使用NDK20编译Android平台的ffmpeg编译环境

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我是靠谱客的博主可靠煎蛋，最近开发中收集的这篇文章主要介绍使用NDK20编译Android平台的ffmpeg编译环境，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

使用NDK编译Android平台的ffmpeg

编译环境
- 安装
- 编译
- 避坑
- 如何添加h264支持

编译环境

注意选择Linux版本的包下载

Ubuntu 16 下载
ndk20 下载
ffmpeg4.3.4 下载

安装

略

编译

参考：https://blog.csdn.net/qq_28478281/article/details/104000015

将ndk 以及ffmpeg 分别解压路径随意，配置环境也不是必要的。

#!/bin/bash
# 这个对应的是ndk的解压路径
NDK=/opt/ndk/android-ndk-r20b
# darwin-x86_64是mos版本的路径，Linux 用linux-x86_64
TOOLCHAIN=$NDK/toolchains/llvm/prebuilt/linux-x86_64
API=21
function build_android
{
echo "Compiling FFmpeg for $CPU"
./configure 
--prefix=$PREFIX 
--libdir=$LIB_DIR 
--enable-shared 
--disable-static 
--enable-jni 
--disable-doc 
--disable-symver 
--disable-programs 
--target-os=android 
--arch=$ARCH 
--cpu=$CPU 
--cc=$CC 
--cxx=$CXX 
--enable-cross-compile 
--sysroot=$SYSROOT 
--extra-cflags="-Os -fpic $OPTIMIZE_CFLAGS" 
--extra-ldflags="$ADDI_LDFLAGS" 
--disable-asm 
$COMMON_FF_CFG_FLAGS
make clean
make -j8
make install
echo "The Compilation of FFmpeg for $CPU is completed"
}
# # armv8-a
# source "config-env.sh"
# OUTPUT_FOLDER="arm64-v8a"
# ARCH=arm64
# CPU="armv8-a"
# TOOL_CPU_NAME=aarch64
# TOOL_PREFIX="$TOOLCHAIN/bin/$TOOL_CPU_NAME-linux-android"
# CC="$TOOL_PREFIX$API-clang"
# CXX="$TOOL_PREFIX$API-clang++"
# SYSROOT="$NDK/toolchains/llvm/prebuilt/linux-x86_64/sysroot"
# PREFIX="${PWD}/android/$OUTPUT_FOLDER"
# LIB_DIR="${PWD}/android/libs/$OUTPUT_FOLDER"
# OPTIMIZE_CFLAGS="-march=$CPU"
# build_android
# # armv7-a
# source "config-env.sh"
# OUTPUT_FOLDER="armeabi-v7a"
# ARCH="arm"
# CPU="armv7-a"
# TOOL_CPU_NAME=armv7a
# TOOL_PREFIX="$TOOLCHAIN/bin/arm-linux-androideabi"
# CC="$TOOLCHAIN/bin/armv7a-linux-androideabi$API-clang"
# CXX="$TOOLCHAIN/bin/armv7a-linux-androideabi$API-clang++"
# SYSROOT="$NDK/toolchains/llvm/prebuilt/linux-x86_64/sysroot"
# PREFIX="${PWD}/android/$OUTPUT_FOLDER"
# LIB_DIR="${PWD}/android/libs/$OUTPUT_FOLDER"
# OPTIMIZE_CFLAGS="-march=$CPU"
# build_android
# x86
source "config-env.sh"
OUTPUT_FOLDER="x86"
ARCH="x86"
CPU="x86"
TOOL_CPU_NAME="i686"
TOOL_PREFIX="$TOOLCHAIN/bin/${TOOL_CPU_NAME}-linux-android"
CC="$TOOL_PREFIX$API-clang"
CXX="$TOOL_PREFIX$API-clang++"
SYSROOT="$NDK/toolchains/llvm/prebuilt/linux-x86_64/sysroot"
PREFIX="${PWD}/android/$OUTPUT_FOLDER"
LIB_DIR="${PWD}/android/libs/$OUTPUT_FOLDER"
OPTIMIZE_CFLAGS="-march=i686 -mtune=intel -mssse3 -mfpmath=sse -m32"
build_android
# x86_64
# source "config-env.sh"
# OUTPUT_FOLDER="x86_64"
# ARCH="x86_64"
# CPU="x86-64"
# TOOL_CPU_NAME="x86_64"
# TOOL_PREFIX="$TOOLCHAIN/bin/${TOOL_CPU_NAME}-linux-android"
# CC="$TOOL_PREFIX$API-clang"
# CXX="$TOOL_PREFIX$API-clang++"
# SYSROOT="$NDK/toolchains/llvm/prebuilt/linux-x86_64/sysroot"
# PREFIX="${PWD}/android/$OUTPUT_FOLDER"
# LIB_DIR="${PWD}/android/libs/$OUTPUT_FOLDER"
# OPTIMIZE_CFLAGS="-march=$CPU"
# build_android

