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• Use palette when using FFMpeg overlay

  16 avril 2017, par nbrogi

  I’m trying to add an overlay to an animated GIF with FFMpeg.

  It works, but the quality is pretty dismal. Basically, I’m unable to use the palette that I generate, and that leads to a lot of dither. The main GIF (meaning, not the overlay) is also very low resolution.

  I would also like to apply opacity to the watermark (and at one point that worked, too), but that’s a plus.

  This is what I have :

  ffmpeg -v error -i image.gif -vf 'palettegen' palette.png -y;
  
  ffmpeg -v error -i image.gif -i watermark.gif -i palette.png -filter_complex '[1:v]scale=80:30, [0:v]overlay=(main_w-overlay_w) - main_h/30:(main_h-overlay_h) - main_h/30, paletteuse' -an image-watermark.gif -y

  At one point I was able to use the palette for the main GIF, so its quality improved. However, the watermark looked pretty bad. It’s pretty obvious that I have to do the overlay, and then the palette, so that the palette include the colors present in the watermark. However, I have no idea how to do that.

  Can someone point me in the right direction ?

• Next drawtext clears the previous one ffmpeg

  27 août 2021, par Макс Шульдинер

  ffmpeg.exe -i ffmpeg_inputs/zheltiy_chelik.mp4  -vf "[in]drawtext=fonts/Temporarium.otf:text='r':fontcolor=orange:fontsize=100:x=(w-text_w)/2+0:y=0:enable='between(t,0, 11)', drawtext =fonts/Temporarium.otf:text = 'r':fontcolor=orange:fontsize=100:x=(w-text_w)/2+20:y=0:enable='between(t,11, 22)', drawtext =fonts/Temporarium.otf:text = 'r':fontcolor=orange:fontsize=100:x=(w-text_w)/2+40:y=0:enable='between(t,22, 33)'[out]" ffmpeg_outputs/test2.mp4 -y 


  


  There is such a ffmpeg line. Its meaning is to draw a letter 20 pixels to the right of the current position of the word every 11 seconds, and in this way "write the word". But here's the problem - when the second letter starts to render, it overwrites the first, and the third, respectively, overwrites the second. The string seems to have prescribed [in] and [out] but does not help, maybe someone has ideas

  


• 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>