我想从网络摄像头捕获视频并使用opencv将其保存到mp4文件。我在stackoverflow（下面）上找到了很好的示例代码。唯一的障碍是我试图将其保存为mp4，而不是avi。我不能得到的部分是＆＃39; XVID＆＃39;传递给FOURCC作家的论点应该是，我认为是一个mp4编解码器（来自this link）。如果我将文件名更改为＆＃39; output.mp4＆＃39;它告诉我标签无效，所以我不得不相信XVID编解码器实际上是在创建一个avi文件。这是一个愚蠢的问题吗？我怎么写mp4？
我发现链接显示如何在事后将avi转换为mp4，但这似乎效率低下。好像我应该能够在最初的写作中做到这一点。
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
# Define the codec and create VideoWriter object
fourcc = cv2.cv.CV_FOURCC(*'XVID')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))
while(cap.isOpened()):
ret, frame = cap.read()
if ret==True:
frame = cv2.flip(frame,0)
# write the flipped frame
out.write(frame)
cv2.imshow('frame',frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
# Release everything if job is finished
cap.release()
out.release()
cv2.destroyAllWindows()
答案 0 :(得分：33)
这对我有用。
self._name = name + '.mp4'
self._cap = VideoCapture(0)
self._fourcc = VideoWriter_fourcc(*'MP4V')
self._out = VideoWriter(self._name, self._fourcc, 20.0, (640,480))
答案 1 :(得分：6)
您的代码中有些事情需要更改：
0x7634706d：out = cv2.VideoWriter('output.mp4',0x7634706d , 20.0, (640,480)) 答案 2 :(得分：2)
对我有用的是确保输入“帧”的大小等于输出视频的大小（在这种情况下为（680，480））。
http://answers.opencv.org/question/27902/how-to-record-video-using-opencv-and-python/
这是我的工作代码（Mac OSX Sierra 10.12.6）：
brew install openh264
注意：我按照@ 10SecTom的建议安装了openh264，但不确定是否与问题有关。
以防万一：
node_modules答案 3 :(得分：2)
这对我有用，我添加了images.sort（）来保持顺序顺序：
import cv2
import numpy as np
import os
image_folder = 'data-set-race-01'
video_file = 'race-01.mp4'
image_size = (160, 120)
fps = 24
images = [img for img in os.listdir(image_folder) if img.endswith(".jpg")]
images.sort()
out = cv2.VideoWriter(video_file, cv2.VideoWriter_fourcc(*'MP4V'), fps, image_size)
img_array = []
for filename in images:
img = cv2.imread(os.path.join(image_folder, filename))
img_array.append(img)
out.write(img)
out.release()
答案 4 :(得分：1)
这是default code用于保存摄像机拍摄的视频
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
# Define the codec and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))
while(cap.isOpened()):
ret, frame = cap.read()
if ret==True:
frame = cv2.flip(frame,0)
# write the flipped frame
out.write(frame)
cv2.imshow('frame',frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
# Release everything if job is finished
cap.release()
out.release()
cv2.destroyAllWindows()
捕获了FULL HD
使用
cap = cv2.VideoCapture(0,cv2.CAP_DSHOW)
cap.set(3,1920)
cap.set(4,1080)
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (1920,1080))
保存的文件超过150MB
然后必须使用ffmpeg来减少保存的文件的大小，具体取决于使用30MB更改的视频质量，60MB至crf CRF越低，视频质量越好，生成的文件越大。您还可以更改格式avi，mp4，mkv等
然后我发现了ffmpeg-python
以下代码使用numpy array将每个帧的ffmpeg-python保存为视频
import numpy as np
import cv2
import ffmpeg
def save_video(cap,saving_file_name,fps=33.0):
while cap.isOpened():
ret, frame = cap.read()
if ret:
i_width,i_height = frame.shape[1],frame.shape[0]
break
process = (
ffmpeg
.input('pipe:',format='rawvideo', pix_fmt='rgb24',s='{}x{}'.format(i_width,i_height))
.output(saved_video_file_name,pix_fmt='yuv420p',vcodec='libx264',r=fps,crf=37)
.overwrite_output()
.run_async(pipe_stdin=True)
