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• ffmpeg : create slideshow of unknown number of images with transition

  13 août 2022, par FreddyVi

  hope someone could help me with this. Kinda new with ffmpeg and a bit stumped.

  


  Given an input of a set of numbered images in a folder, I want to generate a video with each image shown for 60 seconds. I would love to use a default transition between each images.

  


  The following code, correctly generates an mp4 without transitions :

  


  ffmpeg -framerate 1/60 -pattern_type glob -i "*.png" -vcodec libx264 \
-pix_fmt yuv420p -r 30 -threads 4 -crf 25 -refs 1 -bf 0 -coder 0 -g 25 \
-keyint_min 15 -movflags +faststart no_audio_output.mp4


  


  But when I try to add a default transition (supported in the version of ffmpeg I'm using that is the 5.1) :

  


  ffmpeg -framerate 1/60 -pattern_type glob -i "WC*.png" -filter_complex 
xfade=transition=circleopen:duration=5:offset=55 -vcodec libx264 \
-pix_fmt yuv420p -r 30 -threads 4 -crf 25 -refs 1 -bf 0 -coder 0 -g 25 \
-keyint_min 15 -movflags +faststart no_audio_output.mp4


  


  I have as error :

  


  Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_xfade_0


  


  I googled a lot but still the solution is unclear. All the examples I found have been designed to deal with a slideshow/input with a define number of pieces while in my case the folder could contain any number of images.

  


  Thanks all for your help !

  


• Overlaying a list of video files on top of another list of video files

  2 août 2023, par sybr

  I'm currently working on a way to improve my production process for the videos that I'm making. The source files consist of a list of two side-by-side clips that I handpick and stitch together in Premiere Pro. I recently came across FFmpeg and thought, 'surely there's a way to automate the rendering of these videos'.

  


  I've managed to get the general overlay working, where I have one clip overlaid on top of the other one, but the overlaid clip doesn't have any audio, and the overlaid clip currently doesn't scale to the height of the background clip.

  


  Here's what i'd like it to look like :


  


  As illustrated in the image, I want to overlay the overlay clip on top of the background clip, preserving audio for both clips, and shift the background clip's position to the right by 33%. Now, instead of both "clips" being just one clip, I want to use two folders with each about 1 hour's worth of clips to compile an hour-long video containing both folders.

  


  Is there a way to achieve what I want to do here ? Or would it make more sense to compile two separate videos first by concatenating all videos in their respective folders first, and then overlaying one video on top of the other one ?

  


  Would love some help here, also eager to learn more about FFmpeg, so some explanation would be highly appreciated !

  


• How to generate a video of set duration in frames from image sequence

  4 septembre 2021, par Sherali Karimov

  I have a sequence of images, one per frame. Sometimes some frames are missing in random parts.

  


  If it possible to instruct ffmpeg to generate a video of a pre-set length in number of frames from this sequence replacing missing frames with a black screen ?

  


  This would allow us to notice that frames are missing during the visual inspection.

  


  I tried to overlay the stream of images with a loop of another, black, image but I don't know how to tell it to force continue looping for N frames...

  


  The OS is CentOS 8.
Here is how I am combining them now :

  


  ffmpeg -y -nostdin -hide_banner -thread_queue_size 4096 
    -start_number 1 -framerate 25 -apply_trc iec61966_2_1 -i /data/OUT/RENDER/MG013/MG013_007/beauty/MG013_007.Beauty.%04d.exr 
    -start_number 1 -framerate 25 -apply_trc iec61966_2_1 -i /data/OUT/RENDER/MG013/MG013_007/chars/MG013_007.Beauty.%04d.exr 
    -filter_complex "[0:v]copy[out];[out][1:v]overlay=x=(W-w)/2:y=(H-h)/2[out];[out][out]" -c:v libx264  -pix_fmt yuv420p  
    -profile:v baseline  -refs 2  -crf 18 -map '[out]' -s 1920x1080  /data/MG/episodes/MG013/story/playblasts/render/MG013_007.mov


  


  This is working, except for the cases of missing frames...

  


  Ideally I would love to instruct it to generate, for instance, 450
frames and it to fill in the missing frames with blanks.

  


  Thank you !