Adopt FindFFMPEG.cmake (#2125)

Summary:
Preparation for updating the build process of ffmpeg-related feature
to support Windows.

Checking-in FindFFMPEG.cmake from Kitware/VTK repo without modification
so that later it's easy to follow our modification on it with git tool.

Pull Request resolved: https://github.com/pytorch/audio/pull/2125

Reviewed By: carolineechen

Differential Revision: D33405408

Pulled By: mthrok

fbshipit-source-id: 5faea8940d2dfcf0b2f647eda3754f713d21fcd1

cmake/FindFFMPEG.cmake

+#[==[
+
+Originally taken from: https://github.com/Kitware/VTK/blob/8485477f9aa41f3c33094c3beb201e747abf5541/CMake/FindFFMPEG.cmake
+License: https://github.com/Kitware/VTK/blob/8485477f9aa41f3c33094c3beb201e747abf5541/Copyright.txt
+
+/*=========================================================================
+
+  Program:   Visualization Toolkit
+  Module:    Copyright.txt
+
+Copyright (c) 1993-2015 Ken Martin, Will Schroeder, Bill Lorensen
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+ * Neither name of Ken Martin, Will Schroeder, or Bill Lorensen nor the names
+   of any contributors may be used to endorse or promote products derived
+   from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+=========================================================================*/
+
+=========================================================================
+ 
+Provides the following variables:
+
+  * `FFMPEG_INCLUDE_DIRS`: Include directories necessary to use FFMPEG.
+  * `FFMPEG_LIBRARIES`: Libraries necessary to use FFMPEG. Note that this only
+    includes libraries for the components requested.
+  * `FFMPEG_VERSION`: The version of FFMPEG found.
+
+The following components are supported:
+
+  * `avcodec`
+  * `avdevice`
+  * `avfilter`
+  * `avformat`
+  * `avresample`
+  * `avutil`
+  * `swresample`
+  * `swscale`
+
+For each component, the following are provided:
+
+  * `FFMPEG_<component>_FOUND`: Libraries for the component.
+  * `FFMPEG_<component>_INCLUDE_DIRS`: Include directories for
+    the component.
+  * `FFMPEG_<component>_LIBRARIES`: Libraries for the component.
+  * `FFMPEG::<component>`: A target to use with `target_link_libraries`.
+
+Note that only components requested with `COMPONENTS` or `OPTIONAL_COMPONENTS`
+are guaranteed to set these variables or provide targets.
+#]==]
+
+function (_ffmpeg_find component headername)
+  find_path("FFMPEG_${component}_INCLUDE_DIR"
+    NAMES
+      "lib${component}/${headername}"
+    PATHS
+      "${FFMPEG_ROOT}/include"
+      ~/Library/Frameworks
+      /Library/Frameworks
+      /usr/local/include
+      /usr/include
+      /sw/include # Fink
+      /opt/local/include # DarwinPorts
+      /opt/csw/include # Blastwave
+      /opt/include
+      /usr/freeware/include
+    PATH_SUFFIXES
+      ffmpeg
+    DOC "FFMPEG's ${component} include directory")
+  mark_as_advanced("FFMPEG_${component}_INCLUDE_DIR")
+
+  # On Windows, static FFMPEG is sometimes built as `lib<name>.a`.
+  if (WIN32)
+    list(APPEND CMAKE_FIND_LIBRARY_SUFFIXES ".a" ".lib")
+    list(APPEND CMAKE_FIND_LIBRARY_PREFIXES "" "lib")
+  endif ()
+
+  find_library("FFMPEG_${component}_LIBRARY"
+    NAMES
+      "${component}"
+    PATHS
+      "${FFMPEG_ROOT}/lib"
+      ~/Library/Frameworks
+      /Library/Frameworks
+      /usr/local/lib
+      /usr/local/lib64
+      /usr/lib
+      /usr/lib64
+      /sw/lib
+      /opt/local/lib
+      /opt/csw/lib
+      /opt/lib
+      /usr/freeware/lib64
+      "${FFMPEG_ROOT}/bin"
+    DOC "FFMPEG's ${component} library")
+  mark_as_advanced("FFMPEG_${component}_LIBRARY")
+
+  if (FFMPEG_${component}_LIBRARY AND FFMPEG_${component}_INCLUDE_DIR)
+    set(_deps_found TRUE)
+    set(_deps_link)
+    foreach (_ffmpeg_dep IN LISTS ARGN)
+      if (TARGET "FFMPEG::${_ffmpeg_dep}")
+        list(APPEND _deps_link "FFMPEG::${_ffmpeg_dep}")
+      else ()
+        set(_deps_found FALSE)
