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• Batch Programming Looping ?

  13 mai 2013, par Michael Barth

  I'm not an expert in batch programming, my only skill is in C\C++. I'm not even sure how to go about this really.

  I've got a bunch of videos like Video1.mp4, Video2.mp4 (that's not their actual names, but they do have numbers indicating beginning and end)

  Basically I have this FFMPEG command that I can use to convert all of these to an aspect ratio of 16:10 that looks something like this :

  "ffmpeg -i "Section 1 Video 1.mp4" -aspect 16:10 OutSection 1 Video 1.mp4"
  
  "ffmpeg -i "Section 1 Video 2.mp4" -aspect 16:10 OutSection 1 Video 2.mp4"
  
  "ffmpeg -i "Section 2 Video 1.mp4" -aspect 16:10 OutSection 2 Video 1.mp4"

  Now instead of writing this command over and over again, is there anyway for me to substitute the numbers for actual variables ? I know that Section 1 ends at Video 27 and Section 2 ends at Video 26 and so on. Basically I need the loop to run 165 times so I don't need to write the command 165 times.

  Or is this beyond the scope of capability of a mere batch program ?

• avcodec/webp : Switch to ff_vlc_init_from_lengths()

  18 avril, par Andreas Rheinhardt

  avcodec/webp : Switch to ff_vlc_init_from_lengths()
  The earlier code would traverse over the code lengths
  
  mutliple times (namely max_length + 1 times - once to get
  
  the maximum length and once for each max_length to assign
  
  codes) before calling ff_vlc_init_sparse() (which may traverse
  
  them twice and sort them). The new code only traverses them once
  
  (+ the one time in ff_vlc_init_from_lengths()).
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/webp.c

• FFmpeg, how to skip late input ?

  14 novembre 2017, par user3343357

  I’m running ffmpeg to display incoming stream on a Decklink BlackMagic card with the following command line :

  ffmpeg -y -f ourFmt -probesize 32 -i - -f decklink -preset ultrafast 
  
     -pix_fmt uyvy422 -s 1920x1080 -r 30 -af volume=0.1 -max_delay 10000 
  
       DeckLink Mini Monitor

  Basically I get the video over the internet by UDP and stream it to ffmpeg stdin. Both audio and video streams have pts and dts and are fully in sync, if the connection is good there is no problems.

  However if there are issues with the connection i start getting errors, sometimes the video delay grows significantly, and audio stops working.
  The errors i get are :

  ffmpeg : [decklink @ 0x26cc600] There are not enough buffered video
  frames. Video may misbehave ! ffmpeg : [decklink @ 0x26cc600] There’s no
  buffered audio. Audio will misbehave ! ffmpeg : Last message
  repeated 4 times ffmpeg : [decklink @ 0x26cc600] There are not enough
  buffered video frames. Video may misbehave ! ffmpeg : [decklink @
  0x26cc600] There’s no buffered audio. Audio will misbehave ! ffmpeg :
  Last message repeated 3 times ffmpeg : frame= 5204 fps= 30 q=-0.0
  size=N/A time=00:02:53.76 bitrate=N/A dup=385 drop=5 speed=0.993x
  ffmpeg : [decklink @ 0x26cc600] There’s no buffered audio. Audio will
  misbehave ! ffmpeg : Last message repeated 18 times ffmpeg :
  [decklink @ 0x26cc600] There are not enough buffered video frames.
  Video may misbehave ! ffmpeg : [decklink @ 0x26cc600] There’s no
  buffered audio. Audio will misbehave !

  The problem is when the connection is back to normal, the video keeps misbehaving until I restart the stream. What I want to do is for FFmpeg to skip to the content of the last second and play synchronized video from there, drop all the late data in between, is it possible ?