个 mp4 文件时才有效文件夹：

import cv2     # for capturing videos
import math   # for mathematical operations
import matplotlib.pyplot as plt    # for plotting the images
import pandas as pd
from keras.preprocessing import image   # for preprocessing the images
import numpy as np    # for mathematical operations
from keras.utils import np_utils
from skimage.transform import resize   # for resizing images


count = 0
videoFile = "sample_vid.mp4"
cap = cv2.VideoCapture(videoFile)   # capturing the video from the given path
frameRate = cap.get(5) #frame rate
x=1
while(cap.isOpened()):
    frameId = cap.get(1) #current frame number
    ret, frame = cap.read()
    if (ret != True):
        break
    if (frameId % math.floor(frameRate) == 0):
        filename ="frame%d.jpg" % count;count+=1
        cv2.imwrite(filename, frame)
cap.release()
print ("Done!")

同样，我在处理 python 中的文件目录和循环它时遇到了一些问题，以便它遍历另一个文件夹中的所有文件并将提取的帧发送到另一个文件夹中。

Answer 1

您可以use os.walk to fetch all mp4 names and iterate over them. There are other ways detailed in Find all files in a directory with extension .txt in Python（将txt替换为mp4）。

创建一些文件以查找：

import os

with open("tata.mp4","w") as f: f.write(" ")
with open("tata1.mp4","w") as f: f.write(" ")
with open("tata2.mp4","w") as f: f.write(" ")

os.makedirs("./1/2/3")
with open("./1/subtata.mp4","w") as f: f.write(" ")
with open("./1/2/subtata1.mp4","w") as f: f.write(" ")
with open("./1/2/3/subtata2.mp4","w") as f: f.write(" ")

查找文件：

startdir = "./"
all_files = []
for root,dirs,files in os.walk(startdir):
    for file in files:
        if file.endswith(".mp4"):
            all_files.append(os.path.join(root,file))

print(all_files) 

for f in all_files:
    # do your thing

输出：

['./tata2.mp4', './tata1.mp4', './tata.mp4', 
 './1/subtata.mp4', 
 './1/2/subtata1.mp4', 
 './1/2/3/subtata2.mp4']

Answer 2

使用 glob 库查找文件夹中的所有 mp4 文件。然后运行 video2frames 方法针对所有视频。

import cv2
import math
import glob

def video2frames(video_file_path):
    count = 0
    cap = cv2.VideoCapture(video_file_path)
    frame_rate = cap.get(5)
    while cap.isOpened():
        frame_id = cap.get(1)
        ret, frame = cap.read()
        if not ret:
            break
        if frame_id % math.floor(frame_rate) == 0:
            filename = '{}_frame_{}.jpg'.format(video_file_path, count)
            count += 1
            cv2.imwrite(filename, frame)
    cap.release()

videos = glob.glob('/home/adam/*.mp4')
for i, video in enumerate(videos):
    print('{}/{} - {}'.format(i+1, len(videos), video))
    video2frames(video)

在两个视频上进行了测试。这是我得到的：

如何从 mp4 视频文件夹中提取帧并将它们传输到另一个文件夹？

How do I extract the frames from a folder of mp4 videos and transfer them to another folder?

python

opencv

python-3.x

scikit-image

cv2