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• MSVC fatal error LNK1120 : 1 unresolved externals with FFMPEG libs

  16 août 2019, par Jared

  I am trying to utilize the ffmpeg libraries in a program of my own and am having trouble linking them. Specifically, In my a basic program I am receiving fatal error LNK1120: 1 unresolved externals errors. The program is :

  #include <iostream>
  
  #include <libswresample></libswresample>swresample.h>
  
  
  
  int main()
  
  {
  
      std::cout &lt;&lt; "Hello World!\n";
  
      struct SwrContext* swr_ctx = swr_alloc();
  
      if (!swr_ctx) {
  
          std::cout &lt;&lt; "Could not allocate resampler context";
  
      }
  
  }
  
  </iostream>

  I downloaded prebuild libraries from https://ffmpeg.zeranoe.com/builds/, specifically the Windows x64 dev package which includes the .def/.lib as well as .dll files.

  I originally tried (and intend to ultimately use) cmake to generate the MSVC sln files. The cmake file is :

  cmake_minimum_required(VERSION 3.5)
  
  
  
  project(ffmpeg_jni)
  
  
  
  # Find the JNI bits
  
  find_package(JNI)
  
  
  
  # Search for the ffmpeg libraries
  
  set(ffmpeg_include_hint "ffmpeg-dev/include")
  
  set(ffmpeg_lib_hint "ffmpeg-dev/lib")
  
  
  
  find_path(SWRESAMPLE_INCLUDE_DIR libswresample/swresample.h PATHS ${ffmpeg_include_hint})
  
  find_library(SWRESAMPLE_LIBRARY swresample PATHS ${ffmpeg_lib_hint})
  
  add_library(swresample SHARED IMPORTED)
  
  set_target_properties(swresample PROPERTIES
  
      IMPORTED_LOCATION "${SWRESAMPLE_LIBRARY}"
  
      IMPORTED_IMPLIB "${SWRESAMPLE_LIBRARY}"
  
      INTERFACE_INCLUDE_DIRECTORIES "${SWRESAMPLE_INCLUDE_DIR}"
  
  )
  
  
  
  # Setup basic include dirs
  
  set(includeDIRS
  
          src/main/cpp
  
          ${JAVA_INCLUDE_PATH})
  
  
  
  # Setup windows specific includes
  
  set(includeDIRS
  
          ${includeDIRS}
  
          ${JAVA_INCLUDE_PATH}/Win32)
  
  
  
  include_directories(${includeDIRS})
  
  
  
  set(WRAPPER_SRC
  
          src/main/cpp/logging.c
  
          src/main/cpp/logging.h
  
          src/main/cpp/main.cpp)
  
  
  
  add_library(ffmpeg_jni SHARED ${WRAPPER_SRC})
  
  target_link_libraries(ffmpeg_jni PRIVATE swresample)

  The generated solution compiles and has proper access to the include files (Visual Studio can even take me to the declarations). The issue comes in the linking phase of the build where I receive :

  error LNK2019 : unresolved external symbol "struct SwrContext * __cdecl
  swr_alloc(void)" (?swr_alloc@@YAPEAUSwrContext@@XZ) referenced in
  function main

  Thinking that I perhaps had something wrong in cmake since I am still pretty new with it I tried making a simple demo as a pure visual studio project following what I have found in countless online demos for adding an external library to a project. Specifically this included :

  • Adding the directory containing the header files to Properties->C/C++->General->Additional Include Directories
  • Adding the directory containing the .lib files to Properties->Linker->General->Additional Library Directories (Note that the cmake path did not do this but instead added the lib file via a relative path)
  • Adding the .lib file to Properties->Linker->Input->Additional Dependencies

  At this point any searching efforts I undertake show me different people doing the same things which tells me I’ve been looking at this too long to find the answer myself and its something trivial that I’m missing/not understanding.

• "Undefined Reference" when compiling FFMPEG with librtmp on Android

  5 mars 2019, par elBradford

  I have searched, and while Building FFMPEG with librtmp for android answered part of my question, I ran into other issues further along in the compilation process.

