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• Different video players showing incorrect mp4 resolution after ffmpeg conversion

  18 novembre 2016, par Nova

  After getting help from http://stackoverflow.com/a/40601020/6318164 on how to convert webm to mp4. The result avoiding losing the video ratio by setting the height resolution with -vf scale=-2:720.

  I then came across another problem. I’ve found both width and height had to be supported for the video players, when I thought it was just the height that had to be specified.

  After browsing around I found this script http://stackoverflow.com/a/35487394/6318164 were I can change the video’s canvas to a common width and height standard. It shrinks the video to fit inside the center of specified canvas without losing the ratio while filling the empty space with black padding if I’m correct, which is the result I want.

  However, although it solved the playback problems in all the players, I’ve found different video players show different resolution information of the same video.

  I’ve modified the script here for Linux terminal use.

  X=1280; Y=720; ffmpeg -i old.webm -t 5 -vf "scale=min(iw*$Y/ih\,$X):min($Y\,ih*$X/iw),pad=$X:$Y:($X-iw)/2:($Y-ih)/2" new.mp4

  This is the research on the resolution differences I’ve found for value I set.

  X=1280; Y=720;
  
  
  
  webm          -> mp4
  
  =========================================================
  
  1280x752      -> 1280x720 X-plore (Android)
  
  Not supported -> 1339x720 Telegram (Android)
  
  1338x752      -> 1340x720 GNOME MPlayer (Linux)
  
  Not supported -> ???????? Built-in Video Player (Android)

  The question is, I’m I doing anything wrong with the ffmpeg conversion to return incorrect resolutions for different players ? I checked out some other videos I have and they show the correct resolutions except this converted one.

  Edit

  With the help of the accepted answer. This was my working output if anyone needs it :

  X=1280; Y=720; ffmpeg -i input.webm -vf "scale='if(gt(a*sar,16/9),${X},${Y}*iw*sar/ih)':'if(gt(a*sar,16/9),${X}*ih/iw/sar,${Y})',pad=${X}:${Y}:(ow-iw)/2:(oh-ih)/2,setsar=1" output.mp4

• FFMpeg and Python Videos - skipping frames and resulting in incorrect video outputs

  29 septembre 2022, par S.A.D.

  I have a couple of videos recorded (I recorded them using opencv in python)- they are rougly 4 minutes long. I want to trim only 10s of each of them.

  


  Trimming them with FFMpeg tho (ffmpeg -i input.mp4 -ss 00:02:01 -t 00:00:10 -c:v copy -c:a copy output.mp4) results in an incorrect output.

  


  Whats incorrect about it ?

  


  

  1. When I open it with VLC media player, it shows it is indeed 10s long, but it plays only one second, from 9 to 10th second, and ends the video.

  


  2. I chose a specific fragment to be cut, and yet, the trimmed output is not this fragment - it is like, 10s earlier.

  


  


  I literary have no idea why this is happening - this sounds like some corrupted input file, and results in another corrupted output.
Why is this happening ? How to fix this ?

  


  Thanks tons

  


• libFLAC/stream_decoder : Fix double free

  22 août 2015, par Erik de Castro Lopo

  libFLAC/stream_decoder : Fix double free
  The american-fuzzy-lop fuzzer found a couple of instances of double
  
  free() resulting from commit 15a9062609.
  The problematic free() were the ones associated with use of the
  
  safe_realloc_mul_2op_() function which can call realloc(ptr,0) which
  
  according to the realloc manpage is already an implicit free().
  

  • [DH] src/libFLAC/stream_decoder.c