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• FFMpeg : how to merge video and audio and tail align video to audio length ?

  28 septembre 2021, par Bobby

  I have a video file and an audio file to merge together. Audio duration is shorter than video. I want to align them at tail and cut off the head part of the video.

  


  Graph illustration :

  


  [xxxx------] video
    [------] audio
    [======] merged


  


  Where "x" parts of the video is removed.

  


  The duration of the video/audio is unknown but the audio duration is guaranteed to be shorter than video. The reason of it being unknown is because I'm generating video dynamically and pipe to FFmpeg, so it is not possible to know the duration beforehand.

  


• How to generate a video by looping an image and then concat with another very long video without re-encoding using ffmpeg ?

  23 mars 2021, par Linghao Chen

  I have an image and a very long video (1.5h).
Now I want to generate a heading video about 5 seconds by looping the image, and then concatenate it with the long video. Since the video is long, I don't want to re-encode the videos.
I have tried to generate the heading video using

  


  ffmpeg -loop 1 -i image.png -c:v libx264 -t 5 -pix_fmt yuv420p head.mp4


  


  and then

  


  ffmpeg -f concat -i list.txt -c:v copy concat.mp4


  


  where the list.txt contains

  


  file head.mp4
file longvideo.mp4


  


  I have tried these operations on two machines.
On one machine, the concatenated video has no audio. Moreover, it stucks at 5-10 seconds and directly jump to 11s.
On the other machine, the video and audio are not synchronized.

  


  To provide more information, I have checked the codecs of the two videos by

  


  ffprobe -v error -select_streams v:0 -show_entries stream=codec_name \
  -of default=noprint_wrappers=1:nokey=1 xxxxx.mp4


  


  Both of them are h264.

  


  My question is, how to generate it correctly with ffmpeg ? If it is hard using ffmpeg, is there any method to do it fast ? As far as I know, Adobe Premiere and Final Cut Pro do not export as fast as I expect because they re-encode the videos.

  


• 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 !!