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• Ffmpeg , overlay two sequences of png's and turn them into a movie

  12 mai 2014, par Lau Llobet

  i’ve found how to turn a png sequence into a movie, also i’ve found how to overlay two movies using transparency but I don’t know how to do both things at once (using png’s tranparency).

  The bottom layer of png’s is smaller than the top one and needs to be stretched to a certain resolution and also have a padding to be centered.

  The output dont have to have alpha (black for alpha is ok).

  I’m a bit confused by the abundance of filter options

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  Edit :

  for the moment i’ve found :

  ./ffmpeg -i ./seq1/%d.bmp -vf "movie=./%d.png [a]; [in][a] overlay=0:366" combined.m2v

  it works , now i’ve got to find the padding and resize things

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  thank you in advance.

• How to split a video up into 2.5GB parts with FFmpeg

  2 avril 2019, par Helmut S

  I am trying to achieve a way to send large video files through Firefox Send.

  Because Firefox Send has a 2.5 GB limit per file that one sends, I need to break up a video file into parts that are each less than 2.5GB.

  Is there a relatively simple way to reliably split a video based on data limits using FFmpeg, rather than using duration ? (Using duration would be unreliable, because different equal length portions of a video can be different sized)

  EDIT 1 : I apoligize for the lack of clarity, I was planning on using a Bash script using FFmpeg and ffsend. I was wondering if there is any way to do this through video processing rather than zip compression.

• Colors messed up when converting an image sequence to video using ffmpeg

  10 février 2024, par Form

  I'm generating a video from a PNG sequence using ffmpeg but the resulting video has wrong colors compared to the source files. Getting the correct colors is important because we're using our video assets side-by-side with image assets and the colors must match perfectly (or at least, be as visually similar as possible so as not to be jarring).

  


  Our PNG input files are in the sRGB color profile.

  


  Here's the command we're running :

  


  ffmpeg -r 30 -f image2 -s 1920x1080 -i bg_analyse_%05d.png -vcodec libx264 -crf 25 -pix_fmt yuv420p output5.mp4


  


  And here's a comparison of a source PNG (left) and the same frame in the video (right) :

  


  

  


  From what we've gathered, H.264 does not support sRGB as a built-in color profile so I suppose ffmpeg must perform some kind of color conversion. However, the default ffmpeg settings seem to get the conversion wrong.

  


  How can I get ffmpeg to export a video with colors as close visually as our PNG source files in the native H.264 color profile ? I've tried various flags to try and specify input color profiles and more but nothing produced the expected results yet.

  


  I didn't see many mention color profiles when it comes to generating videos from PNG sequences using ffmpeg. Must be because most aren't too picky on the output colors or simply don't notice ? When putting our source assets with the video output side-by-side in our app, however, the difference is clear.

  


  I already tried playing the video file in multiple players to make sure it's not a display issue (QuickTime Player X, Chrome, etc.). The video is exactly the same (lighter than the source PNGs) in all players.

  


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  Edit 1 :

  


  In the end, the image and video will be displayed in Electron (Chromium). If that changes anything to how the video should be generated.

  


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  Edit 2 :

  


  We have an AfterEffects project from which the files are exported. We couldn't find any way to have that output correct colors so we hoped that using ffmpeg with a sequence of PNGs (which AE exports correctly) would give us more control over the final colors. Open to ideas on how to manage colors properly in AE, too.