T A B L E o f C O N T E N T S
---------------------------------
1 Building Adobe XMPsdk and Samples in Terminal with the ./Generate_XXX_mac.sh scripts
1.1 Amazing Discovery 1 DumpFile is linked to libstdc++.6.dylib
1.2 Amazing Discovery 2 Millions of "weak symbol/visibility" messages
2 Puzzle with autotools/--with-adobe MacOS-X Only
2.1 To build without the external Adobe SDK:
2.2 To add the external Adobe SDK to the mix:
2.3 Notes (mostly to remind me of painful discoveries)
2.4 Compiler options used to build Adobe XMPsdk
2.5 Compiler options used to build DumpFile sample Application
2.6 Linker Options used to link DumpFile
3 Features to Add to the CMake code
4 Build design for v0.26.1
4.1 Backwards compatibility
4.2 New Options for ./configure
4.3 New Options for msvc
4.4 New Options for CMake
4.5 New Options for contrib/cmake/msvc
4.6 Scripts xmpsdk/buildXMPsdk.sh and xmpsdk/buildXMPsdk.cmd
4.7 Support for 32/64 bit builds, Release/Debug, Shared/Static
4.8 Support for MinGW
4.9 Linking XMPsdk with libexiv2
5 Refactoring the Tiff Code
5.1 Background
5.2 How does Exiv2 decode the ExifData in a JPEG?
5.3 How is metadata organized in Exiv2
5.4 Where are the tags defined?
5.5 How do the MakerNotes get decoded?
5.6 How do the encoders work?
==========================================================================
1 Building XMPsdk and Samples in Terminal with the ./Generate_XXX_mac.sh scripts
Added : 2017-08-18
Modified: 2017-08-18
$ cd <exiv2dir>/xmpsdk
# XMP-Toolkit-SDK-CC201607 or XMP-Toolkit-SDK-CC201407
$ mkdir Adobe
$ curl -O http://download.macromedia.com/pub/developer/xmp/sdk/XMP-Toolkit-SDK-CC201607.zip
$ find third-party -type d -maxdepth 1 -exec cp -R '{}' Adobe/XMP-Toolkit-SDK-CC201607/third-party ';'
$ cd XMP-Toolkit-SDK-CC201607/build
$ echo '3' | ./GenerateXMPToolkitSDK_mac.sh
$ xcodebuild -project xcode/static/intel_64/XMPToolkitSDK64.xcodeproj/ -target XMPCoreStatic -configuration Release
$ xcodebuild -project xcode/static/intel_64/XMPToolkitSDK64.xcodeproj/ -target XMPFilesStatic -configuration Release
Building Samples:
$ cd Adobe
$ curl --insecure -O https://cmake.org/files/v3.5/cmake-3.5.2-Darwin-x86_64.tar.gz
$ tar xzf cmake-3.5.2-Darwin-x86_64.tar.gz
$ mkdir XMP-Toolkit-SDK-CC201607/tools/cmake/bin
$ ditto cmake-3.5.2-Darwin-x86_64/CMake.app/ XMP-Toolkit-SDK-CC201607/tools/cmake/bin/cmake.app
$ cd XMP-Toolkit-SDK-CC201607/samples/build
$ echo '2' | ./GenerateSamples_mac.sh
$ xcodebuild -project xcode/intel_64/XMP_Samples_64.xcodeproj -configuration Release [-target Sample]
$ cd XMP-Toolkit-SDK-CC201607
$ samples/target/macintosh/intel_64/Release/DumpFile ~/Stonehenge.jpg
Samples:
CustomSchema
CustomSchemaNewDOM
DumpFile
DumpMainXMP
DumpScannedXMP
ModifyingXMP
ModifyingXMPNewDOM
ReadingXMP
ReadingXMPNewDOM
XMPCommand
XMPCoreCoverage
XMPFilesCoverage
XMPIterations
1.1 Amazing Discovery 1 DumpFile is linked to libstdc++.6.dylib
------------------------------------------------------------------
XMP-Toolkit-SDK-CC201607/samples $ otool -L target/macintosh/intel_64/Release/DumpFile
target/macintosh/intel_64/Release/DumpFile:
/System/Library/Frameworks/Cocoa.framework/Versions/A/Cocoa (compatibility version 1.0.0, current version 22.0.0)
/usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 104.1.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1225.1.1)
/System/Library/Frameworks/CoreServices.framework/Versions/A/CoreServices (compatibility version 1.0.0, current version 728.4.0)
XMP-Toolkit-SDK-CC201607/samples $
Conclusion: We should link -lXMPCore with libexiv2.26.dylib
We should not link -lXMPCore with applications such as exiv2(.exe)
We should build exiv2 code with visibility disabled "CXXFLAGS=-fvisibility=hidden -fvisibility-inlines-hidden"
We must compile and link everything with "CXXFLAGS=-stdlib=libstdc++ -Wno-deprecated"
1.2 Amazing Discovery 2 Millions of "weak symbol/visibility" messages
------------------------------------------------------------------------
$ cd samples/build
$ rm -rf cmake/DumpFile/build_x64 # remove the build of DumpFile
$ env VERBOSE=1 xcodebuild -project xcode/intel_64/XMP_Samples_64.xcodeproj -configuration Release -target DumpFile
==========================================================================
2 Puzzle with autotools/--with-adobe MacOS-X Only
Added : 2017-08-17
Modified: 2017-08-18
The --with-adobe code is new (added on Monday/Tuesday 2017-08-15).
