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• Compiling FFmpeg with Libass using MSVC

  2 avril 2019, par maxhap

  First a bit of background.

  I’m trying to compile ffmpeg on windows with the libass extensions/configuration option.

  Using the visual studio project libass-msvc I built libass using Visual Studio as a static lib.

  I then installed MinGW with MSYS and pkg-config. Following the instructions on the ffmpeg MSVC installation guide I configured the environment to build with the MSVC linker and to build in x64.

  When I try to configure libass for compilation using ./configure —enable-libass —toolchain=msvc I get the following error in the log file :

  File not found ass/ass.h

  pkg-config can not find libass

  I have tried the following to fix this.

  1. Create a .pc file for libass and add this to the PKG_CONFIG_PATH environment variable. See file content below. (After doing this pkg-config libass —version prints 0.81, not the right version number but at least something.)

  2. Copy libass .h files into a MinGW/include/ass folder and the .lib file into the MinGW/libs folder.

  3. Add libass include and bin folders to PATH environment variable

  4. Download libass and dependencies source then try to build it using MSYS with MSVC compiler. My aim here was to be able to use "make install" and let MinGW install libass to the correct locations. After hours of trying to fix linker errors, I abandoned this idea as some of the libass dependencies make files only work with the GCC GNU compiler.

  5. Compile libass with GCC GNU using MinGW make/make install then try and install libass using the GNU libs. Again this led to linker errors (I know this was a bad idea but was worth a try).

  6. Tried using extra lib and include build configuration options —extra-cflags="ffmpeg-dir/extra/include" \
     — extra-ldflags="ffmped-dir/extra/ffmpeg_build/lib" then adding the libs and .h files into those locations

  .pc file

  libass.pc:
  
  prefix=/MinGW
  
  includedir=libass-directory/include
  
  libdir=libass-director/x64/bin/
  
  
  
  Name: libass
  
  Description: Libass project
  
  Version: 0.13.7

  I am now completely stuck and out of ideas if anyone could give any insight or suggestions into what I’m doing wrong that would be fantastic.

  Update

  I created INCLUDE and LIBDIR environment path variable containing the libass paths. Which now correctly includes libass. However, I now get the following linker error for the function check_ass_library_init.

  check_func_headers ass/ass.h ass_library_init
  check_ld cc
  check_cc
  BEGIN ./ffconf.RZMYFWdc/test.c
  1 #include
  2 #include
  3 long check_ass_library_init(void) return (long)
  ass_library_init ;
  4 int main(void) int ret = 0 ;
  5 ret |= ((intptr_t)check_ass_library_init) & 0xFFFF ;
  6 return ret ;
  END ./ffconf.RZMYFWdc/test.c
  cl -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -
  D_USE_MATH_DEFINES -D_CRT_SECURE_NO_WARNINGS -D_CRT_NONSTDC_NO_WARNINGS -
  D_WIN32_WINNT=0x0502 -nologo -c -Fo./ffconf.RZMYFWdc/test.o
  ./ffconf.RZMYFWdc/test.c
  test.c
  ./ffconf.RZMYFWdc/test.c(3) : warning C4311 : ’type cast’ : pointer truncation
  from ’ASS_Library *(__cdecl *)(void)’ to ’long’
  ./compat/windows/mslink -nologo -out :./ffconf.RZMYFWdc/test.exe
  ./ffconf.RZMYFWdc/test.o psapi.lib advapi32.lib shell32.lib ole32.lib
  test.o : error LNK2019 : unresolved external symbol ass_library_init
  referenced in function check_ass_library_init
  ./ffconf.RZMYFWdc/test.exe : fatal error LNK1120 : 1 unresolved externals
  ERROR : libass not found using pkg-config

  The libass test project which uses ass_library_init compiles fine using the same lib files, the libs appear to be fine.

  From what I see from this line "./compat/windows/mslink -nologo -out:./ffconf.RZMYFWdc/test.exe ./ffconf.RZMYFWdc/test.o psapi.lib advapi32.lib shell32.lib ole32.lib" libass is not being passed to the linker.
  I suspect that the configuration file is not creating the link to libass in the make file when compiling with MSVC.

  Am I correct or am I going about compiling this in the wrong way ?

• avutil/imgutils : Add wrapper for av_image_copy() to avoid casts

  6 septembre 2023, par Andreas Rheinhardt

  avutil/imgutils : Add wrapper for av_image_copy() to avoid casts
  av_image_copy() accepts const uint8_t* const * as source ;
  
  lots of user have uint8_t* const * and therefore either
  
  cast (the majority) or copy the array of pointers.
  This commit changes this by adding a static inline wrapper
  
  for av_image_copy() that casts between the two types
  
  so that we do not need to add casts everywhere else.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] doc/APIchanges
  • [DH] doc/examples/demux_decode.c
  • [DH] libavcodec/amfenc.c
  • [DH] libavcodec/libkvazaar.c
  • [DH] libavcodec/libopenh264dec.c
  • [DH] libavcodec/libvpxdec.c
  • [DH] libavcodec/mediacodecenc.c
  • [DH] libavcodec/mmaldec.c
  • [DH] libavcodec/nuv.c
  • [DH] libavcodec/nvenc.c
  • [DH] libavcodec/omx.c
  • [DH] libavcodec/v210dec.c
  • [DH] libavdevice/xv.c
  • [DH] libavfilter/lavfutils.c
  • [DH] libavfilter/vf_framepack.c
  • [DH] libavfilter/vf_pullup.c
  • [DH] libavfilter/yadif_common.c
  • [DH] libavutil/frame.c
  • [DH] libavutil/hwcontext_d3d11va.c
  • [DH] libavutil/hwcontext_dxva2.c
  • [DH] libavutil/imgutils.h
  • [DH] libavutil/version.h

• How to stack several videos using ffmpeg ?

  13 juillet 2019, par John

  I have four cameras that are recording videos and wand to stack all videos into one video file. The final video must be a 2x2 grid.

  

  THE HARD PART is that sometimes cameras are not recording simultaneously.

  Here you can see one situation of how cameras are recording :

  Camera 1 timeline: |recording....................................|
  
  Camera 2 timeline: |stopped....|recording........................|
  
  Camera 3 timeline: |recording.........|stopped....|recording.....|
  
  Camera 4 timeline: |recording..................|stopped..........|

  Explanation :

  • Camera 1 is recording all time.
  • Camera 2 is starting recording later.
  • Camera 3 is recording, then stopped a period of time, then again recording.
  • Camera 4 is recording a period of time, then stopped.

  In the final video I want to synchronize each video by timestamps.

  If a camera is stopped a period of time then at its position must be a black portion.

  How can I do this ?