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• how to concat two videos in ffmpeg with adelay ?

  4 janvier 2023, par SMART

  i have 2 videos : outs.mp4 & V2.mp4 .

  


  outs.mp4 is 4 seconds long (no audio).

  


  V2 is 30 seconds long with audio .

  


  now , i want to concat these files ,when i concat , 2nd video's audio is playing at 00:00:00 . what i want is 2nd video's audio should start play after 4 seconds, 00:00:04.002 . so tried this command ,but it runs forever .

  


  ffmpeg -i outs.mp4 -i V2.mp4 -filter_complex "[0:v][1:v]concat=n=2 [v] ;[1:a]adelay=4s [a] ;[a]amix=inputs=1 [a1]" -map "[v]" -map "[a1]" -y output.mp4

  


  what to do ? how to concat 2 or more videos (with or without audio) [audio should match with the video] in ffmpeg ?

  


• How to display name and phone number of a student as dynamic watermark (randomly floating on entire screen) in videos of a paid online video course ?

  22 mai 2020, par Arjun

  I wish to make a Learning Management System using PHP-MySQL and wish to put videos from my computer or embed YouTube videos on it.

  



  Videos will be displayed to only those students who have paid for the course.

  



  I want to show their name and phone number (which they'll be giving during Sign Up) as a dynamic watermark floating randomly on all the videos of that course to prevent screen capturing of the video.

  



  How to do it and how to call those Name and Phone Number values from the MySQL database ?

  


• Scaling videos for device that doesn't support aspect ratio metadata

  18 juillet 2017, par forthrin

  I have hundreds of videos which are all approximately 4:3 format, but with different resolutions and various cropping (eg. videos may be 640x480, 640x470, 630x480, etc.).

  I converted the videos into a fixed screen size (160x128) for a primitive device. When playing the videos on the device, some appear "thin", while in VLC on my computer, the aspect ratio is correct.

  I assume the reason for this is that the video player on the primitive device doesn’t honour the aspect ratio metadata in the video file. Here are two examples of metadata :

  • 320x240 SAR=1:1 DAR=4:3 (Displays correctly on device and desktop)
  • 480x480 SAR=4:3 DAR=4:3 (Displays thin on device, correct on desktop)

  How can I create a general command line that will give all videos correct playback on my primitive device, regardless of their original size and aspect ratio ?

  The best would be to somehow ask ffmpeg to remove the metadata, and compensate for it when scaling. Another possible option would be to add black bars so the video is always 160x128 pixels.

  I’m open to any solution. Below is my current version :

  for f in *; do ffmpeg -i $f -vcodec mpeg4 -vf scale=160:-1 out/$f; done