  First, I am trying to use the script in this github repo, changing the flags to include

    --enable-librtmp \
  
    --extra-cflags=-I/home/bradford/Development/FFMPEG/rtmp/rtmpdump/librtmp/ \
  
    --extra-ldflags=-L/home/bradford/Development/FFMPEG/rtmp/rtmpdump/librtmp"

  I build librtmp with polarSSL following S74ck3r’s instructions on his github repo and stream-recorder thread. That appears to work correctly, and I have a librtmp.so, librtmp.a and rtmp.h

  When I try to compile ffmpeg with librtmp, I get the error

  ERROR: librtmp not found

  This SO question helped, and I modified ffmpeg’s config file so that it wouldn’t look at pkg-config for librtmp (even though pkg-config was aware of librtmp...) :

  #enabled librtmp    && require_pkg_config librtmp librtmp/rtmp.h RTMP_Socket

  When I build now, it starts successfully, and I get the hopeful line :

  librtmp enabled           yes

  And later on I see more good news :

  ...
  
  Enabled protocols:
  
  applehttp       http            mmsh
  
  cache           httpproxy       mmst
  
  concat          librtmp         mmsu
  
  crypto          librtmpe        pipe
  
  fd          librtmps        rtp
  
  file            librtmpt        tcp
  
  gopher          librtmpte       udp
  
  hls         md5
  
  ...

  but finally, after compiling everything and during the installation phase, I get these types of errors :

  INSTALL   libavutil/libavutil.pc
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_get_file_handle:libavformat/librtmp.c:190: error: undefined reference to 'RTMP_Socket'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_read_seek:libavformat/librtmp.c:180: error: undefined reference to 'RTMP_SendSeek'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_read_pause:libavformat/librtmp.c:161: error: undefined reference to 'RTMP_Pause'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_close:libavformat/librtmp.c:64: error: undefined reference to 'RTMP_Close'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_write:libavformat/librtmp.c:145: error: undefined reference to 'RTMP_Write'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_read:libavformat/librtmp.c:153: error: undefined reference to 'RTMP_Read'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_open:libavformat/librtmp.c:96: error: undefined reference to 'RTMP_LogSetLevel'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_open:libavformat/librtmp.c:97: error: undefined reference to 'RTMP_LogSetCallback'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_open:libavformat/librtmp.c:118: error: undefined reference to 'RTMP_Init'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_open:libavformat/librtmp.c:119: error: undefined reference to 'RTMP_SetupURL'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_open:libavformat/librtmp.c:127: error: undefined reference to 'RTMP_Connect'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_open:libavformat/librtmp.c:127: error: undefined reference to 'RTMP_ConnectStream'
  
  /tmp/FFMPEG/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: libavformat/librtmp.o: in function rtmp_open:libavformat/librtmp.c:125: error: undefined reference to 'RTMP_EnableWrite'
  
  collect2: ld returned 1 exit status

  And I can’t get past them. It sounds like it can’t find rtmp.h, which includes references to those functions, but that is present where it should be (afaik).

  Also, my project requires librtmp - the built-in rtmp features of ffmpeg are not sufficient because I require the authentication features of librtmp.

• Invalid data found in the last hls segment after transcoding

  28 février 2024, par GalaDOS

  When I use ffmpeg to transcode some pure audio flv files to hls segments, the last .ts segment contains some decoding errors. It seems that it happens when the last segment's duration is short enough (about 1.5 second).

  



  Here is my transcode command :

  



  ffmpeg -i 111.flv -c:a aac -b:a 128k -f hls -hls_time 10.00 -hls_list_size 9999 tmp.m3u8


  



  And output :

  



