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• Concatenate multiple mp2 files with constant frame rate 30 results in output with variable frame rate 29.xxx

  2 juin 2020, par cipacda

  I am looking to concatenate multiple mp4 files (hundreds) that I am generating using ffmpeg previously.

  



  I am making sure they have the same codec details and all of them have a constant frame rate of 30FPS.

  



  However, when I concat them using either demuxer or protocol methods, the result has a lower frame rate (i.e. 29.96).

  



  Investigating using ffprobe, looks like the total number of frames match, but the duration is the one that changes.

  



  It is important to be able to do the concatenation without re-encoding as a fast result is needed (all the individual files are created in parallel tasks).

  


• Imageio unable to read webcam at correct framerate

  28 mai 2019, par Jason Nick Porter

  I’m trying to read frames from a webcam and analyze them in realtime, but since my function AnalyzeFrame() is faster than the framerate, it ends up pulling the same frame 1-4 times in a row, messing up my data. Here’s basically what I’m running.

  import imageio
  
  
  
  cam = imageio.get_reader('<video0>', fps=30)
  
  
  
  while not cam.closed:
  
      print(AnalyzeFrame(cam.get_next_data()))
  
  </video0>

  A few notes : My webcam should be able to handle 30fps, but I’m averaging 12-14 fps. I’ve timed each individual process and there’s very little regularity to the framerate. Some frames only get analyzed once, because they’re in the buffer for 20 or so milliseconds. Others get analyzed 4 times over a span of 100+ ms. Is there something in my code that’s causing this framerate problem ?

• How do I convert this ffmpeg command to be used in ffmpy ?

  8 janvier 2017, par user7389159

  I have a gif that I am taking apart frame by frame in order to write text onto it. I used ffmpeg to put the frames (saved as individual .png files) back together and it worked nicely. This is the code I used :

  ffmpeg -f image2 -i newimg%d.png out.gif

  But now I want to use the python wrapper ffmpy. Following the docs, I tried a variety of things but I keep getting syntax errors.

  Here is one instance of my efforts :

  ff = ffmpy(FFmpeg(inputs = {ffmpeg -f image2 -i "newimg%d.png"}, outputs = {"gif_with_text.gif"}))
  
  ff.run()

  In this attempt, the syntax error points to the "2" in image2. Could someone help me out ? Note - I’m new to python, let alone ffmpeg and ffmpy.