FFmpeg4.2.2 cross compilation

Enterprise 2023-07-11 18:25:37 views: null

I have been compiling the FFmpeg library for the past two days. To be honest, I have stepped on a lot of pitfalls. I also know how to troubleshoot problems, so I still plan to record them, which can be regarded as a summary.

Baidu understands FFmpeg

Environment and Downloads

1. CentOs 8

2. android-ndk-r17c

3. ffmpeg-4.2.2

Pay attention to download the ndk of the linux version. When obtaining the download link, download it to linux through wget

Configure Help Options

view help options ./configure --help

Usage: configure [options]
Options: [defaults in brackets after descriptions]

帮助选项
Help options:
  --help                   print this message
  --quiet                  Suppress showing informative output
  --list-decoders          show all available decoders
  --list-encoders          show all available encoders
  --list-hwaccels          show all available hardware accelerators
  --list-demuxers          show all available demuxers
  --list-muxers            show all available muxers
  --list-parsers           show all available parsers
  --list-protocols         show all available protocols
  --list-bsfs              show all available bitstream filters
  --list-indevs            show all available input devices
  --list-outdevs           show all available output devices
  --list-filters           show all available filters

标准选项
Standard options:
  --logfile=FILE           log tests and output to FILE [ffbuild/config.log]
  --disable-logging        do not log configure debug information
  --fatal-warnings         fail if any configure warning is generated

  我们最终产出的目录
  --prefix=PREFIX          install in PREFIX [/usr/local]

  --bindir=DIR             install binaries in DIR [PREFIX/bin]
  --datadir=DIR            install data files in DIR [PREFIX/share/ffmpeg]
  --docdir=DIR             install documentation in DIR [PREFIX/share/doc/ffmpeg]
  --libdir=DIR             install libs in DIR [PREFIX/lib]
  --shlibdir=DIR           install shared libs in DIR [LIBDIR]
  --incdir=DIR             install includes in DIR [PREFIX/include]
  --mandir=DIR             install man page in DIR [PREFIX/share/man]
  --pkgconfigdir=DIR       install pkg-config files in DIR [LIBDIR/pkgconfig]
  --enable-rpath           use rpath to allow installing libraries in paths
                           not part of the dynamic linker search path
                           use rpath when linking programs (USE WITH CARE)
  --install-name-dir=DIR   Darwin directory name for installed targets

Licensing options:
  --enable-gpl             allow use of GPL code, the resulting libs
                           and binaries will be under GPL [no]
  --enable-version3        upgrade (L)GPL to version 3 [no]
  --enable-nonfree         allow use of nonfree code, the resulting libs
                           and binaries will be unredistributable [no]

--disable  代表关闭状态
--enable   代表开启状态

Configuration options:
  --disable-static         do not build static libraries [no] == 开启静态库
  --enable-shared          build shared libraries [no] == 关闭动态库
  --enable-small           optimize for size instead of speed == 可以优化库的大小

  --disable-runtime-cpudetect disable detecting CPU capabilities at runtime (smaller binary)
  --enable-gray            enable full grayscale support (slower color)
  --disable-swscale-alpha  disable alpha channel support in swscale
  --disable-all            disable building components, libraries and programs
  --disable-autodetect     disable automatically detected external libraries [no]

Program options:
  --disable-programs       do not build command line programs == 默认是关闭的，如果我们开启

  --disable-ffmpeg         disable ffmpeg build  == 使用FFmpeg命令
  --disable-ffplay         disable ffplay build  == 播放器
  --disable-ffprobe        disable ffprobe build

Documentation options:
  --disable-doc            do not build documentation
  --disable-htmlpages      do not build HTML documentation pages
  --disable-manpages       do not build man documentation pages
  --disable-podpages       do not build POD documentation pages
  --disable-txtpages       do not build text documentation pages

