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• How to use ffmpeg's sws_scale from multiple threads ?

  25 avril 2013, par Asik

  I have a color space conversion function based on sws_scale. It will be called from multiple different threads during the lifetime of the application. I don't know, however, how thread-safe sws_scale is and I did not find it mentionned in its documentation.

  I would assume that each thread requires its own SwsContext as this parameter will be shared, but is this enough to guarantee there won't be any internal collisions ?

• FFmpeg compile for Android (configure, make)

  11 août 2013, par manutd

  I want to compile ffmpeg for Android ver.
  But everytime I try, I can't compile the source of ffmpeg.
  I think my configuration option may be invalid.

  I used this script for configure.

  #!/bin/sh
  
  NDK_PATH=$HOME/android-ndk-r8
  
  PREBUILT=$NDK_PATH/toolchains/arm-linux-androideabi-4.4.3/prebuilt/darwin-x86
  
  
  
  LDFLAGS="-Wl,-T,$PREBUILT/armelf_linux_eabi.x -Wl,-rpath-link=$NDK_PATH/platforms/android-8/arch-arm/usr/lib \
  
       -L$NDK_PATH/platforms/android-8/arch-arm/usr/lib -nostdlib $PREBUILT/lib/gcc/arm-linux-androideabi/4.4.3/crtbegin.o \
  
       $PREBUILT/lib/gcc/arm-linux-androideabi/4.4.3/crtend.o -lc -lm -ldl"
  
  COMMON_CONFIG="\
  
            ./configure --target-os=linux \
  
            --arch=arm \
  
            --enable-cross-compile \
  
            --cc=$PREBUILT/bin/arm-linux-androideabi-gcc \
  
            --as=$PREBUILT/bin/arm-linux-androideabi-gcc \
  
            --cross-prefix=$PREBUILT/bin/arm-linux-androideabi- \
  
            --sysinclude=$NDK_PATH/platforms/android-8/arch-arm/usr/include \
  
            --nm=$PREBUILT/bin/arm-linux-androideabi-nm \
  
            --extra-ldflags=\"$LDFLAGS\" \
  
            --extra-cflags=-I$NDK_PATH/platforms/android-8/arch-arm/usr/include \
  
  
  
  eval "$COMMON_CONFIG"
  
  if [ $? -ne 0 ]; then
  
    exit 1
  
  fi

  I have to give compiler a new header file path (by —extra-cflags) because when I typed 'make', compiler didn't know where are header files (like math.h, ctime.h)

  After configure using this scripts and type 'make', I got these error.

  CC  libavdevice/alldevices.o
  
  In file included from /Users/gyeongmingim/android-ndk-r8/platforms/android-8/arch-arm/usr/include/stdlib.h:42,
  
               from ./libavutil/common.h:35,
  
               from ./libavutil/avutil.h:126,
  
               from libavdevice/avdevice.h:22,
  
               from libavdevice/alldevices.c:22:
  
  /Users/gyeongmingim/android-ndk-r8/platforms/android-8/arch-arm/usr/include/strings.h:49: warning: redundant redeclaration of 'index'
  
  /Users/gyeongmingim/android-ndk-r8/platforms/android-8/arch-arm/usr/include/string.h:47: note: previous declaration of 'index' was here
  
  /Users/gyeongmingim/android-ndk-r8/platforms/android-8/arch-arm/usr/include/strings.h:50: warning: redundant redeclaration of 'strcasecmp'
  
  /Users/gyeongmingim/android-ndk-r8/platforms/android-8/arch-arm/usr/include/string.h:57: note: previous declaration of 'strcasecmp' was here
  
  /Users/gyeongmingim/android-ndk-r8/platforms/android-8/arch-arm/usr/include/strings.h:51: warning: redundant redeclaration of 'strncasecmp'
  
  /Users/gyeongmingim/android-ndk-r8/platforms/android-8/arch-arm/usr/include/string.h:58: note: previous declaration of 'strncasecmp' was here
  
  In file included from ./libavutil/internal.h:178,
  
               from ./libavutil/common.h:342,
  
               from ./libavutil/avutil.h:126,
  
               from libavdevice/avdevice.h:22,
  
               from libavdevice/alldevices.c:22:
  
  ./libavutil/libm.h:62: error: static declaration of 'lrint' follows non-static declaration
  
  ./libavutil/libm.h:69: error: static declaration of 'lrintf' follows non-static declaration
  
  ./libavutil/libm.h:76: error: static declaration of 'round' follows non-static declaration
  
  ./libavutil/libm.h:90: error: static declaration of 'trunc' follows non-static declaration
  
  make: *** [libavdevice/alldevices.o] Error 1

  What is the wrong ?
  Does my configuration have wrong info ? or any missing flag ?

  OS : Mac Lion
  Android-ndk ver : android-ndk-r8

• Fill patterns

  9 juin 2010, par Mikko Koppanen — Imagick, PHP stuff

  My work life has been quite busy lately and I haven’t had a chance to sit down and blog. I have been touring around London and some parts of the northern England consulting and organizing some training here and there. Luckily I have had the chance to do some work on Imagick and the 2.2.0 beta release is getting closer. The internal structure was completely restructured and broken down into several smaller files. During this time Imagick was adapted to follow the PHP Coding Standards more closely. Still a work in progress

  I committed slightly modified version of this example to PHP Manual http://uk.php.net/manual/en/imagick.examples.php page a few days ago. The example illustrates using an image as a part of a named fill pattern. The fill pattern is used to annotate text but the named pattern could also be used to fill any shapes that allow fill to be specified (include circles, ellipses, rectangles, polygons etc etc). The code itself is pretty straight forward : Read the image, create the pattern and use the pattern as a fill.

  The ice formations image is from http://www.photoeverywhere.co.uk/west/winterholiday/slides/iceformations5679.htm.

  php

  < view plain text >

  1. < ?php
  2.  
  3. /* Create a new imagick object */
  4. $im = new Imagick( ’iceformations5679.JPG’ ) ;
  5.  
  6. /* Create imagickdraw object */
  7. $draw = new ImagickDraw() ;
  8.  
  9. /* Start a new pattern called "ice" */
  10. $draw->pushPattern( ’ice’ , 0 , 0 , 50 , 50 ) ;
  11.  
  12. /* Composite the image on the pattern */
  13. $draw->composite( Imagick: :COMPOSITE_OVER, 0, 0, 50, 50, $im ) ;
  14.  
  15. /* Close the pattern */
  16. $draw->popPattern() ;
  17.  
  18. /* Use the pattern called "ice" as the fill */
  19. $draw->setFillPatternURL( ’#ice’ ) ;
  20.  
  21. /* Set font size to 52 */
  22. $draw->setFontSize( 52 ) ;
  23.  
  24. /* Annotate some text */
  25. $draw->annotation( 5, 50, "Hello World !" ) ;
  26.  
  27. /* Create a new canvas and white image */
  28. $canvas = new Imagick() ;
  29. $canvas->newImage( 310, 70, "white" ) ;
  30.  
  31. /* Add black border around the resulting image */
  32. $canvas->borderImage( ’black’, 1, 1 ) ;
  33.  
  34. /* Draw the ImagickDraw on to the canvas */
  35. $canvas->drawImage( $draw ) ;
  36.  
  37. /* Set the format to PNG */
  38. $canvas->setImageFormat( ’png’ ) ;
  39.  
  40. /* Output the image */
  41. header( "Content-Type : image/png" ) ;
  42. echo $canvas ;
  43.  ?>

  And the result is here :