It's very much "Work in Progress" and will get lots more polishing.
This builds and links on Mac and Linux (Cygwin isn't ready yet).
Autotools isn't used with Visual Studio
Default build (which compile/links xmpsdk/src) is fine (and passes test suite)
$ sudo make distclean ; make config ; ./configure ; make ; sudo make install ; make samples ; make tests
Status: The 2016/AdobeXMPsdk requires an entry point that's not in the C++ STL library
./configure is building and passing the test suite
./configure --with-adobe=2014 is broken on __ZNSs4_Rep11_S_terminalE
./configure --with-adobe=2016 is broken on __ZNSiD0Ev
The missing entry points are in /usr/lib/libstdc++.6.dylib
When I use install_name_tool to change to libstdc++.6.dylib, I crash in this:
$ c++filt __ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEED1Ev
std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::~basic_string()
$
There's something mixed up concerning the libraries used by Adobe's XMPSDK and libexiv2.26.dylib
-stdlib=libstdc++ will link /usr/lib/libstdc++.6.dylib, however the compiler warns:
clang: warning: libstdc++ is deprecated; move to libc++ [-Wdeprecated]
2.1 To build without the external Adobe SDK:
--------------------------------------------
Edit config/config.mk.in and modify:
XMPSDK_LIBS= -lXMPCore
to
XMPSDK_LIBS = ''
$ sudo make distclean ; make config ; ./configure --with-adobe ; make
The following command works:
$ bin/exiv2 http://clanmills.com/Stonehenge.jpg is working
On 2017-08-15 The following command crashes when it attempts to execute XMPsdk code
$ bin/exiv2 --verbose --version
........
config_path=/Users/rmills/.exiv2
uid=501
euid=501
gid=20
dyld: lazy symbol binding failed: Symbol not found: _WXMPMeta_Initialize_1
Referenced from: /Users/rmills/gnu/github/exiv2/src/.libs/libexiv2.26.dylib
Expected in: flat namespace
dyld: Symbol not found: _WXMPMeta_Initialize_1
Referenced from: /Users/rmills/gnu/github/exiv2/src/.libs/libexiv2.26.dylib
Expected in: flat namespace
Abort trap: 6
$
This is correct. libXMPCore.a is not in the mix.
ls -alt src/.libs/libexiv2.26.dylib
-rwxr-xr-x+ 1 rmills staff 2238124 Aug 17 11:07 src/.libs/libexiv2.26.dylib
-------
2.2 To add the external Adobe SDK to the mix:
---------------------------------------------
Edit src/Makefile#242 and change:
@$(LIBTOOL) --mode=link $(LINK.cc) -o ../bin/$@ $(LIBRARY) $(EXIV2OBJ) $(EXIV2COBJ) -rpath $(libdir)
to:
@$(LIBTOOL) --mode=link $(LINK.cc) -lXMPCore -o ../bin/$@ $(LIBRARY) $(EXIV2OBJ) $(EXIV2COBJ) -rpath $(libdir)
$ touch src/version.cpp src/exiv2.cpp ; make
$ ls -alt src/.libs/libexiv2.26.dylib
-rwxr-xr-x+ 1 rmills staff 4312308 Aug 17 11:17 src/.libs/libexiv2.26.dylib
-------
$ bin/exiv2
dyld: Symbol not found: __ZNSiD0Ev
Referenced from: /Users/rmills/gnu/github/exiv2/src/.libs/libexiv2.26.dylib
Expected in: flat namespace
in /Users/rmills/gnu/github/exiv2/src/.libs/libexiv2.26.dylib
Abort trap: 6
605 rmills@rmillsmbp:~/gnu/github/exiv2 $
$ c++filt _ZNSiD0Ev
std::basic_istream<char, std::char_traits<char> >::~basic_istream()
This code is being accessed by Adobe XMPSDK 2016 libXMPCore.a and isn't in the c++ library.
