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• #/bin/sh in one line

  27 juillet 2012, par GoodGuyGreg

  I'm working on some Haskell project using FFmpeg. I need to batch create from a media folder with MP4 files and create screenshots from all of them. I got the code and am using it on a terminal in Unix. It works, but how do I make it in one line to be executed in system "xxxx" in Haskell ?

  If not using several system"xx"...

  #/bin/sh
  
  for i in $(ls *.mp4)
  
  do
  
      ffmpeg -i $i -vframes 7 -y -ss 10 -s 150x150 -an -sameq -f image2 -r 1/5  $i%1d.jpg
  
  done

  I tried :

  import System.Cmd
  
  function = do{system "#/bin/sh";
  
  system "for i in $(ls *.mp4)";
  
  system "do";
  
  system "ffmpeg -i $i -vframes 7 -y -ss 10 -s 150x150 -an -sameq -f image2 -r 1/5  $i%1d.jpg";
  
  system "done";}

  but it gives a error :

  -vframes: No such file or directory
  
  /bin/sh: Syntax error: "done" unexpected

• ffmpeg record audio from Xvfb on Centos

  25 mai 2017, par boygiandi

  I’m trying to record audio from Xvfb. And I have some problems :

  1. What’s the different between alsa and pulse. I get confuse
  2. Server Centos have no soud card :

  arecord -l

  arecord : device_list:268 : no soundcards found...

  3. I may have many Xvfb process, how to record video and audio from specific Xvfb process. I checked this https://trac.ffmpeg.org/wiki/Capture/ALSA#Recordaudiofromanapplication but still don’t understand how it works.

  ffmpeg -f alsa -ac 2 -i hw:0,0 -acodec pcm_s16le output.wav

  I seen many command like this, but I don’t know how to get hw:0,0 ( id of sound card ? )

  Please help. Thanks

• Text backdrop by ass formatting

  14 septembre 2024, par Armen Sanoyan

  I want to add box behind a word using ass subtitles formatting. The box should have border radius. the ass file later will be used by ffmpeg.

  


  I have tried the BorderStyle=3 form stack ansers 1, 2 both of them do not provide a way to get rounded boxes. Also the BorderStyle=4 didn't work for me. In comments of last stack answer I found a possible reason that my libraries can be old, but anyway it doesn't seem that BorderStyle=4 will solve my problem of border radius. There is another way to achieve rounded box link to answer. I didn't figure it out how to install all the libs he explained there. Also the later answer seems to me over complicated. Is there an other way to make the borders of box rounded without suffering and pain ? I also tried drawing the box with Drawing commands like

  


  {\p1}m 0 0 s 100 0 100 100 0 100 c{\p0}


  


  But it still doesn't seem to be the best way to achieve rounded borders.