BUILD.gn - chromium/third_party/ffmpeg - Git at Google

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

 import("ffmpeg_options.gni")
 import("ffmpeg_generated.gni")

 # Path to platform configuration files.
 platform_config_root =
     "chromium/config/$ffmpeg_branding/$os_config/$ffmpeg_arch"

 # Stub generator script and signatures of all functions used by Chrome.
 generate_stubs_script = "//tools/generate_stubs/generate_stubs.py"

 # Used by ffmpeg_generate_stubs and ffmpeg_generate_def
 sig_files = [ "chromium/ffmpegsumo.sigs" ]

 # TODO(ajwong): Should be in ffmpeg_generate_stubs if we could grab the
 # outputs of an action via a function.
 stubs_filename_root = "ffmpeg_stubs"

 if (cpu_arch != "arm" && os_config != "linux-noasm") {
   import("//third_party/yasm/yasm_assemble.gni")
   yasm_assemble("ffmpeg_yasm") {
     sources = ffmpeg_yasm_sources

     # Ensure the architecture defines go in the command line before the -P
     # file below, so don't use defines.
     yasm_flags = []
     if (cpu_arch == "x86") {
       yasm_flags += [ "-DARCH_X86_32" ]
     } else if (cpu_arch == "x64") {
       yasm_flags += [ "-DARCH_X86_64" ]
     }

     defines = [ "PIC" ]
     include_dirs = [
       platform_config_root,
       "libavcodec/x86",
       "libavutil/x86",
       ".",
     ]

     # Disable warnings, prevents log spam for things we won't fix.
     yasm_flags += [
       "-w",
       "-P", rebase_path("$platform_config_root/config.asm", root_build_dir),
     ]

     if (is_mac) {
       # Necessary to ensure symbols end up with a _ prefix; added by
       # yasm_compile.gypi for Windows, but not Mac.
       defines += [ "PREFIX" ]
     }
   }
 }

 # FFMpeg is dynamically loaded on all platforms but our code calls it
 # as if it were directly linked. To make this work, the build system needs
 # to generate stubs that indirect into the library calls.
 #
 # On Windows, this script calls the windows stub generator. Otherwise, assume
 # this is a POSIX platform and generate our own wrapper stubs.
 action("ffmpeg_generate_stubs") {
   extra_header = "chromium/ffmpeg_stub_headers.fragment"

   script = generate_stubs_script
   sources = sig_files
   inputs = [ extra_header ]

   if (is_win) {
     if (build_cpu_arch == "x64") {
       outfile_type = "windows_lib_x64"
     } else {
       outfile_type = "windows_lib"
     }

     # TODO(ajwong): these need to be in the ffmpeg build.
     outputs = [
       "$target_gen_dir/$stubs_filename_root.lib",
     ]

     args = [
       # TODO(ajwong): In gyp, this uses different directories for the
       # windows build. We should think this through.
       "-i", rebase_path(target_gen_dir, root_build_dir),
       "-o", rebase_path(target_gen_dir, root_build_dir),
       "-t", outfile_type,
     ]
   } else {
     # If it's not windows, clearly it must be posix.

     # TODO(ajwong): these need to be included in the ffmpeg build.
     outputs = [
       "$target_gen_dir/$stubs_filename_root.cc",
       "$target_gen_dir/$stubs_filename_root.h",
     ]
     args = [
       # TODO(ajwong): IN gyp, this used to output the .h file into a shared
       # directory that other targets could reference. The .cc ends up in a
       # special generated directory that gyp would guaranteed that no one else
       # could look at. Now we're dumping both into the generated directory.
       # Verify what the best + simplest behavior is here and use that.
       "-i", rebase_path(target_gen_dir, root_build_dir),
       "-o", rebase_path(target_gen_dir, root_build_dir),
       "-t", "posix_stubs",
       "-e", rebase_path(extra_header, root_build_dir),
       "-s", stubs_filename_root,
       "-p", "third_party/ffmpeg",
     ]
   }

   args += rebase_path(sources, root_build_dir)
 }

 if (build_ffmpegsumo) {
   shared_library("ffmpegsumo") {
     sources = ffmpeg_c_sources + ffmpeg_gas_sources + [
       "$platform_config_root/config.h",
       "$platform_config_root/libavutil/avconfig.h",
     ]
     include_dirs = [
       platform_config_root,
       ".",
     ]
     defines = [
       "HAVE_AV_CONFIG_H",
       "_POSIX_C_SOURCE=200112",
       "_XOPEN_SOURCE=600",
       "PIC",
       # Disable deprecated features which generate spammy warnings.
       "FF_API_PIX_FMT_DESC=0",
       "FF_API_OLD_DECODE_AUDIO=0",
       "FF_API_DESTRUCT_PACKET=0",
       "FF_API_GET_BUFFER=0",
     ]

