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• How to use Visual Studio Compiled libs with MSYS pkg-config

  18 août 2017, 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.

  Thanks in advanced !

• FFMPEG using a screen capture for an overlay results in serious visual flaws

  3 octobre 2017, par Joey

  I’m trying to overlay a screen capture of a specific window on top of a background image, and output the result - it works but results in unacceptable visual flaws.

  The command I’m using is :

  ffmpeg -loop 1 -r 30 -i background.jpg -f gdigrab -r 30 -i title=Calculator \
  
  -filter_complex "[0:v][1:v]overlay=10:10[video]" -map "[video]" -c:v libx264 \
  
  -f flv output.flv

  which places a screencap of the calculator window on the background at position 10,10.

  This is what the output looks like :

  

  All the buttons on the calculator are super muddied and appear bold, almost as if it was overlaid several times at slightly different positions. Is there something wrong with the command or any way to fix it and preserve visual integrity of the original ? Changing the output format doesn’t have any effect, nor does setting -crf 0 or adjusting any other encoding settings.

  This doesn’t happen when I screen capture just the calculator by itself without overlaying it on anything. For reference here is what the output looks like when I only record the calculator with no overlaying :

  

• Fix visual glitch with XvMC, caused by wrong idct permutation.

  9 octobre 2017, par Ivan Kalvachev

  Fix visual glitch with XvMC, caused by wrong idct permutation.
  In the past XvMC forced simple_idct since
  
  it was using FF_IDCT_PERM_NONE.
  
  However now we have SIMD variants of simple_idct that
  
  are using FF_IDCT_PERM_TRANSPOSE and if they are selected
  
  XvMC would get coefficients in the wrong order.
  The patch creates new FF_IDCT_NONE that
  
  is used only for this kind of hardware decoding
  
  and that fallbacks to the old C only simple idct.
  Signed-off-by : Ivan Kalvachev <ikalvachev@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/avcodec.h
  • [DH] libavcodec/idctdsp.c
  • [DH] libavcodec/mpeg12dec.c