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• How would I dynamically link FFmpeg in a C# Project for use with FFMpegCore ?

  15 octobre 2024, par liamliam

  So far, I have FFMpegCore working in my project with a ffmpeg.exe dropped into the project directory. This works, but for LGPL license compliance FFmpeg requires dynamic linking :
  
Use dynamic linking (on windows, this means linking to dlls) for linking with FFmpeg libraries..

  


  While I understand the basic concept of dynamic vs static linking, my problem is likely a misunderstanding of how .dlls work and how they apply to C# and .NET.
  
Would it be possible to compile ffmpeg into a single .dll that could be accessed by FFMpegCore cross-platform ? From what I can gather in the source, FFMpegCore looks for an ffmpeg or ffmpeg.exe file in its configuration path.

  


  Is it possible to have .NET dynamically link FFmpeg and expose it to libraries for use or is that a complete misunderstanding and would I then need a wrapper library with different capabilities ?

  


  I've attempted to find the answer in the relevant documentation, but I found none for this specific use of either library. I suspect my problem might be a fundamental misunderstanding of how these tools work and work together.
My ideal result would be using FFMpegCore with an FFmpeg.dll that works cross-platform instead of the .exe.

  


  Edit 1 : @taratect's answer and graphic sent me down a path that cleared up quite a bit about exes and dlls. .Net compiles source code down to platform agnostic Intermediate Language in the form of a .dll or .exe(completely different to C++ variants of these files), which is executed by the Common Language Runtime using a Just In Time compiler to convert that Intermediate Language to Machine Code that can be run on the specific platform .Net is installed on. C++(FFmpeg) compiles directly to platform specific Machine Code (as shown in the graphic), confusingly in the form of a .dll or .exe (on Windows). .Net can indeed load and run machine code unmanaged by Common Language Runtime, since everything is run as Machine Code by the end, however memory and other complexities must then be managed by me, which seems to be what FFMpegCore does in wrapping the executable. I might still be confused/incorrect on some of this, unmanaged code is beyond my understanding so far.
This does more or less confirm that FFMpegCore probably can't be expected to use FFmpeg in the way I hoped and a better workaround might be having the user just supply an FFmpeg source or implement a downloader as part of installation so that I don't have to redistribute it at all.

  


• ios ffmpeg with support for floating-point ABI

  20 juin 2013, par user1881371

  How do I collect on ios ffmpeg with support for floating-point ABI ?

  I have an application that shows the video, but slow decoding.

  ffmpeg compiled without support for floating-point ABI

  ./configure --prefix=armv7 --disable-ffmpeg --disable-ffplay --disable-ffprobe 
  
  --disable-ffserver --enable-avresample --enable-cross-compile 
  
  --sysroot="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk" 
  
  --target-os=darwin 
  
  --cc="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc" 
  
  --extra-cflags="-arch armv7 -mfpu=neon -mfloat-abi=hard 
  
  -miphoneos-version-min=6.1" --extra-ldflags="-arch armv7 
  
  -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk -miphoneos-version-min=1.0" 
  
  --arch=arm --cpu=cortex-a9 --enable-pic

  I always get a warning

  WARNING: Compiler does not indicate floating-point ABI, guessing soft.

  I have tried

  -mfloat-abi=hard

• Building FFMpeg Error in IOS6.1 unable to create an executable file

  10 juillet 2013, par 2vision2

  I am trying to build ffmpeg on iOS6.1 (armv7), when I try to run ./configure like this :

  ./configure --disable-doc --disable-ffmpeg --disable-ffplay
  
  --disable-ffserver    --enable-cross-compile --arch=arm --target-os=darwin    --cc=/applications/xcode.app/contents/Developer/usr/bin/gcc    --as='gas-preprocessor/gas-preprocessor.pl /applications/xcode.app/contents/Developer/usr/bin/gcc'   
  
  --sysroot=/applications/xcode.app/contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk
  
  --cpu=cortex-a8 --extra-cflags='-arch armv7'    --extra-ldflags='-arch armv7 -isysroot /applications/xcode.app/contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk'
  
  --enable-pic

  I get the following error :

  /applications/xcode.app/contents/Developer/usr/bin/gcc is unable to
  create an executable file. C compiler test failed.

  Could somebody please provide the correct parameters in iOS6.1 ?

  Update Command :

  ./configure —disable-doc —disable-ffmpeg —disable-ffplay
  —disable-ffserver —enable-cross-compile —arch=arm —target-os=darwin —cc=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/llvm-gcc-4.2/bin/arm-apple-darwin10-llvm-gcc-4.2
  —as='gas-preprocessor/gas-preprocessor.pl /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/llvm-gcc-4.2/bin/arm-apple-darwin10-llvm-gcc-4.2'
  —sysroot=/applications/xcode.app/contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk
  —cpu=cortex-a8 —extra-cflags='-arch armv7' —extra-ldflags='-arch armv7 -isysroot
  /applications/xcode.app/contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk'
  —enable-pic

  Error in Update Command :

  /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/llvm-gcc-4.2/bin/arm-apple-darwin10-llvm-gcc-4.2
  is unable to create an executable file. C compiler test failed.

  If you think configure made a mistake, make sure you are using the latest
  version from Git. If the latest version fails, report the problem to the
  ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.freenode.net.
  Include the log file "config.log" produced by configure as this will help
  solving the problem.