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• avutil/avutil : make AV_TIME_BASE_Q available in C++

  18 septembre 2023, par Zhao Zhili

  avutil/avutil : make AV_TIME_BASE_Q available in C++
  ISO C++ forbids compound-literals. It's not available with MSVC.
  
  This is a known issue from 10 years ago, and that's why there is a
  
  av_get_time_base_q().
  Since we have no plan to remove AV_TIME_BASE_Q, just make it
  
  available in C++.
  There are multiple choices :
  
  1. Use C++11 syntax : AVRational1, AV_TIME_BASE
  Users may still use C++98 to write new code. So no.
  2. Use av_get_time_base_q().
  It's for this purpose. But it's not compile time constants as
  
  AV_TIME_BASE_Q in C.
  So I choose av_make_q() as Anton's suggestion.
  https://libav-devel.libav.narkive.com/ZQCWfTun/patch-0-2-fix-avutil-h-usage-from-c
  
  Signed-off-by : Zhao Zhili <zhilizhao@tencent.com>
  

  • [DH] doc/APIchanges
  • [DH] libavutil/avutil.h
  • [DH] libavutil/version.h

• avcodec/tiff : Don't cast const away

  7 septembre 2023, par Andreas Rheinhardt

  avcodec/tiff : Don't cast const away
  lzma_stream.next_in is const for more than 15 years now
  
  and has been so in every release of liblzma.
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/tiff.c

• FFmpeg : Trying to fade out first and later fade back in doesn't work [duplicate]

  6 septembre 2023, par Paul S

  While I just became a registered user on the site, I've been utilizing Stack Overflow for years, virtually always being able to find solutions to problems I've encountered. Unfortunately, not this time ; I have encountered a problem with the ffmpeg video fade filter. There are lots of previously proposed issues along with their solutions, but none (that I can find) that address a twist that I have.

  


  Most questions ask, "how do I fade in", or "how do I fade out", and "how do I fade in at the beginning and fade out at the end." If I want to fade in and later fade out, my below code works just fine.

  


  ffmpeg -ss 00.0 -accurate_seek -to 15.0 -i My.Test.File.mkv -c:v h264 -vf fade=t=in:st=0:d=2,fade=t=out:st=13:d=2 -b:v 825k -s 1280x720 -r 29.97 -c:a aac -ar 44100 -ac 2 -b:a 96k output.mp4


  


  However, I actually want to fade out somewhere in the middle, and then fade back in shortly after, and that doesn't seem to work. I structured the ffmpeg command as so :

  


  ffmpeg -ss 00.0 -accurate_seek -to 15.0 -i My.Test.File.mkv -c:v h264 -vf fade=t=out:st=6:d=2,fade=t=in:st=9:d=2 -b:v 825k -s 1280x720 -r 29.97 -c:a aac -ar 44100 -ac 2 -b:a 96k output.mp4


  


  This fails and yields a completely blank video. I've also tried some -filter_complex variations, but get similar results ; fading in and later fading out works, but fading out and later fading in does not.

  


  I'm using the latest ffmpeg windows version on Windows 10. I would have attached a sample video file but I'm seeing how to do that. It is not the original video file that started my issue, but it does duplicate the issue. Not sure what other info might help in coming up with a solution. Thoughts ?