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• develop with ffmpeg link failed [duplicate]

  13 mai 2021, par Turing Zhu

  I write to test ffmpeg and call ffmpeg function, but it alwasy tell me link err : can not found ffmpeg function :
this is my code :

  


  #ifdef __STDC_CONSTANT_MACROS&#xA;#define __STDC_CONSTANT_MACROS&#xA;#endif&#xA;#ifndef INT64_C&#xA;#define INT64_C(c) (c ## LL)&#xA;#define UINT64_C(c) (c ## ULL)&#xA;#endif&#xA;#include <libavutil></libavutil>imgutils.h>&#xA;#include <libavutil></libavutil>samplefmt.h>&#xA;#include <libavutil></libavutil>timestamp.h>&#xA;#include <libavformat></libavformat>avformat.h>&#xA;static const char *src_filename = NULL;&#xA;static const char *video_dst_filename = NULL;&#xA;static const char *audio_dst_filename = NULL;&#xA;static AVFormatContext *fmt_ctx = NULL;&#xA;int main(int argc, char **argv) {&#xA;    int ret = 0;&#xA;    if (argc != 4) {&#xA;        fprintf(stderr, "usage: %s  input_file video_output_file audio_output_file\n"&#xA;                    "API example program to show how to read frames from an input file.\n"&#xA;                    "This program reads frames from a file, decodes them, and writes decoded\n"&#xA;                    "video frames to a rawvideo file named video_output_file, and decoded\n"&#xA;                    "audio frames to a rawaudio file named audio_output_file.\n",&#xA;            argv[0]);&#xA;        exit(1);&#xA;    }&#xA;    // src_filename = argv[1];&#xA;    src_filename = "/tmp/a.mp4";&#xA;    video_dst_filename = argv[2];&#xA;    audio_dst_filename = argv[3];&#xA;&#xA;    /* open input file, and allocate format context */&#xA;    if (avformat_open_input(&amp;fmt_ctx, src_filename, NULL, NULL) &lt; 0) {&#xA;        fprintf(stderr, "Could not open source file %s\n", src_filename);&#xA;        exit(1);&#xA;    }&#xA;    avformat_close_input(&amp;fmt_ctx);&#xA;}&#xA;

  


  the follow is build command :

  


  clang++ -I /usr/local/apps/homebrew/Cellar/ffmpeg/4.4_1/include/ -L/usr/local/apps/homebrew/Cellar/ffmpeg/4.4_1/lib -lavformat main.cpp


  


  and the terminal output :

  


  Undefined symbols for architecture x86_64:
  "avformat_open_input(AVFormatContext**, char const*, AVInputFormat*, AVDictionary**)", referenced from:
      _main in main-f2a6f0.o
  "avformat_close_input(AVFormatContext**)", referenced from:
      _main in main-f2a6f0.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)



  


  then Who can tell me why.

  


• how to solve unsatisfied link error when two dependencies use FFmpeg

  5 août 2022, par user2925078

  In my Android app I'm using Amplituda https://github.com/lincollincol/Amplituda and video trimmer https://github.com/a914-gowtham/android-video-trimmer
they both use FFmpeg which causes this error

  


  


  Execution failed for task ':app:mergeDebugNativeLibs'.
A failure occurred while executing com.android.build.gradle.internal.tasks.MergeJavaResWorkAction
2 files found with path 'lib/x86/libavcodec.so' from inputs ...

  


  


  I tried to use pick first in my build.gradle

  


  


  pickFirst 'lib/x86/libavcodec.so' and then gradlew clean

  


  


  the project builds fine but gives a runtime error whenever I try to trim the video

  


  


  java.lang.UnsatisfiedLinkError : dlopen failed : cannot locate symbol "avpriv_init_elbg" referenced by ... ==/lib/x86/libavfilter.so"

  


  


  Any idea how to solve this ?
Thanks

  


• How to link FFmpeg libraries with CMake in windows

  4 juillet 2021, par ldall03

  I'm new to CMake and not very familiar with how linking/compiling works. I am on windows 10 using MinGW in CLion. As the title says I want to use FFmpeg libraries in my c++ code. I downloaded the source code from : https://ffmpeg.org/download.html (Download Source Code button). I unzipped it and put the libavcodec library in my project. Here is my project structure :

  


  project
   \-- cmake-build-debug
   \-- src
      \-- vendor
         \-- libavcodec
   \-- main.cpp
   \--CMakeLists.txt


  


  Here is my main.cpp file :

  


  extern "C" {&#xA;#include "libavcodec/avcodec.h"&#xA;}&#xA;&#xA;#include <iostream>&#xA;&#xA;int main(int argc, char *argv[]) {&#xA;    std::cout &lt;&lt; "Hello World\n";&#xA;    return 0;&#xA;}&#xA;&#xA;</iostream>

  


  And my CMakeLists.txt file :

  


  cmake_minimum_required(VERSION 3.19)
project(VidShare)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_PREFIX_PATH  "C:/Qt/6.1.1/mingw81_64/lib/cmake")

find_package(Qt6Widgets REQUIRED)

set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_AUTOUIC ON)

add_executable(VidShare main.cpp)
include_directories(src src/vendor)
target_link_libraries(VidShare Qt6::Widgets Qt6::Core Qt6::Gui)


  


  Ignore the Qt stuff it works fine.

  


  And well when I build I get this error message :

  


  fatal error: libavutil/avconfig.h: No such file or directory
 #include "libavutil/avconfig.h"


  


  I've seen that I had to run a configure script in the FFmpeg main file but I'm on windows so I can't really do that. I don't know if I have to use other kinds of libraries or if I downloaded the wrong thing... I am really at lost here. There is probably a better or more convenient way of doing what I want but I could not find many resources on it... Help would be appreciated :)