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• Linker error LNK2019 with ffmpeg and VC++ [duplicate]

  9 octobre 2015, par Dom

  This question already has an answer here :

  • What is an undefined reference/unresolved external symbol error and how do I fix it ?
    
    21 answers
    

  I have the following code :

  extern "C" 
  
  {
  
     #include <libavcodec></libavcodec>avcodec.h>
  
     #include <libavformat></libavformat>avformat.h>
  
     #include <libswscale></libswscale>swscale.h>
  
  }
  
  
  
  int main(int argc, char *argv[]) {
  
     av_register_all();
  
     return 0;
  
  }

  And when I try to build, I get the following error :

  error LNK2019: unresolved external symbol _av_register_all referenced in function _main

  I’m using the Zeranoe build for Windows and my Linker is configured to the ffmpeg folder and my Aditional Includes are set to the include folder.

  I added all the lib files to my Linker Input.

• doc/filters : Clarify scale2ref example

  27 mai 2017, par Kevin Mark

  doc/filters : Clarify scale2ref example
  Signed-off-by : Kevin Mark <kmark937@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] doc/filters.texi

• Cut a video in between key frames without re-encoding the full video using ffpeg ?

  1er septembre 2020, par bguiz

  I would like to cut a video at the beginning at any particular timestamp, and it need to be precise, so the nearest key frame is not good enough.

  


  Also, these videos are rather long - an hour or longer - so I would like to avoid re-encoding this altogether if possible, or otherwise only re-encode a minimal fraction of the total duration. Thus, would like to maximise the use of -vcodec copy.

  


  How can I accomplish this using ffmpeg ?

  


  NOTE : See scenario, and my own rough idea for a possible solution below.

  


  ---

  


  Scenario :

  


  

  • Original video

    

    • Length of 1:00:00

    


    • Has a key frame every 10s

    


    


  


  • Desired cut :

    

    • From 0:01:35 through till the end

    


    


  


  • Attempt #1 :

    

    • Using -ss 0:01:35 -i blah.mp4 -vcodec copy, what results is a file where :

    


    • audio starts at 0:01:30

    


    • video also starts at 0:01:30

    


    • this starts both the audio and the video too early

    


    


  


  • using -i blah.mp4 -ss 0:01:35 -vcodec copy, what results is a file where :

    

    • audio starts at 0:01:35,

    


    • but the video is blank/ black for the first 5 seconds,

      

      • until 0:01:40, when the video starts

      


      


    


    • this starts the audio on time,
but the video starts too late

    


    


  


  


  ---

  


  Rough idea

  


  

  • (1) cut 0:01:30 to 0:01:40

    

    • re-encode this to have new key frames,
including one at the target time of 0:01:35

    


    • then cut this to get the 5 seconds from 0:01:35 through 0:01:40

    


    


  


  • (2) cut 0:01:40 through till the end

    

    • without re-encoding, using -vcodec copy

    


    


  


  • (3) ffmpeg concat the first short clip (the 5 second one)
with the second long clip

  


  


  I know/ can work out the commands for (2) and (3), but am unsure about what commands are needed for (1).