     # So we can append below and assume they're defined.
     cflags = []
     ldflags = []
     libs = []
     deps = []

     configs -= [ "//build/config/compiler:chromium_code" ]
     configs += [ "//build/config/compiler:no_chromium_code" ]

     # Since we are not often debugging FFmpeg, and performance is
     # unacceptable without optimization, freeze the optimizations to -O2.
     # If someone really wants -O1 , they can change these in their checkout.
     # If you want -O0, see the Gotchas in README.Chromium for why that
     # won't work.
     #
     # In addition to the above reasons, /Od optimization won't remove symbols
     # that are under "if (0)" style sections.  Which lead to link time errors
     # when for example it tries to link an ARM symbol on X86.
     if (is_debug) {
       configs -= [ "//build/config/compiler:no_optimize" ]
     } else {
       configs -= [ "//build/config/compiler:optimize" ]
     }
     if (is_win) {
       # Setting the optimizations to 'speed' or to 'max' on Windows results in
       # a lot of unresolved symbols. The only supported mode is 'size' (see
       # crbug.com/264459).
       configs += [ "//build/config/compiler:optimize" ]
     } else {
       configs += [ "//build/config/compiler:optimize_max" ]
     }

     if (is_posix) {
       cflags += [
         "-fPIC",
         "-fomit-frame-pointer",
         # ffmpeg uses its own deprecated functions.
         "-Wno-deprecated-declarations",
       ]

       if (is_clang) {
         cflags += [
           "-Wno-absolute-value",
           "-Wno-incompatible-pointer-types",
           "-Wno-logical-op-parentheses",
           "-Wno-parentheses",
           "-Wno-pointer-sign",
           "-Wno-switch",
         ]
       } else {
         # gcc doesn't have flags for specific warnings, so disable them
         # all.
         cflags += [ "-w" ]
       }
       if (cpu_arch == "x86") {
         # Turn off valgrind build option that breaks ffmpeg builds.
         # TODO(ajwong): The gyp file had special removals for
         # debug_extra_cflags and release_extra_cflags. Do we care?
 #cflags -= [ "-fno-omit-frame-pointer" ]
       } else if (cpu_arch == "arm") {
         # TODO(ihf): See the long comment in build_ffmpeg.sh
         # We want to be consistent with CrOS and have configured
         # ffmpeg for thumb. Protect yourself from -marm.
         if (is_chromeos) {
           cflags += [ "-marm" ]
         }
         cflags += [
           "-mthumb",
           "-march=armv7-a",
           "-mtune=cortex-a8",
           "-mfpu=${arm_fpu}"
         ]
         if (arm_float_abi == "hard") {
           cflags += [ "-DHAVE_VFP_ARGS=1" ]
         } else {
           cflags += [ "-DHAVE_VFP_ARGS=0" ]
         }
       } else if (cpu_arch == "mipsel") {
         cflags += [
           "-mips32",
           "-EL -Wl,-EL",
         ]
       }
     }

     if (is_posix && !is_mac) {
       defines += [
         "_ISOC99_SOURCE",
         "_LARGEFILE_SOURCE",
         # BUG(ihf): ffmpeg compiles with this define. But according to
         # ajwong: I wouldn't change _FILE_OFFSET_BITS.  That's a scary change
         # cause it affects the default length of off_t, and fpos_t,
         # which can cause strange problems if the loading code doesn't
         # have it set and you start passing FILE*s or file descriptors
         # between symbol contexts.
         # "_FILE_OFFSET_BITS=64",
       ]
       cflags += [
         "-std=c99",
         "-pthread",
         "-fno-math-errno",
         "-fno-signed-zeros",
         "-fno-tree-vectorize",
         "-fomit-frame-pointer",
       ]
       # Ensure the symbols are exported.
       #
       # TODO(ajwong): Manually tag the API that we use to be
       # exported.
       configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
       ldflags = [
         "-Wl,-Bsymbolic",
         "-L", rebase_path(target_gen_dir, root_build_dir),
       ]
       libs = [ "z" ]
 # TODO(ajwong): How to handle openbsd? Especially w/o the is_posix?
 #      if (is_openbsd) {
 #       # OpenBSD's gcc (4.2.1) does not support this flag
 #       cflags -= [ "-fno-signed-zeros" ]
 #      }
     }
     if (is_mac) {
       defines += [ "_DARWIN_C_SOURCE" ]

