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• blank transparent pngs behave like black canvas

  10 novembre 2015, par Anay Bose

  I am trying to create a scrolling image with imagemagick’s roll and crop functions. Its a frame-by—frame animation. The source image is a transparent png with some text written on it. The following code works and it creates the required frames, including some blank png images at first for a nice, smooth effect. These blank pngs are what creating problems when I am trying to convert my image frames into video with ffmpeg. FFMPEG is seemingly considering these blank pngs as black/dark images, so the resulting video contains a blackout for a few seconds in the beginning—which I do not want.

  I am using png codec with bgra pixel format. My ffmpeg command (shown below) creates smooth, clear animation with images that have some text on it.

  "ffmpeg -i trans/trans-%d.png -vcodec png -pix_fmt bgra overlay-0.mov";

  The blank pngs behave like black canvas, but as I try to write some text on them or surround them with a border (i.e. colorize in some way) the problem disappears—which seems very strange. I have tested all my images ; they are all transparent. For the past few hours, I have been searching for a solution, no luck so far. Please note those blank pngs are required in the beginning for a smooth effect, and I cannot omit them. I have uploaded a sample video in Youtube. Please note the black fade out.

  https://www.youtube.com/watch?v=Te3LuItxcDk&feature=youtu.be

  https://youtu.be/Te3LuItxcDk

  PHP code :

     $increment = 40;
  
     $count = 0; 
  
  
  
     for ($x=40; $x <= 640 ; $x+=$increment) 
  
     {
  
       $roll = new Imagick(DOCROOT . '/composite-0.png');
  
       $roll->rollImage($x, 0);
  
       $roll->writeImage(DOCROOT . '/roll/roll-' . $x . '.png');
  
  
  
      $crop = new Imagick(DOCROOT . '/roll/roll-' . $x . '.png');
  
      $crop->cropImage($x, 720, 0, 0);
  
      $crop->writeImage(DOCROOT . '/roll/crop-' . $x . '.png');
  
  
  
      $extent = new Imagick(DOCROOT . '/roll/crop-' . $x . '.png'); 
  
      # $extent->setImageBackgroundColor(new ImagickPixel('none'));
  
      $extent->setImageBackgroundColor(new ImagickPixel('transparent'));
  
      $extent->extentImage(640, $extent->getImageHeight(), 0, 0);
  
      $extent->setImageFormat('png'); 
  
      $extent->writeImage(DOCROOT . '/trans/trans-' . $count . '.png');
  
  
  
      $count++; 
  
     }

• Concatenating Video Files using FFMPEG YUV issue

  3 novembre 2015, par SpoiledTechie.com

  I am concatenating three videos with FFMPEG.

  The 1st and 3rd video of the concatenation were pulled from an AVI file using FFMPEG and converted into MP4.

  Their codec information is below.

  

  The 2nd video in the concatenation is compiled using FFMPEG. I am compiling frames with FFMPEG to create this video.

  Its codec information is below.

  
  As you can see, the videos share the same codec, resolution and frame rate.

  The only thing they don’t share is the Decoded format. One being 4:4:4 and one being 4:2:2

  I think I understand what YUV means from this link, https://msdn.microsoft.com/en-us/library/windows/desktop/dd391027%28v=vs.85%29.aspx?f=255&MSPPError=-2147217396

  When I concatenate these three videos together, using concat demuxer, it works, but when I try to watch the final video, the video shows the first file playing just right, then the 2nd video in the final video shows up BLANK and the third video plays just fine as well.

  So my question is, how do I concat 3 MP4 files, but change what seems to be the decoded format for the 2nd video to 4:2:2. When I compile the frames, I imagine I can change the YUV format, but I don’t know how just yet.

• Error : avformat_open_input : Protocol not found : -1330794744

  27 octobre 2015, par Lin Juan

  I am building an android stream player using Vitamio.
  Here is my codes :

      mVideoView = (VideoView) findViewById(R.id.videoView);
  
  
  
      path = "https://www.youtube.com/watch?v=vic5gj2qXKg";
  
      mVideoView.setVideoPath(path);
  
  
  
      mVideoView.setMediaController(new MediaController(this));
  
      mVideoView.requestFocus();
  
  
  
      mVideoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
  
          @Override
  
          public void onPrepared(MediaPlayer mediaPlayer) {
  
              mediaPlayer.setPlaybackSpeed(1.0f);
  
          }
  
      });

  But it returns ERROR :

  avformat_open_input : Protocol not found : -1330794744
  error (1, -1330794744)

  I think this error is related to FFMpeg for Vitamio.
  Who can solve this problem ?
  Thank you.