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• Is there a way to cut movement "dead air" on a screen recording ? [closed]

  16 mai 2023, par Raelbe

  I have got a couple of screen recordings of a painting I've done, and I've managed to concat the files together.

  


  Unfortunately, there is a lot of "dead air" in the video (where I have left my desk, so there is no movement happening on screen) is there a way to cut out this down time ?

  


  I found an example that another artist uses for his screen recordings, so I plugged it in with my file directory's. This is what I used :

  


  .\ffmpeg -f concat -safe 0 -i "merge.txt" -vf npdecimate=hi=64*12:lo=64*5:frac=0.33,seipts=N/30/TB,"setpts=0.25*PTS" -r 30 -crf 30 -an Illu_Test.mp4


  


  I got this error message at the end :

  


  [AVFilterGraph @ 000001cadfe5b1c0] No option name near 'N/30/TB'
[AVFilterGraph @ 000001cadfe5b1c0] Error parsing a filter description around: ,setpts=0.25*PTS
[AVFilterGraph @ 000001cadfe5b1c0] Error parsing filterchain 'npdecimate=hi=64*12:lo=64*5:frac=0.33,seipts=N/30/TB,setpts=0.25*PTS' around: ,setpts=0.25*PTS
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #0:0`


  


  So I chopped it up a bit and this is what I used to concat the files and it worked perfectly.

  


  .\ffmpeg -f concat -safe 0 -i "merge.txt" -crf 30 -an Illu_Test.mp4


  


  Now, I'm looking to cut out the seconds of no movement. I'm unsure what the -crf command does (as stated I am brand new to this) OG artist states that :

  


  "This is the tolerance level that determines whether there has been enough change between frames or not to be considered as detected motion."

  


  Any help would be appreciated.

  


  (Apologies if the format of this question is wrong)

  


• Video playing, how to play a video back a a rapid rate at random timestamp locations

  10 avril 2020, par Zarc Rowden

  Note : this is a mildly general question that is looking more for pointers in the right direction and not exactly requiring a concise coded answer. I appreciate any and all input, thank you for lending your brain power to me for this moment :)

  



  I have a script that receives midi messages in real time and triggers playback of a single video on various timestamps that are changed/selected regularly and randomly by a user. Currently this is working in the browser, however, I've realized that there is some noticeable latency between (i'm guessing the cause here so please correct me) the moment a request to play a video at a specific time is made(note : the video is not being requested over the wire, this action does not take place until a JS Blob Url is loaded into the player) and the moment where that request is fulfilled and delivered from storage to pixels on the screen.

  



  My question is : Is it reasonable to assume that there is a tool out there, that given the correct video format and optimizations both in the code and in the file that could load an entire, say : 1 gb video into memory and play it back at random timestamps every 60 milliseconds at completely random, constantly changing timestamps.

  



  If you're now all the way down here... Thanks for reading this far, or scanning ! Please let me know if this question makes any sense / could be improved, I'm happy to clarify further.

  


• avfilter/drawbox+drawgrid - add option to prevent overwriting of source pixels

  11 décembre 2017, par Gyan Doshi

  avfilter/drawbox+drawgrid - add option to prevent overwriting of source pixels
  If the user-supplied color in drawbox and drawgrid filters is non-opaque,
  
  the box & grid painting overwrites the input's pixels (including alpha).
  
  Users typically expect the alpha of the specified color to only act as a key
  
  for compositing on top of the main input.
  Added option allows users to select between replacement and composition.
  
  Tested and documented.
  

  • [DH] doc/filters.texi
  • [DH] libavfilter/vf_drawbox.c