FFmpeg 是由多个模块组成的：
Component options:
  --disable-avdevice       disable libavdevice build  == 模块之一（可以操控我们的摄像头-（Android中是不支持））
  --disable-avcodec        disable libavcodec build == audio video codec(编码 和 解码)
  --disable-avformat       disable libavformat build == 音视频格式生成和解析相关
  --disable-swresample     disable libswresample build == 音频 重采样（如果想把单声道，变成双声道）
  --disable-swscale        disable libswscale build == 对视频显示相关（对视频的缩放，放大 缩小）
  --disable-postproc       disable libpostproc build == 后期处理，很少用，可以关闭掉
  --disable-avfilter       disable libavfilter build == 给视频加水印，加字幕，特殊效果
  --enable-avresample      enable libavresample build (deprecated) [no]
  --disable-pthreads       disable pthreads [autodetect]
  --disable-w32threads     disable Win32 threads [autodetect]
  --disable-os2threads     disable OS/2 threads [autodetect]
  --disable-network        disable network support [no]
  --disable-dct            disable DCT code
  --disable-dwt            disable DWT code
  --disable-error-resilience disable error resilience code
  --disable-lsp            disable LSP code
  --disable-lzo            disable LZO decoder code
  --disable-mdct           disable MDCT code
  --disable-rdft           disable RDFT code
  --disable-fft            disable FFT code
  --disable-faan           disable floating point AAN (I)DCT code
  --disable-pixelutils     disable pixel utils in libavutil

Individual component options:
  --disable-everything     disable all components listed below
  --disable-encoder=NAME   disable encoder NAME
  --enable-encoder=NAME    enable encoder NAME
  --disable-encoders       disable all encoders  == 如果我们去播放视频，不需要编码，那么此功能就可以关闭掉
  --disable-decoder=NAME   disable decoder NAME
  --enable-decoder=NAME    enable decoder NAME
  --disable-decoders       disable all decoders
  --disable-hwaccel=NAME   disable hwaccel NAME
  --enable-hwaccel=NAME    enable hwaccel NAME
  --disable-hwaccels       disable all hwaccels
  --disable-muxer=NAME     disable muxer NAME
  --enable-muxer=NAME      enable muxer NAME
  --disable-muxers         disable all muxers
  --disable-demuxer=NAME   disable demuxer NAME
  --enable-demuxer=NAME    enable demuxer NAME
  --disable-demuxers       disable all demuxers
  --enable-parser=NAME     enable parser NAME
  --disable-parser=NAME    disable parser NAME
  --disable-parsers        disable all parsers
  --enable-bsf=NAME        enable bitstream filter NAME
  --disable-bsf=NAME       disable bitstream filter NAME
  --disable-bsfs           disable all bitstream filters
  --enable-protocol=NAME   enable protocol NAME
  --disable-protocol=NAME  disable protocol NAME
  --disable-protocols      disable all protocols
  --enable-indev=NAME      enable input device NAME
  --disable-indev=NAME     disable input device NAME
  --disable-indevs         disable input devices
  --enable-outdev=NAME     enable output device NAME
  --disable-outdev=NAME    disable output device NAME
  --disable-outdevs        disable output devices
  --disable-devices        disable all devices
  --enable-filter=NAME     enable filter NAME
  --disable-filter=NAME    disable filter NAME
  --disable-filters        disable all filters
...

When writing FFmpeg scripts, it needs to be configured according to the above help options, so it is pasted on it. Compiling FFmpeg is a modification of its configuration.

