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• ffmpeg : Combine png frames with transparent background into a video and merge with an image

  15 avril 2023, par andyts93

  I'm trying to combine multiple png frames into a video with ffmpeg, keeping the transparency, to then combine it with an image.
The png video comes with a black background so when i try to combine it with an image, the image is completely overlayed by the black background, how can I keep the transparency ?

  


  Here's the command to combine the PNGs :

  


  ffmpeg -y -i src/tmp/%d.png -c:v libx264 -vf fps=25 -pix_fmt yuva420p land.mov

  


• How to convert 4:3 video to 16:9 without stretching the original in ffmpeg

  5 novembre 2016, par carvil

  I would like to convert some 4:3 videos that I took on an iPhone to 16:9, by adding black bars to both sides instead of stretching the video.

  I tried something like this without success :

  ffmpeg -y -i input.mov -aspect 1.7777777777777777 -s 640x360 output.mp4

  Even though the output has the correct size, the video is stretched, which is not what I want.

  How can I keep the proportion between the width and height of the original video, and add extra black bars to both sides to avoid stretching ?

  This would be similar to how YouTube does it when uploading a video from an iPhone directly to YouTube.

  Thanks !

• How to trim multiple videos and position them to specific position using -filter_complex ?

  16 décembre 2023, par Pavlo Holotiuk

  How do I mix several videos and have them not overlap each other ?
I need to use -filter_complex as I cram many more commands there and seems weird how when I trim video its frames remain and overlap with the other video. I also use tpad to paint the video black where it supposed to be cut but it just makes black images to overlap with other videos instead.

  


  How do I trim and position videos with mix and make sure their frames do not overlap in result ?
Here's the version vithout tpad

  


  ./ffmpeg.exe -i input1.mp4 -i input2.mp4 -filter_complex "[0]trim=start=0:end=5[t0];[1]trim=start=5:end=10[t1];[t0][t1]mix=inputs=2" ./output.mp4

  


  It produces such overlapping frames


  


  When adding tpad overlapping changes to mix of frame and black image

  


  ./ffmpeg.exe -i input1.mp4 -i input2.mp4 -filter_complex "[0]trim=start=0:end=5[t0];[1]trim=start=5:end=10,setpts=PTS-5/TB,tpad=start_duration=5:start_mode=add:color=black@0x00[t1];[t0][t1]mix=inputs=2" ./output.mp4

  


  

  


  The alpha in tpad doesn't seem to do anything either.