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• avformat/framecrcenc : Don't read after the end of side-data

  6 décembre 2020, par Andreas Rheinhardt

  avformat/framecrcenc : Don't read after the end of side-data
  Nothing guarantees that the size of side data containing a palette
  
  is actually divisible by four (although it should be) ; but for
  
  big-endian systems, an algorithm is used that presupposed this.
  
  So switch to an algorithm that does not overread : It processes
  
  four bytes at a time, but only if all of them are contained in
  
  the side data.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/framecrcenc.c

• avutil/adler32 : Switch av_adler32_update() to size_t on bump

  18 mars 2021, par Andreas Rheinhardt

  avutil/adler32 : Switch av_adler32_update() to size_t on bump
  av_adler32_update() is used by av_hash_update() which will be switched
  
  to size_t at the next bump. So it also has to be made to use size_t.
  
  This is also necessary for framecrcenc.c, because the size of side data
  
  will become a size_t, too.
  Reviewed-by : James Almer <jamrial@gmail.com>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] doc/APIchanges
  • [DH] libavutil/adler32.c
  • [DH] libavutil/adler32.h
  • [DH] libavutil/version.h

• ffmpeg : two videos side-by-side with audio1 lang=ger & audio2 lang=eng

  19 janvier 2023, par miridigital

  I have two videos from two GoPro cameras. Both videos are rendered via ffmpeg side-by-side into a single video (left and right) and the audio is currently combined/mixed into two channels (stereo). I can hear both camera audio channels at the same time.

  


  Two channels stereo :

  


  ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[v]; [0:a][1:a]amerge[a]" -map "[v]" -map "[a]" -ac 2 side-by-side.mp4


  


  audio from both videos mixed into a single file with 2 channels - mediainfo

  


  Now I want to switch between the two audio channels (cam1 or cam2) while I'm playing the side-by-side video.

  


  My first try : With four channels (without -ac 2 parameter) :

  


  ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[v]; [0:a][1:a]amerge[a]" -map "[v]" -map "[a]" side-by-side.mp4


  


  audio from both videos mixed into a single file with 4 channels - mediainfo

  


  But the most video players can't easily select the channels 1+2 or 3+4 while playing.

  


  So I tried two languages :

  


  ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[v]; [0:a][1:a]amerge[a]" -map "[v]" -map "[a]" -metadata:s:a:0 language=ger -metadata:s:a:1 language=eng side-by-side.mp4


  


  audio from both videos mixed into a single file with 4 channels with languages - mediainfo

  


  But that's wrong. I can only see german with 4 channels. How can I put channels 1+2 into german and channels 3+4 into english ? Afterwards I should be able to use the multi language feature from most video players to switch the audio between cameras.

  


  Thank you,
  
Miriam