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• x264 Downsides of a high CRF (22) intermediary codec between conversions instead of lossless

  18 décembre 2019, par bobtheencoder

  I have a huge collection of video files that are in the range of CRF 16-20 taking up TB’s of space. The only need I have for these originals is that I have to encode them from time to time but the CRF of these final encodes is very low (CRF 26-28).

  I understand that a lossy to lossy converstion ALWAYS results in some quality loss but my question is what if the intermediate file is almost visually lossless compared to the final output.

  So to sum up, what quality difference should I expect from the following routes ?

  CRF 18 (original) -----> CRF 28 (final)
  
  CRF 18 (original) -----> CRF 22 (long-term storage) -----> Lossy  CRF 28 (final)

• Link to ffmpeg libraries using mingw c++ -> undefined reference [duplicate]

  16 juillet 2016, par Gerhard

  This question already has an answer here :

  • Libav linking error : undefined references
    
    3 answers
    

  I read about a lot of very similar problems here, but none of them seems
  to solve my problem. I feel that I need only a very small step to succeed...

  I have an existing c++ project and try to include some FFmpeg functions.
  When linking with MinGW on Windows OS against the FFmpeg libraries, I get always
  the error message "undefined reference to...".

  I reduced my code totally to the following sample :

  // START of file simple.cpp
  
  #ifndef INT64_C
  
  #define INT64_C(c) (c ## LL)
  
  #define UINT64_C(c) (c ## ULL)
  
  #endif
  
  
  
  #include 
  
  
  
  #include <libavutil></libavutil>opt.h>
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavutil></libavutil>channel_layout.h>
  
  #include <libavutil></libavutil>common.h>
  
  #include <libavutil></libavutil>imgutils.h>
  
  #include <libavutil></libavutil>mathematics.h>
  
  #include <libavutil></libavutil>samplefmt.h>
  
  
  
  int main(int argc, char **argv){
  
      avcodec_register_all();
  
      return 0;
  
  }
  
  // END of file simple.cpp

  I compile with :

  g++ -o simple.o -c simple.cpp -std=gnu++11

  which worked well.
  My link command is :

  g++ -o simple.exe simple.o -lavcodec -std=gnu++11

  and I get the error message :

  simple.o:simple.cpp:(.text+0xc): undefined reference to avcodec_register_all()

  So, at least the libraries are found ;-)
  I used the libraries directly from Zeranoe and I also managed to compile
  new ones from source. The error message is the same in both cases.

  A step to find the solution might be the following test (compile with gcc instead of g++) :

  1. I rename simple.cpp to simple.c

  2. I compile with :

     gcc -o simple.o -c simple.c

  3. I link with :

     g++ -o simple.o -c simple.c -lavcodec

  And that will work !!!

  But, unfortunately, that is no solution for me, because my main program
  is definitely c++ und must be compiled using g++.

  So, what the hell is wrong here ?
  Is that a FFmpeg topic or is that a gcc/g++ topic ?
  Please, all hints are welcome.

  I already tried out all possible ’extern’ and extern "C"- statements, no success.

• ffmpeg bit_rate error - Android [duplicate]

  6 juin 2016, par Adroid Freak

  This question already has an answer here :

  • ffmpeg Too many bits per frame requested
    
    2 answers
    

  I’m getting the following error "maybe incorrect parameters such as bit_rate, rate, width or height" in some android phones, what am I doing wrong ?

  /data/data/com.exampleapp.android/app_bin/ffmpeg -y -i /storage/emulated/0/example/test/recording.mp4 -af asetrate=9600*4/3 -strict -2 /storage/emulated/0/example/media/example/test.m4a 
  
     libavutil      54.  7.100 / 54.  7.100
  
     libavcodec     56.  1.100 / 56.  1.100
  
     libavformat    56.  4.101 / 56.  4.101
  
     libavdevice    56.  0.100 / 56.  0.100
  
     libavfilter     5.  1.100 /  5.  1.100
  
     libswscale      3.  0.100 /  3.  0.100
  
     libswresample   1.  1.100 /  1.  1.100
  
     libpostproc    53.  0.100 / 53.  0.100
  
   Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/storage/emulated/0/example/test/recording.mp4':
  
     Metadata:
  
       major_brand     : isom
  
       minor_version   : 0
  
       compatible_brands: isom3gp4
  
       creation_time   : 2016-06-06 00:51:05
  
     Duration: 00:00:03.33, start: 0.000000, bitrate: 14 kb/s
  
       Stream #0:0(eng): Audio: aac (mp4a / 0x6134706D), 16000 Hz, mono, fltp, 12 kb/s (default)
  
       Metadata:
  
         creation_time   : 2016-06-06 00:51:05
  
         handler_name    : SoundHandle
  
   [aac @ 0x42136170] Too many bits per frame requested
  
   Output #0, ipod, to '/storage/emulated/0/example/media/example/test.m4a':
  
     Metadata:
  
       major_brand     : isom
  
       minor_version   : 0
  
       compatible_brands: isom3gp4
  
       Stream #0:0(eng): Audio: aac, 0 channels, 128 kb/s (default)
  
       Metadata:
  
         creation_time   : 2016-06-06 00:51:05
  
         handler_name    : SoundHandle
  
         encoder         : Lavc56.1.100 aac
  
   Stream mapping:
  
     Stream #0:0 -> #0:0 (aac (native) -> aac (native))
  
   Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
  
  exitValue 1