# 基于Ubuntu源码编译ffmpeg
## 编译SDL2(可选)
```shell
https://github.com/libsdl-org/SDL/releases/tag/release-2.30.8 # 下载源码
cd sdl/source/folder
./configure --prefix=/usr/local
make
sudo make install
```
## 安装ffmpeg依赖
1. 安装包管理工具 aptitude
   aptitude 与 apt-get一样,是 Debian 系中功能极其强大的包管理工具。 与 apt-get 不同的是,aptitude 在处理依赖问题上更佳一些,当 aptitude 在删除一个包时,会同时删除本身所依赖的包。
    ```shell
    sudo apt install aptitude
    ```
2. 安装 yasm、nasm
   yasm、nasm 是两个汇编器,编译 FFmpeg 需要用到。
   安装命令:
    ```shell
    sudo aptitude install yasm nasm
    ```
3. 其他依赖
   FFmpeg 的安装依赖许多库(如,音频编码库,音频解码库,视频编解码库等),这里不介绍每个库的具体作用,按照命令安装即可。
    ```shell
    sudo apt-get install libgmp3-dev
    sudo apt install pkg-config
    sudo apt install gnutls-bin
    sudo aptitude install libaom-dev
    sudo aptitude install libass-dev
    sudo aptitude install libbluray-dev
    sudo aptitude install libfdk-aac-dev
    sudo aptitude install libmp3lame-dev
    sudo aptitude install libopencore-amrnb-dev
    sudo aptitude install libopencore-amrwb-dev
    sudo aptitude install libopenmpt-dev
    sudo aptitude install libopus-dev
    sudo aptitude install libshine-dev
    sudo aptitude install libsnappy-dev
    sudo aptitude install libsoxr-dev
    sudo aptitude install libspeex-dev
    sudo aptitude install libtheora-dev
    sudo aptitude install libtwolame-dev
    sudo aptitude install libvo-amrwbenc-dev
    sudo aptitude install llibvpx-dev
    sudo aptitude install libwavpack-dev
    sudo aptitude install libwebp-dev
    sudo aptitude install libx264-dev
    sudo aptitude install libx265-dev
    sudo aptitude install libxvidcore-dev
    sudo aptitude install liblzma-dev
    ```
## 编译ffmpeg
1. 从官网下载源码
2. 进入根目录编译
    ```shell
    ./configure --enable-shared --enable-gpl  --enable-sdl2 --enable-libx264 --enable-libx265  --enable-nvdec --enable-nvenc --enable-cuda --enable-cuvid
   # 其中 --enable-gpl --enable-libx264 --enable-libx265 必不可少 --enable-sdl2 是ffmpeg播放器需要的
   # 由于需要硬件英伟达显卡加速编解码 --enable-nvdec --enable-nvenc --enable-cuda --enable-cuvid
   # --enable-shared 使make install时,将动态库也正确安装,否则运行ffmpeg时,会显示缺少动态库
   
   make
   sudo make install
   # 安装完后,确保安装目录,确保已经配置好动态库搜索的路径,
   ```
   如果需要硬件英伟达显卡加速编解码,需要安装相关依赖
    ```shell
    sudo apt install libdssialsacompat-dev
    git clone https://git.videolan.org/git/ffmpeg/nv-codec-headers.git
    cd nv-codec-headers
    make
    sudo make install
    # ./ffmpeg -hwaccels 查看支持哪些硬件编码
    ```

### 编译ffmeg arm64安卓版本

在源码目录下创建buildarm64.sh,内容如下

```shell
#!/bin/bash

export NDK=~/android/android-ndk-r20b #这里配置先你的 NDK 路径
TOOLCHAIN=$NDK/toolchains/llvm/prebuilt/linux-x86_64