#!/bin/bash

#NDK_ROOT 变量指向ndk目录
NDK_ROOT=/root/android-ndk-r17c
#TOOLCHAIN 变量指向ndk中的交叉编译gcc所在的目录
TOOLCHAIN=$NDK_ROOT/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64

#指定android api版本
ANDROID_API=21

#此变量用于编译完成之后的库与头文件存放在哪个目录
PREFIX=./android/arm64

#执行configure脚本，用于生成makefile
#--prefix : 安装目录
#--enable-small : 优化大小
#--disable-programs : 不编译ffmpeg程序(命令行工具)，我们是需要获得静态(动态)库。
#--disable-avdevice : 关闭avdevice模块，此模块在android中无用
#--disable-encoders : 关闭所有编码器 (播放不需要编码)
#--disable-muxers :  关闭所有复用器(封装器)，不需要生成mp4这样的文件，所以关闭
#--disable-filters :关闭视频滤镜
#--enable-cross-compile : 开启交叉编译
#--cross-prefix: gcc的前缀 xxx/xxx/xxx-gcc 则给xxx/xxx/xxx-
#disable-shared enable-static 不写也可以，默认就是这样的。
#--sysroot: 
#--extra-cflags: 会传给gcc的参数
#--arch --target-os : 必须要给
./configure \
--prefix=$PREFIX \
--enable-small \
--disable-programs \
--disable-avdevice \
--disable-encoders \
--disable-muxers \
--disable-filters \
--disable-yasm \
--enable-cross-compile \
--cross-prefix=$TOOLCHAIN/bin/aarch64-linux-android- \
--enable-shared \ # 开启动态库
--disable-static \ # 关闭静态库
--sysroot=$NDK_ROOT/platforms/android-$ANDROID_API/arch-arm64 \
--extra-cflags="-isysroot $NDK_ROOT/sysroot -isystem $NDK_ROOT/sysroot/usr/include/aarch64-linux-android -D__ANDROID_API__=$ANDROID_API -U_FILE_OFFSET_BITS  -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -Wa,--noexecstack -Wformat -Werror=format-security  -O0 -fPIC" \
--arch=arm64 \
--target-os=android

#上面运行脚本生成makefile之后，使用make执行脚本
make clean
make install

This script can be dynamically configured according to your own needs.

stepped on the pit

1 . arm-linux-androideabi-gcc is unable to create an executable file

Reason: FFmpeg 4.2.2 uses clang to compile by default. Solution:

//1. 修改 configure 文件
vim configure
//2. 把 默认的 clang 修改为 gcc
if test "$target_os" = android; then
   # cc_default="clang"
		 cc_default="gcc"
fi

2. The .config.mak file is not generated

Solution: Execute ./configure --disable-x86asm to generate the config.mak file

More pits can refer to here

generate object file

I generated the abi architecture of arm64-v8a, and I will post the script of armeabi-v7a later, which is available for personal testing. Basically, the two abi architectures used now

lib directory

include directory

share directory

If the library file is not generated in the target directory, it must be a configuration problem. At this time, you can ffbuild/config.logcheck the error message. Generally, it will tell you where there is a problem at the end, and then modify the corresponding file.

Build library file download

You can use other tools to download the generated library file. I am too lazy to download the software here. I downloaded it directly with lrzszthe command. It needs to be installed for the first time.

yum -y install lrzsz

Library file compression

tar -zcvf ffmpeg_android.tar.gz android

download

sz ffmpeg_android.tar.gz

Ported to android for testing

file copy

The files in lib need to be copied to arm64-v8a, and the header files are copied to the include directory

Modify CMakeLists.txt

cmake_minimum_required(VERSION 3.4.1)

file(GLOB allCpp *.cpp)

add_library(
        native-lib

        SHARED

        ${allCpp})

find_library(
        log-lib

        log)

# 引入FFmpeg的头文件
include_directories(${CMAKE_SOURCE_DIR}/include)

#message("CMAKE_ANDROID_ARCH_ABI版本是:" + ${CMAKE_ANDROID_ARCH_ABI})

# 引入FFmpeg的库文件，设置内部的方式引入，指定库的目录是 -L  指定具体的库-l
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -L${CMAKE_SOURCE_DIR}/${CMAKE_ANDROID_ARCH_ABI}")

target_link_libraries(
        native-lib

        # 具体的库文件，链接到总库
        # 这样写会报错，有坑
        # avcodec avfilter avformat avutil swresample swscale

        # 先把有依赖的库，先依赖进来
        avformat avcodec avfilter avutil swresample swscale

        ${log-lib})

