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• Issues grabbing frames from an mp4 video using ffmpeg on java

  31 mars 2015, par TamirW

  I am trying to grab a few frames from an mp4 video files using the ffmpeg library (java). Code snippet below.
  The issues I’m facing are :

  • In some (but not all) the videos I’m testing, I am getting the following warning when grabbing the frames : [swscaler @ 0x7fa642a53600] bad src image pointers
  • Sometimes, the frames I get are just blanks (black), sometimes they contain the last frame in the video (meaning that ALL the frames show the same image). Interestingly, when I’m not getting the above warning, the frames are just fine.

  Any clue or direction about how to debug/solve this issue would be greatly appreciated.

      FFmpegFrameGrabber g = new FFmpegFrameGrabber(video);
  
      List<bufferedimage> frames = new ArrayList<bufferedimage>();
  
      try {
  
          g.start();
  
  
  
          int i = 1, noOfFrames = g.getLengthInFrames();
  
          long FR = Math.round(g.getFrameRate());
  
  
  
          while (i &lt; noOfFrames) {
  
              g.setFrameNumber(i);
  
              IplImage img = g.grab();
  
              BufferedImage bimg = img.getBufferedImage();
  
              frames.add(bimg);
  
  
  
              i += FR;
  
          }
  
  </bufferedimage></bufferedimage>

• Understanding ffmpeg -benchmark results

  6 septembre 2022, par Ivy Growing

  Adding -benchmark flag to ffmpeg command resutls with addition of following 2 lines in the shell output :

  


  bench: utime=10.125s stime=4.234s rtime=5.606s
bench: maxrss=110080kB


  


  The maxrss serves to indicate the maximum RAM used during the ffmpeg execution. The utime, stime, rtime indicate accordingly :

  


  

  • user time ;

  


  • system time ;

  


  • real time.

  


  


  I tried to understand the meaning of these times from the source code and failed. Please, help.

  


  

  1. Which of these times indicate how much time was human waiting while the ffpmeg was processing the video ?

  


  2. Can this time be seen directly or it's a combination/calculation of these 3 parameters ?

  


  3. How it can be for certain videos utime > rtime and for others utime < rtime ?

  


  


• vaapi_h264 : Add trivial support for low-power encoding

  18 mai 2016, par Mark Thompson

  vaapi_h264 : Add trivial support for low-power encoding
  Experimental ; requires Skylake and VAAPI 0.39.1 (not yet released).
  
  Also increases the allowed range of the quality option - in low-power
  
  mode, the Intel driver supports levels 1-8 (and 0 meaning default).
  

  • [DBH] libavcodec/vaapi_encode_h264.c