# 编译到安卓上,尽可能小一些(--enable-small),只是用来解码,也就取消编译封装编码相关的
function build_android
{

./configure \
--disable-programs \
--disable-avdevice \
--disable-encoders \
--disable-muxers \
--disable-filters \
--enable-neon  \
--enable-gpl   \
--disable-sdl2 \
--disable-postproc \
--disable-debug \
--enable-small \
--enable-static \
--enable-shared \
--disable-doc \
--enable-ffmpeg \
--disable-ffplay \
--disable-ffprobe \
--disable-avdevice \
--disable-doc \
--disable-symver \
--prefix=$PREFIX \
--cross-prefix=$CROSS_PREFIX \
--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"


make clean
make -j16
make install

echo "============================ build android arm64-v8a success =========================="

}

#arm64-v8a
ARCH=arm64
CPU=armv8-a
API=21
CC=$TOOLCHAIN/bin/aarch64-linux-android$API-clang
CXX=$TOOLCHAIN/bin/aarch64-linux-android$API-clang++
SYSROOT=$NDK/toolchains/llvm/prebuilt/linux-x86_64/sysroot
CROSS_PREFIX=$TOOLCHAIN/bin/aarch64-linux-android-
PREFIX=$(pwd)/android/$CPU
OPTIMIZE_CFLAGS="-march=$CPU"

build_android


```

```shell
chomd +x buildarm64.sh
./buildarm64.sh
# 编译好后,对应的源文件和库文件会安装到./android/armv-v8a中
```
### 在rk3568上交叉编译ffmpeg
使用瑞芯微上使用其硬件加速编码和解码
创建一个目录 ~/dev 之后所有的操作在这个目录下进行
1. 编译mpp
   ```shell
   git clone -b jellyfin-mpp --depth=1 https://github.com/nyanmisaka/mpp.git rkmpp
   mkdir rkmpp_build
   pushd rkmpp_build
   # 在cmake中指定交叉工具链gcc和g++ 改成自己的目录
   # 注意在不要安装到本机的系统目录,最好新建一个目录,之后把所有的依赖安装到这个目录
   cmake \
   -DCMAKE_INSTALL_PREFIX=~/dev/rkffmpeg \
   -DCMAKE_BUILD_TYPE=Release \
   -DBUILD_SHARED_LIBS=ON \
   -DBUILD_TEST=OFF \
   -DCMAKE_C_COMPILER=/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/bin/aarch64-linux-gcc \
    -DCMAKE_CXX_COMPILER=/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/bin/aarch64-linux-g++ \
   ..
   make -j $(nproc)
   make install
   ```
2. build rga

   创建一个在~/dev 目录下创建cross_file.txt, 将工具链换成自己的,以及安装目录
   ```txt
   [host_machine]
   system = 'linux'
   cpu_family = 'aarch64'
   cpu = 'armv8-a'
   endian = 'little'

   [binaries]
   c = '/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/bin/aarch64-linux-gcc'
   cpp = '/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/bin/aarch64-linux-g++'
   ar = '/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/aarch64-rockchip-linux-gnu/bin/ar'
   strip = '/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/aarch64-rockchip-linux-gnu/bin/strip'
   
   [properties]
   c_args = ['-fpermissive']
   cpp_args = ['-fpermissive']
   
   [paths]
   prefix = '~/dev/rkffmpeg'
   libdir = 'lib'
   ```
   ```shell
    git clone -b jellyfin-rga --depth=1 https://github.com/nyanmisaka/rk-mirrors.git rkrga
    # 不需要cd 进行
    meson setup rkrga rkrga_build \
    --prefix=/usr \
    --libdir=lib \
    --buildtype=release \
    --default-library=shared \
    -Dcpp_args=-fpermissive \
    -Dlibdrm=false \
    -cross-file=./cross_file.txt \
    -Dlibrga_demo=false
    meson configure rkrga_build
    ninja -C rkrga_build install
   ```
3. 编译drm

   首先去官网下载源码包https://dri.freedesktop.org/libdrm/
   下载完成后,开始解压缩,解压缩完成后,进入源码目录,首先创建install和build目录,然后创建cross_file.txt文件,文件内容如下
    ```txt
   [host_machine]
   system = 'linux'
   cpu_family = 'aarch64'
   cpu = 'armv8-a'
   endian = 'little'
   
   [binaries]
   c = '/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/bin/aarch64-linux-gcc'
   cpp = '/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/bin/aarch64-linux-g++'
   ar = '/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/aarch64-rockchip-linux-gnu/bin/ar'
   strip = '/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/aarch64-rockchip-linux-gnu/bin/strip'
   
   [properties]
   c_args = ['-fpermissive']
   cpp_args = ['-fpermissive']
   
   [paths]
   prefix = '~/dev/rkffmpeg'
   libdir = 'lib'
   ```
   然后直接执行指令ninja && ninja install即可使用