避坑

编译报错：……………………/bin/arm-linux-androideabi-gcc is unable to create an executable file.
答疑：ndk版本太高，gcc编译在早期ndk版本支持，但是18b之后就弃用了，采用clang方式。添加 --cc= $KaTeX parse error: Undefined control sequence: at position 4: CC ̲ ̲ --cxx=$ CXX 两个属性并参照以上脚本填写参数
编译显示

Unknown option "".
See ./configure --help for available options.

答疑：脚本的编码格式有错，建议别直接复制文件，可以新建一个sh脚本，再复制内容。

编译显示

 error: can't create dynamic relocation R_386_32 against local symbol in readonly segment; recompile object files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in the output

答疑：网上查到的资料比较少，我猜测是Ubuntu版本太高，我在使用ubuntu18的时候就出现这个问题，后来用16就没有。有知道原因的麻烦评论吱一声。

编译路径错误

Compiling FFmpeg for x86
/opt/ndk/android-ndk-r20b/toolchains/llvm/prebuilt/darwin-x86_64/bin/i686-linux-android21-clang is unable to create an executable file.
C compiler test failed.
If you think configure made a mistake, make sure you are using the latest
version from Git.
If the latest version fails, report the problem to the
ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.libera.chat.
Include the log file "ffbuild/config.log" produced by configure as this will help
solve the problem.

答疑：这种情况最多的是ndk 版本和脚本中输入的路径不一致，导致找不到某个文件，第一次编译可能还会出现 config.mak 找不到的情况，具体可以根据脚本对照ndk是否有对应的路径。

编译中出现：strip: Unable to recognise the format of the input file " xxxx/libavdevice.so"
答疑：strip是有关去除符号表的选项，可以添加–disable-stripping 选择项指明希望不去除符号表。也可以添加–disable-avdevice选项表示不编译libavdevice.so这个模块。随后网上的参考解决方案是在ffbuild路径下的config.mak 修改 STRIP=xxx .这里的xxx是指ndk 目录下的android-ndk-r20b/toolchains/llvm/prebuilt/linux-x86_64/bin中的xxx-linux-androideabi-strip.

6 编译报错：

clang is unable to create an executable file.
If clang is a cross-compiler, use the --enable-cross-compile option.
Only do this if you know what cross compiling means.
C compiler test failed.
If you think configure made a mistake, make sure you are using the latest
version from Git.
If the latest version fails, report the problem to the
ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.libera.chat.
Include the log file "ffbuild/config.log" produced by configure as this will help
solve the problem.

答疑：最朴素的原因是没有安装 gcc .但是一般不是。这这里遇到的情况是在bash函数中不合理的穿插了了注释，例如：

function build_android
{
echo "Compiling FFmpeg for $CPU"
./configure 
--prefix=$PREFIX 
--libdir=$LIB_DIR 
--enable-shared 
--disable-static 
--enable-jni 
--disable-doc 
--disable-symver 
--disable-programs 
--target-os=android 
#
--disable-stripping 
这这里的注释不能穿插在这里，会识别不出最好不要在./configure 指令中添加注释
--disable-avdevice 
--arch=$ARCH 
--cpu=$CPU 
--cc=$CC 
--cxx=$CXX 
--enable-cross-compile 
--sysroot=$SYSROOT 
--extra-cflags="-Os -fpic $OPTIMIZE_CFLAGS" 
--extra-ldflags="$ADDI_LDFLAGS" 
--disable-asm 
$COMMON_FF_CFG_FLAGS
make clean
make -j8
make install
}