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• Building ffmpeg libraries for third party usage

  23 mars 2023, par mikeProgrammer

  I am trying to create bindings for FFmpeg in Elixir programming language and would love to handle FFmpeg binaries for users of my library.

  


  The whole flow is as follows :

  


  

  1. Write some function definition in Elixir

  


  2. Implement it in in C using ffmpeg libs

  


  3. Compile C code as shared library

  


  4. When running application, Erlang Virtual Machine will load my dynamic library

  


  


  The question is how to compile and include ffmpeg libs in my shared lib so that users of my Elixir lib don't have to install any native dependencies.

  


  Here is what I was trying :

  


  


  1. Compile ffmpeg libs as shared ones. When my Elixir lib is compiling, it downloads precompiled ffmpeg archive, extracts its content and links to it when compiling native functions. I realized that this still won't work as ffmpeg shared libs depend on other shared libs that user has to install on their own.

     


  


  2. Compile ffmpeg libs as static ones and include them in my native shared library using —whole-archive linker option. Here I am getting

     


  


  


  /usr/bin/ld : ffmpeg_build/lib/libavcodec.a(vp9lpf_16bpp.o) : warning : relocation against ff_pw_1' in read-only section .text'
/usr/bin/ld : ffmpeg_build/lib/libavcodec.a(cavsdsp.o) : relocation R_X86_64_PC32 against symbol `ff_pw_5' can not be used when making a shared object ; recompile with -fPIC
/usr/bin/ld : final link failed : bad value
collect2 : error : ld returned 1 exit status

  


  The command I am using

  


  cc -fPIC -I/home/michal/.asdf/installs/erlang/25.1/erts-13.1/include -Iffmpeg_build/include -Ic_src/xav -shared -DXAV_DEBUG=1 c_src/xav/xav_nif.c c_src/xav/reader.c c_src/xav/utils.c -o /home/michal/Repos/xav/_build/test/lib/xav/priv/libxav.so -Lffmpeg_build/lib -Wl,--whole-archive -lavcodec -lswscale -lavutil -lavformat -Wl,--no-whole-archive


  


  FFmpeg configuration

  


  ./configure \
--prefix="$PWD/ffmpeg_build" \
--extra-cflags="-fPIC -I$PWD/ffmpeg_build/include" \
--extra-ldflags="-L$PWD/ffmpeg_build/lib" \
--enable-pic
--disable-programs


  


  Does anything that I am trying to do make sense to you ?

  


  When I am installing ffmpeg-libs package on Fedora, it depends on other shared libs that are automatically downlaoded but what I would love to achieve is to provide self-contained ffmpeg build that can be used in other shared libraries.

  


• Is there a way of making ffmpeg start with the largest folders first ? [closed]

  5 décembre 2024, par tuqueque

  I have the following script (snippet), where I search for all the folders and then pass the result to xargs, where I run ffmpeg in parallel for as many threads as my CPU has (32) to convert the image sequences inside each folder :

  


  find . -type d -print0 | xargs -0 -P32 -I{} ffmpeg...


  


  The thing is that there are folders with just 10 images inside and other folders with 150 images... I'd love if ffmpeg started with the largest folders first and then continue in a descending order... not one at a time, but keeping the parallel nature of the script.

  


  Is that even possible without radically altering the one-line script I have ?

  


• Replace Special Characters In Batch-File Variable Feeding FFMPEG Programme

  6 janvier 2019, par whereswaller

  I am attempting to write a batch-file that leverages the FFMPEG programme to convert all files in a folder structure to mp3 format (specifically 128kbps).

  My batch-file is presently unable to process filenames (constructed by concatenating the %_SOURCE% and %% F variables) containing certain special characters, for example :

  ’
   
  "
  ö

  How can I modify my script so that the %% F variable escapes these characters correctly ?

  Example current filename input : "C :\Users\Test\Documents\Input\Peter Bjorn And John - I Know You Don’t Love Me.mp3"

  Example desired filename input : "C :\Users\Test\Documents\Input\Peter Bjorn And John - I Know You Don"^’"t Love Me.mp3"

  Script (see line beginning "C :\ffmpeg\bin\ffmpeg.exe") :

  @echo off
  
  setlocal EnableExtensions DisableDelayedExpansion
  
  
  
  rem // Define constants here:
  
  set "_SOURCE=C:\Users\Test\Documents\Input" & rem // (absolute source path)
  
  set "_TARGET=C:\Users\Test\Documents\Output"  & rem // (absolute target path)
  
  set "_PATTERN=*.*" & rem // (pure file pattern for input files)
  
  set "_FILEEXT=.mp3"   & rem // (pure file extension of output files)
  
  
  
  pushd "%_TARGET%" || exit /B 1
  
  for /F "delims=" %%F in ('
  
      cd /D "%_SOURCE%" ^&^& ^(rem/ list but do not copy: ^
  
          ^& xcopy /L /S /Y /I ".\%_PATTERN%" "%_TARGET%" ^
  
          ^| find ".\" ^& rem/ remove summary line;
  
      ^)
  
  ') do (
  
      2> nul mkdir "%%~dpF.
  
  
  
      rem // Set up the correct `ffmpeg` command line here:
  
      set "FFREPORT=file=C\:\\Users\\Test\\Documents\\Output\\ffreport-%%~F.log:level=32"
  
      "C:\ffmpeg\bin\ffmpeg.exe" -report -n -i "%_SOURCE%\%%~F" -vn -c:a libmp3lame -b:a 128k "%%~dpnF%_FILEEXT%"
  
      if not errorlevel 1  if exist "%%~dpnF%_FILEEXT%" del /f /q "%_SOURCE%\%%~F"
  
  
  
  )
  
  popd
  
  
  
  endlocal
  
  pause