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• avfilter/f_graphmonitor : show also current timeline status of filter

  21 mai 2023, par Paul B Mahol

  avfilter/f_graphmonitor : show also current timeline status of filter
  

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

• ffmpeg - Understand images to video output, players show different images and lengths

  8 juillet 2023, par Matt C

  I'm using multiple images to create a video with each image on a 1-second long frame. This is the command I'm using :

  


   ffmpeg -framerate 1 -i 'image%d.jpg' -c:v libx264 -r 1 -pix_fmt yuv420p out.mp4


  


  This seems straightforward and exactly what many others have done with success. However, the output I get is an mp4 which windows file explorer says is 4 seconds long, and is different in VLC and Windows media player and neither is the desired output.

  


  In Windows : the video plays for 4 seconds with a black screen and at this point the time line at the bottom is filled up at 4 seconds, indicating the video is over. But it keeps playing, for another 4 seconds. And the last 4 seconds (from 0:04 to 0:07) is actually the desired output.

  


  





  


  


  


  


  



  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  Frame	Image
  1	black screen
  2	black screen
  3	black screen
  4	black screen
  5	image1.jpg
  6	image2.jpg
  7	image3.jpg
  8	image4.jpg

  


  


  In VLC : the video shows last image supplied as input for 3 seconds, followed by the second to last image for 1 second.

  


  





  


  


  


  


  



  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  Frame	Image
  1	image4.jpg
  2	image4.jpg
  3	image4.jpg
  4	image3.jpg

  


  


  Questions :

  


  

  1. How/Why are these different in different players ?

  


  2. Why, in VLC, are only two images showing up, and why would one of them last for 3 seconds ?

  


  3. In Windows, why/how is the video 8 seconds long but shows up as 4 seconds both in the file explorer and in the actual media player ?

  


  4. How do I get the desired output, and what caused my case to not work as it did for seemingly most others ?

  


  


• How can I show that a frame has been duplicated to extend the video framerate using ffprobe ?

  14 juillet 2023, par Brandon J

  As the title suggests I have a video.mp4 which I know visually has been extended from 5fps to 20fps. I know this because there are 256 frames and when I run ffprobe it reports 20fps and the video is 12.8 sec long. I also run

  


  ffprobe -v 0 -select_streams v -show_entries stream=duration_ts,time_base,nb_frames video.mp4

  


  reports to me 256 frames, 1/20 timebase adn 256 duration. This matches the expected 12.8 s duration. When I manually sort through the extracted frames I can see the frames have been held for 4 ticks. So it should be 5fps.

  


  I then run the below to view the packets and the frames (cmd not typed)

  


  ffprobe -show_packets -select_streams v:0 video.mp4

  


  and the packets or frames don't seem to give me a huge indication that the frames have been duplicated.

  


  With the -show_packets cmd the only possible indication of duplication I can see is that every 0.2 seconds, (consistent with 5fps) the size of the packets go from a consistent 150-300 size to around 16000 or so. Is there a way I can better articulate what I am seeing with the packet size change ? Why has their compression or encoder (forgive any error in verbiage) decided to duplicate frames to achieve 20fps vs extending the pts to 0.2 seconds for each packet ? It seems like simply defining a longer pts would reduce overall file size anyways ?

  


  All that said, is there something within ffprobe or other tool I can use to more efficiently confirm what I am visually seeing to say yep these frames were just duplicated from another program ? Thanks !