 # TODO(ajwong): What does this do in mac? There isn't anything in ffmpeg.gyp that
 # uses mac_real_dsym
 #                ['mac_breakpad == 1', {
 #                  'variables': {
 #                    # A real .dSYM is needed for dump_syms to operate on.
 #                    'mac_real_dsym': 1,
 #                  },
 #              }],
       if (cpu_arch != "x64") {
         # This is needed because even though FFmpeg now builds
         # with -fPIC, it's not quite a complete PIC build, only
         # partial :( Thus we need to instruct the linker to allow
         # relocations for read-only segments for this target to be
         # able to generated the shared library on Mac.
         #
 #TODO(ajwong): Check if this can be cpu_arch == "x86"
         # Note -read_only_relocs cannot be used in x86_64
         #
         # This makes Mark sad, but he's okay with it since it is
         # isolated to this module. When Mark finds this in the
         # future, and has forgotten this conversation, this
         # comment should remind him that the world is still nice
         # and butterflies still exist...as do rainbows, sunshine,
         # tulips, etc., etc...but not kittens. Those went away
         # with this flag.
         ldflags = [
           "-Wl,-read_only_relocs,suppress",
         ]
       }
 # TODO(ajwong): How to handle SDKROOT?
 #                'libraries': [
 #                  '$(SDKROOT)/usr/lib/libz.dylib',
 #                ],
       # Ensure the symbols are exported.
       #
       # TODO(ajwong): Manually tag the API that we use to be exported.
       if (!is_win) {
         configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
       }
 # TODO(ajwong): How to handle @loader_path?
 #              'xcode_settings': {
 #                'DYLIB_INSTALL_NAME_BASE': '@loader_path',
 #              }
       lib_dirs = [ target_gen_dir ]
     } else if (is_win) {
       defines += [
         "inline=__inline",
         "strtoll=_strtoi64",
         "_ISOC99_SOURCE",
         "_LARGEFILE_SOURCE",
         "HAVE_AV_CONFIG_H",
         "strtod=avpriv_strtod",
         "snprintf=avpriv_snprintf",
         "_snprintf=avpriv_snprintf",
         "vsnprintf=avpriv_vsnprintf",
       ]

       include_dirs += [
         "chromium/include/win"
       ]
       # TODO(dalecurtis): We should fix these.  http://crbug.com/154421
       cflags += [
         "/wd4996", # 'function': was declared deprecated
         "/wd4018", # 'expression': signed/unsigned mismatch
         "/wd4090", # 'operation' : different 'modifier' qualifiers
         "/wd4305", # 'identifier': truncation from 'type1' to 'type2'
         "/wd4133", # 'type' : incompatible types - from 'type1' to 'type2'
         "/wd4146", # unary minus operator applied to unsigned type, result
                    #   still unsigned
         "/wd4554", # 'operator' : check operator precedence for possible
                    #   error; use parentheses to clarify precedence
         "/wd4028", # formal parameter 'number' different from declaration
         "/wd4334", # 'operator' : result of 32-bit shift implicitly
                    #   converted to 64 bits (was 64-bit shift intended?)
         "/wd4101", # 'identifier' : unreferenced local variable
         "/wd4102", # 'label' : unreferenced label
         "/wd4116", # unnamed type definition in parentheses
         "/wd4307", # 'operator' : integral constant overflow
         "/wd4273", # 'function' : inconsistent DLL linkage
         "/wd4005", # 'identifier' : macro redefinition
         "/wd4056", # overflow in floating point constant arithmetic
         "/wd4756", # overflow in constant arithmetic
       ]
 # TODO(ajwong): Verify this is true.
       # Ignore warnings about a local symbol being inefficiently imported,
       # upstream is working on a fix.
       ldflags += [
         "/ignore:4049", # locally defined symbol 'symbol' imported
         "/ignore:4217", # locally defined symbol 'symbol' imported in
                         #   function 'function'
       ]
       if (cpu_arch == "x64") {
         # TODO(wolenetz): We should fix this.  http://crbug.com/171009
         cflags += [
           "/wd4267"  # Conversion from size_t to 'type'.
         ]
       }
       deps += [ ":ffmpeg_generate_def" ]
     }

