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• awkward behaviour in bash find-loop with ffmpeg

  25 avril 2018, par Alexander

  There is something weird going on when running following script with Docker.

  The dockerfile for this is :

  FROM debian:9
  
  WORKDIR /app
  
  RUN apt-get -y update && \
  
      apt-get -y install ffmpeg curl
  
  COPY . /app

  The script run.sh :

  #!/bin/bash
  
  find /pfs/in -maxdepth 1 -name "*.flac" -print0 | while IFS= read -r -d $'\0' inFile; do
  
      echo "\n##### Process '${inFile}' #####"
  
      ffmpeg -y -i ${inFile} -ar 16000 tmp.wav # use 16kHz - default for EML
  
  done

  Starting this, when mounting 3 files into the container :

  $ ls pfs/in/
  
  Testaudio16k_2.flac  Testaudio16k.flac  Testaudio16k.wav  TestSprache_Saetze.flac
  
  $ docker run --rm -t -v $(pwd)/pfs/in:/pfs/in test-img:latest /bin/bash run.sh

  I get an error on processing the second file : pfs/in/Testaudio16k_2.flac: No such file or directory. The leading / is missing. It is also missing in the preceeding echo. Indeed this happens every second file (if I put more than 3 files in that folder).

  Now coming to the counter example :
  If I comment out the ffmpeg line in the script, rebuild and run, The echo prints for every file the correct path.

  Does anybody have an idea about this ?
  Is it about the find or is the ffmpegdoing something weird ? Something completely different ?

• Overlay video onto another video at multiple points in time

  22 décembre 2024, par kbcool

  I have a case where I want to have a background video and use a second video overlaying the first but at multiple points in time. The second video is shorter.

  



  So for example the main video is a minute long and the second video is 10 seconds. I want to overlay the second video once at 15seconds then again at 35 seconds and then again at 55 seconds (terminating when the main video does).

  



  I am able to get the second video to overlay successfully using overlay filter and between option but it only ever works for the first overlay. The second overlay seems to show the last or first frame of the video(??) but for the period I set in between. I am guessing it needs to be rewound and played somehow.

  



  Eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[out][1]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  I have also tried specifying the overlay as an input twice eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[out][2]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  The same thing happens.

  



  I'm sure the answer is simple and probably to do with how I'm using inputs but I'm not able to wrap my head around how to get the overlay video to play twice at different times on top of the original.

  



  I have also tried using the setpts filter to rewind the overlay but again the results are exactly the same.

  



  Eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[1]setpts=PTS-STARTPTS,[out]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  There are a lot of similar questions involving overlaying multiple videos but I can't find anything about reusing the same video at multiple points in time.

  


• How can start a process and stop the process if "error" string appear in the console output strings in one line commands set

  25 janvier 2018, par Thm Lee

  Now I want one line cmd commands set which start a process and monitor the consol output strings stream. And so if error message appear in the process’s console output, then could stop the process immediately.

  For example, I tried below commends sets, but failed. It seems find command didn’t get any strings streams in which search key word "error"

  ffmpeg "endcoding process options set" | find "error" && exit

  or,

  ffmpeg "endcoding process options set" 2>&1 find "error" && exit

  Is there any solutions about this ?

  Thanks in advance