Recherche avancée

Sur d’autres sites (10850)

• ffmpeg : How to replace a series of frames with a series of image files ?

  14 septembre 2020, par Arnon Weinberg

  Given a video file, start and end timestamps, there is a known number of frames between those timestamps in the video file, and I have an equal number of .png files in a directory to replace them with. The .png files are sorted as 001.png ... NNN.png. How would I go about updating the video file with the replacement frames using ffmpeg ?

  


  This is a followup to using ffmpeg to replace a single frame based on timestamp, but I'm asking about replacing multiple sequential frames based on 2 timestamps.

  


  Presumably something like :

  


  ffmpeg -i input.mp4 -i %3d.png -filter_complex "something including the timestamps 4.40,5.20" -c:a copy output.mp4


  


  I would also be okay with using frame numbers instead of timestamps if that makes things easier, and it's reasonable if start and end frames must be keyframes.

  


  Background :

  


  Many machine learning algorithms for video processing use ffmpeg to extract specific scenes from videos based on start and end timestamps, dump them into a sequence of .png files, process them in some way (denoise, deblur, colorize, annotate, inpainting, etc), and output the results into an equal number of .png files. The output frames are usually assembled into a new video file, but I would like instead to update the source video file so as to preserve audio, unedited video, and other video properties (fps, keyframes, etc).

  


  This approach will not work as-is for some categories of video processing algorithms. For example, interpolation results in more frames than were originally extracted, and upscaling results in higher-resolution images. As such, I would appreciate an explanation of any solution so that I can adapt it for such cases (or I will ask separate questions for those).

  


• avformat : add demuxer for Pro Pinball Series' Soundbanks

  4 mai 2020, par Zane van Iperen

  avformat : add demuxer for Pro Pinball Series' Soundbanks
  Adds support for the soundbank files used by the Pro Pinball series of games.
  https://lists.ffmpeg.org/pipermail/ffmpeg-devel/2020-May/262094.html
  Signed-off-by : Zane van Iperen <zane@zanevaniperen.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] Changelog
  • [DH] libavformat/Makefile
  • [DH] libavformat/allformats.c
  • [DH] libavformat/pp_bnk.c
  • [DH] libavformat/version.h

• How can I split a series of clips from a video and then stitch them together without audio or video gaps ?

  16 avril 2020, par Dr. Cyber Sec

  I'm developing an application where I take a video and (1) split it up into a bunch of 1 second chunks. Then, I need to (2) stitch a subset of those chunks back together, resulting in a slice of the original video.

  



  For example, let's say I have an original, 10s clip. I split it up into 1s chunks for each second (a clip from 0s to 1s, a clip from 1s to 2s, etc.). I now need to stitch, say, seconds 2-4 together into one video.

  



  I'm currently attempting both steps using ffmpeg.

  



  For clip-cutting :

  



  ffmpeg -ss 33 -i video.ts -t 1 33to34.ts


  



  This should seek to second 33 and output a 1s clip duration, yielding a video clip containing seconds 33-34 of the original video. I noticed that ffmpeg doesn't always seek accurately, so after following the instructions in this post, which says to manually add keyframes to the parts of the video you want to cut, I tried this :

  



  First, setting the keyframes :

  



  ffmpeg -i video.ts -force_key_frames 00:00:01.000,00:00:02.000,00:00:03.000,00:00:04.000 out.ts


  



  And then cutting the clips as I did before with the new output clip.

  



  While this did get the videos to be exactly 1s long each, (which I wanted) there is a small gap (just a slight jitter) in audio when I combine the clips back together. I cannot have this, and am looking for a solution.

  



  Can anyone help me understand why this is happening and help me find a solution ? Thank you so much in advance.