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• advanced ffmpeg compression control

  18 juillet 2017, par Daniel Mahler

  I am using very aggressive video compression, eg -crf 51. I am using this for ’artistic’ effect, so what I am doing may not make sense from a normal video compression point of view.

  So far I have only been using very basic compression control using only the -crf or -b:v flags. The results look like ffmpeg divides images into square patches and the makes smooth approximations within the patches. This gives 2 control dimensions to the process : the patch size and the aggressiveness of the smoothing within the patches.

  It have found that ffmpeg uses both parameters to some extent, but there appears to be an absolute maximum patch size in pixels beyond which it will not go regardless of the frame size.
  After that it will only increase compression by reducing the detail within the patches.

  This is suboptimal for high resolution video, where this becomes equivalent to reducing the resolution. The problem is particularly noticeable on fractal like images which have large featureless region as well as regions of high detail.

  How can I tell ffmpeg to increase the maximum patch size and retain more detail within the patches ?

• avcodec/rkmpp : Fix broken build due to missing control operation

  6 janvier 2018, par LongChair

  avcodec/rkmpp : Fix broken build due to missing control operation
  This patch is taking care of https://trac.ffmpeg.org/ticket/6834.
  
  It seems that one of the control operations that was available to get
  
  the free decoders input slots was removed.
  There is another control operation to retrieve the used slots. Given
  
  that the input slot count is hardcoded to 4 in mpp at this point,
  
  replacing the old control operation by the other one.
  This was tested on Rockchip ROCK64.
  Signed-off-by : wm4 <nfxjfg@googlemail.com>
  

  • [DH] configure
  • [DH] libavcodec/rkmppdec.c

• Crontab starts again before the process of conversion in ffmpeg ends (depending on time suppose /2 minutes) How to Control that ?

  4 février 2018, par A Sahra

  I am running a bash .sh file every two minutes with crontab. the problem is that when crontab runs bash file the process of ffmpeg video conversion starts,the conversion time varies depending on length of videos, i have set the crontab to run every two minutes. crontab runs again after two minutes before end of ffmpeg conversion.

  How to Figure out :

  control of crontab and conversion process so the crontab doesn’t starts again until process of conversion is not completed.

  #!/bin/bash
  
  # set PATH to check existance of video file in this directory
  
  checkfiles=/home/webuser/public_html/shareportal/convert_Up_videos/*
  
  checkforfiles=/home/webuser/public_html/shareportal/convert_Up_videos
  
  movetodire=/home/webuser/public_html/shareportal/uploaded_videos/
  
  conversionprocessdir=/home/webuser/public_html/shareportal/conversion_process/
  
  movetoArchive=/home/webuser/public_html/shareportal/Video_Archive/
  
  blockpath=/home/webuser/public_html/shareportal/block.txt
  
  processid=/home/webuser/public_html/shareportal/processid.txt
  
  #format of output video file
  
  webm='webm'
  
  if [ "$(ls -A $checkforfiles)" ]
  
  then 
  
  #check directory for files to convert
  
  for f in $checkfiles
  
      do  
  
          fullfilename="$f"
  
          filename=$(basename "$f")
  
          filewithoutextforimage="${filename%.*}"
  
          nametofile=$filewithoutextforimage | cut -c1-10;
  
          echo $filewithoutextforimage | cut -c1-10 1> $blockpath 2>&1
  
      filewithoutext="${f%.*}"
  
      fileextention="${f##*.}"
  
      image_path='/home/webuser/public_html/shareportal/video_images/'$filewithoutextforimage'.png'
  
      outputfilename=$conversionprocessdir"$filewithoutextforimage.webm"
  
      #ffmpeg conversion process starts here
  
      if (ffmpeg -i "$f" "$outputfilename" 1>> $blockpath 2>&1) 
  
      then 
  
          #Extract Image of video file on provided time stamp
  
          if (ffmpeg -ss 00:00:06 -i "$f" -vframes:v 1 "$image_path") 
  
          then
  
              echo "Image Extracted"
  
          else
  
              echo "Could not Extract Image"
  
          fi
  
          echo "Video Converted";
  
      else
  
          echo "Could Not Convert Video"
  
      fi
  
      #conversion Ends!!
  
      mv "$outputfilename" $movetodire
  
      mv "$fullfilename" $movetoArchive
  
  done
  
  else
  
  echo "File Not Found Directory is empty!!!-----"
  
  fi