     if (cpu_arch != "arm" && cpu_arch != "mipsel" && os_config != "linux-noasm") {
       deps += [ ":ffmpeg_yasm" ]
     }
   }
 }

 if (is_win) {
   config("ffmpeg_win_dependent_config") {
     include_dirs = [
       platform_config_root,
       "chromium/include/win",
       ".",
     ]
     libs = [ "$target_out_dir/ffmpegsumo.lib" ]
     ldflags = [ "/DELAYLOAD:ffmpegsumo.dll" ]
   }

   action("ffmpeg_generate_def") {
     script = generate_stubs_script
     sources = sig_files
     outputs = [ "$target_gen_dir/ffmpegsumo.def" ]
     args = [
 # TODO(ajwong): This was -i <(INTERMEDIATE_DIR). What next?
       "-i", rebase_path(target_out_dir, root_build_dir),
       "-o", rebase_path(target_gen_dir, root_build_dir),
       "-t", "windows_def",
       "-m", "ffmpegsumo.dll",
     ] + rebase_path(sources, root_build_dir)
   }

   group("ffmpeg") {
     public_configs = [ ":ffmpeg_win_dependent_config" ]
     public_deps = [
       ":ffmpeg_generate_stubs",
       ":ffmpegsumo",
     ]
   }
 } else {
   config("ffmpeg_posix_dependent_config") {
     include_dirs = [
       platform_config_root,
       ".",
     ]
   }
   component("ffmpeg") {
     sources = [
       "$target_gen_dir/$stubs_filename_root.cc",
       "$target_gen_dir/$stubs_filename_root.h",
     ]
     configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
     defines = [
       "__STDC_CONSTANT_MACROS",  # FFmpeg uses INT64_C.
     ]

     include_dirs = [
       platform_config_root,
       ".",
     ]

     public_configs = [ ":ffmpeg_posix_dependent_config" ]
     deps = [ ":ffmpeg_generate_stubs", ":ffmpegsumo" ]
   }
 }
	# Copyright 2014 The Chromium Authors. All rights reserved.
	# Use of this source code is governed by a BSD-style license that can be
	# found in the LICENSE file.

	import("ffmpeg_options.gni")
	import("ffmpeg_generated.gni")

	# Path to platform configuration files.
	platform_config_root =
	"chromium/config/$ffmpeg_branding/$os_config/$ffmpeg_arch"

	# Stub generator script and signatures of all functions used by Chrome.
	generate_stubs_script = "//tools/generate_stubs/generate_stubs.py"

	# Used by ffmpeg_generate_stubs and ffmpeg_generate_def
	sig_files = [ "chromium/ffmpegsumo.sigs" ]

	# TODO(ajwong): Should be in ffmpeg_generate_stubs if we could grab the
	# outputs of an action via a function.
	stubs_filename_root = "ffmpeg_stubs"

	if (cpu_arch != "arm" && os_config != "linux-noasm") {
	import("//third_party/yasm/yasm_assemble.gni")
	yasm_assemble("ffmpeg_yasm") {
	sources = ffmpeg_yasm_sources

	# Ensure the architecture defines go in the command line before the -P
	# file below, so don't use defines.
	yasm_flags = []
	if (cpu_arch == "x86") {
	yasm_flags += [ "-DARCH_X86_32" ]
	} else if (cpu_arch == "x64") {
	yasm_flags += [ "-DARCH_X86_64" ]
	}

	defines = [ "PIC" ]
	include_dirs = [
	platform_config_root,
	"libavcodec/x86",
	"libavutil/x86",
	".",
	]

	# Disable warnings, prevents log spam for things we won't fix.
	yasm_flags += [
	"-w",
	"-P", rebase_path("$platform_config_root/config.asm", root_build_dir),
	]

	if (is_mac) {
	# Necessary to ensure symbols end up with a _ prefix; added by
	# yasm_compile.gypi for Windows, but not Mac.
	defines += [ "PREFIX" ]
	}
	}
	}