$ nm -g xmpsdk/Adobe/libXMPCore.a | grep _ZNSiD0Ev
U __ZNSiD0Ev
$
Adobe XMPSDK 2014 has a similar problem with __ZNSs4_Rep11_S_terminalE
$ nm -g Adobe/XMP-Toolkit-SDK-CC201412/libXMPCore.a | grep __ZNSs4_Rep11_S_terminalE | sort --unique
U __ZNSs4_Rep11_S_terminalE
$ c++filt __ZNSs4_Rep11_S_terminalE
std::string::_Rep::_S_terminal
2.3 Notes (mostly to remind me of painful discoveries)
------------------------------------------------------
How does the build get generated?
$ make config
This generates ./configure by reading config/configure.ac
When you use --with-adobe, CXXFLAGS and LDFLAGS are modified and ENABLE_XMP is set to 2016.
Makefile has code to execute the script xmpsdk/buildXMPsdk.sh which
downloads and builds the XMPsdk to create libCore.a (which we need) and libFiles.a
config/config.mk.in is converted into config/config.mk and included in xmpsdk/src/Makefile
This is really ugly. config.mk also messes with CPPFLAGS and LDFLAGS
To get -lXMPCore into the mix, set XMPSDK_LIBS in config/config.mk.in
XMPSDK_LIBS = -lXMPCore
508 rmills@rmillsmbp:~/gnu/github/exiv2 $ finder Makefile | xargs grep -H config.mk | grep include
./contrib/organize/Makefile:include $(top_srcdir)/config/config.mk
./doc/Makefile:include $(top_srcdir)/config/config.mk
./samples/Makefile:include $(top_srcdir)/config/config.mk
./src/Makefile:include $(top_srcdir)/config/config.mk
./xmpsdk/src/Makefile:include $(top_srcdir)/config/config.mk
509 rmills@rmillsmbp:~/gnu/github/exiv2 $
2.4 Compiler options used to build Adobe XMPsdk
-----------------------------------------------
For sure, Adobe's code is being built with MacOSX10.8.sdk and -std=c++11
/usr/bin/c++
-DBUILDING_XMPCORE_AS_STATIC=1
-DBUILDING_XMPCORE_LIB=1
-DENABLE_CPP_DOM_MODEL=1
-DHAVE_EXPAT_CONFIG_H=1
-DMAC_ENV=1
-DXML_STATIC=1
-DXMP_64=1
-DXMP_COMPONENT_INT_NAMESPACE=AdobeXMPCore_Int
-DXMP_StaticBuild=1
-I/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/XMPCore/build/../..
-I/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/XMPCore/build/../../public/include
-I/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/XMPCore/build/../../third-party/expat/public/lib
-I/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/XMPCore/build/../resource/mac
-funsigned-char
-fshort-enums
-fno-common
-Wall
-Wextra
-Wno-missing-field-initializers
-Wno-shadow
-Wno-reorder
-std=c++11
-Wnon-virtual-dtor
-Woverloaded-virtual
-Wno-unused-variable
-Wno-unused-function
-Wno-unused-parameter
-fstack-protector
-O3
-DNDEBUG=1
-D_NDEBUG=1
-arch x86_64
-isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk
-mmacosx-version-min=10.7
-o CMakeFiles/XMPCoreStatic.dir/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/XMPCore/source/XMPMeta-GetSet.cpp.o
-c /Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/XMPCore/source/XMPMeta-GetSet.cpp
2.5 Compiler options used to build DumpFile sample Application
-----------------------------------------------------------
clang -x c++
-arch x86_64
-fmessage-length=0
-fdiagnostics-show-note-include-stack
-fmacro-backtrace-limit=0
-stdlib=libstdc++
-Wno-trigraphs
-fpascal-strings
-O3
-Wno-missing-field-initializers
-Wno-missing-prototypes
-Wno-return-type
-Wno-non-virtual-dtor
-Wno-overloaded-virtual
-Wno-exit-time-destructors
-Wno-missing-braces
-Wparentheses
-Wswitch
-Wno-unused-function
-Wno-unused-label
-Wno-unused-parameter
-Wno-unused-variable
-Wunused-value
-Wno-empty-body
-Wno-uninitialized
-Wno-unknown-pragmas
-Wno-shadow
-Wno-four-char-constants
-Wno-conversion
-Wno-constant-conversion
-Wno-int-conversion
-Wno-bool-conversion
-Wno-enum-conversion
-Wno-shorten-64-to-32
-Wno-newline-eof
-Wno-c++11-extensions
-DCMAKE_INTDIR=\"Release\"
-DMAC_ENV=1
-DXMP_64=1
-DXMP_StaticBuild=1
-isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk
-fasm-blocks
-fstrict-aliasing
-Wdeprecated-declarations
-Winvalid-offsetof
-mmacosx-version-min=10.9
-g
-Wno-sign-conversion
-Wno-infinite-recursion
-Wno-move
-I/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/target/macintosh/intel_64/Release/include
-I/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/../../..
