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• Specifying correct library to link in Xcode when multiple copies exist on search path

  23 avril 2015, par Robotbugs

  I am trying to compile a C++ file that depends on ffmpeg. I have spent a long time trying to fix all the link errors. I found that on the Mac it needs :

  libbz2.dylib
  
  libiconv.dylib
  
  libz.dylib
  
  libavcodec.a
  
  libavformat.a
  
  libswscale.a
  
  libswresample.a
  
  VideoDecodeAcceleration.framework
  
  CodeVideo.framework
  
  CoreFoundation.framework

  The problem I have is that I still get symbol link errors for libiconv even though the library is present in /usr/lib and all the other libraries in this directory are being found there. The compile line includes -liconv.2

  On searching around I found that the problem comes from there being two version of libiconv on my system. One is in /usr/lib and the other is in /opt/local/lib. The one in /usr/lib exports symbols that ffmpeg uses named like "_iconv_open", whereas the one in /opt/local/lib exports the same symbols with "lib" added, e.g. "_libiconv_open". It seems the compiler is picking up the /opt/local/lib library.

  How can I get Xcode to pick up the correct lib ?

• FFmpeg - concat videos error, do not match the corresponding output link ?

  18 février 2021, par wensefu

  I'm trying to concat some video into one single video using ffmpeg.

  



  input information :

  



  a.mp4 1920x808 , b.mkv 1280x720

  



  First I tried command below and it works fine :

  



  


  ffmpeg -i a.mp4 -i b.mkv -f lavfi -t 0.1 -i anullsrc -filter_complex [1:v]scale=1920:808:force_original_aspect_ratio=decrease,pad=1920:808 :(ow-iw)/2 :(oh-ih)/2[v1] ; [0:v][0:a][v1][1:a]concat=n=2:v=1:a=1[outv][outa] -map [outv] -map [outa] -vcodec libx264 -crf 27 -preset ultrafast -threads 2 out.mp4

  


  



  And then I put 'b.mkv' first :

  



  


  ffmpeg -i b.mkv -i a.mp4 -f lavfi -t 0.1 -i anullsrc -filter_complex [0:v]scale=1920:808:force_original_aspect_ratio=decrease,pad=1920:808 :(ow-iw)/2 :(oh-ih)/2[v0] ; [v0][0:a][1:v][1:a]concat=n=2:v=1:a=1[outv][outa] -map [outv] -map [outa] -vcodec libx264 -crf 27 -preset ultrafast -threads 2 out.mp4

  


  



  but this time I got error :

  



  


  Input link in1:v0 parameters (size 1920x808, SAR 0:1) do not match the corresponding output link in0:v0 parameters (1920x808, SAR 3232:3231)

  


  



  I don't understand why ?

  



  Any ideas anyone ?

  



  Many thanks in advance.

  


• Laggy video when downloading from m3u8 link with ffmpeg

  26 décembre 2020, par jagvetinte

  Im trying to download the video in this m3u8 link https://lbs-usp-hls-vod.cmore.se/vod/1aee4/l4fiymehvxx(13287875_ISMUSP).ism/l4fiymehvxx(13287875_ISMUSP).m3u8, and to do that I run this command :

  


  ffmpeg -i "https://lbs-usp-hls-vod.cmore.se/vod/1aee4/l4fiymehvxx(13287875_ISMUSP).ism/l4fiymehvxx(13287875_ISMUSP).m3u8" -vcodec copy -acodec copy output.mp4


  


  The video downloads fine without any errors, but when I play the video it dosen't look great because it looks like the frame rate is very low, but looking in videoproperties in VLC it says that it is 25 fps which is the same as the original video.

  


  The m3u8 link comes from this website if you need to know that : https://www.tv4play.se/program/taskmaster/13287875

  


  Do someone know what is causing this issue and how to fix it ?

  


  Thank you for any advice !

  


  EDIT : I did manage to solve it myself after a lot of research. I just needed to add -fflags +igndts before the -i so the command looked like this

  


  ffmpeg -fflags +igndts -i "https://lbs-usp-hls-vod.cmore.se/vod/1aee4/l4fiymehvxx(13287875_ISMUSP).ism/l4fiymehvxx(13287875_ISMUSP).m3u8" -vcodec copy -acodec copy output.mp4