	# FFMpeg is dynamically loaded on all platforms but our code calls it
	# as if it were directly linked. To make this work, the build system needs
	# to generate stubs that indirect into the library calls.
	#
	# On Windows, this script calls the windows stub generator. Otherwise, assume
	# this is a POSIX platform and generate our own wrapper stubs.
	action("ffmpeg_generate_stubs") {
	extra_header = "chromium/ffmpeg_stub_headers.fragment"

	script = generate_stubs_script
	sources = sig_files
	inputs = [ extra_header ]

	if (is_win) {
	if (build_cpu_arch == "x64") {
	outfile_type = "windows_lib_x64"
	} else {
	outfile_type = "windows_lib"
	}

	# TODO(ajwong): these need to be in the ffmpeg build.
	outputs = [
	"$target_gen_dir/$stubs_filename_root.lib",
	]

	args = [
	# TODO(ajwong): In gyp, this uses different directories for the
	# windows build. We should think this through.
	"-i", rebase_path(target_gen_dir, root_build_dir),
	"-o", rebase_path(target_gen_dir, root_build_dir),
	"-t", outfile_type,
	]
	} else {
	# If it's not windows, clearly it must be posix.

	# TODO(ajwong): these need to be included in the ffmpeg build.
	outputs = [
	"$target_gen_dir/$stubs_filename_root.cc",
	"$target_gen_dir/$stubs_filename_root.h",
	]
	args = [
	# TODO(ajwong): IN gyp, this used to output the .h file into a shared
	# directory that other targets could reference. The .cc ends up in a
	# special generated directory that gyp would guaranteed that no one else
	# could look at. Now we're dumping both into the generated directory.
	# Verify what the best + simplest behavior is here and use that.
	"-i", rebase_path(target_gen_dir, root_build_dir),
	"-o", rebase_path(target_gen_dir, root_build_dir),
	"-t", "posix_stubs",
	"-e", rebase_path(extra_header, root_build_dir),
	"-s", stubs_filename_root,
	"-p", "third_party/ffmpeg",
	]
	}

	args += rebase_path(sources, root_build_dir)
	}

	if (build_ffmpegsumo) {
	shared_library("ffmpegsumo") {
	sources = ffmpeg_c_sources + ffmpeg_gas_sources + [
	"$platform_config_root/config.h",
	"$platform_config_root/libavutil/avconfig.h",
	]
	include_dirs = [
	platform_config_root,
	".",
	]
	defines = [
	"HAVE_AV_CONFIG_H",
	"_POSIX_C_SOURCE=200112",
	"_XOPEN_SOURCE=600",
	"PIC",
	# Disable deprecated features which generate spammy warnings.
	"FF_API_PIX_FMT_DESC=0",
	"FF_API_OLD_DECODE_AUDIO=0",
	"FF_API_DESTRUCT_PACKET=0",
	"FF_API_GET_BUFFER=0",
	]

	# So we can append below and assume they're defined.
	cflags = []
	ldflags = []
	libs = []
	deps = []

	configs -= [ "//build/config/compiler:chromium_code" ]
	configs += [ "//build/config/compiler:no_chromium_code" ]

	# Since we are not often debugging FFmpeg, and performance is
	# unacceptable without optimization, freeze the optimizations to -O2.
	# If someone really wants -O1 , they can change these in their checkout.
	# If you want -O0, see the Gotchas in README.Chromium for why that
	# won't work.
	#
	# In addition to the above reasons, /Od optimization won't remove symbols
	# that are under "if (0)" style sections. Which lead to link time errors
	# when for example it tries to link an ARM symbol on X86.
	if (is_debug) {
	configs -= [ "//build/config/compiler:no_optimize" ]
	} else {
	configs -= [ "//build/config/compiler:optimize" ]
	}
	if (is_win) {
	# Setting the optimizations to 'speed' or to 'max' on Windows results in
	# a lot of unresolved symbols. The only supported mode is 'size' (see
	# crbug.com/264459).
	configs += [ "//build/config/compiler:optimize" ]
	} else {
	configs += [ "//build/config/compiler:optimize_max" ]
	}

	if (is_posix) {
	cflags += [
	"-fPIC",
	"-fomit-frame-pointer",
	# ffmpeg uses its own deprecated functions.
	"-Wno-deprecated-declarations",
	]

