I am attempting to build a very simple command line application, in Xcode, that will print out basic information about MXF video files. In order to do this I need to use the libmxf, libbmx, and libbmx libraries available for download here:
http://sourceforge.net/p/bmxlib/home/Home/
My C++ code is incredibly simple at this point:
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cerrno>
#include <vector>
#include <bmx/mxf_reader/MXFFileReader.h>
#include <bmx/mxf_reader/MXFGroupReader.h>
#include <bmx/mxf_reader/MXFSequenceReader.h>
#include <bmx/mxf_reader/MXFFrameMetadata.h>
#include <bmx/MXFUtils.h>
#include <bmx/Utils.h>
using namespace std;
using namespace bmx;
#define MXF_OPEN_READ(fn, pf) mxf_disk_file_open_read(fn, pf)
int main(int argc, const char * argv[])
{
std::vector<const char *> filenames;
std::cout << "mxfheader: execution beginning...\n";
for (int cmdln_index = 0; cmdln_index < argc; cmdln_index++) {
if (!check_file_exists(argv[cmdln_index])) {
if (argv[cmdln_index][0] == '-') {
fprintf(stderr, "Unknown argument '%s'\n", argv[cmdln_index]);
} else {
fprintf(stderr, "Failed to open input filename '%s'\n", argv[cmdln_index]);
}
return 1;
}
filenames.push_back(argv[cmdln_index]);
}
std::cout << filenames[0] << "\n";
return 0;
}
When I compiled the BMX library, I was sure to run configure with 64-bit support, like so:
./configure --build=x86_64-apple-darwin11.4.2 --host=x86_64-apple-darwin11.4.2 CFLAGS="-arch x86_64" CXXFLAGS="-arch x86_64" LDFLAGS="-arch x86_64" CC=clang CXX=clang++
In the XCode Project under Build Settings, I have added /usr/local/lib to my Search Paths. Under Build Phases, I have added "libbmx-0.1.3.dylib", "libMXF-1.0.4.dylib", and "libMXF++-1.0.4.dylib" to the "Link Binary With Libraries" section.
I have verified that these libraries are, indeed, 64-bit ( file libbmx-0.1.3.dylib returns libbmx-0.1.3.dylib: Mach-O 64-bit dynamically linked shared library x86_64 ).
Every time I try and build the application, I get the following linker error:
Ld /Users/ned/Library/Developer/Xcode/DerivedData/mxfheader-bkwawmplsoqpdadfxartceqkbolo/Build/Products/Debug/mxfheader normal x86_64
cd /Users/ned/Documents/src/mxfheader
setenv MACOSX_DEPLOYMENT_TARGET 10.7
/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/MacOSX10.8.sdk -L/Users/ned/Library/Developer/Xcode/DerivedData/mxfheader-bkwawmplsoqpdadfxartceqkbolo/Build/Products/Debug -L/usr/local/lib -F/Users/ned/Library/Developer/Xcode/DerivedData/mxfheader-bkwawmplsoqpdadfxartceqkbolo/Build/Products/Debug -filelist /Users/ned/Library/Developer/Xcode/DerivedData/mxfheader-bkwawmplsoqpdadfxartceqkbolo/Build/Intermediates/mxfheader.build/Debug/mxfheader.build/Objects-normal/x86_64/mxfheader.LinkFileList -mmacosx-version-min=10.7 -stdlib=libc++ -lbmx-0.1.3 -lMXF-1.0.4 -lMXF++-1.0.4 -o /Users/ned/Library/Developer/Xcode/DerivedData/mxfheader-bkwawmplsoqpdadfxartceqkbolo/Build/Products/Debug/mxfheader
Undefined symbols for architecture x86_64:
"bmx::check_file_exists(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >)", referenced from:
_main in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Any help would be appreciated. Thanks!
You can fix the errors by including the source code file that contains the definitions as part of the compilation. Alternatively, you can pass . obj files or . lib files that contain the definitions to the linker.
Right click on your project in the left hand column (file listing), click “Add existing files”, then go to the prebuilt library (for me it was in /usr/local/lib), and add the file. You don't have to copy it into the directory, you can just add it and it should work.
You will need to add them manually to your Visual Studio project in order to resolve all the symbols. In order to include the required libraries, you will need to add them under Project -> Properties -> Linker -> Input -> Additional dependencies: For example: mclmcrrt. lib, mclmcr.
So when we try to assign it a value in the main function, the linker doesn't find the symbol and may result in an “unresolved external symbol” or “undefined reference”. The way to fix this error is to explicitly scope the variable using '::' outside the main before using it.
Your problem is the option: -stdlib=libc++
in the command line. It's causing a link to the wrong libc++, you need to make it -stdlib=libstdc++
, as this is the stdlib that the libbmx
library is compiled against.
under the Apple LLVM compiler
options for the C++ standard library, select: libstdc++
, or pick compiler default
(which should choose libstdc++ also)
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