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• aaccoder : add a new perceptual noise substitution implementation

  2 juillet 2015, par Rostislav Pehlivanov

  aaccoder : add a new perceptual noise substitution implementation
  This commit finalizes the PNS implementation previously added to the encoder
  
  by moving it to a seperate function search_for_pns() and thus making it
  
  coder-generic. This new implementation makes use of the spread field of
  
  the psy bands and the lambda quality feedback paremeter. The spread of the
  
  spectrum in a band prevents PNS from being used excessively and thus preserve
  
  more phase information in high frequencies.  The lambda parameter allows
  
  the number of PNS-marked bands to vary based on the lambda parameter and the
  
  amount of bits available, making better choices on which bands are to be marked
  
  as noise. Comparisons with the previous PNS implementation can be found
  
  here : https://trac.ffmpeg.org/attachment/wiki/Encode/AAC/
  This is V2 of the patch, the changes from the previous version being that this
  
  version uses the new band->spread metric from aacpsy and normalizes the
  
  energy using the group size. These changes were suggested by Claudio Freire
  
  on the mailing list. Another change is the use of lambda to alter the
  
  frequency threshold. This change makes the actual threshold frequencies
  
  vary between +-2Khz of what’s specified, depending on frame encoding performance.
  Reviewed-by : Claudio Freire <klaussfreire@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/aaccoder.c
  • [DH] libavcodec/aacenc.c
  • [DH] libavcodec/aacenc.h

• Plex DVR File Rename on FFMPEG Encoding

  11 juillet 2021, par Brent Johnson

  I'm currently using a bash shell script to encode all of my Plex DVR recordings to H.264 using FFMPEG. I'm using this little for loop I found online to encode all of the files in a single directory :

  


  for i in *.ts;
    do echo "$i" && ffmpeg -i "$i" -vf yadif -c:v libx264 -preset veryslow -crf 22 -y "/mnt/d/Video/DVR Stash/Seinfeld/${i%.*}.mp4";
done


  


  This has served its purposes well but in the process I would like to rename the file to my preferred naming convention so that the original filename Seinfeld (1989) - S01E01 - Pilot.ts is renamed to Seinfeld S01 E01 Pilot.mp4 in the encoded file. While I am already using a regular expression to change the .ts extension to .mp4, but I'm no expert with regex, especially in the bash shell so any help would be appreciated.

  


  For anyone that's interested in my Plex setup, I'm using an old machine running Linux Mint as my dedicated DVR and actually accessing it over the network with my daily driver which is a gaming machine, so more processing power for video encodes. While that one is a Windows machine, I'm using the Ubuntu bash under WSL2 to run my script, as I prefer it over the Windows command prompt or Powershell (my day job is a web developer on a company issued Mac). So here's a sample of my code for anyone that might consider doing something similar.

  


  if [[ -d "/mnt/sambashare/Seinfeld (1989)" ]]
then
    cd "/mnt/sambashare/Seinfeld (1989)"
    echo "Seinfeld"
    for dir in */; do
        echo "$dir/"
        cd "$dir"
        for i in *.ts;
            do echo "$i" && ffmpeg -i "$i" -vf yadif -c:v libx264 -preset veryslow -crf 22 -y "/mnt/d/Video/DVR Stash/Seinfeld/${i%.*}.mp4";
        done
        cd ..
    done
fi


  


  While I've considered doing a for loop for all shows, for now I am doing each show like this individually as there are a few shows I have custom encoding settings for

  


• avcodec/v4l2_context : Drop empty packet while draining

  10 mai 2020, par Andriy Gelman

  avcodec/v4l2_context : Drop empty packet while draining
  v4l2_m2m devices may send an empty packet/frame while draining
  
  to indicate that all capture buffers have been flushed.
  Currently, the empty packet/frame is not handled correctly :
  
  When encoding, the empty packet is forwarded to the muxer, usually
  
  creating warnings.
  
  When decoding, a reference to the memory is created anyway. Since in
  
  the past this memory contained a decoded frame, it results in an extra
  
  frame being decoded.
  This commit discards the empty packet/frame.
  References :
  
  linux/Documentation/media/uapi/v4l/dev-decoder.rst :
      "The last buffer may be empty (with :c:type :`v4l2_buffer` bytesused = 0)
  
       and in that case it must be ignored by the client, as it does not
  
       contain a decoded frame."
  linux/Documentation/media/uapi/media/v4l/vidioc-encoder-cmd.rst :
      "...This buffer may be empty, indicated by the
  
       driver setting the ``bytesused`` field to 0."
  Reviewed-by : Ming Qian <ming.qian@nxp.com>
  
  Signed-off-by : Andriy Gelman <andriy.gelman@gmail.com>
  

  • [DH] libavcodec/v4l2_context.c