使用python将opencv图像传输到ffmpeg

Question

如何将openCV图像传输到ffmpeg(作为子进程运行ffmpeg)？(我正在使用spyder/anaconda)

我正在从视频文件中读取帧并在每个帧上进行一些处理.

import cv2   
cap = cv2.VideoCapture(self.avi_path)
img = cap.read()
gray = cv2.cvtColor(img[1], cv2.COLOR_BGR2GRAY)
bgDiv=gray/vidMed #background division

然后,为了将处理过的帧传递给ffmpeg,我在一个相关问题中找到了这个命令:

sys.stdout.write( bgDiv.tostring() )

接下来,我试图将ffmpeg作为子进程运行:

cmd='ffmpeg.exe -f rawvideo -pix_fmt gray -s 2048x2048 -r 30 -i - -an -f avi -r 30 foo.avi'
sp.call(cmd,shell=True)

(这也来自上面提到的帖子)然而,这填充了我的IPython控制台与神秘的象形文字然后崩溃它.任何建议？

最终,我想输出4个流并让ffmpeg并行编码这4个流.

Answer 1

我有过类似的问题一次.我在Github上打开了一个问题,原来这可能是一个平台问题.

与您的问题相关,您也可以将OpenCV图像传输到FFMPEG.这是一个示例代码:

# This script copies the video frame by frame
import cv2
import subprocess as sp

input_file = 'input_file_name.mp4'
output_file = 'output_file_name.mp4'

cap = cv2.VideoCapture(input_file)
ret, frame = cap.read()
height, width, ch = frame.shape

ffmpeg = 'FFMPEG'
dimension = '{}x{}'.format(width, height)
f_format = 'bgr24' # remember OpenCV uses bgr format
fps = str(cap.get(cv2.CAP_PROP_FPS))

command = [ffmpeg,
        '-y',
        '-f', 'rawvideo',
        '-vcodec','rawvideo',
        '-s', dimension,
        '-pix_fmt', 'bgr24',
        '-r', fps,
        '-i', '-',
        '-an',
        '-vcodec', 'mpeg4',
        '-b:v', '5000k',
        output_file ]

proc = sp.Popen(command, stdin=sp.PIPE, stderr=sp.PIPE)

while True:
    ret, frame = cap.read()
    if not ret:
        break
    proc.stdin.write(frame.tostring())

cap.release()
proc.stdin.close()
proc.stderr.close()
proc.wait()

Answer 2

我有点晚了，但是我强大的VidGear Python 库可以通过其WriteGear API 的压缩模式，在任何平台上自动将 OpenCV 帧管道化到 FFmpeg 中。OP，您可以按如下方式实现您的答案：

# import libraries
from vidgear.gears import WriteGear
import cv2

output_params = {"-s":"2048x2048", "-r":30} #define FFmpeg tweak parameters for writer

stream = cv2.VideoCapture(0) #Open live webcam video stream on first index(i.e. 0) device

writer = WriteGear(output_filename = 'Output.mp4', compression_mode = True, logging = True, **output_params) #Define writer with output filename 'Output.mp4' 

# infinite loop
while True:
    
    (grabbed, frame) = stream.read()
    # read frames

    # check if frame empty
    if not is grabbed:
        #if True break the infinite loop
        break
    

    # {do something with frame here}
        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    # write a modified frame to writer
    writer.write(gray) 
       
    # Show output window
    cv2.imshow("Output Frame", frame)

    key = cv2.waitKey(1) & 0xFF
    # check for 'q' key-press
    if key == ord("q"):
        #if 'q' key-pressed break out
        break

cv2.destroyAllWindows()
# close output window

stream.release()
# safely close video stream
writer.close()
# safely close writer

来源： https: //abhitronix.github.io/vidgear/latest/gears/writegear/compression/usage/#using-compression-mode-with-opencv

您可以查看VidGear 文档以了解更多高级应用程序和功能。

希望有帮助！