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• swscale/output : Bias 16bps output calculations to improve non overflowing range

  2 novembre 2022, par Michael Niedermayer

  swscale/output : Bias 16bps output calculations to improve non overflowing range
  Fixes : integer overflow
  
  Fixes : ./ffmpeg   -f rawvideo -video_size 66x64 -pixel_format yuva420p10le   -i /videos/overflow_input_w66h64.yuva420p10le   -filter_complex "scale=flags=bicubic+full_chroma_int+full_chroma_inp+bitexact+accurate_rnd:in_color_matrix=bt2020:out_color_matrix=bt2020:in_range=full:out_range=full,format=rgba64[out]"   -pixel_format rgba64 -map '[out]'   -y overflow_w66h64.png
  Found-by : Drew Dunne <asdunne@google.com>
  
  Tested-by : Drew Dunne <asdunne@google.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libswscale/output.c

• pexpect.run() terminates before ending ffmpeg without finishing the conversion

  24 novembre 2012, par Davisein

  I'm working on a python script that does a custom conversion of videos via ffmpeg.

  My problem is that the execution of ffmpeg stops suddenly after a bit of conversion (usually 3-4 mb out of 100mb) with a None exit code.

  I'm using the pexpect library. Currently I do not check the progress but I will in a close future. It seems that I am right using pexpect regarding these questions FFMPEG and Pythons subprocess and Getting realtime output from ffmpeg to be used in progress bar (PyQt4, stdout). This is the command that I'm running (I have checked that it's exactly this one)

  nice ffmpeg -i '/full/path' -s 640x360 -strict experimental -vcodec libx264
  
     -f mp4 -  coder 0 -bf 0 -refs 1 -flags2 -wpred-dct8x8 -level 30 -crf 26
  
     -bufsize 4000k -maxrate 350k -preset medium -acodec libvo_aacenc
  
     -ar 48000.0 -ab 128K -threads 2 -y '/full/path/out'

  I am using nice but I have tried also without it and the result ends up being the same.

  I'm running pexpect this way :

  output, exit = pexpect.run(self.command(), withexitstatus=True,\
  
                                     logfile=logfile)
  
  print output
  
  print exit

  Of course I have tried the same command on the command line and it works fine.

  Any clue on what might be happening ?

• How to rename and move files in a subdirectory with an index and the folder name ... better ?

  29 octobre 2014, par krismajean

  I’m putting together a script to take .mp4 files organized into folders that described the video (eg. cat) and I’d like to do the following :

  1. rename them with the folder name and a number ;
  2. move the video into a folder named and numbered in the same manner
  3. parse the video into frames using ffmpeg

  I’m posting this here to be a reference for others and to ask about how this could be done better. It works well but I’m wondering how to make it better.

  for dir in /path/to/parent/directory/*; do
  
  cd "$dir" && result=${PWD##*/} 
  
  cd video
  
  echo $result
  
  a=1
  
      for i in *.mp4; do
  
          dafile="$(printf "_%02d.mp4" ${a})" 
  
          dafolder="$(printf "_%02d" ${a})"
  
          newfolder=$result$dafolder
  
          newfile=$result$dafile
  
          mkdir ${newfolder}
  
          mv ${i} ${newfolder}/${newfile}
  
  
  
          cd ${newfolder}
  
              ffmpeg -i ${newfile} -r 30 -f image2 ${newfolder}-\%04d.png
  
          cd ..
  
          let a=a+1
  
      done
  
  
  
  done

  I used the following links to figure out a bunch of ideas for the code :

• Get current directory name (without full path) in Bash Script
• Renaming files in a folder to sequential numbers