所以我遵循这个教程,但它似乎没有做任何事情。只是没有。它等待几秒钟并关闭程序。这段代码有什么问题?
import cv2
vidcap = cv2.VideoCapture('Compton.mp4')
success,image = vidcap.read()
count = 0
success = True
while success:
success,image = vidcap.read()
cv2.imwrite("frame%d.jpg" % count, image) # save frame as JPEG file
if cv2.waitKey(10) == 27: # exit if Escape is hit
break
count += 1
此外,在评论中它说这限制帧到1000?为什么?
编辑:
我试着先做success = True,但没有帮助。它只创建了一个0字节的图像。
之前的答案已经失去了第一帧。把图片存储在文件夹里会很好。
# create a folder to store extracted images
import os
folder = 'test'
os.mkdir(folder)
# use opencv to do the job
import cv2
print(cv2.__version__) # my version is 3.1.0
vidcap = cv2.VideoCapture('test_video.mp4')
count = 0
while True:
success,image = vidcap.read()
if not success:
break
cv2.imwrite(os.path.join(folder,"frame{:d}.jpg".format(count)), image) # save frame as JPEG file
count += 1
print("{} images are extacted in {}.".format(count,folder))
顺便说一下,你可以通过VLC检查帧率。进入“windows ->媒体信息->编解码器详细信息”
从这里下载这个视频,这样我们就有了相同的测试视频文件。确保mp4文件与python代码位于同一目录。然后确保从相同的目录运行python解释器。
然后修改代码,抛弃浪费时间的waitKey,也没有窗口,它不能捕捉键盘事件。同时,我们打印success值以确保它成功读取帧。
import cv2
vidcap = cv2.VideoCapture('big_buck_bunny_720p_5mb.mp4')
success,image = vidcap.read()
count = 0
while success:
cv2.imwrite("frame%d.jpg" % count, image) # save frame as JPEG file
success,image = vidcap.read()
print('Read a new frame: ', success)
count += 1
这是怎么回事?
在对如何将帧转换为视频进行了大量研究后,我创建了这个函数,希望这能有所帮助。我们需要opencv来实现:
import cv2
import numpy as np
import os
def frames_to_video(inputpath,outputpath,fps):
image_array = []
files = [f for f in os.listdir(inputpath) if isfile(join(inputpath, f))]
files.sort(key = lambda x: int(x[5:-4]))
for i in range(len(files)):
img = cv2.imread(inputpath + files[i])
size = (img.shape[1],img.shape[0])
img = cv2.resize(img,size)
image_array.append(img)
fourcc = cv2.VideoWriter_fourcc('D', 'I', 'V', 'X')
out = cv2.VideoWriter(outputpath,fourcc, fps, size)
for i in range(len(image_array)):
out.write(image_array[i])
out.release()
inputpath = 'folder path'
outpath = 'video file path/video.mp4'
fps = 29
frames_to_video(inputpath,outpath,fps)
修改fps(帧/秒)的值,输入文件夹路径和输出文件夹路径根据您自己的本地位置
这个函数以1帧/秒的速度从视频中提取图像,此外,它还识别最后一帧并停止读取:
import cv2
import numpy as np
def extract_image_one_fps(video_source_path):
vidcap = cv2.VideoCapture(video_source_path)
count = 0
success = True
while success:
vidcap.set(cv2.CAP_PROP_POS_MSEC,(count*1000))
success,image = vidcap.read()
## Stop when last frame is identified
image_last = cv2.imread("frame{}.png".format(count-1))
if np.array_equal(image,image_last):
break
cv2.imwrite("frame%d.png" % count, image) # save frame as PNG file
print '{}.sec reading a new frame: {} '.format(count,success)
count += 1