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• LNK2019 : unresolved external symbol __imp__dclass

  18 avril 2019, par ssk

  I am trying to build ffmpeg on visual studio for ARM architecture. I run into following linker errors :

  Error   58  error LNK2019: unresolved external symbol __imp__dclass referenced in function mov_read_tkhd avformat.lib(mov.o)
  
  
  
  Error   59  error LNK2001: unresolved external symbol __imp__dclass avformat.lib(thp.o) 
  
  
  
  Error   60  error LNK2001: unresolved external symbol __imp__dclass avutil.lib(rational.o)
  
  
  
  Error   61  error LNK2001: unresolved external symbol __imp__dclass avutil.lib(eval.o)

  What is __imp__dclass and where it is defined in Visual Studio / FFMPEG ?

  I get the following when I do "dumpbin /symbols mov.o"

  22D 00000000 UNDEF  notype       External     | __imp__dclass

  Any ideas ?

• EC2 for video-encoding

  4 avril 2019, par Naftuli Kay

  I have a potential job which will require me to do some video encoding with FFMPEG and x264. I’ll have a series of files which I’ll need to encode once, then I’ll be able to bring down the instances. Since I’m not really sure of the resource utilization of x264 and FFMPEG, what kind of instances should I get ? I’m thinking either a

  High-CPU Extra Large Instance

  7 GB of memory
  20 EC2 Compute Units (8 virtual cores with 2.5 EC2 Compute Units each)
  1690 GB of instance storage
  64-bit platform
  I/O Performance : High
  API name : c1.xlarge

  or, alternatively a

  Cluster GPU Quadruple Extra Large Instance

  22 GB of memory
  33.5 EC2 Compute Units (2 x Intel Xeon X5570, quad-core “Nehalem” architecture)
  2 x NVIDIA Tesla “Fermi” M2050 GPUs
  1690 GB of instance storage
  64-bit platform
  I/O Performance : Very High (10 Gigabit Ethernet)
  API name : cg1.4xlarge

  What should I use ? Does x264/FFMPEG perform better with faster/more CPUs or does it really pound the GPU more ? In any case, it seems that the Cluster GPU seems to be the higher performance instance. What should I prefer ?

• Why does ffmpeg cmake external project is not working

  24 mars 2019, par bottega

  I’m trying to compile ffmpeg with h264 support as an external cmake project. But after compile it, I’m getting libavcodec reference errors.

  The compile problem is occurring on Ubuntu 18.04 machine. I have installed all dependencies for ffmpeg and also libx264-dev.

  Cmake external project

  set( proj ffmpeg )
  
  set( SHARED_FFMPEG )
  
  
  
  
  
  set(BASIC
  
          --extra-ldflags=-L/usr/local/lib
  
          --extra-cflags=-I/usr/local/include
  
          --enable-gpl
  
          --enable-libx264)
  
  
  
  
  
  option( FFMPEG_GPL "Use a GPL version of FFMPEG" OFF )
  
  
  
  set(FFMPEG_INSTALL_DIR  ${CMAKE_BINARY_DIR}/INSTALL )
  
  
  
  ExternalProject_Add(${proj}
  
          # Set up dirs
  
          SOURCE_DIR ${CMAKE_BINARY_DIR}/${proj}
  
          INSTALL_DIR ${FFMPEG_INSTALL_DIR}
  
          # get the project
  
          GIT_REPOSITORY "https://github.com/FFmpeg/FFmpeg.git"
  
          GIT_TAG "n3.2.13"
  
  
  
          # Build the project
  
          BUILD_IN_SOURCE 1
  
  
  
          # Configure step
  
          # DO STH FOR THE ARCHITECTURE...
  
          CONFIGURE_COMMAND /configure --prefix=${FFMPEG_INSTALL_DIR} ${SHARED_FFMPEG} ${FFMPEG_GPL_FLAG} ${BASIC}
  
  
  
          #  BUILD_COMMAND ${CMAKE_MAKE_PROGRAM} -j${NProcessors}
  
          )
  
