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• Revision effd974b16 : Limit arf interval for low fpf clips. This patch limits the maximum arf interv

  16 avril 2015, par paulwilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
   Modify /vp9/encoder/vp9_ratectrl.c

  
  
  Limit arf interval for low fpf clips.

  This patch limits the maximum arf interval length to
  approximately half a second. In some low fps animations in
  particular the existing code was selecting an overly long interval
  which was hurting visual quality. For a sample problem test clip
  (360P animation , 15fps, 200Kbit/s) this change also improved
  metrics by >0.5 db.

  There may be some clips where this hurts metrics a little, but the
  worst case impact visually is likely to be less than having an
  interval that is much too long. On more normal material at 24
  fps or higher, the impact is likely to be nil/minimal.

  Change-Id : Id8b57413931a670c861213ea91d7cc596375a297

• Add buffering to real time input stream with c++ ffmpeg

  7 octobre 2018, par Joel

  I am writing a c++ program in which I am handling a real time udp video stream with the ffmpeg library.

  The video input fps is 25 frames per second in avarage. The gap between two frames can be 10 , 20, 40 milliseconds, but sometimes it can be around 80 milliseconds.
  In those times, when the gap is around 80 milliseconds, the video seems choppy or stuck,

  When I open the same stream with the ffplay player(using the ffplay.exe), using a simple
  "ffplay.exe udp ://ip:port" command, the video has a little delay (around 50 millisends) with respect to the origin stream, but it runs much more smoothly.

  Can I set a buffering time or any minimal delay so that the delay between the frames will be much more steady, in my c++ program ?
  If so, how can I do this ?

  Thanks,
  Joel

• Using an IF-Statement inside a drawtext (FFMPEG)

  22 janvier 2020, par MonsterDruide1

  I’m currently trying to implement a timer on a video with FFMPEG, so it should start at 00.00 and start timing after a number of frames and stop timing again after a set amount of frames. So the timer should work like this :

  00:00 00:00 00.00 (start timing) 00.01 00.02 [...] 05.88 05.89 (stop timing) 05.89 05.89 05.89

  So far I’ve got the following as (minimal) command :

  ffmpeg -i input.mp4 
  
  -filter_complex "[0:v]drawtext=fontfile='C\\:font.ttf':
  
  text='%{eif\\:n/30\\:d\\:2}\\:%{eif\\:((mod(n,30))/30)*100\\:d\\:2}':
  
  fontcolor=black:fontsize=55:x=(1705.5-(text_w/2)):y=(1000.5-(text_h/2)),format=yuv420p" 
  
  -pix_fmt yuv420p -c:a copy out.mp4

  There is some more stuff inside of the filter_complex, so I can’t replace that with -vf or similar.

  Thanks for all of your help !