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• Find the library calls from FFMPEG command line

  6 octobre 2013, par Budius

  I'm trying to create an Android app that will use video edition, thou, using FFMPEG for the task. I already successfully compiled FFMPEG as a library (libavcodec, libavformat, etc) and included them in the Android project.

  Note that it does not contain the ffmpeg.c that can be called as a command line and the problem is that I only know the command lines to be used for all different things I want to accomplish.

  So the question is :

  from my Linux machine, how would I call ffmpeg main() in a "debug mode" to follow line-by-line what is being calling on those libraries, so I can write methods to mimic what I need to get done ? (currently I only have Android Studio installed, but I'm open to install whatever IDE ppl might suggest)

• BASH deletes the first letter from line (ffmpeg) [duplicate]

  21 mars 2020, par LubieCiastka

  Input :

  # cat list
  
  video1.mp4
  
  video2.mp4
  
  video3.mp4
  
  video4.mp4

  My script :

  #!/bin/bash
  
  
  
  while IFS= read -r line || [[ -n "$line" ]]; do
  
    echo $line
  
    ffmpeg -i $line -c copy -bsf:v h264_mp4toannexb -f mpegts $line.ts
  
    echo $line
  
  
  
  done < "./list";
  
  
  
  rm *.ts

  Every second iterations, bash reads "ideo2.mp4" instead of "video2.mp4" or "ideo4.mp4" instead of "video4.mp4"

  FULL output

  + IFS=
  
  + read -r line
  
  + echo video1.mp4
  
  video1.mp4
  
  + ffmpeg -i video1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts video1.mp4.ts
  
  ...
  
  + echo video1.mp4
  
  video1.mp4
  
  + IFS=
  
  + read -r line
  
  + echo ideo2.mp4
  
  ideo2.mp4
  
  + ffmpeg -i ideo2.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts ideo2.mp4.ts
  
  ...
  
  ideo2.mp4: No such file or directory
  
  + echo ideo2.mp4
  
  ideo2.mp4
  
  + IFS=
  
  + read -r line
  
  + echo video3.mp4
  
  video3.mp4
  
  + ffmpeg -i video3.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts video3.mp4.ts
  
  ...
  
  + echo video3.mp4
  
  video3.mp4
  
  + IFS=
  
  + read -r line
  
  + echo ideo4.mp4
  
  ideo4.mp4
  
  + ffmpeg -i ideo4.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts ideo4.mp4.ts
  
  ...
  
  ideo4.mp4: No such file or directory
  
  + echo ideo4.mp4
  
  ideo4.mp4

  When I comment line "ffmpg..." everything works fine.
  Testing on local Ubuntu (bash 4.4.20(1)-release) and on VPS (debian) (bash 4.4.12(1))
  What is going on ?

• Tailing a logfile and processing each line is missing data when converting a file with ffmpeg

  1er août 2018, par Chris.D

  I am running a script to tail a log file as per the code snippet below. I am running into a problem where by the line passed into $line is missing a number amount of bytes from the beginning when several lines are written to the log file at nearly the same time.

  I can check the file afterwards and see that the offending line is complete in the file so why is it incomplete in the script. Some kind of buffering issue perhaps ?

  The processing can sometimes take several seconds to complete would that make a difference ?

  #!/bin/bash
  
  tail -F /var/log/mylog.log | while read line
  
  do
  
     log "$line"
  
     ffmpeg -i "from.wav" "to.mp3"
  
  done

  Full line in file

  "12","","765467657","56753763","test"

  example logged $line

  657","56753763","test"

  Update
  I have done some more debugging of my code and it seems the processing that is causing the problem is a call to ffmpeg used to convert a wav to mp3. If I swap that with just a sleep then the problem goes away. Could ffmpeg effect the buffer somehow ?