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• Recording livestream from m3u8 to pipe using ffmpeg results in video with no audio

  30 juillet 2021, par jcvamp

  I'm not very good with ffmpeg, so this code is something I've created through trial and error.
I'm using ffmpeg from VB.net with the arguments :

  


  Dim CL As String = "-y -i " & Chr(34) & URL & Chr(34) & " -t " & Time & " -acodec copy -vcodec copy -f mpeg pipe:pipe1"

  


  The videos end up having no audio. I tried removing '-acodec copy' and '-vcodec copy' and using '-map 0', which creates a video with audio, but the quality is substantially lower. I'd like to retain the quality and still have audio.

  


• Python pipe ffmpeg FileNotFoundError : [WinError 2]

  14 juin 2021, par Fayssal K

  I want to decimate a video by keeping only one frame /10 using the line

  


  from subprocess import Popen, PIPE

p = Popen(['ffmpeg', '-i', './video/myvideo.mp4', '-vf', "select='not(mod(n\,10))'", './decimated.mp4 '], stdin=PIPE)  


  


  It's my first time using ffmpeg, and I unfortunately can't get the problem with subprocess.
Thanks for your help

  


    File "C:\ProgramData\Anaconda3\lib\subprocess.py", line 997, in _execute_child
    startupinfo)

FileNotFoundError: [WinError 2] The system cannot find the file specified


  


• Pipe video frame to OpenCV image and then to FFmpeg

  8 février 2018, par Pureheart

  There is a similar question here :
  Getting ’av_interleaved_write_frame() : Broken pipe’ error
  

  But what should I do if I want to write the data ?

  I put pipe_out.stdin.write(image.tostring()) in the while loop, like this

  FFMPEG_BIN = "/home/media/Downloads/ffmpeg"
  
  import subprocess as sp
  
  import sys
  
  width = 360
  
  height = 240
  
  command_in = [ FFMPEG_BIN,
  
              '-i', '/home/media/Videos/mytestvideo/zhou.avi',
  
              '-f', 'image2pipe',
  
              '-pix_fmt', 'bgr24',
  
              '-vcodec', 'rawvideo', '-']
  
  pipe_in = sp.Popen(command_in, stdout = sp.PIPE, bufsize = 10**8)
  
  
  
  command_out = [ FFMPEG_BIN,
  
          '-y', # (optional) overwrite output file if it exists
  
          '-f', 'rawvideo',
  
          '-vcodec','rawvideo',
  
          '-s', '360x240', # size of one frame
  
          '-pix_fmt', 'bgr24',
  
          '-r', '28', # frames per second
  
          '-i', '-', # The imput comes from a pipe
  
          '-an', # Tells FFMPEG not to expect any audio
  
          #'-vcodec', 'mpeg',
  
          'my_output_videofile.mp4' ]
  
  
  
  pipe_out = sp.Popen( command_out, stdin=sp.PIPE, stderr=sp.PIPE)
  
  
  
  import numpy
  
  import cv2
  
  import pylab
  
  # read width*height*3 bytes (= 1 frame)
  
  while True:
  
      raw_image = pipe_in.stdout.read(width*height*3)
  
      image =  numpy.fromstring(raw_image, dtype='uint8')
  
      image = image.reshape((height,width,3))
  
      pipe_in.communicate()
  
      pipe_out.stdin.write(image.tostring())
  
      pipe_out.communicate()
  
      pipe_in.stdout.flush()
  
      #cv2.imshow('image',image)
  
      #cv2.waitKey(0)
  
      # throw away the data in the pipe's buffer.
  
  
  
  
  
  '''
  
  pipe_in.stdin.close()
  
  pipe_in.stderr.close()
  
  pipe_in.wait()
  
  pipe_out.stdout.close()
  
  pipe_out.stderr.close()
  
  pipe_out.wait()
  
  '''
  
  #pipe_out.stdin.write(image.tostring())

  However, the output video has only 1 frame(the first frame of input video)

  Any ideas ?

  Thanks !