libpango_video.so / libswscale build error on Linux Ubuntu 18.04.6

[brianm-sra]

OS : Ubuntu Linux 18.04.6 LTS
cmake version : 3.21.3

$ git clone --recursive https://github.com/stevenlovegrove/Pangolin.git
$ cd Pangolin
$ ./scripts/install_prerequisites.sh --dry-run recommended
$ mkdir build && cd build
$ cmake ..
$ cmake --build .

build error:

[ 53%] Linking CXX shared library libpango_video.so
/usr/bin/ld: /usr/local/lib/libswscale.a(swscale.o): relocation R_X86_64_PC32 against symbol `ff_M24A' 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
CMakeFiles/pango_video.dir/build.make:545: recipe for target 'libpango_video.so' failed
make[2]: *** [libpango_video.so] Error 1
CMakeFiles/Makefile2:859: recipe for target 'CMakeFiles/pango_video.dir/all' failed
make[1]: *** [CMakeFiles/pango_video.dir/all] Error 2
Makefile:135: recipe for target 'all' failed
make: *** [all] Error 2

[brianm-sra]

I am trying the suggestion from #27 (comment)

[brianm-sra]

Still having trouble getting it to build

[brianm-sra]

Now I'm running into this ( #323 )
type of issue

git clone --recursive https://github.com/stevenlovegrove/Pangolin.git
cd Pangolin/
./scripts/install_prerequisites.sh recommended
mkdir build && cd build
 cmake ..
cmake --build .
[ 51%] Building CXX object CMakeFiles/pango_video.dir/components/pango_video/src/drivers/ffmpeg.cpp.o
In file included from /home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg.h:32:0,
                 from /home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:37:
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h: In function ‘std::__cxx11::string pangolin::FfmpegFmtToString(AVPixelFormat)’:
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:37:39: error: ‘AV_PIX_FMT_VAAPI_MOCO’ was not declared in this scope
 #define TEST_PIX_FMT_RETURN(fmt) case AV_PIX_FMT_##fmt: return #fmt;
                                       ^
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:97:5: note: in expansion of macro ‘TEST_PIX_FMT_RETURN’
     TEST_PIX_FMT_RETURN(VAAPI_MOCO);
     ^~~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:37:39: note: suggested alternative: ‘AV_PIX_FMT_VAAPI’
 #define TEST_PIX_FMT_RETURN(fmt) case AV_PIX_FMT_##fmt: return #fmt;
                                       ^
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:97:5: note: in expansion of macro ‘TEST_PIX_FMT_RETURN’
     TEST_PIX_FMT_RETURN(VAAPI_MOCO);
     ^~~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:37:39: error: ‘AV_PIX_FMT_VAAPI_IDCT’ was not declared in this scope
 #define TEST_PIX_FMT_RETURN(fmt) case AV_PIX_FMT_##fmt: return #fmt;
                                       ^
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:98:5: note: in expansion of macro ‘TEST_PIX_FMT_RETURN’
     TEST_PIX_FMT_RETURN(VAAPI_IDCT);
     ^~~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:37:39: note: suggested alternative: ‘AV_PIX_FMT_VAAPI’
 #define TEST_PIX_FMT_RETURN(fmt) case AV_PIX_FMT_##fmt: return #fmt;
                                       ^
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:98:5: note: in expansion of macro ‘TEST_PIX_FMT_RETURN’
     TEST_PIX_FMT_RETURN(VAAPI_IDCT);
     ^~~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:37:39: error: ‘AV_PIX_FMT_VAAPI_VLD’ was not declared in this scope
 #define TEST_PIX_FMT_RETURN(fmt) case AV_PIX_FMT_##fmt: return #fmt;
                                       ^
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:99:5: note: in expansion of macro ‘TEST_PIX_FMT_RETURN’
     TEST_PIX_FMT_RETURN(VAAPI_VLD);
     ^~~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:37:39: note: suggested alternative: ‘AV_PIX_FMT_VAAPI’
 #define TEST_PIX_FMT_RETURN(fmt) case AV_PIX_FMT_##fmt: return #fmt;
                                       ^
/home/b1.miller/src/github_com/Pangolin/components/pango_video/include/pangolin/video/drivers/ffmpeg_common.h:99:5: note: in expansion of macro ‘TEST_PIX_FMT_RETURN’
     TEST_PIX_FMT_RETURN(VAAPI_VLD);
     ^~~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp: In member function ‘void pangolin::FfmpegVideo::InitUrl(std::__cxx11::string, std::__cxx11::string, std::__cxx11::string, bool, int, pangolin::ImageDim)’:
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:62:5: error: ‘av_register_all’ was not declared in this scope
     av_register_all();
     ^~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:62:5: note: suggested alternative: ‘avdevice_register_all’
     av_register_all();
     ^~~~~~~~~~~~~~~
     avdevice_register_all
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:69:35: error: invalid conversion from ‘const AVInputFormat*’ to ‘AVInputFormat*’ [-fpermissive]
         fmt = av_find_input_format(codec_hint.c_str());
               ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:120:36: error: ‘AVStream {aka struct AVStream}’ has no member named ‘codec’
         if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
                                    ^~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:123:42: error: ‘AVStream {aka struct AVStream}’ has no member named ‘codec’
         }else if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO)
                                          ^~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:139:54: error: ‘AVStream {aka struct AVStream}’ has no member named ‘codec’
     pVidCodecCtx = pFormatCtx->streams[videoStream]->codec;
                                                      ^~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:142:35: error: invalid conversion from ‘const AVCodec*’ to ‘AVCodec*’ [-fpermissive]
     pVidCodec=avcodec_find_decoder(pVidCodecCtx->codec_id);
               ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:180:17: error: ‘avpicture_get_size’ was not declared in this scope
     numBytesOut=avpicture_get_size(fmtout, w, h);
                 ^~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:180:17: note: suggested alternative: ‘av_opt_get_int’
     numBytesOut=avpicture_get_size(fmtout, w, h);
                 ^~~~~~~~~~~~~~~~~~
                 av_opt_get_int
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:185:21: error: ‘AVPicture’ was not declared in this scope
     avpicture_fill((AVPicture *)pFrameOut, buffer, fmtout, w, h);
                     ^~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:185:21: note: suggested alternative: ‘AVPictureType’
     avpicture_fill((AVPicture *)pFrameOut, buffer, fmtout, w, h);
                     ^~~~~~~~~
                     AVPictureType
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:185:32: error: expected primary-expression before ‘)’ token
     avpicture_fill((AVPicture *)pFrameOut, buffer, fmtout, w, h);
                                ^
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:185:5: error: ‘avpicture_fill’ was not declared in this scope
     avpicture_fill((AVPicture *)pFrameOut, buffer, fmtout, w, h);
     ^~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp: In member function ‘virtual bool pangolin::FfmpegVideo::GrabNext(unsigned char*, bool)’:
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:254:13: error: ‘avcodec_decode_video2’ was not declared in this scope
             avcodec_decode_video2(pVidCodecCtx, pFrame, &gotFrame, &packet);
             ^~~~~~~~~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:254:13: note: suggested alternative: ‘avcodec_decode_subtitle2’
             avcodec_decode_video2(pVidCodecCtx, pFrame, &gotFrame, &packet);
             ^~~~~~~~~~~~~~~~~~~~~
             avcodec_decode_subtitle2
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:264:9: error: ‘av_free_packet’ was not declared in this scope
         av_free_packet(&packet);
         ^~~~~~~~~~~~~~
/home/b1.miller/src/github_com/Pangolin/components/pango_video/src/drivers/ffmpeg.cpp:264:9: note: suggested alternative: ‘av_get_packet’
         av_free_packet(&packet);
         ^~~~~~~~~~~~~~
         av_get_packet
CMakeFiles/pango_video.dir/build.make:433: recipe for target 'CMakeFiles/pango_video.dir/components/pango_video/src/drivers/ffmpeg.cpp.o' failed
make[2]: *** [CMakeFiles/pango_video.dir/components/pango_video/src/drivers/ffmpeg.cpp.o] Error 1
CMakeFiles/Makefile2:859: recipe for target 'CMakeFiles/pango_video.dir/all' failed
make[1]: *** [CMakeFiles/pango_video.dir/all] Error 2
Makefile:135: recipe for target 'all' failed
make: *** [all] Error 2

