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• FFMpeg Command work in command line, but not in python script. (Semi Solved)

  20 février 2015, par Fooldj

  Okay, kind of a weird problem. But I’m not sure whether it’s python, ffmpeg, or some stupid thing I’m doing wrong.

  I’m trying to take a video, and take 1 frame a second, and output that frame to an image. Right now, if i use the command line with ffmpeg :

  ffmpeg -i test.avi -r 1 -f image2 image-%3d.jpeg -pix_fmt rgb24 -vcodec rawrvideo

  It outputs about 10 images, the images look fine, awesome. Now I have this code (right now some code from some github, as I wanted stuff that i was relatively sure would work, and mine is allll convoluted)

  import subprocess as sp
  
  import numpy as np
  
  import re
  
  import cv2
  
  import time
  
  
  
  FFMPEG_BIN = r'ffmpeg.exe'
  
  INPUT_VID = 'test.avi'
  
  
  
  def getInfo():
  
      command = [FFMPEG_BIN,'-i', INPUT_VID, '-']
  
      pipe = sp.Popen(command, stdout=sp.PIPE, stderr=sp.PIPE)
  
      pipe.stdout.readline()
  
      pipe.terminate()
  
      infos = pipe.stderr.read()
  
      infos_list = infos.split('\r\n')
  
      res = re.search(' \d+x\d+ ',infos)
  
      res = [int(x) for x in res.group(0).split('x')]
  
      return res
  
  res = getInfo()
  
  command = [ FFMPEG_BIN,
  
          '-i', INPUT_VID,
  
          '-f', 'image2pipe',
  
          '-pix_fmt', 'rgb24',
  
          '-vcodec', 'rawvideo', '-']
  
  pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=10**8)
  
  n = 0
  
  im2 = []
  
  try:
  
      mog = cv2.BackgroundSubtractorMOG2(120,2,True)
  
      while True:
  
          raw_image = pipe.stdout.read(res[0]*res[1]*3)
  
          # transform the byte read into a numpy array
  
          image =  np.fromstring(raw_image, dtype='uint8')
  
          image = image.reshape((res[1],res[0],3))
  
          rgbImg = image.copy()
  
  
  
          fname = ('_tmp%03d.png'%time.time())
  
          cv2.imwrite(fname, rgbImg)
  
          # throw away the data in the pipe's buffer.
  
          #pipe.stdout.flush()
  
          n += 1
  
          print n
  
  except:
  
      print 'done',n
  
      pipe.kill()
  
      cv2.destroyAllWindows()

  When I run this, I get 10 images, but they all have a Blue Tint ! I cannot for the life of me figure out why. I’ve done tons of searches, I’ve tried quite a few different codecs (usually just messes things up worse). The media info for the video file is here :

   General
  
   Complete name                            : test.avi
  
  Format                                   : AVI
  
  Format/Info                              : Audio Video Interleave
  
  File size                                : 85.0 KiB
  
  Duration                                 : 133ms
  
  Overall bit rate                         : 5 235 Kbps
  
  
  
  Video
  
  ID                                       : 0
  
  Format                                   : JPEG
  
  Codec ID                                 : MJPG
  
  Duration                                 : 133ms
  
  Bit rate                                 : 1 240 Kbps
  
  Width                                    : 640 pixels
  
  Height                                   : 480 pixels
  
  Display aspect ratio                     : 4:3
  
  Frame rate                               : 30.000 fps
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:2
  
  Bit depth                                : 8 bits
  
  Compression mode                         : Lossy
  
  Bits/(Pixel*Frame)                       : 0.135
  
  Stream size                              : 20.1 KiB (24%)

  Any suggestions ? It seems like it should be an RGB mixup...just not sure where at...

  EDIT : So I fixed the problem by switching the blue and red channels with this code :
  bChannel = rgbImg[ :, :,0]
  rChannel = rgbImg[ :, :,2]
  gChannel = rgbImg[ :, :,1]

              rgbArray = np.zeros((res[1],res[0],3), 'uint8')
  
              rgbArray[...,0] = rChannel
  
              rgbArray[...,1] = gChannel
  
              rgbArray[...,2] = bChannel

  So I guess this is now a question of, why is python mixing up these channels ? Is it a problem with python, or ffmpeg, the codec ?

  Thanks !

• ffmpeg concatenate videos - what metadata needs to match [duplicate]

  13 juillet 2022, par yarrichar

  I am trying to concatenate videos that can come from a variety of sources.

  


  I was just using the -f concat option, but this runs into issues when the formats don't watch.

  


  I can use the filter_complex option (as described in the wiki - https://trac.ffmpeg.org/wiki/Concatenate) but this is much slower.

  


  What metadata (codec, bitrate, fps, etc) needs to match so that I can use the faster -f concat option to join the videos ? My understanding here is not great atm.

  


• Error : "No such option : -l" when running yt-dlp

  12 juin 2022, par garson

  I have adapted code from this Stack Overflow answer to try to download a video and use ffmpeg to alter it

  


  yt-dlp    "https://www.youtube.com/watch?v=PtkqwslbLY8" -o  ffmpeg -i in.mp4 -vcodec libx264 -crf 23 -preset fast -profile:v baseline \
-level 3 -refs 6 -vf "scale=640:-1,pad=iw:480:0:(oh-ih)/2,format=yuv420p" \
-acodec copy output.mp4


  


  However, when I run this I'm getting the error :

  


  yt-dlp: error: no such option: -l


  


  Any ideas of how to fix this ?