-I/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/../../../public/include
-I/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/DumpFile/build_x64/XMP_Samples_64.build/Release/DumpFile.build/DerivedSources/x86_64
-I/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/DumpFile/build_x64/XMP_Samples_64.build/Release/DumpFile.build/DerivedSources
-Wmost
-Wno-four-char-constants
-Wno-unknown-pragmas
-F/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/target/macintosh/intel_64/Release
-F/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/System/Library/Frameworks
-funsigned-char
-fshort-enums
-fno-common
-Wall
-Wextra
-Wno-missing-field-initializers
-Wno-shadow
-Wno-reorder
-std=c++11
-Wnon-virtual-dtor
-Woverloaded-virtual
-Wno-unused-variable
-Wno-unused-function
-Wno-unused-parameter
-fstack-protector
-DNDEBUG=1
-D_NDEBUG=1
-MMD
-MT dependencies
-MF /Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/DumpFile/build_x64/XMP_Samples_64.build/Release/DumpFile.build/Objects-normal/x86_64/DumpFile.d
--serialize-diagnostics /Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/DumpFile/build_x64/XMP_Samples_64.build/Release/DumpFile.build/Objects-normal/x86_64/DumpFile.dia
-c /Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/source/common/DumpFile.cpp
-o /Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/DumpFile/build_x64/XMP_Samples_64.build/Release/DumpFile.build/Objects-normal/x86_64/DumpFile.o
2.6 Linker Options used to link DumpFile
----------------------------------------
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++
-arch x86_64
-isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk
-L/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/target/macintosh/intel_64/Release
-F/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/target/macintosh/intel_64/Release
-F/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/System/Library/Frameworks
-filelist /Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/DumpFile/build_x64/XMP_Samples_64.build/Release/DumpFile.build/Objects-normal/x86_64/DumpFile.LinkFileList
-mmacosx-version-min=10.9
-Xlinker
-object_path_lto
-Xlinker
/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/DumpFile/build_x64/XMP_Samples_64.build/Release/DumpFile.build/Objects-normal/x86_64/DumpFile_lto.o
-stdlib=libstdc++
-Wl,-search_paths_first
-Wl,-headerpad_max_install_names
/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/../../../public/libraries/macintosh/intel_64/Release/libXMPCoreStatic.a
/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/../../../public/libraries/macintosh/intel_64/Release/libXMPFilesStatic.a
-framework Cocoa
-Xlinker
-dependency_info
-Xlinker
/Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/build/cmake/DumpFile/build_x64/XMP_Samples_64.build/Release/DumpFile.build/Objects-normal/x86_64/DumpFile_dependency_info.dat
-o /Users/rmills/gnu/github/exiv2/xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/samples/target/macintosh/intel_64/Release/DumpFile
==========================================================================
3 Features to Add to the CMake code
* Auto usage of ccache on Linux and Mac.
* Remove the trick to compile the documentation using the configure script. Native documentation generation on CMake.
==========================================================================
4 Build design for v0.26.1
Added : 2017-08-18
Modified: 2017-08-23
The purpose of the v0.26.1 is to release bug fixes and
experimental new features which may become defaults with v0.27
4.1 Backwards compatibility
This feature is being added to v0.26.1 DOT release and therefore existing
behaviour of ./configure, CMake and msvc does not change.
./configure --enable-xmp (default is true) will build a library libxmpsdk.a
using the code in xmpsdk/src. This library is linked into libexiv2.26.dylib
4.2 New Options for ./configure
./configure --with-std=c++11
The default behaviour is the same as v0.26.0 --with-std=-std=c++98
If the user requests --with-adobe, --with-std=c++11 is the default
./configure --with-adobe[=2016|2014]
This causes the Adobe XMPsdk to be downloaded and built
into the directory xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/libXMPCore.a
The dynamic library libexiv2.26.dylib will not have libXMPCore.a linked
All applications (such as exiv2, exifprint etc) will require:
-Lxmpsdk/Adobe/XMP-Toolkit-SDK-CC201607 -lXMPCore
This is an important architectural change in libexiv2.26.dylib
However this is the way to achieve architecture independence between
exiv2 and Adobe XMPsdk. A longer term goal is to totally remove
all Adobe code from the exiv2 tarball.
