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• How to stack several videos using ffmpeg ?

  13 juillet 2019, par John

  I have four cameras that are recording videos and wand to stack all videos into one video file. The final video must be a 2x2 grid.

  

  THE HARD PART is that sometimes cameras are not recording simultaneously.

  Here you can see one situation of how cameras are recording :

  Camera 1 timeline: |recording....................................|
  
  Camera 2 timeline: |stopped....|recording........................|
  
  Camera 3 timeline: |recording.........|stopped....|recording.....|
  
  Camera 4 timeline: |recording..................|stopped..........|

  Explanation :

  • Camera 1 is recording all time.
  • Camera 2 is starting recording later.
  • Camera 3 is recording, then stopped a period of time, then again recording.
  • Camera 4 is recording a period of time, then stopped.

  In the final video I want to synchronize each video by timestamps.

  If a camera is stopped a period of time then at its position must be a black portion.

  How can I do this ?

• ffmpeg_kit_flutter operation not permitted for audio operations

  25 août 2023, par Black Eyed Beans

  I'm trying to trim an audio file using ffmpeg_kit_flutter but I keep getting the error :

  


  audio/path/output.mp3: Operation not permitted.


  


  This is the ffmpeg command that I'm using :

  


  final cmd="-y -i \"$audioPath\" -ss $audioStartTime -to $audioEndTime -c:a libmp3lame $outPutName";


  


  And I've also tried :

  


  final cmd="-y -i \"$audioPath\" -ss $audioStartTime -to $audioEndTime -c copy $outPutName";


  


  But the error is still the same.
I'm using the ffmpeg_kit_flutter_full_gpl package.

  


• Combining multiple image files into a video while using filter_complex to apply a watermark

  14 décembre 2017, par Geuis

  I’m trying to combine two ffmpeg operations into a single one.

  Currently I have two sets of ffmpeg commands that first generate a video from existing images, then runs that video through ffmpeg again to apply a watermark.

  I’d like to see if its possible to combine these into a single operation.

  # Create the source video
  
  ffmpeg -y \
  
  -framerate 1/1 \
  
  -i layer-%d.png \
  
  -r 30 -vcodec libx264 -preset ultrafast -crf 23 -pix_fmt yuv420p \
  
  output.mp4
  
  
  
  # Apply the watermark and render the final output
  
  ffmpeg -y \
  
  -i output.mp4 \
  
  -i logo.png \
  
  -filter_complex "[1:v][0:v]scale2ref=40:40[a][b];[b][a]overlay=(80):(main_h-200-80)" \
  
  final.mp4