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• Revision 29926 : On branche spip_piwik

  17 juillet 2009, par kent1@… — Log

  On branche spip_piwik

• Writing frames from camera using skvideo.io.FFmpegWriter

  28 juin 2018, par Liam Deacon

  I’m trying to finely control the video encoding of camera image frames captured on the fly using skvideo.io.FFmpegWriter and cv2.VideoCapture, e.g.

  from skvideo import io
  
  import cv2
  
  
  
  fps = 60
  
  stream = cv2.VideoCapture(0)                    # 0 is for /dev/video0
  
  print("fps: {}".format(stream.set(cv2.CAP_PROP_FPS, fps)))
  
  
  
  stream.set(cv2.CAP_PROP_FRAME_WIDTH, 1920)
  
  stream.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080)
  
  print("bit_depth: {}".format(stream.set(cv2.CAP_PROP_FORMAT, cv2.CV_8U)))
  
  
  
  video = io.FFmpegWriter('/tmp/test_ffmpeg.avi', 
  
              inputdict={'-r': fps, '-width': 1920, '-height': 1080},
  
              outputdict={'-r': fps, '-vcodec': 'libx264', '-pix_fmt': 'h264'}
  
  )
  
  
  
  try:
  
      for i in range(fps*10):  # 10s of video
  
          ret, frame = stream.read()
  
          video.writeFrame(frame)
  
  finally:
  
      stream.release()
  
  
  
  try:
  
      video.close()
  
  except:
  
      pass

  However, I get the following exception (in Jupyter notebook) :

  ---------------------------------------------------------------------------
  
  TypeError                                 Traceback (most recent call last)
  
  
  
   in <module>()
  
       18     while range(fps*10):
  
       19         ret, frame = stream.read()
  
  ---> 20         video.writeFrame(frame)
  
       21 except BaseException as err:
  
       22     raise err
  
  
  
  /usr/local/lib/python3.6/site-packages/skvideo/io/ffmpeg.py in writeFrame(self, im)
  
      446         T, M, N, C = vid.shape
  
      447         if not self.warmStarted:
  
  --> 448             self._warmStart(M, N, C)
  
      449 
  
      450         # Ensure that ndarray image is in uint8
  
  
  
  /usr/local/lib/python3.6/site-packages/skvideo/io/ffmpeg.py in _warmStart(self, M, N, C)
  
      412         cmd = [_FFMPEG_PATH + "/" + _FFMPEG_APPLICATION, "-y"] + iargs + ["-i", "-"] + oargs + [self._filename]
  
      413 
  
  --> 414         self._cmd = " ".join(cmd)
  
      415 
  
      416         # Launch process
  
  
  
  TypeError: sequence item 3: expected str instance, int found
  
  </module>

  Changing this to video.writeFrame(frame.tostring()) results in ValueError: Improper data input, leaving me stumped.

  How should I go about writing each frame (as returned by OpenCV) to my FFmpegWriter instance ?

  EDIT

  The code works fine if I remove inputdict and outputdict from the io.FFmpegWriter call, however this defeats the purpose for me as I need fine control over the video encoding (I am experimenting with lossless/near-lossless compression of the raw video captured from the camera and trying to establish the best compromise in terms of compression vs fidelity for my needs).

• ultimate video player not working with one video (Uncaught in promise)

  29 octobre 2018, par completeidiothereDoh

  So I have a small website that I have yet to launch using PHP / MySQL. One section there is a video player, and I am using the Ultimate video player script beecause it easily allowed me to change some codes to insert ads, etc. So far I’ve only added about 20 videos, mostly downloaded from archive.org. The uploads are processed using FFMPEG, specifically this command :
  exec(’ffmpeg -i ’.$uploadfile.’ -f mp4 ’.$new_flv) ;

  I also do some other things with ffmpeg such as create an animated .gif and a video thumbnail. So far everything has worked. Prior to using the current video script I was using video.js and this issue didn’t happen. Once I switched over to the new script I noticed this one video won’t play. It acts like it wants to play (spinner spins for a few seconds) but ultimately goes back to the pre-play video thumbnail rather than playing the video.

  I am experiencing this in Google Chrome, though the same thing using Edge. The Chrome console messages reads as follows : Uncaught (in promise) DOMException : The play() request was interrupted by a call to pause().

  The video worked prior to switching to this video player. The file also works attempting to open in Windows. The file works opening directly in Chrome. Plus all other videos work except for this one. I contacted the author and was told that it sounds like an encoding issue and that he isn’t very good at that sort of thing.

  I won’t post the paid script’s js source file here, but I guess I am wondering if anything I’ve listed points to maybe he is correct (although then why did it work in video.js and not uvp ?) and my rudimentary ffmpeg mp4 conversion command needs some work, or else perhaps some of the research I’ve done on this google chrome console message can fix the issue. I don’t believe I can make the corrections myself but I’m curious if anyone suspects this is really an encoding issue.

  I’ve only managed to add about 20 videos, so so far 1/20, or 5% videos aren’t working. I am worried that ignoring a video that isn’t working now, once there are thousands of videos, then maybe 100 won’t work, etc. Furthermore, although probably mostly SERPS (since I haven’t technically launched yet), the video in question has the most views haha. So if it is attracting more organic traffic than the other videos I would obviously like to have it working again.

  I may need to move back to video.js, but the reason I switched was I was having a difficult time (not being an excellent coder) attempting to implement an ads system. Oh well, thanks if anyone has any suggestions or ideas.