linux下使用ffmpeg将amr转成mp3

系统环境：

CentOS Linux release 8.2.2004 (Core)

1. 首先安装系统编译环境

yum install -y automake autoconf libtool gcc gcc-c++

2. 编译所需源码包

#yasm：汇编器，新版本的ffmpeg增加了汇编代码
wget http://www.tortall.net/projects/yasm/releases/yasm-1.3.0.tar.gz
tar -xzvf yasm-1.3.0.tar.gz
cd yasm-1.3.0
./configure
make
make install

#lame：Mp3音频解码
wget https://nchc.dl.sourceforge.net/project/lame/lame/3.100/lame-3.100.tar.gz
tar -xzvf lame-3.100.tar.gz
cd lame-3.100
./configure
make
make install

#amr支持
wget https://nchc.dl.sourceforge.net/project/opencore-amr/opencore-amr/opencore-amr-0.1.5.tar.gz
tar -xzvf opencore-amr-0.1.5.tar.gz
cd opencore-amr-0.1.5
./configure
make
make install

#amrnb支持
wget http://www.penguin.cz/~utx/ftp/amr/amrnb-11.0.0.0.tar.bz2
tar -xjvf amrnb-11.0.0.0.tar.bz2
cd amrnb-11.0.0.0
./configure
make
make install

#amrwb支持
wget http://www.penguin.cz/~utx/ftp/amr/amrwb-11.0.0.0.tar.bz2
tar -xjvf amrwb-11.0.0.0.tar.bz2
cd amrwb-11.0.0.0
./configure
make
make install

#ffmpeg
wget https://ffmpeg.org/releases/ffmpeg-snapshot.tar.bz2
tar -xjvf ffmpeg-snapshot.tar.bz2
cd ffmpeg
./configure --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-version3 --enable-shared
make
make install

#加载配置
#最后写入config后，终端运行ffmpeg命令，出现success和已安装的扩展，则运行成功。
ldconfig

3.使用方法

ffmpeg -i 1.mp3 -ac 1 -ar 8000 1.amr  #MP3转换AMR
ffmpeg -i 1.amr 1.mp3                 #AMR转换MP3

附录：
附录1. ffmpeg默认安装目录为“/usr/local/lib”，有些64位系统下软件目录则为“/usr/lib64”，编译过程中可能会出现
“ffmpeg: error while loading shared libraries: libmp3lame.so.0: cannot open shared object file: No such file or directory”等类似的错误，解决办法是建立软链接：
# ln -s /usr/local/lib/libmp3lame.so.0.0.0 /usr/lib64/libmp3lame.so.0

附录2. 如果出现以下提示：ffmpeg: error while loading shared libraries: libavdevice.so.54: cannot open shared object file: No such file or directory
可以通过如下方式查看ffmpeg的动态链接库哪些没有找到：

ldd `which ffmpeg`
        libavdevice.so.54 => not found
        libavfilter.so.3 => not found
        libavformat.so.54 => not found
        libavcodec.so.54 => not found
        libswresample.so.0 => not found
        libswscale.so.2 => not found
        libavutil.so.51 => not found
        libm.so.6 => /lib64/libm.so.6 (0x00002ab7c0eb6000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00002ab7c100b000)
        libc.so.6 => /lib64/libc.so.6 (0x00002ab7c1125000)
        /lib64/ld-linux-x86-64.so.2 (0x00002ab7c0d9a000)
#如果类似于上面的输出内容，查找以上类库，会发现全部在/usr/local/lib/下
find /usr/local/lib/ | grep -E "libavdevice.so.54|libavfilter.so.3|libavcodec.so.54"
/usr/local/lib/libavfilter.so.3.17.100
/usr/local/lib/libavcodec.so.54.59.100
/usr/local/lib/libavdevice.so.54
/usr/local/lib/libavcodec.so.54
/usr/local/lib/libavfilter.so.3
/usr/local/lib/libavdevice.so.54.2.101
 
#查看链接库配置文件
more  /etc/ld.so.conf | grep /usr/local/lib
#如果不包含的话，需要编辑此文添加：
vi /etc/ld.so.conf
/usr/local/lib
/usr/local/lib64
#运行配置命令
ldconfig