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• Trying to choose first audio stream of specific language in ffmpeg using python

  3 avril 2024, par R41D

  I have .mkv files that some of them have more than 1 audio stream in the same language so i need to first map the audio streams with specific language and then use only first of them to output .mp4 file. So it would need two -map audio arguments which doesn't work in ffmpeg.

  


  I found out that i could execute ffmpeg mapping audio with that specific language and then pipe the output to another ffmpeg command that would take the first audio stream from the first ffmpeg command and do the rest of things (scaling, burning-in subtitles, encoding it to different format), but i'm not sure how to pipe that output in python's Popen and if it is even possible in windows.

  


  The solution i found with piping :
FFMPEG Pick First Audio Stream of Specific Language

  


• A C language ffmpeg project organized with CMakeLists, encounters errors in the Windows MinGW64 environment

  20 juin 2023, par flywen

  Project Structure

  


  ffmpeg-tutorial

  


  

  • include

    

    • libavcodec

    


    • libavdevice

    


    • libavfilter

    


    • libavformat

    


    • libavutil

    


    • libswresample

    


    • libswscale

    


    


  


  • lib

    

    • pkgconfig

    


    • libavcodec.a

    


    • libavdevice.a

    


    • libavfilter.a

    


    • libformat.a

    


    • libavutil.a

    


    • libswresample.a

    


    • libswscale.a

    


    


  


  • CMakeLists.txt

  


  • main.c

  


  


  CMakeLists.txt

  


  cmake_minimum_required(VERSION 3.20)
project(ffmpeg_tutorial)

set(CMAKE_C_STANDARD 11)

include_directories(include)
link_directories(lib)
add_executable(ffmpeg_tutorial main.cpp)
target_link_libraries(ffmpeg_tutorial
        avformat
        avcodec
        avutil
        swscale
        swresample
        z
        bz2
        iconv
        ws2_32
        schannel
        kernel32
        advapi32
        kernel32
        user32
        gdi32
        winspool
        shell32
        ole32
        oleaut32
        uuid
        comdlg32
        advapi32
        )


  


  main.c

  


  #include 
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswresample/swresample.h"
int main() {
    std::cout << "Hello, World!" << std::endl;
    std::cout << av_version_info() << std::endl;
    printf("ffmpeg version is %s\n", av_version_info());
    // Open input file
    AVFormatContext *inputContext = nullptr;
    if (avformat_open_input(&inputContext, "input.mp3", nullptr, nullptr) != 0) {
        printf("Couldn't open input file\n");
        return -1;
    }

    // Read input stream
    if (avformat_find_stream_info(inputContext, nullptr) < 0) {
        printf("Couldn't find stream information\n");
        return -1;
    }

    // Get audio stream index
    int audioStream = -1;
    for (int i = 0; i < inputContext->nb_streams; i++) {
        if (inputContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
            audioStream = i;
            break;
        }
    }

    if (audioStream == -1) {
        printf("Couldn't find audio stream\n");
        return -1;
    }
}



  


  IDE

  


  clion

  


  ERRORS

  


  [ 50%] Building CXX object CMakeFiles/ffmpeg_tutorial.dir/main.cpp.obj
[100%] Linking CXX executable ffmpeg_tutorial.exe
D:/Msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: G:/cywen_private/cpp_projects/ffmpeg-tutorial/lib/libavformat.a(tls_schannel.o): in function `tls_write':
D:\Msys64\usr\src\ffmpeg/libavformat/tls_schannel.c:563: undefined reference to `EncryptMessage'
D:/Msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: G:/cywen_private/cpp_projects/ffmpeg-tutorial/lib/libavformat.a(tls_schannel.o): in function `tls_read':
D:\Msys64\usr\src\ffmpeg/libavformat/tls_schannel.c:441: undefined reference to `DecryptMessage'
D:/Msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: G:/cywen_private/cpp_projects/ffmpeg-tutorial/lib/libavcodec.a(mfenc.o):mfenc.c:(.rdata$.refptr.IID_ICodecAPI[.refptr.IID_ICodecAPI]+0x0): undefined reference to `IID_ICodecAPI'
D:/Msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: G:/cywen_private/cpp_projects/ffmpeg-tutorial/lib/libavcodec.a(tiff.o): in function `tiff_uncompress_lzma':
D:\Msys64\usr\src\ffmpeg/libavcodec/tiff.c:577: undefined reference to `lzma_stream_decoder'
D:/Msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: D:\Msys64\usr\src\ffmpeg/libavcodec/tiff.c:582: undefined reference to `lzma_code'
D:/Msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: D:\Msys64\usr\src\ffmpeg/libavcodec/tiff.c:583: undefined reference to `lzma_end'
D:/Msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: G:/cywen_private/cpp_projects/ffmpeg-tutorial/lib/libavutil.a(random_seed.o): in function `av_get_random_seed':
D:\Msys64\usr\src\ffmpeg/libavutil/random_seed.c:127: undefined reference to `BCryptOpenAlgorithmProvider'
D:/Msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: D:\Msys64\usr\src\ffmpeg/libavutil/random_seed.c:130: undefined reference to `BCryptGenRandom'
D:/Msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: D:\Msys64\usr\src\ffmpeg/libavutil/random_seed.c:131: undefined reference to `BCryptCloseAlgorithmProvider'
collect2.exe: error: ld returned 1 exit status
mingw32-make[3]: *** [CMakeFiles\ffmpeg_tutorial.dir\build.make:95: ffmpeg_tutorial.exe] Error 1
mingw32-make[2]: *** [CMakeFiles\Makefile2:82: CMakeFiles/ffmpeg_tutorial.dir/all] Error 2
mingw32-make[1]: *** [CMakeFiles\Makefile2:89: CMakeFiles/ffmpeg_tutorial.dir/rule] Error 2
mingw32-make: *** [Makefile:123: ffmpeg_tutorial] Error 2


  


  What is the way I compile ffmpeg

  


  


  • downlaod msys2

    


  


  • install mingw64

    


  


  


  pacman -S mingw-w64-x86_64-toolchain


  


  


  • install make,diffutils,nasm,yasm,pkg-config

    


  


  


  pacman -S base-devl yasm nasm pkg-config


  


  


  • download ffmpeg 5.1

    


  


  • compile

    


  


  


  cd ffmpeg
./configure --disable-shared --enable-static --arch=x86_64 --target-os=mingw32 --cross-prefix=x86_64-w64-mingw32- --pkg-config-flags=--static --prefix=../ffmpeg-build

make -j $(nproc)

make install



  


  Project Repoistory

  


  https://github.com/joinwen/learn_ffmpeg.git

  


  Expectation

  


  

  1. How to solve errors

  


  2. In CMakeLists target_link_libraries's parameters is too much, Can I make it short

  


  3. some advices on the project

  


  


• doc/developer.texi : update the language feature section

  14 novembre 2022, par Anton Khirnov

  doc/developer.texi : update the language feature section
  It is currently very out of touch with reality.
  * declare we are using C99 fully, rather than C90 plus extensions
  
  * mention our use of stdatomic.h
  
  * mention forbidden C99 features, like VLAs and complex numbers
  

  • [DH] doc/developer.texi