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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.

• FFmpeg How to write video to a file

  9 décembre 2014, par NoviceAndNovice

  What i want is

   1. Get video packet from stream source
  
   2. Decode it
  
   3. And write  that decoded data as video file(avi, mpeg etc)

  I can able to get video Packets from a file (as AVPacket) and also can decode and save as an image.(raw)( FFmpeg tutorials show how to do it).
  But i can not ( do not know ) write that video data to a file(other) which can be played by media players(such as VLC).

  Best Wishes

  Ps : Real code samples will be great if possible...

  Now i make test with av_interleaved_write but i got strange error "non monotone timestamps" ( i have no control over pts values of media source )

  Some Extra Info

  In FFmpeg I have to

  1. Read media packets from media source ( it may be real file(.avi,mov) or even rtsp server).
  2. Then write those media packets to a real file (physical .avi, .mov etc file)

  I need reader and writer. I can read the media source file ( even encode packets according to given format). But i can not write to file...(which any player can play)

  And some pseudoCode

  File myFile("MyTestFile.avi");
  
  
  
  while ( source ->hasVideoPackets)
  
  {
  
       packet = source->GetNextVideoPacket();
  
       Frame decodedFrame = Decode(packet);
  
       VideoPacket encodedPacket = Encode( decodedFrame);
  
       myFile.WriteFile(encodedPacket);
  
   }

  Or Just write the original file without encode decode

       File myFile("MyTestFile.avi");
  
  
  
       while ( source ->hasVideoPackets)
  
       {
  
           packet = source->GetNextVideoPacket();
  
           myFile.WriteFile(packet);
  
       }

  Then

  I can able to open MyTest.avi file with a player.

• Simple mp3 audio extract from video (mp4/avi/webm etc) using Python script (moviepy)

  28 mai 2016, par Bam

  I’m trying to run this very simple python script to extract mp3 from a video.

  Here’s the code :

  import moviepy.editor as mp
  
  clip = mp.VideoFileClip("test.webm")
  
  clip.audio.write_audiofile("test.mp3")

  I’m running this on a Mac and moviepy/ffmpeg seem to be correctly installed. I get the following error :

  Traceback (most recent call last):
  
    File "/Users/XXXXXX/Code/python/000014 - convert mp4 to mp3.py", line 2, in <module>
  
      clip = mp.VideoFileClip("test.webm")
  
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/moviepy/video/io/VideoFileClip.py", line 55, in __init__
  
      reader = FFMPEG_VideoReader(filename, pix_fmt=pix_fmt)
  
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/moviepy/video/io/ffmpeg_reader.py", line 32, in __init__
  
      infos = ffmpeg_parse_infos(filename, print_infos, check_duration)
  
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/moviepy/video/io/ffmpeg_reader.py", line 250, in ffmpeg_parse_infos
  
      if "No such file or directory" in lines[-1]:
  
  IndexError: list index out of range
  
  </module>

  The source file is in the same directory as the code is being run in.

  The same code ran fine on a Windows pc.

  Any ideas ? thanks