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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 ?

  


• How do I combine two videos or add a logo using ffmpeg via VB.Net ? [on hold]

  25 janvier 2014, par user3235437

  How do I combine two videos or add a logo using ffmpeg via VB.Net ?

  EG : copy file1.mpg /b + file2.mpg /b output.mpg /b

  How do I execute this code through VB.Net ?

  Thank you for giving example code.

• Merging four videos with differnt resolution in a Grid with ffmpeg

  5 juillet 2015, par Taufiq

  I want to marge four videos in to one as show below. I have achieve the correct output given all the videos have the same resolution. But I get an undesirable result with different resolution. See below for more details.

  ffmpeg code to get to merge 4 videos of different resution in a grid format

  ffmpeg.exe -i "1.avi" -vf "[in] scale=iw:ih, pad=2*iw:ih [left];movie=2.avi, scale=iw:ih [right]; [left][right] overlay=main_w/2:0 [out]" -b:v 768k "Output1.mp4"
  
  ffmpeg.exe -i "3.avi" -vf "[in] scale=iw:ih, pad=2*iw:ih [left];movie=4.avi, scale=iw:ih [right]; [left][right] overlay=main_w/2:0 [out]" -b:v 768k "Output2.mp4"
  
  ffmpeg.exe -i "Output1.mp4" -vf "pad=iw:2*ih [top]; movie=Output2.mp4 [bottom]; [top][bottom] overlay=0:main_h/2" "Output_Stacked.mp4"

  Code above gives the follow output.

  

  But the problem arises when I rotate one of the videos and merge them.
  .

  Please tell me what I need to change to get the desired result. Thanks