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• 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.

  


• how to add overlay at the end of video without knowing time duration of video file - ffmpeg

  13 décembre 2019, par Luka mikic

  I have a bunch of video files to which I add animated overlay at the beginning of video, but I would like to add it again at the end of it t-13 seconds. This is my bash script :

  do
  
     ffmpeg -i "${f}" -i /app/logo/lower.mov -i /app/logo/logo.png -filter_complex \
  
        "[0:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:x=(1280-iw)/2:y=(720-ih)/2:color=black[bg0]; \
  
        [bg0][1:v]overlay=10:10[bg1]; \
  
        [bg1][2:v]overlay=10:10,drawtext=fontfile=/app/logo/Courier Prime.ttf:text=$(basename "${f}" | cut -f 1 -d '.'): \
  
        fontcolor=white:fontsize=25:x=256:y=h-th-130:alpha=1:enable='between(t,2,15)'" \
  
        -c:v libx264 -crf 21 -preset ultrafast "${f%.*}.mp4" -y
  
  done

  Is there any way to do this ? I know how to extract the duration with FFProbe, but do not know how to add duration dynamically to a variable and then apply it to code I have.

• Using ffmpeg to cut up video into smaller video with exactly 30 frames

  30 mars 2018, par MonsieurBeilto

  I need to cut a video with >300 frames into ten videos, where the first video comprises the first 30 frames, the second video comprises frames from 31 to 60 and so on.