[brianm-sra]

I was able to workaround this issue by modifying file components/pango_video/CMakeLists.txt
and removing these lines:

option(BUILD_PANGOLIN_FFMPEG "Build support for ffmpeg video input" ON)
if(BUILD_PANGOLIN_FFMPEG)
find_package(FFMPEG QUIET)
if(FFMPEG_FOUND)
target_sources( ${COMPONENT} PRIVATE
${DRIVER_DIR}/ffmpeg.cpp
${DRIVER_DIR}/ffmpeg_convert.cpp
${DRIVER_DIR}/ffmpeg_output.cpp
)
target_link_libraries(${COMPONENT} PRIVATE ${FFMPEG_LIBRARIES} )
target_include_directories(${COMPONENT} PRIVATE ${FFMPEG_INCLUDE_DIRS} )
PangolinRegisterFactory( VideoInterface FfmpegVideo FfmpegVideoConvert)
PangolinRegisterFactory( VideoOutputInterface FfmpegVideoOutput)
if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
# FFMPEG is a real pain for deprecating the API.
set_source_files_properties(${DRIVER_DIR}/ffmpeg.cpp PROPERTIES COMPILE_FLAGS "-Wno-deprecated-declarations")
endif()
message(STATUS "ffmpeg Found and Enabled")
endif()
endif()

[stevenlovegrove]

You can also disable any feature of Pangolin by setting the appropriate CMake option (in this case BUILD_PANGOLIN_FFMPEG to Off with ccmake or cmake-gui for instance)

The link below talks about static linking of ffmpeg into a shared library in case that is related to this issue. You could try their suggestion or make sure find_package is locating a dynamic version of the library.
https://stackoverflow.com/questions/34936080/gcc-relocation-r-x86-64-pc32-against-symbol-ff-m24a-error-when-linking-stati