Modify the build.gradle file

The configuration in the cmake closure is to specify the ABI output in CmakeList.
The configuration in the ndk closure is to prevent the abi architecture from being packaged into a package. When I use a 32-bit (mobile phone 64-bit) library, there is no Add the closure configuration of ndk, resulting in a crash all the time, just add it

Add code test in cpp

#include <jni.h>
#include <string>

// 有坑，会报错，必须混合编译
// #include <libavutil/avutil.h>
extern "C" {
    #include <libavutil/avutil.h>
}

extern "C" JNIEXPORT jstring JNICALL
Java_com_example_ffmpegdemo_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = av_version_info();
    return env->NewStringUTF(hello.c_str());
}

run test

At this time, the version of the underlying FFmpeg library can be obtained at the java layer, which means that the library is compiled and transplanted successfully.

armeabi-v7a script

#!/bin/bash
​
#NDK_ROOT 变量指向ndk目录
NDK_ROOT=/root/android-ndk-r17c
#TOOLCHAIN 变量指向ndk中的交叉编译gcc所在的目录
TOOLCHAIN=$NDK_ROOT/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64
​
#指定android api版本
ANDROID_API=17
​
#此变量用于编译完成之后的库与头文件存放在哪个目录
PREFIX=./android/armeabi-v7a
​
#执行configure脚本，用于生成makefile
#--prefix : 安装目录
#--enable-small : 优化大小
#--disable-programs : 不编译ffmpeg程序(命令行工具)，我们是需要获得静态(动态)库。
#--disable-avdevice : 关闭avdevice模块，此模块在android中无用
#--disable-encoders : 关闭所有编码器 (播放不需要编码)
#--disable-muxers :  关闭所有复用器(封装器)，不需要生成mp4这样的文件，所以关闭
#--disable-filters :关闭视频滤镜
#--enable-cross-compile : 开启交叉编译
#--cross-prefix: gcc的前缀 xxx/xxx/xxx-gcc 则给xxx/xxx/xxx-
#disable-shared enable-static 不写也可以，默认就是这样的。
#--sysroot: 
#--extra-cflags: 会传给gcc的参数
#--arch --target-os : 必须要给
./configure \
--prefix=$PREFIX \
--enable-small \
--disable-programs \
--disable-avdevice \
--disable-encoders \
--disable-muxers \
--disable-filters \
--enable-cross-compile \
--cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
--disable-shared \
--enable-static \
--sysroot=$NDK_ROOT/platforms/android-$ANDROID_API/arch-arm \
--extra-cflags="-isysroot $NDK_ROOT/sysroot -isystem $NDK_ROOT/sysroot/usr/include/arm-linux-androideabi -D__ANDROID_API__=$ANDROID_API -U_FILE_OFFSET_BITS  -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -mthumb -Wa,--noexecstack -Wformat -Werror=format-security  -O0 -fPIC" \
--arch=arm \
--target-os=android
​
#上面运行脚本生成makefile之后，使用make执行脚本
make clean
make install

Summarize

There will be many pitfalls when compiling FFmpeg. Basically, the shell scripting of each version is different, so if you don't know much about Shell, it is recommended to review it first .

the code

reference

1. Audio and video learning (6) FFmpeg 4.2.2 cross-compilation
2. Clang compilation FFmpeg FAQ
3. FFmpeg installation and compilation - tutorial and pitfalls

Original  FFmpeg4.2.2 cross compilation

★The business card at the end of the article can receive audio and video development learning materials for free, including (FFmpeg, webRTC, rtmp, hls, rtsp, ffplay, srs) and audio and video learning roadmaps, etc.

see below!

 

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