+      endif ()
+    endforeach ()
+    if (_deps_found)
+      if (NOT TARGET "FFMPEG::${component}")
+        add_library("FFMPEG::${component}" UNKNOWN IMPORTED)
+        set_target_properties("FFMPEG::${component}" PROPERTIES
+          IMPORTED_LOCATION "${FFMPEG_${component}_LIBRARY}"
+          INTERFACE_INCLUDE_DIRECTORIES "${FFMPEG_${component}_INCLUDE_DIR}"
+          IMPORTED_LINK_INTERFACE_LIBRARIES "${_deps_link}")
+      endif ()
+      set("FFMPEG_${component}_FOUND" 1
+        PARENT_SCOPE)
+
+      set(version_header_path "${FFMPEG_${component}_INCLUDE_DIR}/lib${component}/version.h")
+      if (EXISTS "${version_header_path}")
+        string(TOUPPER "${component}" component_upper)
+        file(STRINGS "${version_header_path}" version
+          REGEX "#define  *LIB${component_upper}_VERSION_(MAJOR|MINOR|MICRO) ")
+        string(REGEX REPLACE ".*_MAJOR *\([0-9]*\).*" "\\1" major "${version}")
+        string(REGEX REPLACE ".*_MINOR *\([0-9]*\).*" "\\1" minor "${version}")
+        string(REGEX REPLACE ".*_MICRO *\([0-9]*\).*" "\\1" micro "${version}")
+        if (NOT major STREQUAL "" AND
+            NOT minor STREQUAL "" AND
+            NOT micro STREQUAL "")
+          set("FFMPEG_${component}_VERSION" "${major}.${minor}.${micro}"
+            PARENT_SCOPE)
+        endif ()
+      endif ()
+    else ()
+      set("FFMPEG_${component}_FOUND" 0
+        PARENT_SCOPE)
+      set(what)
+      if (NOT FFMPEG_${component}_LIBRARY)
+        set(what "library")
+      endif ()
+      if (NOT FFMPEG_${component}_INCLUDE_DIR)
+        if (what)
+          string(APPEND what " or headers")
+        else ()
+          set(what "headers")
+        endif ()
+      endif ()
+      set("FFMPEG_${component}_NOT_FOUND_MESSAGE"
+        "Could not find the ${what} for ${component}."
+        PARENT_SCOPE)
+    endif ()
+  endif ()
+endfunction ()
+
+_ffmpeg_find(avutil     avutil.h)
+_ffmpeg_find(avresample avresample.h
+  avutil)
+_ffmpeg_find(swresample swresample.h
+  avutil)
+_ffmpeg_find(swscale    swscale.h
+  avutil)
+_ffmpeg_find(avcodec    avcodec.h
+  avutil)
+_ffmpeg_find(avformat   avformat.h
+  avcodec avutil)
+_ffmpeg_find(avfilter   avfilter.h
+  avutil)
+_ffmpeg_find(avdevice   avdevice.h
+  avformat avutil)
+
+if (TARGET FFMPEG::avutil)
+  set(_ffmpeg_version_header_path "${FFMPEG_avutil_INCLUDE_DIR}/libavutil/ffversion.h")
+  if (EXISTS "${_ffmpeg_version_header_path}")
+    file(STRINGS "${_ffmpeg_version_header_path}" _ffmpeg_version
+      REGEX "FFMPEG_VERSION")
+    string(REGEX REPLACE ".*\"n?\(.*\)\"" "\\1" FFMPEG_VERSION "${_ffmpeg_version}")
+    unset(_ffmpeg_version)
+  else ()
+    set(FFMPEG_VERSION FFMPEG_VERSION-NOTFOUND)
+  endif ()
+  unset(_ffmpeg_version_header_path)
+endif ()
+
+set(FFMPEG_INCLUDE_DIRS)
+set(FFMPEG_LIBRARIES)
+set(_ffmpeg_required_vars)
+foreach (_ffmpeg_component IN LISTS FFMPEG_FIND_COMPONENTS)
+  if (TARGET "FFMPEG::${_ffmpeg_component}")
+    set(FFMPEG_${_ffmpeg_component}_INCLUDE_DIRS
+      "${FFMPEG_${_ffmpeg_component}_INCLUDE_DIR}")
+    set(FFMPEG_${_ffmpeg_component}_LIBRARIES
+      "${FFMPEG_${_ffmpeg_component}_LIBRARY}")
+    list(APPEND FFMPEG_INCLUDE_DIRS
+      "${FFMPEG_${_ffmpeg_component}_INCLUDE_DIRS}")
+    list(APPEND FFMPEG_LIBRARIES
+      "${FFMPEG_${_ffmpeg_component}_LIBRARIES}")
+    if (FFMEG_FIND_REQUIRED_${_ffmpeg_component})
+      list(APPEND _ffmpeg_required_vars
+        "FFMPEG_${_ffmpeg_required_vars}_INCLUDE_DIRS"
+        "FFMPEG_${_ffmpeg_required_vars}_LIBRARIES")
+    endif ()
+  endif ()
+endforeach ()
+unset(_ffmpeg_component)
+
+if (FFMPEG_INCLUDE_DIRS)
+  list(REMOVE_DUPLICATES FFMPEG_INCLUDE_DIRS)
+endif ()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(FFMPEG
+  REQUIRED_VARS FFMPEG_INCLUDE_DIRS FFMPEG_LIBRARIES ${_ffmpeg_required_vars}
+  VERSION_VAR FFMPEG_VERSION
+  HANDLE_COMPONENTS)
+unset(_ffmpeg_required_vars)