Although --with-adobe causes the default compiler to be --with-std=c++11,
the code will with --with-std=c++98 The Adobe XMPsdk is built using the script
xmpsdk/buildXMPsdk which downloads and builds libXMPCore.a using Adobe provided
CMake code. For the 2016 SDK, libXMPCore.a is built with -std=c++11
4.3 New Options for msvc
This work has not been started. There are at least two possibilities:
1) To provide a new solution msvc/exiv2-adobe.sln
This is the model used by msvc/exiv2-webready.sln
2) To update msvc/configure.py to support options similar to
./configure --with-std= and ./config --with-adobe
4.4 New Options for CMake
Luis is adopting a two stage approach:
1) Cleaning up and refactoring the existing CMake scripts (*.cmake and CMakeLists.txt files)
This work is proceeding well.
2) Adding new EXIV2_ENABLE_XXXXs equivalent to ./configure --with-std and --with-adobe
This work is waiting for Robin to complete the ./configure modifications.
It is expected that the CMake files will execute the script xmpsdk/buildXMPsdk.{sh|cmd}
to perform the build of libXMPCore.a
4.5 New Options for contrib/cmake/msvc
To be written. Luis' great new work may make this obsolete.
4.6 Scripts xmpsdk/buildXMPsdk.sh and xmpsdk/buildXMPsdk.cmd
These scripts download and build the Adobe XMPsdk. Minor modification of the SDK
is necessary to enable the code to build. For example, Adobe does not support Cygwin
and minor change are necessary to build on that platform.
Changes to Adobe code will be minimal and documented in xmpsdk/buildXMPsdk.{sh|cmd}
4.7 Support for 32/64 bit builds, Release/Debug, Shared/Static
1) v0.26.1 will build exactly as v0.26 and support linking static libxmpsdk.a
32/64 static/shared debug/release are supported on all platforms
2) The new features (--with-std and --with-adobe) will only be supported for
a static/release build of libXMPCore.a
msvc will continue to supports 32/64 ReleaseDLL/Release/DebugDLL/Debug of libexiv2
which will include the static libXMPCore.a or libxmpsdk.a
4.8 Support for MinGW
MinGW msys/1.0 was deprecated when v0.26 was released.
No support for MinGW msys/1.0 will be provided.
It's very likely that the MinGW msys/1.0 will build.
I will not provide any user support for MinGW msys/1.0 in future.
MinGW msys/2.0 might be supported as "experimental" in Exiv2 v0.26.2
4.9 Building and linking XMPsdk with libexiv2
Exiv2 v0.26 (and many earlier editions) contain Adobe XMPsdk code.
The precise version of this code is unknown.
The xmpsdk/ directory has files in src/*.cpp and include/*.hpp
The xmpsdk/ has its own Makefile, CMakeLists.txt and msvc/xmpsdk/project files.
Exiv2 v0.26 builds a static library libxmpsdk.a which is linked into libexiv2.a
None of this will change in Exiv2 v0.26.1
Exiv2 v0.26.1 will support a new option to download and build "pure Adobe" XMPsdk.
Three flavours will be supported:
2013 http://download.macromedia.com/pub/developer/xmp/sdk/XMP-Toolkit-SDK-CC-201306.zip
2014 http://download.macromedia.com/pub/developer/xmp/sdk/XMP-Toolkit-SDK-CC201412.zip
2016 http://download.macromedia.com/pub/developer/xmp/sdk/XMP-Toolkit-SDK-CC201607.zip
As Adobe appear to release new editions every 18 months, I guess that Adobe will release
a new version in Spring 2018.
The autotools build supports new ./configure options:
--with-adobe builds and links 4089256 Aug 23 11:19 ./xmpsdk/Adobe/XMP-Toolkit-SDK-CC201306/libXMPCore.a
--with-adobe=2016 as --with-adobe
--with-adobe=2014 4108792 Aug 23 11:18 ./xmpsdk/Adobe/XMP-Toolkit-SDK-CC201412/libXMPCore.a
--with-adobe=2013 22242448 Aug 23 10:25 ./xmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/libXMPCore.a
The build of the Adobe XMPsdk is "pure Adobe". We download the code and build it without modification.
The scripts to download and build the Adobe code is:
xmpsdk/buildXMPsdk.sh
xmpsdk/buildXMPsdk.cmd
Adobe build the 2016 SDK with -std=c++11. This links successfully with the libexiv2 -std=c++98 build.
I haven't investigated which compiler Adobe use to build the 2013 and 2014 editions.
