MLT媒体程序框架01：概述

MLT官网

概述

MLT是一个开源的多媒体框架，专为电视广播而设计和开发。它为广播公司、视频编辑器、媒体播放器、转码器、网络流媒体和更多类型的应用程序提供了一个工具包。该系统的功能是通过各种现成的工具、XML创作组件和基于API的可扩展插件提供的。

它是通过C语言编写的，但是后续它使用C++封装了一遍，所以C++开发可以直接使用mlt++文件夹下的C++ Api

MLT是对FFmpeg的应用，所以设计的和FFmpeg类似，都是基于插件进行拓展。
同时，MLT在FFmpeg的基础上还增加了很多高级功能，比如时间线管理，音视频流的混合，多种过滤器和转场效果。

编译

系统编译

mingw64可以用pacman -S安装完整库
mac可以用homebrew install 安装完整库
Ubuntu可以用apt install安装完整库

自己编译

查看MLT的CMakeLists.txt

cmake_minimum_required(VERSION 3.14)

project(MLT
  VERSION 7.28.0
  DESCRIPTION "Multimedia Framework"
  HOMEPAGE_URL "https://www.mltframework.org"
  LANGUAGES C CXX
)
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} $ENV{CFLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} $ENV{CXXFLAGS}")
set(CMAKE_OBJCXX_FLAGS "${CMAKE_CXX_FLAGS} $ENV{CXXFLAGS}")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} $ENV{LDFLAGS}")

option(GPL "Enable GPLv2 components" ON)
option(GPL3 "Enable GPLv3 components" ON)
option(BUILD_TESTING "Enable tests" OFF)
option(BUILD_DOCS "Enable Doxygen documentation" OFF)
option(CLANG_FORMAT "Enable Clang Format" ON)
option(BUILD_TESTS_WITH_QT6 "Build test against Qt 6" OFF)

option(MOD_AVFORMAT "Enable avformat module" ON)
option(MOD_DECKLINK "Enable DeckLink module" ON)
option(MOD_FREI0R "Enable Frei0r module" ON)
option(MOD_GDK "Enable GDK module" ON)
option(MOD_GLAXNIMATE "Enable Glaxnimate module (Qt5)" OFF)
option(MOD_GLAXNIMATE_QT6 "Enable Glaxnimate module (Qt6)" ON)
option(MOD_JACKRACK "Enable JACK Rack module" ON)
option(USE_LV2 "Enable LV2 features" ON)
option(USE_VST2 "Enable LV2 features" ON)
option(MOD_KDENLIVE "Enable Kdenlive module" ON)
option(MOD_NDI "Enable NDI module" OFF)
option(MOD_NORMALIZE "Enable Normalize module (GPL)" ON)
option(MOD_OLDFILM "Enable Oldfilm module" ON)
option(MOD_OPENCV "Enable OpenCV module" ON)
option(MOD_MOVIT "Enable OpenGL module" ON)
option(MOD_PLUS "Enable Plus module" ON)
option(MOD_PLUSGPL "Enable PlusGPL module (GPL)" ON)
option(MOD_QT "Enable Qt5 module (GPL)" OFF)
option(MOD_QT6 "Enable Qt6 module (GPL)" ON)
option(MOD_RESAMPLE "Enable Resample module (GPL)" ON)
option(MOD_RTAUDIO "Enable RtAudio module" ON)
option(MOD_RUBBERBAND "Enable Rubberband module (GPL)" ON)
option(MOD_SDL1 "Enable SDL1 module" OFF)
option(MOD_SDL2 "Enable SDL2 module" ON)
option(MOD_SOX "Enable SoX module" ON)
option(MOD_SPATIALAUDIO "Enable SpatialAudio module" ON)
option(MOD_VIDSTAB "Enable vid.stab module (GPL)" ON)
option(MOD_VORBIS "Enable Vorbis module" ON)
option(MOD_XINE "Enable XINE module (GPL)" ON)
option(MOD_XML "Enable XML module" ON)

option(SWIG_CSHARP "Enable SWIG C# bindings" OFF)
option(SWIG_JAVA "Enable SWIG Java bindings" OFF)
option(SWIG_LUA "Enable SWIG Lua bindings" OFF)
option(SWIG_NODEJS "Enable SWIG Node.js bindings" OFF)
option(SWIG_PERL "Enable SWIG Perl bindings" OFF)
option(SWIG_PHP "Enable SWIG PHP bindings" OFF)
option(SWIG_PYTHON "Enable SWIG Python bindings" OFF)
option(SWIG_RUBY "Enable SWIG Ruby bindings" OFF)
option(SWIG_TCL "Enable SWIG Tcl bindings" OFF)

if(WIN32)
  option(WINDOWS_DEPLOY "Install exes/libs directly to prefix (no subdir /bin)" ON)
else()
  if(APPLE)
    option(RELOCATABLE "Use standard app bundle layout" ON)
  else()
    option(RELOCATABLE "Look for plugins relative to app" OFF)
  endif()
endif()

list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")

include(FeatureSummary)
include(GNUInstallDirs)

if(WINDOWS_DEPLOY)
  set(CMAKE_INSTALL_BINDIR .)
endif()

set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/out/${CMAKE_INSTALL_BINDIR}")
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/out/lib")
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/out/lib")
set(MLT_MODULE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/out/lib/mlt")
set(MLT_DATA_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/out/share/mlt")

# https://gitlab.kitware.com/cmake/community/-/wikis/doc/cmake/RPATH-handling
set(CMAKE_SKIP_BUILD_RPATH FALSE)
set(CMAKE_BUILD_WITH_INSTALL_RPATH FALSE)
set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib")
set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
list(FIND CMAKE_PLATFORM_IMPLICIT_LINK_DIRECTORIES "${CMAKE_INSTALL_PREFIX}/lib" isSystemDir)

if(NOT "${isSystemDir}" STREQUAL "-1")
  set(CMAKE_INSTALL_RPATH "")
endif()

if(NOT EXISTS ${MLT_DATA_OUTPUT_DIRECTORY})
  if(WIN32) # symlinks require admin rights on Windows
    if("${DEBUGTOOL}" STREQUAL "TRUE")
      file(COPY "${CMAKE_SOURCE_DIR}/../mlt/src/modules" DESTINATION "${CMAKE_BINARY_DIR}/out/share" FILES_MATCHING REGEX yml|txt)
      file(RENAME "${CMAKE_BINARY_DIR}/out/share/modules" "${MLT_DATA_OUTPUT_DIRECTORY}")
      file(COPY "${CMAKE_SOURCE_DIR}/../mlt/presets" DESTINATION "${MLT_DATA_OUTPUT_DIRECTORY}")
      file(COPY "${CMAKE_SOURC