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• Python ffmpeg subprocess : Broken pipe [closed]

  11 décembre 2022, par Pikkostack

  The following script reads a video with OpenCV, applies a transformation to each frame and attempts to write it with ffmpeg. My problem is, that I don't get ffmpeg working with the subprocess module. I always get the error BrokenPipeError: [Errno 32] Broken pipe in the line where I try to write to stdin. Why is that, what am I doing wrong ?

  



  # Open input video with OpenCV
video_in = cv.VideoCapture(src_video_path)
frame_width = int(video_in.get(cv.CAP_PROP_FRAME_WIDTH))
frame_height = int(video_in.get(cv.CAP_PROP_FRAME_HEIGHT))
fps = video_in.get(cv.CAP_PROP_FPS)
frame_count = int(video_in.get(cv.CAP_PROP_FRAME_COUNT))
bitrate = bitrate * 4096 * 2160 / (frame_width * frame_height)

# Process video in ffmpeg pipe
# See http://zulko.github.io/blog/2013/09/27/read-and-write-video-frames-in-python-using-ffmpeg/
command = ['ffmpeg',
           '-loglevel', 'error',
           '-y',
           # Input
           '-f', 'rawvideo',
           '-vcodec', 'rawvideo'
           '-pix_fmt', 'bgr24',
           '-s', str(frame_width) + 'x' + str(frame_height),
           '-r', str(fps),
           # Output
           '-i', '-',
           '-an',
           '-vcodec', 'h264',
           '-r', str(fps),
           '-b:v', str(bitrate) + 'M',
           '-pix_fmt', 'bgr24',
           dst_video_path
           ]
pipe = sp.Popen(command, stdin=sp.PIPE)

for i_frame in range(frame_count):
    ret, frame = video_in.read()
    if ret:
        warped_frame = cv.warpPerspective(frame, homography, (frame_width, frame_height))
        pipe.stdin.write(warped_frame.astype(np.uint8).tobytes())
    else:
        print('Stopped early.')
        break
print('Done!')


  


• FFmpeg : Pipe segments to s3

  24 septembre 2024, par Brendan Kennedy

  I'd like to pipe ffmpeg segments to s3 without writing them to disk.

  


  ffmpeg -i t2.mp4 -map 0 -c copy -f segment -segment_time 20 output_%04d.mkv


  


  Is it possible to modify this command so that ffmpeg writes segments to an s3 bucket ? Something like this perhaps ?

  


  ffmpeg -i t2.mp4 -map 0 -c copy -f segment -segment_time 20 pipe:1 \
  | aws s3 cp - s3://bucket/output_%04d.mkv


  


  When I run the command above I receive this error

  


  Could not write header for output file #0
(incorrect codec parameters ?): Muxer not found


  


  This command works except the entire video is uploaded and not the individual segments

  


  ffmpeg -i t2.mp4 -map 0 -c copy -f segment -segment_time 20 pipe:output_%04d.mkv \
| aws s3 cp - s3://bucket/test.mkv


  


• OpenCV Python, reading video from named-pipe

  29 février 2020, par BlueNut

  I am trying to achieve results as shown on the video (Method 3 using netcat) https://www.youtube.com/watch?v=sYGdge3T30o
  It is to stream video from raspberry pi to PC and process it using openCV and python.

  I use command

  raspivid -vf -n -w 640 -h 480 -o - -t 0 -b 2000000 | nc 192.168.1.137 8000

  to stream the video to my PC and then on the PC I created name pipe ’fifo’ and redirected the output

  nc -l -p 8000 -v > fifo

  then i am trying to read the pipe and display the result in the python script

  import cv2
  
  import subprocess as sp
  
  import numpy
  
  
  
  FFMPEG_BIN = "ffmpeg.exe"
  
  command = [ FFMPEG_BIN,
  
          '-i', 'fifo',             # fifo is the named pipe
  
          '-pix_fmt', 'bgr24',      # opencv requires bgr24 pixel format.
  
          '-vcodec', 'rawvideo',
  
          '-an','-sn',              # we want to disable audio processing (there is no audio)
  
          '-f', 'image2pipe', '-']    
  
  pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=10**8)
  
  
  
  while True:
  
      # Capture frame-by-frame
  
      raw_image = pipe.stdout.read(640*480*3)
  
      # transform the byte read into a numpy array
  
      image =  numpy.frombuffer(raw_image, dtype='uint8')
  
      image = image.reshape((480,640,3))          # Notice how height is specified first and then width
  
      if image is not None:
  
          cv2.imshow('Video', image)
  
  
  
      if cv2.waitKey(1) & 0xFF == ord('q'):
  
          break
  
      pipe.stdout.flush()
  
  
  
  cv2.destroyAllWindows()

  But I got this error :

  Traceback (most recent call last):
  
    File "C:\Users\Nick\Desktop\python video stream\stream.py", line 19, in <module>
  
      image = image.reshape((480,640,3))          # Notice how height is specified first and then width
  
  ValueError: cannot reshape array of size 0 into shape (480,640,3)
  
  </module>

  It seems that the numpy array is empty, so any ideas to fix this ?