Mac Build
Following the analysis of Adobe's build (Topics 1 and 2 in this report), it has been realised that:
1 Adobe build the SDK with (both linker and compiler) -stdlib=libstdc++
2 Visibility should be disabled in the compiler
CPPFLAGS = -I/usr/local/include -I/usr/local/include -std=c++98 -fvisibility=hidden -fvisibility-inlines-hidden \
-stdlib=libstdc++ -Wno-deprecated -Ixmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/public/include
LDFLAGS = -L/usr/local/lib -lpthread -stdlib=libstdc++ -Wno-deprecated -Lxmpsdk/Adobe/XMP-Toolkit-SDK-CC201607
LIBS = -lz -lXMPCore
CXX = g++
Linux Build
CPPFLAGS = -I/usr/local/include -std=c++98 -Ixmpsdk/Adobe/XMP-Toolkit-SDK-CC201607/public/include
LDFLAGS = -L/usr/local/lib -ldl -lpthread -Lxmpsdk/Adobe/XMP-Toolkit-SDK-CC201607
LIBS = -lz -lm -lXMPCore
CXX = g++
When 2013 or 2014 are selected, the appropriate -Ipath and -Lpath should be set.
CMake Build
A new option -DEXIV2_ENABLE_ADOBE[=2016|=2014|=2013] should be added.
The build of XMPsdk should be performed with xmpsdk/buildXMPsdk.sh (or xmpsdk/buildXMPsdk.cmd for Visual Studio)
The build should set same LDFLAGS and CPPFLAGS as the autotools build.
When the options -DEXIV2_ENABLE_ADOBE is not used, we should compile the code in xmpsdk/src
to create and link libxmpsdk.a
==========================================================================
5 Refactoring the Tiff Code
Added : 2017-09-24
Modified: 2017-09-24
5.1 Background
Tiff parsing is the root code of a metadata engine.
The Tiff parsing code in Exiv2 is very difficult to understand and has major architectural shortcomings:
1) It requires the Tiff file to be totally in memory
2) It cannot handle BigTiff
3) The parser doesn't know the source of the in memory tiff image
4) It uses memory mapping on the tiff file
- if the network connection is lost, horrible things happen
- it requires a lot of VM to map the complete file
- BigTiff file can be 100GB+
- The memory mapping causes problems with Virus Detection software on Windows
5) The parser cannot deal with multi-page tiff files
6) It requires the total file to be in contiguous memory and defeats 'webready'.
The Tiff parsing code in Exiv2 is ingenious. It's also very robust. It works well. It can:
1) Handle 32-bit Tiff and Many Raw formats (which are derived from Tiff)
2) It can read and write Manufacturer's MakerNotes which are (mostly) in Tiff format
3) It probably has other great features that I haven't discovered
- because the code is so hard to understand, I can't simply browse and read it.
4) It separates file navigation from data analysis.
The code in image::printStructure was originally written to understand "what is a tiff?"
It has problems:
1) It was intended to be a single threaded debugging function and has security issues.
2) It doesn't handle BigTiff
3) It's messy. It's reading and processing metadata simultaneously.
The aim of this project is to
1) Reconsider the Tiff Code.
2) Keep everything good in the code and address known deficiencies
3) Establish a Team Exiv2 "Tiff Expert" who knows the code intimately.
5.2 How does Exiv2 decode the ExifData in a JPEG?
You can get my test file from http://clanmills.com/Stonehenge.jpg
808 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/build $ exiv2 -pS ~/Stonehenge.jpg
STRUCTURE OF JPEG FILE: /Users/rmills/Stonehenge.jpg
address | marker | length | data
0 | 0xffd8 SOI
2 | 0xffe1 APP1 | 15288 | Exif..II*......................
15292 | 0xffe1 APP1 | 2610 | http://ns.adobe.com/xap/1.0/.<?x
17904 | 0xffed APP13 | 96 | Photoshop 3.0.8BIM.......'.....
18002 | 0xffe2 APP2 | 4094 | MPF.II*...............0100.....
22098 | 0xffdb DQT | 132
22232 | 0xffc0 SOF0 | 17
22251 | 0xffc4 DHT | 418
22671 | 0xffda SOS
809 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/build $
Exiv2 calls JpegBase::readMetadata which locates the APP1/Exif segment.
It invokes the ExifParser:
ExifParser::decode(exifData_, rawExif.pData_, rawExif.size_);
This is thin wrapper over:
TiffParserWorker::decode(....) in tiffimage.cpp
What happens then? I don't know. The metadata is decoded in:
tiffvisitor.cpp TiffDecoder::visitEntry()
The design of the TiffMumble classes is the "Visitor" pattern
described in "Design Patterns" by Addison & Wesley. The aim of the pattern
is to separate parsing from dealing with the data.
The data is being stored in ExifData which is a vector.
Order is important and preserved.
As the data values are recovered they are stored as Exifdatum in the vector.
