macOS build problem.

Created by: bingosna

I have this problem when doing "pip install av" on my mac. I've seen this problem on this, I just am not that good at using terminal and I'm newer to python.

Collecting av
  Using cached https://files.pythonhosted.org/packages/52/56/3ed0d68acc9d1faa92b15e7012c68fad5f21c0405315c90b337104ba7f29/av-0.4.1.tar.gz
Installing collected packages: av
  Running setup.py install for av ... error
    Complete output from command /usr/bin/python -u -c "import setuptools, tokenize;__file__='/private/var/folders/0s/6qyl3ftj1hs4m3whs7_fqq5r0000gn/T/pip-install-i4Ltqf/av/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /private/var/folders/0s/6qyl3ftj1hs4m3whs7_fqq5r0000gn/T/pip-record-6O85Pc/install-record.txt --single-version-externally-managed --compile:
    running install
    running build
    running build_py
    creating build
    creating build/lib.macosx-10.13-intel-2.7
    creating build/lib.macosx-10.13-intel-2.7/av
    copying av/__init__.py -> build/lib.macosx-10.13-intel-2.7/av
    copying av/__main__.py -> build/lib.macosx-10.13-intel-2.7/av
    creating build/lib.macosx-10.13-intel-2.7/av/video
    copying av/video/__init__.py -> build/lib.macosx-10.13-intel-2.7/av/video
    creating build/lib.macosx-10.13-intel-2.7/av/codec
    copying av/codec/__init__.py -> build/lib.macosx-10.13-intel-2.7/av/codec
    creating build/lib.macosx-10.13-intel-2.7/av/container
    copying av/container/__init__.py -> build/lib.macosx-10.13-intel-2.7/av/container
    creating build/lib.macosx-10.13-intel-2.7/av/audio
    copying av/audio/__init__.py -> build/lib.macosx-10.13-intel-2.7/av/audio
    creating build/lib.macosx-10.13-intel-2.7/av/subtitles
    copying av/subtitles/__init__.py -> build/lib.macosx-10.13-intel-2.7/av/subtitles
    creating build/lib.macosx-10.13-intel-2.7/av/filter
    copying av/filter/__init__.py -> build/lib.macosx-10.13-intel-2.7/av/filter
    creating build/lib.macosx-10.13-intel-2.7/av/data
    copying av/data/__init__.py -> build/lib.macosx-10.13-intel-2.7/av/data
    running build_ext
    running reflect
    running config
    looking for avformat_open_input... missing
    looking for pyav_function_should_not_exist... missing
    looking for av_calloc... missing
    looking for av_frame_get_best_effort_timestamp... missing
    looking for avformat_alloc_output_context2... missing
    looking for avformat_close_input... missing
    looking for avcodec_send_packet... missing
    looking for AV_OPT_TYPE_INT...found
    looking for PYAV_ENUM_SHOULD_NOT_EXIST...missing
    looking for AV_OPT_TYPE_BOOL...found
    looking for AVStream.index... found
    looking for PyAV.struct_should_not_exist... missing
    looking for AVFrame.mb_type... missing
    
    We didn't find `avformat_open_input` in the libraries.
    We look for it only as a sanity check to make sure the build
    process is working as expected. It is not, so we must abort.
    
    You can see the compiler output for the reflection process via:
        python setup.py reflect --force --debug
    
    Here is the config we gathered so far:
    
    PyAV: 0.4.1 (unknown commit)
    Python: 2.7.10 (default, Oct  6 2017, 22:29:07) \n[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.31)]
    platform: Darwin-17.6.0-x86_64-i386-64bit
    extension_extra:
    	define_macros: []
    	runtime_library_dirs: []
    	libraries: []
    	library_dirs: []
    	include_dirs: ['include', '/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7']
    config_macros:
    	PYAV_COMMIT_STR="unknown-commit"
    	PYAV_HAVE_AVCODEC_SEND_PACKET=0
    	PYAV_HAVE_AVFORMAT_ALLOC_OUTPUT_CONTEXT2=0
    	PYAV_HAVE_AVFORMAT_CLOSE_INPUT=0
    	PYAV_HAVE_AVFRAME__MB_TYPE=0
    	PYAV_HAVE_AV_CALLOC=0
    	PYAV_HAVE_AV_FRAME_GET_BEST_EFFORT_TIMESTAMP=0
    	PYAV_HAVE_AV_OPT_TYPE_BOOL=1
    	PYAV_HAVE_LIBAVRESAMPLE=0
    	PYAV_HAVE_LIBSWRESAMPLE=1
    	PYAV_VERSION=0.4.1
    	PYAV_VERSION_STR="0.4.1"
    
    ----------------------------------------
Command "/usr/bin/python -u -c "import setuptools, tokenize;__file__='/private/var/folders/0s/6qyl3ftj1hs4m3whs7_fqq5r0000gn/T/pip-install-i4Ltqf/av/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /private/var/folders/0s/6qyl3ftj1hs4m3whs7_fqq5r0000gn/T/pip-record-6O85Pc/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /private/var/folders/0s/6qyl3ftj1hs4m3whs7_fqq5r0000gn/T/pip-install-i4Ltqf/av/