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• avcodec/xbmenc : Allow for making UW images

  19 janvier 2021, par Jose Da Silva

  avcodec/xbmenc : Allow for making UW images
  I've run into some bugs where I was downloading a bunch of data and began
  
  seeing weird hiccups. For example, javascript promises to allow you to push
  
  some very long lines of data, but the hiccups I saw was with data larger
  
  than 2k in length (windows) pushed out of a child process stdout piped into
  
  the stdin of the calling parent program.
  
  Soo much for smooth promises, this was broken and would run into similar
  
  problems on a linux PC with 32k line limits.
  
  The solution was to break the data into smaller chunks than 2k - and then
  
  these data hiccups disappeared (windows PC).
  It would be expected to be similar for linux PCs (32k I think) and other
  
  OSes with different sizes.
  If the ANSI required minimum needs to be 509 chars or larger (assuming
  
  509+<CR>+<LF>+<0>=512), then 509 was chosen as the shortest worst-case
  
  scenario) in this patch.
  
  Most small pictures will go output looking pretty much the same data out
  
  until you get to about 84bytes (672 pixels wide), where lines out begin to
  
  be split. For example a UW 4K will exceed a 2k readln and a UW 10K picture
  
  approaches an 8k readln
  The purpose for this patch is to ensure that data remains below the
  
  readline limits (of 509 chars), so that programs (like javascript) can push
  
  data in large chunks without breaking into hiccups because the data length
  
  is too long to be pushed cleanly in one go.
  
  Subject : [PATCH 3/3] avcodec/xbmenc : Allow for making UW images
  Worst-case ANSI must allow for 509 chars, while Windows allows for 2048
  
  and Linux for 32K line length. This allows an OS with a small readline
  
  access limitation to fetch very wide images (created from ffmpeg).
  

  • [DH] libavcodec/xbmenc.c

• How do I make FFMPEG use localized strftime with drawtext ?

  3 décembre 2022, par Randy Michnovicz

  I'm trying to write a script to use FFMPEG to draw localized timestamps on a video, but I'm not having much luck.

  


  I can confirm I have the locale fr_FR.UTF-8 installed on my system by running the following command : LC_ALL=fr_FR.UTF-8 date

  


  However, the following command produces a 4 second video beginning with the string "Monday 28 November 2022 19:00:47 PST" on both my Mac and an Alpine Linux docker container :

  


  LC_ALL=fr_FR.UTF-8 ffmpeg -hide_banner -f lavfi -i color=size=1024x768:rate=25:color=black -c:v libx264 -c:a aac -filter_complex drawtext=expansion=normal:fontsize=18:fontcolor=white:box=1:boxcolor=black@0.5:text='%{pts\\:localtime\\:1669690847\\:%A %-d %B %Y %X %Z}' -t 4 -y out.mp4

  


  Does anyone know how to make it create strings with non-English text ?

  


• using ffmpeg to automate splitting video into quarters and stacking

  14 novembre 2017, par user3297049

  I need to create a quick FFMPEG batch file that takes a very wide video file and splits it into quarters (dimension wise not time wise), then outputting a file where each quarter is under the previous.

  E.g.

  A B C D

  Would become :

  A
  B
  C
  D

  I know this should be possible with crop and pad commands, and through research I’ve found that someone divided into quarters and put the top left and bottom right next to each other horizontally using :

  "%~dp0\ffmpeg.exe" -i %1 -filter_complex "[0:0]crop=iw/2:ih/2:0:0,pad=iw*2:ih:0:0[tl];[0:0]crop=iw/2:ih:iw/2:ih/2[br];[tl][br]overlay=W/2" -b:v 32000k -b:a 128k %1_2.avi

  Can anyone help as the command line is beyond me ?