	if (is_clang) {
	cflags += [
	"-Wno-absolute-value",
	"-Wno-incompatible-pointer-types",
	"-Wno-logical-op-parentheses",
	"-Wno-parentheses",
	"-Wno-pointer-sign",
	"-Wno-switch",
	]
	} else {
	# gcc doesn't have flags for specific warnings, so disable them
	# all.
	cflags += [ "-w" ]
	}
	if (cpu_arch == "x86") {
	# Turn off valgrind build option that breaks ffmpeg builds.
	# TODO(ajwong): The gyp file had special removals for
	# debug_extra_cflags and release_extra_cflags. Do we care?
	#cflags -= [ "-fno-omit-frame-pointer" ]
	} else if (cpu_arch == "arm") {
	# TODO(ihf): See the long comment in build_ffmpeg.sh
	# We want to be consistent with CrOS and have configured
	# ffmpeg for thumb. Protect yourself from -marm.
	if (is_chromeos) {
	cflags += [ "-marm" ]
	}
	cflags += [
	"-mthumb",
	"-march=armv7-a",
	"-mtune=cortex-a8",
	"-mfpu=${arm_fpu}"
	]
	if (arm_float_abi == "hard") {
	cflags += [ "-DHAVE_VFP_ARGS=1" ]
	} else {
	cflags += [ "-DHAVE_VFP_ARGS=0" ]
	}
	} else if (cpu_arch == "mipsel") {
	cflags += [
	"-mips32",
	"-EL -Wl,-EL",
	]
	}
	}

	if (is_posix && !is_mac) {
	defines += [
	"_ISOC99_SOURCE",
	"_LARGEFILE_SOURCE",
	# BUG(ihf): ffmpeg compiles with this define. But according to
	# ajwong: I wouldn't change _FILE_OFFSET_BITS. That's a scary change
	# cause it affects the default length of off_t, and fpos_t,
	# which can cause strange problems if the loading code doesn't
	# have it set and you start passing FILE*s or file descriptors
	# between symbol contexts.
	# "_FILE_OFFSET_BITS=64",
	]
	cflags += [
	"-std=c99",
	"-pthread",
	"-fno-math-errno",
	"-fno-signed-zeros",
	"-fno-tree-vectorize",
	"-fomit-frame-pointer",
	]
	# Ensure the symbols are exported.
	#
	# TODO(ajwong): Manually tag the API that we use to be
	# exported.
	configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
	ldflags = [
	"-Wl,-Bsymbolic",
	"-L", rebase_path(target_gen_dir, root_build_dir),
	]
	libs = [ "z" ]
	# TODO(ajwong): How to handle openbsd? Especially w/o the is_posix?
	# if (is_openbsd) {
	# # OpenBSD's gcc (4.2.1) does not support this flag
	# cflags -= [ "-fno-signed-zeros" ]
	# }
	}
	if (is_mac) {
	defines += [ "_DARWIN_C_SOURCE" ]

	# TODO(ajwong): What does this do in mac? There isn't anything in ffmpeg.gyp that
	# uses mac_real_dsym
	# ['mac_breakpad == 1', {
	# 'variables': {
	# # A real .dSYM is needed for dump_syms to operate on.
	# 'mac_real_dsym': 1,
	# },
	# }],
	if (cpu_arch != "x64") {
	# This is needed because even though FFmpeg now builds
	# with -fPIC, it's not quite a complete PIC build, only
	# partial :( Thus we need to instruct the linker to allow
	# relocations for read-only segments for this target to be
	# able to generated the shared library on Mac.
	#
	#TODO(ajwong): Check if this can be cpu_arch == "x86"
	# Note -read_only_relocs cannot be used in x86_64
	#
	# This makes Mark sad, but he's okay with it since it is
	# isolated to this module. When Mark finds this in the
	# future, and has forgotten this conversation, this
	# comment should remind him that the world is still nice
	# and butterflies still exist...as do rainbows, sunshine,
	# tulips, etc., etc...but not kittens. Those went away
	# with this flag.
	ldflags = [
	"-Wl,-read_only_relocs,suppress",
	]
	}
	# TODO(ajwong): How to handle SDKROOT?
	# 'libraries': [
	# '$(SDKROOT)/usr/lib/libz.dylib',
	# ],
	# Ensure the symbols are exported.
	#
	# TODO(ajwong): Manually tag the API that we use to be exported.
	if (!is_win) {
	configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
	}
	# TODO(ajwong): How to handle @loader_path?
	# 'xcode_settings': {
	# 'DYLIB_INSTALL_NAME_BASE': '@loader_path',
	# }
	lib_dirs = [ target_gen_dir ]
	} else if (is_win) {
	defines += [
	"inline=__inline",
	"strtoll=_strtoi64",
	"_ISOC99_SOURCE",
	"_LARGEFILE_SOURCE",
	"HAVE_AV_CONFIG_H",
	"strtod=avpriv_strtod",
	"snprintf=avpriv_snprintf",
	"_snprintf=avpriv_snprintf",
	"vsnprintf=avpriv_vsnprintf",
	]