  
  
  # define the library suffix
  
  if( SUPER_SHARED_LIBS )
  
      if( APPLE )
  
          set(LIBRARY_SUFFIX .dylib)
  
      else( APPLE )
  
          set(LIBRARY_SUFFIX .so)
  
      endif( APPLE )
  
  else( SUPER_SHARED_LIBS )
  
      set(LIBRARY_SUFFIX .a)
  
  endif( SUPER_SHARED_LIBS )
  
  
  
  # ADD DIRECTORIES FOR DEPENDENCIES IN Main/CMakeLists.txt
  
  set( FFMPEG_LIBRARYS libavcodec.a
  
          libavformat.a
  
          libavutil.a
  
          libswscale.a
  
          )
  
  
  
  include_directories(${FFMPEG_INSTALL_DIR}/include)
  
  
  
  set(FFMPEG_LIBRARY_DIRS ${FFMPEG_INSTALL_DIR}/lib/)
  
  link_directories(${FFMPEG_LIBRARY_DIRS})

  C++ Where I used the library

  extern "C" {
  
  #include 
  
  #include 
  
  #include 
  
  
  
  #include "libavcodec/avcodec.h"
  
  #include "libavformat/avformat.h"
  
  #include "libavutil/mathematics.h"
  
  #include "libswscale/swscale.h"
  
  
  
  #define INBUF_SIZE 4096
  
  #define AUDIO_INBUF_SIZE 20480
  
  #define AUDIO_REFILL_THRESH 4096
  
  }
  
  
  
  ...
  
  
  
   fReceiveBuffer = new u_int8_t[DUMMY_SINK_RECEIVE_BUFFER_SIZE];
  
      fReceiveBufferAV = new u_int8_t[DUMMY_SINK_RECEIVE_BUFFER_SIZE+4];
  
      fReceiveBufferAV[0] = 0;
  
      fReceiveBufferAV[1] = 0;
  
      fReceiveBufferAV[2] = 0;
  
      fReceiveBufferAV[3] = 1;
  
  
  
  
  
      av_init_packet(&avpkt);
  
      avpkt.flags |= AV_PKT_FLAG_KEY;
  
      avpkt.pts = avpkt.dts = 0;
  
  
  
      av_init_packet(&avpkt);
  
      avpkt.flags |= AV_PKT_FLAG_KEY;
  
      avpkt.pts = avpkt.dts = 0;
  
  
  
      /* set end of buffer to 0 (this ensures that no overreading happens for damaged mpeg streams) */
  
      memset(inbuf + INBUF_SIZE, 0, FF_INPUT_BUFFER_PADDING_SIZE);
  
  
  
      //codec = avcodec_find_decoder(CODEC_ID_MPEG1VIDEO);
  
      codec = avcodec_find_decoder(AV_CODEC_ID_H264);
  
  
  
  ...

  Error :

  [100%] Linking CXX executable ../../bin/awesom-o
  
  /home/tiburcio/CLionProjects/awesom-o/cmake-build-debug/INSTALL/lib/libavcodec.a(libx264.o): In function `X264_frame':
  
  /home/tiburcio/CLionProjects/awesom-o/cmake-build-debug/ffmpeg/libavcodec/libx264.c:280: undefined reference to `x264_picture_init'
  
  /home/tiburcio/CLionProjects/awesom-o/cmake-build-debug/INSTALL/lib/libavcodec.a(libx264.o): In function `reconfig_encoder':
  
  /home/tiburcio/CLionProjects/awesom-o/cmake-build-debug/ffmpeg/libavcodec/libx264.c:266: undefined reference to `x264_encoder_reconfig'
  
  /home/tiburcio/CLionProjects/awesom-o/cmake-build-debug/INSTALL/lib/libavcodec.a(libx264.o): In function `X264_frame':
  
  /home/tiburcio/CLionProjects/awesom-o/cmake-build-debug/ffmpeg/libavcodec/libx264.c:340: undefined reference to `x264_encoder_encode'