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• how to use ffmpeg filter_complex left to right transition

  23 octobre 2016, par Sylvie Shamir

  I’m trying to use ffmpeg filter_complex left to right transition so I have used this code :

  ffmpeg  -loop 1 -t 3.3333333333333 -i /tmp/img_580cb3cc39080_0.png 
  
          -loop 1 -t 5 -i /tmp/img_580cb3cc39080_0.png 
  
          -loop 1 -t 3.3333333333333 -i /tmp/img_580cb3cc39080_1.png 
  
          -loop 1 -t 5 -i /tmp/img_580cb3cc39080_1.png 
  
          -loop 1 -t 3.3333333333333 -i /tmp/img_580cb3cc39080_2.png 
  
          -loop 1 -t 5 -i /tmp/img_580cb3cc39080_2.png 
  
          -filter_complex "
  
          [1:v][3:v] overlay=x='(-w+(t)*((1/5)*(w)))':y=0[b1v];
  
          [3:v][5:v] overlay=x='(-w+(t)*((1/5)*(w)))':y=0[b3v]; 
  
          [0:v][b1v][2:v][b3v][4:v]concat=n=5:v=1:a=0,format=yuv420p[v]" -map "[v]" /var/zelda/public_dyn/tmp/video_580cb3cc39080.mp4

  and it works fine for the first transition but for the rest it gets stack on the middle and then changes to the next image.
  anyway, if I’m switching between the videos : [1:v][3:v] to be : [3:v][1:v] it works fine.

  Am I using it wrong ? or is it just a bug ?

  here are the two videos to demonstrate :
  video 1 (doesn’t work),
  video 2 (works but images switched)

• avconv : only retry decoding on actual decoding errors

  1er octobre 2016, par Anton Khirnov

  avconv : only retry decoding on actual decoding errors
  Errors during decoding are currently considered non-fatal and do not
  
  terminate transcoding, so even if parts of the data are corrupted, the
  
  rest may be decodable.
  However, that should apply only to the actual decoding calls, not to the
  
  failures elsewhere (e.g. configuring filters).
  

  • [DBH] avconv.c

• FFmpeg : Create a Video Slideshow from PNG Images for MS PowerPoint

  20 septembre 2016, par Klaidonis

  I am using FFmpeg on Windows 7 to create a video from PNG image sequence for Microsoft PowerPoint.

  The best results I have achieved so far, is by using the following command :

  ffmpeg -framerate 10 -start_number 3 -i .\folder\name_%d.png -q:v 0 -c:v libx264 -pix_fmt yuv420p output-video.avi

  It seems perfect, 50 images of total size 30 MB are converted into 200 KB video with no loss in the quality. Placing it in PowerPoint also seems right, but there is a slight color shift (yellow appears darker and possibly more orangish). By using some other conversion options, I obtained a video in PowerPoint where the first image of the video (like album cover art) is exactly as the original but the rest of the video plays with the mentioned color shift.

  When I play this file in VLC, it’s good. Although, if in the settings "Use hardware YUV->RGB conversions" is enabled, colors appear a bit washed out, and white color is a bit gray.

  I also tried to convert the images to a GIF file and at first it seems good but outer edges and numbers from the left and top side are blurred, and the background has turned from white to a bit gray color, although, white segments not on the background are white. The output size is 18 MB. I ended up with a way better GIF 600 KB by converting from the first video file ; just it is slightly more dotted, and the background again is grayish.

  ffmpeg -i output-video.avi output-video.gif

  Could someone help ?