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• Mingw-w64 - printf does not work

  27 décembre 2013, par Gosha U.

  First I wanted to modificate ffplay according to my requirments. Then I noticed that original ffplay from my build can't play some video files, but it didn't write any message to console. Then I noticed that ffmpeg also don't write any usage message when I run it without params. But it works. If I run it from terminal it's like running asynchronously ! The terminal just shows next row. I mean it asks for a next command. But the ffmpeg process is visible in task manager and it writes the output video file what I had requested !

  I created following souce file. I have modified the Makefile. So it have built the exe-file works just the same way. I have no idea how it can be.

  #include 
  
  #include "cmdutils.h"
  
  
  
  const char program_name[] = "hello";
  
  const int program_birth_year = 2013;
  
  
  
  void show_help_default(const char *opt, const char *arg)
  
  {
  
      printf("zxcvbnm\n");
  
  }
  
  
  
  int main(int argc, char **argv)
  
  {
  
      printf("1234567890\n");
  
      return 0;
  
  }

  And after that I created real hello world app with MinGW-w64 and qmake without eny extra libs. And its printf does not work.

  I want to prevent this behavior.

  I want to make printf working in traditional manner.

  How I build FFmpeg :

  PKG_CONFIG_PATH=/home/developer/workspace/MinGW32fs/lib/pkgconfig/ \
  
  SDL_CONFIG=/home/developer/workspace/MinGW32fs/bin/sdl-config \
  
  ./configure \
  
    --prefix=/home/developer/workspace/MinGW32fs \
  
    --extra-ldflags="-L/home/developer/workspace/MinGW32fs/lib" \
  
    --extra-cflags="-I/home/developer/workspace/MinGW32fs/include" \
  
    --arch=x86 --target-os=mingw32 --cross-prefix=i686-w64-mingw32-  \
  
    --pkg-config=pkg-config   --enable-libtheora --enable-libvorbis --enable-libvpx \
  
    --enable-outdev=sdl --enable-shared --disable-static \
  
    --disable-doc --disable-manpages --disable-podpages
  
  
  
  make

• Mingw-w64 builded FFmpeg doesn't show any usage information

  26 octobre 2013, par user1240328

  First I wanted to modificate ffplay according to my requirments. Then I noticed that original ffplay from my build can't play some video files, but it didn't write any message to console. Then I noticed that ffmpeg also don't write any usage message when I run it without params. But it works. If I run it from terminal it's like running asynchronously ! The terminal just shows next row. I mean it asks for a next command. But the ffmpeg process is visible in task manager and it writes the output video file what I had requested !

  I created following souce file. I have modified the Makefile. So it have built the exe-file works just the same way. I have no idea how it can be.

  #include 
  
  #include "cmdutils.h"
  
  
  
  const char program_name[] = "hello";
  
  const int program_birth_year = 2013;
  
  
  
  void show_help_default(const char *opt, const char *arg)
  
  {
  
      printf("zxcvbnm\n");
  
  }
  
  
  
  int main(int argc, char **argv)
  
  {
  
      printf("1234567890\n");
  
      return 0;
  
  }

  I want to prevent this behavior.

  I want to make printf working in traditional manner.

  How I build FFmpeg :

  PKG_CONFIG_PATH=/home/developer/workspace/MinGW32fs/lib/pkgconfig/ \
  
  SDL_CONFIG=/home/developer/workspace/MinGW32fs/bin/sdl-config \
  
  ./configure \
  
    --prefix=/home/developer/workspace/MinGW32fs \
  
    --extra-ldflags="-L/home/developer/workspace/MinGW32fs/lib" \
  
    --extra-cflags="-I/home/developer/workspace/MinGW32fs/include" \
  
    --arch=x86 --target-os=mingw32 --cross-prefix=i686-w64-mingw32-  \
  
    --pkg-config=pkg-config   --enable-libtheora --enable-libvorbis --enable-libvpx \
  
    --enable-outdev=sdl --enable-shared --disable-static \
  
    --disable-doc --disable-manpages --disable-podpages
  
  
  
  make

• About image opacity

  23 octobre 2013, par Mikko Koppanen — Imagick

  There is a common misconception that Imagick::setImageOpacity() would work to reduce the opacity of the image. However, as the name says the method actually sets the opacity throughout the image and thus affects also transparent areas.

  To demonstrate let’s first look at this image of a red circle on a transparent background :

  

  Now, let’s apply setImageOpacity on the image :

  php

  < view plain text >

  1. < ?php
  2. $im = new Imagick (’red-circle.png’) ;
  3. $im->setImageOpacity (0.5) ;
  4. $im->writeImage (’red-circle-setopacity.png’) ;
  5.  ?>

  

  As we can see from the resulting image the transparent background is affected as well.

  In order to actually reduce the opacity of the opaque parts Imagick::evaluateImage can be used instead :

  php

  < view plain text >

  1. < ?php
  2. $im = new Imagick (’red-circle.png’) ;
  3.  
  4. /* Divide the alpha channel value by 2 */
  5. $im->evaluateImage(Imagick: :EVALUATE_DIVIDE, 2, Imagick: :CHANNEL_ALPHA) ;
  6. $im->writeImage (’red-circle-divide.png’) ;
  7.  ?>

  And here are the results :

  

  As the background is already fully transparent so the divide operation causes no changes to it.

  Similar example is available in the PHP manual http://php.net/imagick.evaluateimage and I added a note to setImageOpacity page as well (at the time of writing it has not synced to documentation mirrors yet).