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• Android - merge videos taken with front and back cameras

  3 mai 2023, par Raz Leshem

  I am having an orientation problem when merging videos taken with front and back cameras in portrait, recorded using Android CameraX.

  


  This issue is explained here, but I am yet to find a working solution. I have tried multiple solutions, such as using mp4parser as suggested in the issue explanation, but the result is a that every alternate camera video is upside down.
I also tried using FFmpeg for android - mobile-ffmpeg.
Using ffmpeg Concat demuxer resulted in the same result as mp4parser did.

  


  Concat demuxer command I used : ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mp4

  


  I also tried changing the rotation metadata of the videos to match before concatenating, similar to how it's done here, but that did not seem to have any effect on the end result.

  


  Lastly, I used ffmpeg Concat filter. That solution took longer obviously because of the re-encoding of the video but it did fix the problem of the orientation of the videos, but the output video quality was poor.

  


  Concat filter command :

  


  ffmpeg -i front1.mp4 -i rear1.mp4 -i front2.mp4 \
-filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] \
concat=n=3:v=1:a=1 [v] [a]" \
-map "[v]" -map "[a]" output.mp4


  


  Has anyone found a solution on how to fix the orientation problem in android ? or maybe how can I keep the videos quality as much as possible when using the FFmpeg Concat filter to merge the videos ?

  


• Trim video with ffmpeg is very slow

  29 septembre 2020, par mdkamrul

  I wanted to trim video with ffmpeg worker mp4 but this going very slow during the process the video here is my command for this

  


  ["-y", "-i", "video.mp4", "-ss", "00:00", "-to", "00:07", "output.mp4"]


  


  the video is trimming but with very slow and not working with mobile device showing memory allocation error. please help me for this

  


• ffmpeg encoded video has video/audio sync delay when uploading to Facebook & WhatsApp

  13 décembre 2019, par royherma

      "fluent-ffmpeg": "^2.1.2",
  
      "ffmpeg": "^0.0.4",
  
      node : 8

  Code to reproduce

  let command = ffmpeg()
  
          .input(tempFilePath)
  
          .input(watermarkFilePath)
  
          .complexFilter([
  
              "[0:v][1:v]overlay=W-w-20:H-h-20"
  
          ])
  
          .videoBitrate(2500)
  
          .videoCodec('libx264')
  
          .audioCodec('aac')
  
          .format('mp4')
  
          .output(targetTempFilePath)

  When applying the ffmpeg encoding command on the attached video, it plays fine on a local device - the issue however is when uploading to Facebook/WhatsApp the audio/video becomes out of sync

  Any ideas on what i need to change in terms of the video/audio settings so that the audio + video are in sync, even when uploaded to the various social networks ?

  Here’s a link to the 3 video files (original, post ffmpeg, post whatsapp upload that includes delay) if you want to get a better idea !

  https://wetransfer.com/downloads/445dfaf0f323a73c56201b818dc0267b20191213052112/24e635

  Thank you and appreciate any help !!