ubuntu编译FFmpeg代码
安装依赖库
sudo apt install nasm
sudo apt install libsdl2-dev
sudo apt install libxcb-dev
sudo apt install libxcb-xfixes0-dev
sudo apt install libxcb-shm0-dev
sudo apt install lksctp-tools-dev
sudo apt install libsctp-dev
sudo apt install libfdk-aac-dev
sudo apt install libx264-dev
sudo apt install liblz-dev
sudo apt install liblzma-dev
sudo apt install libfdk-aac-dev
下载编译FFmpeg代码
git clone https://github.com/FFmpeg/FFmpeg.git
cd FFmpeg
mkdir out
cd out
../configure --enable-static --enable-shared --enable-libx264 --enable-gpl \
--enable-nonfree --enable-sdl --enable-ffplay --disable-optimizations --enable-debug \
--extra-cflags=-g --enable-libfdk-aac --enable-libopenh264 --enable-libx264 \
--enable-demuxer=dash --enable-libxml2 --enable-libmp3lame
sudo make -j8 install
这个configure项解决依赖问题，有些库可以直接安装dev库，有些需要自己编译。
建一个out目录，编译生成的临时文件都会放在out目录下，不会存在于代码目录，看着干净很多。
编译开关
enable dash demuxer
增加：
--enable-demuxer=dash --enable-libxml2
--enable-static --enable-shared --enable-libx264 --enable-gpl --enable-nonfree \
--enable-sdl --enable-ffplay --disable-optimizations --enable-debug --extra-cflags=-g --enable-libfdk-
aac --enable-libopenh264 --enable-libx264 --enable-demuxer=dash
disable-optimizations
ffmpeg中gdb调试的时候关掉编译器优化使用
--extra-cflags='-g -O0'
发现不起作用，要用
--disable-optimizations
才生效。
编译ffplay
编译出来找不到ffplay，如果没有
--disable-ffplay
，那就不是编译开关的事：
-
增加编译选项
--enable-ffplay
，其实不用，只要没有
--disable-ffplay
-
原因是sdl2-dev库没有安装：
sudo apt install libsdl2-dev
编译libx264依赖
git clone https://github.com/mirror/x264.git
cd x264
./configure
sudo make install
编译openh264依赖
git clone https://github.com/cisco/openh264.git
cd openh264
meson build
sudo ninja -C build/ install
编译libxml2依赖
git clone https://github.com/GNOME/libxml2.git
./autogen.sh
./configure
sudo make -j8 install
找不到pyton2.7
checking for PYTHON... no
configure: error: Package requirements (python-2.7) were not met:
No package 'python-2.7' found
发现ubuntu20.04上已经没有源能安装pyton2.7-dev，所以就找了下电脑上以后的，实际上开发项目比较多的话会有很多可以用的，不用自己安装了：
locate *.pc | grep "python-2.7.pc"
/home/hui/disk4t/codes/gstreamer/gst-open-source/build/android-ndk-18/prebuilt/\
linux-x86_64/lib/pkgconfig/python-2.7.pc
配置PKG_CONFIG_PATH后重新configure，然后再执行sudo make install（默认路径
/usr/local/lib/pkgconfig/libxml-2.0.pc
）：
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/home/hui/disk4t/codes/gstreamer/\
gst-open-source/build/android-ndk-18\/prebuilt/linux-x86_64/lib/pkgconfig/
当然，还需要配置下cflags和ldflags，如下就可以了：
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:"/home/hui/disk4t/codes/gstreamer/\
gst-open-source/build/android-ndk-18\/prebuilt/linux-x86_64/lib/pkgconfig/"
export PYTHON27_INC="/home/hui/disk4t/codes/gstreamer/gst-open-source/build/\
android-ndk-18/prebuilt/linux-x86_64/include/python2.7"
export PYTHON27_LIBS="/home/hui/disk4t/codes/gstreamer/gst-open-source/build/\
android-ndk-18/prebuilt/linux-x86_64/lib/"
./configure CFLAGS="-I${PYTHON27_INC}" LDFLAGS="-L${PYTHON27_LIBS}/lib" --without-python
apt search
apt search xxx可以查找一些库可用apt安装的版本，找到之后，然后通过
sudo apt install xxx
安装即可。
比如：
$ apt search libogg
Sorting... Done
Full Text Search... Done
libogg-dbg/focal 1.3.4-0ubuntu1 amd64
debugging symbols for libogg
libogg-dev/focal,now 1.3.4-0ubuntu1 amd64 [installed,automatic]
Ogg bitstream library development files
libogg0/focal,now 1.3.4-0ubuntu1 amd64 [installed,automatic]
Ogg bitstream library
安装：
$ sudo apt install libogg-dev
生成coredump
将core文件统一生成到当前目录下，产生的文件名为core.pid
sudo sysctl -w kernel.core_pattern=core.%p
设置core文件大小：
ulimit -c unlimited