	include_dirs += [
	"chromium/include/win"
	]
	# TODO(dalecurtis): We should fix these. http://crbug.com/154421
	cflags += [
	"/wd4996", # 'function': was declared deprecated
	"/wd4018", # 'expression': signed/unsigned mismatch
	"/wd4090", # 'operation' : different 'modifier' qualifiers
	"/wd4305", # 'identifier': truncation from 'type1' to 'type2'
	"/wd4133", # 'type' : incompatible types - from 'type1' to 'type2'
	"/wd4146", # unary minus operator applied to unsigned type, result
	# still unsigned
	"/wd4554", # 'operator' : check operator precedence for possible
	# error; use parentheses to clarify precedence
	"/wd4028", # formal parameter 'number' different from declaration
	"/wd4334", # 'operator' : result of 32-bit shift implicitly
	# converted to 64 bits (was 64-bit shift intended?)
	"/wd4101", # 'identifier' : unreferenced local variable
	"/wd4102", # 'label' : unreferenced label
	"/wd4116", # unnamed type definition in parentheses
	"/wd4307", # 'operator' : integral constant overflow
	"/wd4273", # 'function' : inconsistent DLL linkage
	"/wd4005", # 'identifier' : macro redefinition
	"/wd4056", # overflow in floating point constant arithmetic
	"/wd4756", # overflow in constant arithmetic
	]
	# TODO(ajwong): Verify this is true.
	# Ignore warnings about a local symbol being inefficiently imported,
	# upstream is working on a fix.
	ldflags += [
	"/ignore:4049", # locally defined symbol 'symbol' imported
	"/ignore:4217", # locally defined symbol 'symbol' imported in
	# function 'function'
	]
	if (cpu_arch == "x64") {
	# TODO(wolenetz): We should fix this. http://crbug.com/171009
	cflags += [
	"/wd4267" # Conversion from size_t to 'type'.
	]
	}
	deps += [ ":ffmpeg_generate_def" ]
	}

	if (cpu_arch != "arm" && cpu_arch != "mipsel" && os_config != "linux-noasm") {
	deps += [ ":ffmpeg_yasm" ]
	}
	}
	}

	if (is_win) {
	config("ffmpeg_win_dependent_config") {
	include_dirs = [
	platform_config_root,
	"chromium/include/win",
	".",
	]
	libs = [ "$target_out_dir/ffmpegsumo.lib" ]
	ldflags = [ "/DELAYLOAD:ffmpegsumo.dll" ]
	}

	action("ffmpeg_generate_def") {
	script = generate_stubs_script
	sources = sig_files
	outputs = [ "$target_gen_dir/ffmpegsumo.def" ]
	args = [
	# TODO(ajwong): This was -i <(INTERMEDIATE_DIR). What next?
	"-i", rebase_path(target_out_dir, root_build_dir),
	"-o", rebase_path(target_gen_dir, root_build_dir),
	"-t", "windows_def",
	"-m", "ffmpegsumo.dll",
	] + rebase_path(sources, root_build_dir)
	}

	group("ffmpeg") {
	public_configs = [ ":ffmpeg_win_dependent_config" ]
	public_deps = [
	":ffmpeg_generate_stubs",
	":ffmpegsumo",
	]
	}
	} else {
	config("ffmpeg_posix_dependent_config") {
	include_dirs = [
	platform_config_root,
	".",
	]
	}
	component("ffmpeg") {
	sources = [
	"$target_gen_dir/$stubs_filename_root.cc",
	"$target_gen_dir/$stubs_filename_root.h",
	]
	configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
	defines = [
	"__STDC_CONSTANT_MACROS", # FFmpeg uses INT64_C.
	]

	include_dirs = [
	platform_config_root,
	".",
	]

	public_configs = [ ":ffmpeg_posix_dependent_config" ]
	deps = [ ":ffmpeg_generate_stubs", ":ffmpegsumo" ]
	}
	}