4. 编译ffmpeg
   
   上面的依赖编译并安装好后,正式开始编译ffmpeg,添加rk芯片的mpp来加速编解码
   在~/dev 下载ffmpeg 进入到源码目录 创建build.sh 内容如下
   ```shell
   #!/bin/bash
   export TOOLCHAIN=/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/bin/aarch64-linux
   export GCC=$TOOLCHAIN-gcc
   export GXX=$TOOLCHAIN-g++
   
   # 编译到开发版,尽可能小一些(--enable-small),取消了一些其它硬件加速和封装
   # 更换 cc cxx ar strip 以及--extra-cflags --extra-ldflags
   function build_android
   {
   
   ./configure \
   --sysroot=./ \
   --extra-cflags="-I~/dev/rkffmpeg/include" \
   --extra-ldflags="-L~/dev/rkffmpeg/lib" \
   --prefix=$PREFIX \
   --enable-cross-compile \
   --arch=arm64 \
   --cpu=armv8-a \
   ar=/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/aarch64-rockchip-linux-gnu/bin/ar \
   strip=/home/user/baidu/buildroot-cross/gcc_for_rk356x_buildroot/aarch64-rockchip-linux-gnu/bin/strip \
   --cc=$GCC \
   --cxx=$GXX \
   --enable-libdrm \
   --disable-nvenc \
   --disable-nvdec \
   --disable-vdpau \
   --disable-vaapi \
   --enable-rkmpp \
   --enable-rkrga \
   --enable-version3 \
   --disable-programs \
   --disable-avdevice \
   --disable-muxers \
   --disable-filters \
   --enable-neon  \
   --enable-gpl   \
   --disable-sdl2 \
   --disable-postproc \
   --disable-debug \
   --enable-small \
   --enable-static \
   --enable-shared \
   --disable-doc \
   --enable-ffmpeg \
   --disable-ffprobe \
   --disable-avdevice \
   --disable-doc \
   --disable-symver
   
   
   
   echo "============================ build android arm64-v8a success =========================="
   
   }
   
   #arm64-v8a
   
   
   PREFIX=$(pwd)/rk-arm64
   
   build_android
   ```
   编译
   ```shell
   chmod +x build.sh
   
   make clean
   make -j16
   make install
   ```
   最后把编译好的ffmpeg 放到~/dev/rkffmpeg 中 一并打包移植到开发版上


## 硬编码

```c++
// 与软编码相比,没有很多额外的配置
// 仅仅是在查找编码器时按名称查找 hevc_nvenc ,其余和软编码一样
auto pCodec = avcodec_find_encoder_by_name("hevc_nvenc");
// ...
// 其次就是注意软编码出来的每一帧数据 前面都会带有SEI增强帧,关键帧后面才是I帧或者P帧
	auto naluHeader = (pkt->data[4] & 0x7E) >> 1; // 前四个字节是0x00 00 00 01 分隔符
    if (naluHeader == 39) { // SEI
        auto header = getNextSplit(pkt->data, pkt->size); // 往后找,跳过这个SEI
        if (header == nullptr)
            return 0;
        naluHeader = ((*header) & 0x7E) >> 1;
        // cout << "naluHeader: " << naluHeader << endl;
    }
```