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• Python gets stuck at pipe.stdin.write(image.tostring())

  10 mars 2020, par Vandana Rajan

  I am reading each frame of video and adding time stamp to it as given below.

  command = ['ffmpeg',
  
              '-y', # (optional) overwrite output file if it exists
  
              '-f', 'rawvideo', #Input is raw video
  
              '-pix_fmt', 'bgr24', #Raw video format
  
              '-s', str(int(width)) + 'x' + str(int(height)), # size of one frame
  
              '-i', '-', # The input comes from a pipe
  
              '-an', # Tells FFMPEG not to expect any audio
  
              '-vcodec', 'mpeg4',
  
              '-b:v', '10M', #Sets a maximum bit rate
  
              Output_name]
  
      #Open the pipe
  
      pipe = sp.Popen(command, stdin=sp.PIPE, stderr=sp.PIPE)
  
  
  
      print('Processing....')
  
      print(' ')
  
      #Reads through each frame, calculates the timestamp, places it on the frame and exports the frame to the output video.
  
      #import pdb
  
      #pdb.set_trace()
  
      while current_frame < total_frames:
  
          success, image = video.read()
  
          if success:
  
              elapsed_time = video.get(cv2.CAP_PROP_POS_MSEC)
  
              current_frame = video.get(cv2.CAP_PROP_POS_FRAMES)
  
              timestamp = initial + dt.timedelta(microseconds = elapsed_time*1000)
  
              cv2.putText(image, 'Date: ' + str(timestamp)[0:10], (50,int(height-150)), cv2.FONT_HERSHEY_COMPLEX_SMALL, 2, (255, 255, 255), 3)
  
              cv2.putText(image, 'Time: ' + str(timestamp)[11:-4], (50,int(height-100)), cv2.FONT_HERSHEY_COMPLEX_SMALL, 2, (255, 255, 255), 3)
  
              pipe.stdin.write(image.tostring())
  
              print('frame number',current_frame)
  
          else:
  
              print('video reader fail')    
  
      video.release()
  
      pipe.stdin.close()
  
      pipe.stderr.close()

  However, after around 18k frames, Python gets stuck at ’pipe.stdin.write(image.tostring())’. It does not produce any error, but simply hangs. How to resolve this issue ?

  Thanks in advance.

• Pipe PhantomJS output to FFmpeg

  10 avril 2017, par Hasse Andersen

  I am running PhantomJS using Selenium WebDriver (C#).

  I’m trying to video record my browser using FFmpeg as shown in the 2 tutorials :

  https://mindthecode.com/recording-a-website-with-phantomjs-and-ffmpeg/

  https://gist.github.com/phanan/e03f75082e6eb114a35c

  As explained in the tutorials, I’ll need to pipe output the phantomJS process to ffmpeg.

  I know how to add arguments to phantomjs, like the following :

      var svz = PhantomJSDriverService.CreateDefaultService();
  
      svz.AddArgument("ffmpeg -y -c:v png -f image2pipe -r 24 -t 10  -i - -c:v libx264 -pix_fmt yuv420p -movflags +faststart output.mp4");
  
      var driver = new PhantomJSDriver(svz);

  However, I don’t know how to add the argument as pipe. I have tried adding the pipe symbol before the actual argument but that doesn’t seem to work.

  So, my question is, how do I pipe the output of PhantomJS using selenium webdriver ?

• ffmpeg in a bash pipe

  27 décembre 2019, par Martin Wang

  I have a rmvb file path list, and want to convert this files to mp4 files. So I hope to use bash pipeline to handle it. The code is

  Convert() {
  
      ffmpeg -i "$1" -vcodec mpeg4 -sameq -acodec aac -strict experimental "$1.mp4"
  
  }
  
  
  
  Convert_loop(){
  
      while read line; do
  
         Convert $line
  
      done
  
  }
  
  
  
  cat list.txt | Convert_loop

  However, it only handle the first file and the pipe exits.

  So, does ffmpeg affect the bash pipe ?