在opencv中按下指定键时是否可以倒带?我有以下内容,但它不会倒带播放。
def run(self, filepath, fps, width, height, monochrome=False):
video_file = self.read_file(filepath)
previous_frame = None
while (video_file.isOpened()):
ret, frame = video_file.read()
if previous_frame is not None:
pass
previous_frame = frame
if ret:
frame = self.color(frame, monochrome)
final_frame = self.resolution(frame, width, height)
delaytime = self.frame_per_second(fps)
cv2.imshow('frame', final_frame)
key = cv2.waitKey(delaytime)
if key & 0xFF == ord("p"):
cv2.waitKey(234320)
if key & 0xFF == ord("r"):
cv2.set(cv2.CV_CAP_PROP_POS_FRAMES(2, previous_frame))
video_file.release()
cv2.destroyAllWindows()
上面的代码把它带到上一帧但不播放。
最佳答案
理想的解决方案是设置视频暂停时需要播放的帧数,以达到倒带效果。这可以通过 video capture properties 完成:
cv2.VideoCapture.set(propId, value)
CAP_PROP_POS_FRAMES 0-based index of the frame to be decoded/captured next.
“Jumping between frames in video files ”中提供了有用的示例。
这是一个 源代码示例 暂停视频并提供一些控制,让您倒带到前一帧或跳到第 0 帧并重新启动视频:
import cv2
import sys
# load input video
cap = cv2.VideoCapture('TheMandalorian.mkv')
if (cap.isOpened() == False):
print("!!! Failed cap.isOpened()")
sys.exit(-1)
# retrieve the total number of frames
frame_count = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
# loop to read every frame of the video
while (cap.isOpened()):
# capture a frame
ret, frame = cap.read()
if ret == False:
print("!!! Failed cap.read()")
break
cv2.imshow('video', frame)
# check if 'p' was pressed and wait for a 'b' press
key = cv2.waitKey(int(frame_count/1000))
if (key & 0xFF == ord('p')):
# sleep here until a valid key is pressed
while (True):
key = cv2.waitKey(0)
# check if 'p' is pressed and resume playing
if (key & 0xFF == ord('p')):
break
# check if 'b' is pressed and rewind video to the previous frame, but do not play
if (key & 0xFF == ord('b')):
cur_frame_number = cap.get(cv2.CAP_PROP_POS_FRAMES)
print('* At frame #' + str(cur_frame_number))
prev_frame = cur_frame_number
if (cur_frame_number > 1):
prev_frame -= 1
print('* Rewind to frame #' + str(prev_frame))
cap.set(cv2.CAP_PROP_POS_FRAMES, prev_frame)
# check if 'r' is pressed and rewind video to frame 0, then resume playing
if (key & 0xFF == ord('r')):
cap.set(cv2.CAP_PROP_POS_FRAMES, 0)
break
# exit when 'q' is pressed to quit
elif (key & 0xFF == ord('q')):
break
# release resources
cap.release()
cv2.destroyAllWindows()
按键选项:
q
退出应用程序。 p
暂停。 p
继续播放。 b
快退单帧。您必须按 p
才能再次继续播放。 r
回退到第 0 帧并自动恢复播放。 关于python - 在opencv中使用倒带,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/59964279/