  ffmpeg version n4.0.1-5-gb5106c5 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-4)
  configuration: --prefix=/home/zx/ffmpeg_build --extra-cflags=-I/home/zx/ffmpeg_build/include --extra-ldflags='-L/home/zx/ffmpeg_build/lib -ldl' --bindir=/home/zx/bin --pkg-config-flags=--static --enable-gpl --enable-nonfree --enable-version3 --enable-libfdk_aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libspeex --enable-libvpx --enable-libx264 --disable-shared --enable-static --disable-debug
  libavutil      56. 14.100 / 56. 14.100
  libavcodec     58. 18.100 / 58. 18.100
  libavformat    58. 12.100 / 58. 12.100
  libavdevice    58.  3.100 / 58.  3.100
  libavfilter     7. 16.100 /  7. 16.100
  libswscale      5.  1.100 /  5.  1.100
  libswresample   3.  1.100 /  3.  1.100
  libpostproc    55.  1.100 / 55.  1.100
Input #0, flv, from '111.flv':
  Metadata:
    major_brand     : M4A 
    minor_version   : 512
    compatible_brands: isomiso2
    date            : 2018-05-31 01:31
    encoder         : Lavf57.25.100
  Duration: 00:12:11.40, start: 0.000000, bitrate: 135 kb/s
    Stream #0:0: Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[hls @ 0x25d4280] Opening 'tmp0.ts' for writing
[mpegts @ 0x26feb80] frame size not set
Output #0, hls, to 'tmp.m3u8':
  Metadata:
    major_brand     : M4A 
    minor_version   : 512
    compatible_brands: isomiso2
    date            : 2018-05-31 01:31
    encoder         : Lavf58.12.100
    Stream #0:0: Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s
    Metadata:
      encoder         : Lavc58.18.100 aac
[hls @ 0x25d4280] Opening 'tmp1.ts' for writing
[hls @ 0x25d4280] Opening 'tmp.m3u8.tmp' for writing
[hls @ 0x25d4280] Opening 'tmp2.ts' for writing
[hls @ 0x25d4280] Opening 'tmp.m3u8.tmp' for writing
[hls @ 0x25d4280] Opening 'tmp3.ts' for writing
[hls @ 0x25d4280] Opening 'tmp.m3u8.tmp' for writing
[hls @ 0x25d4280] Opening 'tmp4.ts' for writing
......
[hls @ 0x25d4280] Opening 'tmp71.ts' for writing
[hls @ 0x25d4280] Opening 'tmp.m3u8.tmp' for writing
[hls @ 0x25d4280] Opening 'tmp72.ts' for writingx    
[hls @ 0x25d4280] Opening 'tmp.m3u8.tmp' for writing
[hls @ 0x25d4280] Opening 'tmp73.ts' for writing
[hls @ 0x25d4280] Opening 'tmp.m3u8.tmp' for writing
[hls @ 0x25d4280] Opening 'tmp.m3u8.tmp' for writing
size=N/A time=00:12:11.39 bitrate=N/A speed=84.7x    
video:0kB audio:11421kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
[aac @ 0x25a0580] Qavg: 567.976


  



  After transcoding, the duration of the last segment in m3u8 file is 1.39 second :

  



  ....
#EXTINF:9.984000,
tmp71.ts
#EXTINF:10.005333,
tmp72.ts
#EXTINF:1.386667,
tmp73.ts
#EXT-X-ENDLIST


  



  But when I use ffprobe to parse the last segment, I got an error :

  



  ffprobe -i tmp73.ts 
ffprobe version n4.0.1-5-gb5106c5 Copyright (c) 2007-2018 the FFmpeg developers
  built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-4)
  configuration: --prefix=/home/zx/ffmpeg_build --extra-cflags=-I/home/zx/ffmpeg_build/include --extra-ldflags='-L/home/zx/ffmpeg_build/lib -ldl' --bindir=/home/zx/bin --pkg-config-flags=--static --enable-gpl --enable-nonfree --enable-version3 --enable-libfdk_aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libspeex --enable-libvpx --enable-libx264 --disable-shared --enable-static --disable-debug
  libavutil      56. 14.100 / 56. 14.100
  libavcodec     58. 18.100 / 58. 18.100
  libavformat    58. 12.100 / 58. 12.100
  libavdevice    58.  3.100 / 58.  3.100
  libavfilter     7. 16.100 /  7. 16.100
  libswscale      5.  1.100 /  5.  1.100
  libswresample   3.  1.100 /  3.  1.100
  libpostproc    55.  1.100 / 55.  1.100
tmp73.ts: Invalid data found when processing input


  



  The input flv :

  



  http://45.76.56.248/hls_transcode_fail.flv
md5sum: 4627bbb27bcb22c143ad4dfa47359650


  



  Since my statistic module relies on the output of ffprobe, this exception will cause the entire transcoding task to fail. My temporary solution is to skip the last segment which is too short in the statistics phase. But I need a more reasonable and robust way to fix or bypass this issue. Any suggestion will be appreciated.