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• Generating Gif from Mp4 directly - ffmpeg

  20 janvier 2016, par senty

  I am trying to generate a gif from an mp4 video file. I want to scale it and crop it while generating.

  I achieved that (cropping & scaling) from mp4 to mp4 with the below line , (so I can extract pngs with ffmpeg and use Imagick to make animated gif), but I believe there is a better way of achieving purely with ffmpeg.

  ffmpeg -i in.mp4 -filter:v "scale=300:ih*300/iw, crop=200:500:50:80" -c:a copy out.mp4

  My question is how to achieve the same this code is doing, but for directly generating gif from mp4.

  ---

  Then I started tweaking with mp4 to gif conversion, but when palette comes in, I couldn’t fully understand what’s going on.

  I found this answer and I made it work, however I couldn’t understand how to adapt scaling & cropping.

  $ ffmpeg -y -ss 30 -t 3 -i in.mp4 \
-vf fps=10,scale=320:-1:flags=lanczos,palettegen palette.png

  $ ffmpeg -ss 30 -t 3 -i in.flv -i palette.png -filter_complex \ "fps=10,scale=320:-1:flags=lanczos[x];[x][1:v]paletteuse" out.gif

  I partially understand what this bit does -y -ss 30 -t 3 -i in.mp4 (getting the first 30 seconds and generating a 3 second gif out of it). But for the next lines, I am completely lost what it is actually doing.

  It’d be amazing if someone can explain what each command does, or refer a link explaining this topic.

• Tell a java servlet when to return from an external command line call

  20 septembre 2011, par Morgan

  I have a java servlet api, that when requested, starts a live conversion of a video file using ffmpeg and pipes it to mediastreamsegmenter to segment it for http live streaming. What I want is for the java servlet to return the url of the index file as soon as it has been generated (after the 4th transport stream file is written) so the user can start watching the video without waiting for it to fully finish converting.

  How I was thinking of achieving this was to pass a command into the -file-complete-command argument of mediastreamsegmenter, and have it call some sort of a command that could tell the java servlet to return its response if the last file completed was the index file.

  Another idea I had was to just segment the first 30 seconds or so of the video, and then return the response, and add the remainder of the video into some sort of a background task in the servlet. I'm not sure how this would be done though. Could I create a separate thread to do this conversion that will continue to run after the servlet returns ? I'm sure there must be a better way of doing this. Any thoughts would be appreciated.

• avcodec/exr : Avoid signed overflow in displayWindow

  21 mars 2022, par Michael Niedermayer

  avcodec/exr : Avoid signed overflow in displayWindow
  The inputs are unused except for this computation so wraparound
  
  does not give an attacker any extra values as they are already fully
  
  controlled
  Fixes : signed integer overflow : 0 - -2147483648 cannot be represented in type 'int'
  
  Fixes : 45820/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EXR_fuzzer-5766159019933696
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/exr.c