IOError: [Errno 2] No such file or directory: 'extern/ffmpeg/config.mak':
  File "C:\bf-blender\blender\SConstruct", line 286:
    SConscript(B.root_build_dir+'/extern/SConscript')
  File "C:\Python24\scons-0.96.96\SCons\Script\SConscript.py", line 583:
    return apply(method, args, kw)
  File "C:\Python24\scons-0.96.96\SCons\Script\SConscript.py", line 520:
    return apply(_SConscript, [self.fs,] + files, subst_kw)
  File "C:\Python24\scons-0.96.96\SCons\Script\SConscript.py", line 245:
    exec _file_ in call_stack[-1].globals
  File "C:\bf-blender\blender\extern\SConscript", line 18:
    SConscript(['ffmpeg/SConscript']);
  File "C:\Python24\scons-0.96.96\SCons\Script\SConscript.py", line 583:
    return apply(method, args, kw)
  File "C:\Python24\scons-0.96.96\SCons\Script\SConscript.py", line 520:
    return apply(_SConscript, [self.fs,] + files, subst_kw)
  File "C:\Python24\scons-0.96.96\SCons\Script\SConscript.py", line 245:
    exec _file_ in call_stack[-1].globals
  File "C:\bf-blender\blender\extern\ffmpeg\SConscript", line 99:
    vars = getmakevars([root + '/config.mak', root + "/" + lib + '/Makefile'])
  File "C:\bf-blender\blender\extern\ffmpeg\SConscript", line 75:
    fp = open(filename)