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• How to extract tiles from ffmpeg thumbnails by cutting them to the length of the video

  22 mars 2021, par JeeNi

  I have searched in many ways to solve this problem. But I can't find an answer, so I leave a question.

  


  ffmpeg -i thumb_test.mp4 -filter_complex "select='isnan(prev_selected_t)+gte(t-prev_selected_t\,5)',scale=120:-1,tile=layout=60x60" -vframes 1 -q:v 2 thumb.jpg


  


  The result of the command I used is as follows.

  


  enter image description here

  


  The remaining space remains black, making the file size larger.
To solve this method, I would like to specify the tile size as much as the video length when extracting thumbnails.
Please let me know if there is a solution.

  


  Thank you.

  


• Segmenting .flac files with ffmpeg truncates audio but not file length

  5 avril 2022, par Yan White

  I am trying to get Twitter spaces audio (.ts) files into a format I can easily edit, on OSX.

  


  So far I was able to convert the files in bulk to .flac with this :

  


  for i in *.ts;
do name=`echo "$i" | cut -d'.' -f1`
echo "$name"
ffmpeg -i "$i" -sample_fmt s16 -ar 41000 "${name}.flac"
done


  


  That worked, and reduced the file sizes somewhat, but..
Because most of the files are around 7 hours long, my editor of choice cannot process that much audio in one file.

  


  So I looked around and was able to find this command to segment the files into 3hr long sections.

  


  ffmpeg -i space-1OdKrBealBqKX_0.flac -map 0 -f segment -segment_time 10800 -c copy space-1OdKrBealBqKX_0__%03d.flac


  


  This works, but each file contains as much empty / silent space at the end as the orginal file. That's going to be a problem for sharing with a team that will help edit these files, as each file has the original file's length and file size. There are a lot of files.
The audio segments and naming did work though.

  


  How to truncate the actual length of the file to the audio segment ?

  


  Caveat : I am no expert on any of these matters, I just managed to google and get this far, so if someone knows and wants to provide working code that would be very much appreciated !

  


• alsdec : check block length

  8 décembre 2013, par Reinhard Tartler

  alsdec : check block length
  Fix writing over the end
  Found-by : Mateusz "j00ru" Jurczyk and Gynvael Coldwind
  
  Addresses : CVE-2013-0845
  

  • [DBH] libavcodec/alsdec.c