import os
import cv2 ##加载OpenCV模块
def video2frames(pathIn='',
pathOut='',
only_output_video_info=False,
extract_time_points=None,
initial_extract_time=0,
end_extract_time=None,
extract_time_interval=-1,
output_prefix='frame',
jpg_quality=100,
isColor=True):
'''
pathIn：视频的路径，比如：F:\python_tutorials\test.mp4
pathOut：设定提取的图片保存在哪个文件夹下，比如：F:\python_tutorials\frames1\。如果该文件夹不存在，函数将自动创建它
only_output_video_info：如果为True，只输出视频信息（长度、帧数和帧率），不提取图片
extract_time_points：提取的时间点，单位为秒，为元组数据，比如，(2, 3, 5)表示只提取视频第2秒， 第3秒，第5秒图片
initial_extract_time：提取的起始时刻，单位为秒，默认为0（即从视频最开始提取）
end_extract_time：提取的终止时刻，单位为秒，默认为None（即视频终点）
extract_time_interval：提取的时间间隔，单位为秒，默认为-1（即输出时间范围内的所有帧）
output_prefix：图片的前缀名，默认为frame，图片的名称将为frame_000001.jpg、frame_000002.jpg、frame_000003.jpg......
jpg_quality：设置图片质量，范围为0到100，默认为100（质量最佳）
isColor：如果为False，输出的将是黑白图片
'''
cap = cv2.VideoCapture(pathIn) ##打开视频文件
n_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT)) ##视频的帧数
fps = cap.get(cv2.CAP_PROP_FPS) ##视频的帧率
dur = n_frames / fps ##视频的时间
##如果only_output_video_info=True, 只输出视频信息，不提取图片
if only_output_video_info:
print('only output the video information (without extract frames)::::::')
print("Duration of the video: {} seconds".format(dur))
print("Number of frames: {}".format(n_frames))
print("Frames per second (FPS): {}".format(fps))
##提取特定时间点图片
elif extract_time_points is not None:
if max(extract_time_points) > dur: ##判断时间点是否符合要求
raise NameError('the max time point is larger than the video duration....')
try:
os.mkdir(pathOut)
except OSError:
pass
success = True
count = 0
while success and count < len(extract_time_points):
cap.set(cv2.CAP_PROP_POS_MSEC, (1000 * extract_time_points[count]))
success, image = cap.read()
if success:
if not isColor:
image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY) ##转化为黑白图片
print('Write a new frame: {}, {}th'.format(success, count + 1))
cv2.imwrite(os.path.join(pathOut, "{}_{:06d}.jpg".format(output_prefix, count + 1)), image,
[int(cv2.IMWRITE_JPEG_QUALITY), jpg_quality]) # save frame as JPEG file
count = count + 1
else:
##判断起始时间、终止时间参数是否符合要求
if initial_extract_time > dur:
raise NameError('initial extract time is larger than the video duration....')
if end_extract_time is not None:
if end_extract_time > dur:
raise NameError('end extract time is larger than the video duration....')
if initial_extract_time > end_extract_time:
raise NameError('end extract time is less than the initial extract time....')
##时间范围内的每帧图片都输出
if extract_time_interval == -1:
if initial_extract_time > 0:
cap.set(cv2.CAP_PROP_POS_MSEC, (1000 * initial_extract_time))
try:
os.mkdir(pathOut)
except OSError:
pass
print('Converting a video into frames......')
if end_extract_time is not None:
N = (end_extract_time - initial_extract_time) * fps + 1
success = True
count = 0
while success and count < N:
success, image = cap.read()
if success:
if not isColor:
image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
print('Write a new frame: {}, {}/{}'.format(success, count + 1, n_frames))
cv2.imwrite(os.path.join(pathOut, "{}_{:06d}.jpg".format(output_prefix, count + 1)), image,
[int(cv2.IMWRITE_JPEG_QUALITY), jpg_quality]) # save frame as JPEG file
count = count + 1
else:
success = True
count = 0
while success:
success, image = cap.read()
if success:
if not isColor:
image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
print('Write a new frame: {}, {}/{}'.format(success, count + 1, n_frames))
cv2.imwrite(os.path.join(pathOut, "{}_{:06d}.jpg".format(output_prefix, count + 1)), image,
[int(cv2.IMWRITE_JPEG_QUALITY), jpg_quality]) # save frame as JPEG file
count = count + 1
##判断提取时间间隔设置是否符合要求
elif extract_time_interval > 0 and extract_time_interval < 1 / fps:
raise NameError('extract_time_interval is less than the frame time interval....')
elif extract_time_interval > (n_frames / fps):
raise NameError('extract_time_interval is larger than the duration of the video....')
##时间范围内每隔一段时间输出一张图片
else:
try:
os.mkdir(pathOut)
except OSError:
pass
print('Converting a video into frames......')
if end_extract_time is not None:
N = (end_extract_time - initial_extract_time) / extract_time_interval + 1
success = True
count = 0
while success and count < N:
cap.set(cv2.CAP_PROP_POS_MSEC, (1000 * initial_extract_time + count * 1000 * extract_time_interval))
success, image = cap.read()
if success:
if not isColor:
image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
print('Write a new frame: {}, {}th'.format(success, count + 1))
cv2.imwrite(os.path.join(pathOut, "{}_{:06d}.jpg".format(output_prefix, count + 1)), image,
[int(cv2.IMWRITE_JPEG_QUALITY), jpg_quality]) # save frame as JPEG file
count = count + 1
else:
success = True
count = 0
while success:
cap.set(cv2.CAP_PROP_POS_MSEC, (1000 * initial_extract_time + count * 1000 * extract_time_interval))
success, image = cap.read()
if success:
if not isColor:
image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
print('Write a new frame: {}, {}th'.format(success, count + 1))
cv2.imwrite(os.path.join(pathOut, "{}_{:06d}.jpg".format(output_prefix, count + 1)), image,
[int(cv2.IMWRITE_JPEG_QUALITY), jpg_quality]) # save frame as JPEG file
count = count + 1
##### 测试
# import cv2 as cv
# cap = cv.VideoCapture("H:\pyImage\cs.mp4")
pathIn = 'H:\pyImage\cs.mp4'
video2frames(pathIn, only_output_video_info=True)
pathOut = './frames1/'
video2frames(pathIn, pathOut)
pathOut = './frames2'
video2frames(pathIn, pathOut, extract_time_points=(1, 2, 5))
pathOut = './frames3'
video2frames(pathIn, pathOut,
initial_extract_time=1,
end_extract_time=3,
extract_time_interval=0.5)
pathOut = './frames4/'
video2frames(pathIn, pathOut, extract_time_points=(0.3, 2), isColor=False)
pathOut = './frames5/'
video2frames(pathIn, pathOut, extract_time_points=(0.3, 2), jpg_quality=50)