How does the tiff visitor work? I think the reader and processor
are connected by this line in TiffParser::
rootDir->accept(reader);
The class tree for the decoder is:
class TiffDecoder : public TiffFinder {
class TiffReader ,
class TiffFinder : public TiffVisitor {
class TiffVisitor {
public:
//! Events for the stop/go flag. See setGo().
enum GoEvent {
geTraverse = 0,
geKnownMakernote = 1
};
void setGo(GoEvent event, bool go);
virtual void visitEntry(TiffEntry* object) =0;
virtual void visitDataEntry(TiffDataEntry* object) =0;
virtual void visitImageEntry(TiffImageEntry* object) =0;
virtual void visitSizeEntry(TiffSizeEntry* object) =0;
virtual void visitDirectory(TiffDirectory* object) =0;
virtual void visitSubIfd(TiffSubIfd* object) =0;
virtual void visitMnEntry(TiffMnEntry* object) =0;
virtual void visitIfdMakernote(TiffIfdMakernote* object) =0;
virtual void visitIfdMakernoteEnd(TiffIfdMakernote* object);
virtual void visitBinaryArray(TiffBinaryArray* object) =0;
virtual void visitBinaryArrayEnd(TiffBinaryArray* object);
//! Operation to perform for an element of a binary array
virtual void visitBinaryElement(TiffBinaryElement* object) =0;
//! Check if stop flag for \em event is clear, return true if it's clear.
bool go(GoEvent event) const;
}
}
}
The reader works by stepping along the Tiff directory and calls the visitor's
"callbacks" as it reads.
There are 2000 lines of code in tiffcomposite.cpp and, to be honest,
I don't know what most of it does!
Set a breakpoint in src/exif.cpp#571.
That’
Exactly how did he get here? That’
void ExifData::add(const ExifKey& key, const Value* pValue)
{
add(Exifdatum(key, pValue));
}
5.3 How is metadata organized in Exiv2
section.group.tag
section: Exif | IPTC | Xmp
group: Photo | Image | MakerNote | Nikon3 ....
tag: YResolution etc ...
820 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/src $ exiv2 -pa ~/Stonehenge.jpg | cut -d' ' -f 1 | cut -d. -f 1 | sort | uniq
Exif
Iptc
Xmp
821 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/src $ exiv2 -pa --grep Exif ~/Stonehenge.jpg | cut -d'.' -f 2 | sort | uniq
GPSInfo
Image
Iop
MakerNote
Nikon3
NikonAf2
NikonCb2b
NikonFi
NikonIi
NikonLd3
NikonMe
NikonPc
NikonVr
NikonWt
Photo
Thumbnail
822 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/src $ 533 rmills@rmillsmbp:~/Downloads $ exiv2 -pa --grep Exif ~/Stonehenge.jpg | cut -d'.' -f 3 | cut -d' ' -f 1 | sort | uniq
AFAperture
AFAreaHeight
AFAreaMode
...
XResolution
YCbCrPositioning
YResolution
534 rmills@rmillsmbp:~/Downloads $
823 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/src $
The data in IFD0 of is Exiv2.Image:
826 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/src $ exiv2 -pR ~/Stonehenge.jpg | head -20
STRUCTURE OF JPEG FILE: /Users/rmills/Stonehenge.jpg
address | marker | length | data
0 | 0xffd8 SOI
2 | 0xffe1 APP1 | 15288 | Exif..II*......................
STRUCTURE OF TIFF FILE (II): MemIo
address | tag | type | count | offset | value
10 | 0x010f Make | ASCII | 18 | 146 | NIKON CORPORATION
22 | 0x0110 Model | ASCII | 12 | 164 | NIKON D5300
34 | 0x0112 Orientation | SHORT | 1 | | 1
46 | 0x011a XResolution | RATIONAL | 1 | 176 | 300/1
58 | 0x011b YResolution | RATIONAL | 1 | 184 | 300/1
70 | 0x0128 ResolutionUnit | SHORT | 1 | | 2
82 | 0x0131 Software | ASCII | 10 | 192 | Ver.1.00
94 | 0x0132 DateTime | ASCII | 20 | 202 | 2015:07:16 20:25:28
106 | 0x0213 YCbCrPositioning | SHORT | 1 | | 1
118 | 0x8769 ExifTag | LONG | 1 | | 222
STRUCTURE OF TIFF FILE (II): MemIo
address | tag | type | count | offset | value
224 | 0x829a ExposureTime | RATIONAL | 1 | 732 | 10/4000
236 | 0x829d FNumber | RATIONAL | 1 | 740 | 100/10
827 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/src $ exiv2 -pa --grep Image ~/Stonehenge.jpg
Exif.Image.Make Ascii 18 NIKON CORPORATION
Exif.Image.Model Ascii 12 NIKON D5300
Exif.Image.Orientation Short 1 top, left
Exif.Image.XResolution Rational 1 300
Exif.Image.YResolution Rational 1 300
Exif.Image.ResolutionUnit Short 1 inch
Exif.Image.Software Ascii 10 Ver.1.00
Exif.Image.DateTime Ascii 20 2015:07:16 20:25:28
Exif.Image.YCbCrPositioning Short 1 Centered
Exif.Image.ExifTag Long 1 222
Exif.Nikon3.ImageBoundary Short 4 0 0 6000 4000
Exif.Nikon3.ImageDataSize Long 1 6173648
Exif.NikonAf2.AFImageWidth Short 1 0
Exif.NikonAf2.AFImageHeight Short 1 0
Exif.Photo.ImageUniqueID Ascii 33 090caaf2c085f3e102513b24750041aa
Exif.Image.GPSTag Long 1 4060
828 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/src $
The data in IFD1 is Exiv2.Photo
The data in the MakerNote is another embedded TIFF (which more embedded tiffs)
829 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/src $ exiv2 -pa --grep MakerNote ~/Stonehenge.jpg
Exif.Photo.MakerNote Undefined 3152 (Binary value suppressed)
Exif.MakerNote.Offset Long 1 914
Exif.MakerNote.ByteOrder Ascii 3 II
830 rmills@rmillsmbp:~/gnu/github/exiv2/exiv2/src $
The MakerNote decodes them into:
Exif.Nikon1, Exiv2.NikonAf2 and so on. I don't know exactly it achieves this.