)
return process
if __name__=='__main__':
cap = cv2.VideoCapture(0,cv2.CAP_DSHOW)
cap.set(3,1920)
cap.set(4,1080)
saved_video_file_name = 'output.avi'
process = save_video(cap,saved_video_file_name)
while(cap.isOpened()):
ret, frame = cap.read()
if ret==True:
frame = cv2.flip(frame,0)
process.stdin.write(
cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
.astype(np.uint8)
.tobytes()
)
cv2.imshow('frame',frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
process.stdin.close()
process.wait()
cap.release()
cv2.destroyAllWindows()
break
else:
process.stdin.close()
process.wait()
cap.release()
cv2.destroyAllWindows()
break
答案 5 :(得分：1)
任何正在寻找使用OpenCV或FFmpeg编写MP4文件的最方便，最可靠的方法的人，可以看到我最新的VidGear视频处理Python库的WriteGear API可以同时使用OpenCV backend和FFmpeg backend甚至supports GPU encoders。这是在带有FFmpeg后端的WriteGear中使用H264编码器进行编码的示例：
# import required libraries
from vidgear.gears import WriteGear
import cv2
# define suitable (Codec,CRF,preset) FFmpeg parameters for writer
output_params = {"-vcodec":"libx264", "-crf": 0, "-preset": "fast"}
# Open suitable video stream, such as webcam on first index(i.e. 0)
stream = cv2.VideoCapture(0)
# Define writer with defined parameters and suitable output filename for e.g. `Output.mp4`
writer = WriteGear(output_filename = 'Output.mp4', logging = True, **output_params)
# loop over
while True:
# read frames from stream
(grabbed, frame) = stream.read()
# check for frame if not grabbed
if not grabbed:
break
# {do something with the frame here}
# lets convert frame to gray for this example
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
# write gray frame to writer
writer.write(gray)
# Show output window
cv2.imshow("Output Gray Frame", gray)
# check for 'q' key if pressed
key = cv2.waitKey(1) & 0xFF
if key == ord("q"):
break
# close output window
cv2.destroyAllWindows()
# safely close video stream
stream.release()
# safely close writer
writer.close()
答案 6 :(得分：0)
诸如OpenCV: FFMPEG: tag 0x5634504d/'MP4V' is not supported with codec id 13 and format 'mp4 / MP4 (MPEG-4 Part 14)' OpenCV: FFMPEG: fallback to use tag 0x00000020/' ???'之类的问题可能是您输出的视频大小与原始视频不同。您可以先查看视频的帧大小。
答案 7 :(得分：0)
对于仍在解决问题的人。根据{{3}}，我使用了此示例，它对我有用：
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
# Define the codec and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc(*'X264')
out = cv2.VideoWriter('output.mp4',fourcc, 20.0, (640,480))
while(cap.isOpened()):
ret, frame = cap.read()
if ret==True:
frame = cv2.flip(frame,0)
# write the flipped frame
out.write(frame)
cv2.imshow('frame',frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
# Release everything if job is finished
cap.release()
out.release()
cv2.destroyAllWindows()
所以我不得不使用cv2.VideoWriter_fourcc(*'X264')编解码器。使用从源代码编译的OpenCV 3.4.3进行测试。
答案 8 :(得分：0)
fourcc = cv2.VideoWriter_fourcc（*' mp4v '）
与在fourcc中定义的“ MP4V”不同，“ mp4v”不会返回任何错误
对于错误“ OpenCV：FFMPEG：标签0x5634504d /'MP4V'，编解码器ID 13和格式'mp4 / MP4（MPEG-4 Part 14）'不支持'OpenCV：FFMPEG：回退以使用标签0x00000020 /”？ ??'“
答案 9 :(得分：0)
只需将编解码器更改为"DIVX"。该编解码器适用于所有格式。
fourcc = cv2.VideoWriter_fourcc(*'DIVX')
我希望这对您有用！