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• How to scroll image using ffmpeg, and stop immediately when bottom of image is aligned with bottom of video ?

  5 septembre 2022, par eivindml

  I'm using this command to create a video of a long image (webpage screenshot) :

  


  ffmpeg -f lavfi -i color=s=1920x1080 -loop 1 -t 0.08 -i "input.png" -filter_complex "[1:v]scale=1920:-2,setpts=if(eq(N\,0)\,0\,1+1/0.02/TB),fps=25[fg]; [0:v][fg]overlay=y=-'t*h*0.02':eof_action=endall[v]" -map "[v]" output.mp4


  


  It works, but and issue is that it scrolls the image all the way out of the view. How can I change the command, so that it stops just as the last row of pixels of the image is visible ?

  


• How to perform Video Trimming & Merging Performance in Mobile App ? [closed]

  5 mai 2024, par Harpreet Singh.8052

  I am in the process of developing an app that will allow users to trim and merge recorded videos similar to Snapchat and Instagram stories. Currently, I am using FFmpeg for video processing, but it is taking too long to complete. I have come up with an idea to use ExoPlayer to minimize processing time. My plan is to store the trimmed duration of multiple videos and only play the trimmed part when the video is played. ExoPlayer allows playing multiple videos seamlessly, so it will appear as if the videos have been trimmed and merged. However, I am uncertain about how to handle video playback on the server-side when a user uploads all the videos and metadata about the video, such as the trimmed part from where to where they want to play. If I follow this approach, I will need to first get all the videos to the user's device before playback, but the videos can be long, ranging from 10 to 30 minutes, making this approach impractical. I would like to play them in a video stream manner. 

  


  I am also curious about how other video editing apps such as CapCut or Kinemaster handle video processing tasks like trimming, merging, and slow-mo. What video processing tools do they use ? When I tried merging ten one-minute videos, it took around 10 minutes on my Android phone, but these editing apps take less time. 

  


  I would appreciate any approach or idea to improve the processing time for video trimming and merging

  


• mp4 subtitle issue of traf/trun

  24 octobre 2023, par Tany

  I'm implementing a progressive mp4 muxer to create a fmp4 with h264 video, aac audio, and tx3g subtitles. VLC can currently play the video I created (link), but the subtitles are not shown. I use ffmpeg to create a different video (link) for comparison. I examine the mp4 boxes of these two films using the mp4 parsers bento4-mp4dump(https://www.bento4.com/) and online mp4 parser(https://gpac.github.io/mp4box.js/test/filereader.html) (in particular, moov, moof, tref, trun and subtitle samples)

  


  subtitle samples of ffmpeg generated video :


  


  subtitle samples of my muxer generated video :


  


  moov-trak-mdia-stbl-stsd-tx3g boxes are basically the same.
I can not figure out what's wrong with the moof-traf-trun boxes.

  


  Any help would be greatly appreciated.