However it means that tag-numbers can be reused in different IFDs.
Tag 0x0016 = Nikon GPSSpeed and can mean something different elsewhere.
5.4 Where are the tags defined?
There's an array of "TagInfo" data structures in each of the makernote decoders.
These define the tag (a number) and the tag name, the groupID (eg canonId) and the default type.
There's also a callback to print the value of the tag. This does the "interpretation"
that is performed by the -pt in the exiv2 command-line program.
TagInfo(0x4001, "ColorData", N_("Color Data"), N_("Color data"), canonId, makerTags, unsignedShort, -1, printValue),
5.5 How do the MakerNotes get decoded?
I don't know. It has something to do with this code in tiffcomposite.cpp#936
TiffMnEntry::doAccept(TiffVisitor& visitor) { ... }
Most makernotes are TiffStructures. So the TiffXXX classes are invoked recursively to decode the maker note.
#0 0x000000010058b4b0 in Exiv2::Internal::TiffDirectory::doAccept(Exiv2::Internal::TiffVisitor&) at /Users/rmills/gnu/github/exiv2/exiv2/src/tiffcomposite.cpp:916
This function iterated the array of entries
#1 0x000000010058b3c6 in Exiv2::Internal::TiffComponent::accept(Exiv2::Internal::TiffVisitor&) at /Users/rmills/gnu/github/exiv2/exiv2/src/tiffcomposite.cpp:891
#2 0x00000001005b5357 in Exiv2::Internal::TiffParserWorker::parse(unsigned char const*, unsigned int, unsigned int, Exiv2::Internal::TiffHeaderBase*) at /Users/rmills/gnu/github/exiv2/exiv2/src/tiffimage.cpp:2006
This function creates an array of TiffEntries
#3 0x00000001005a2a60 in Exiv2::Internal::TiffParserWorker::decode(Exiv2::ExifData&, Exiv2::IptcData&, Exiv2::XmpData&, unsigned char const*, unsigned int, unsigned int, void (Exiv2::Internal::TiffDecoder::* (*)(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, unsigned int, Exiv2::Internal::IfdId))(Exiv2::Internal::TiffEntryBase const*), Exiv2::Internal::TiffHeaderBase*) at /Users/rmills/gnu/github/exiv2/exiv2/src/tiffimage.cpp:1900
#4 0x00000001005a1ae9 in Exiv2::TiffParser::decode(Exiv2::ExifData&, Exiv2::IptcData&, Exiv2::XmpData&, unsigned char const*, unsigned int) at /Users/rmills/gnu/github/exiv2/exiv2/src/tiffimage.cpp:260
#5 0x000000010044d956 in Exiv2::ExifParser::decode(Exiv2::ExifData&, unsigned char const*, unsigned int) at /Users/rmills/gnu/github/exiv2/exiv2/src/exif.cpp:625
#6 0x0000000100498fd7 in Exiv2::JpegBase::readMetadata() at /Users/rmills/gnu/github/exiv2/exiv2/src/jpgimage.cpp:386
#7 0x000000010000bc59 in Action::Print::printList() at /Users/rmills/gnu/github/exiv2/exiv2/src/actions.cpp:530
#8 0x0000000100005835 in Action::Print::run(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) at /Users/rmills/gnu/github/exiv2/exiv2/src/actions.cpp:245
5.6 How do the encoders work?
I understand writeMetadata() and will document that soon.
I still have to study how the TiffVisitor writes metadata.
# That's all Folks!
==========================================================================
