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• Overlay video onto another video at multiple points in time

  22 décembre 2024, par kbcool

  I have a case where I want to have a background video and use a second video overlaying the first but at multiple points in time. The second video is shorter.

  



  So for example the main video is a minute long and the second video is 10 seconds. I want to overlay the second video once at 15seconds then again at 35 seconds and then again at 55 seconds (terminating when the main video does).

  



  I am able to get the second video to overlay successfully using overlay filter and between option but it only ever works for the first overlay. The second overlay seems to show the last or first frame of the video(??) but for the period I set in between. I am guessing it needs to be rewound and played somehow.

  



  Eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[out][1]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  I have also tried specifying the overlay as an input twice eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[out][2]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  The same thing happens.

  



  I'm sure the answer is simple and probably to do with how I'm using inputs but I'm not able to wrap my head around how to get the overlay video to play twice at different times on top of the original.

  



  I have also tried using the setpts filter to rewind the overlay but again the results are exactly the same.

  



  Eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[1]setpts=PTS-STARTPTS,[out]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  There are a lot of similar questions involving overlaying multiple videos but I can't find anything about reusing the same video at multiple points in time.

  


• Text Watermarking on video without loss of audio and video quality

  8 janvier 2021, par Aditya Kumar

  I am using following command to add text watermark on a video file(for mp4, mpg,m4v,flv,mov etc..) :

  


  ffmpeg -i input.mp4 -vf "drawtext=text='Opentext':x=(w-text_w)/2:y=(h-text_h)/2:fontsize=24:fontcolor=white" TextOutput.mp4


  


  For some of the file transformation the property of video file changes. for example- When I tried to add text watermark on a mkv file I got this message :

  


  


  [matroska @ 0000001867d36ec0] Non-monotonous DTS in output stream 0:1 ;
previous : 2273, current : 1596 ; changing to 2273. This may result in
incorrect timestamps in the output file.

  


  


  This is one of the issues, i have mentioned here. There are others as well, such as :

  


  

  • video quality is reduced

  


  • video file size is changed(increses/decreases drastically)

  


  • Audio lagging occurs etc...

  


  


  So, I want to preserve the quality of video after adding the text watermark. How can I do that ?

  


• Is there a way to extract every nth frame from an online video without downloading the entire video ?

  13 avril 2018, par Arif

  I’m looking for a website or app that lets you to download individual frames from a video as jpg without downloading the full thing. If there is no such website or app, is it possible via ffmpeg ?