RTMP与FFmpeg编译问题集

1.error: undefined reference to ‘av_version_info()’

出错原因： ffmpeg是纯C的库，头文件没有做好C++调用的准备用extern “C”{}套住ffmpeg头文件，用C 语言的编译规则来编译ffmpeg代码，就可以了

解决办法：
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extern "C"{ 
#include <libavutil/avutil.h>
}

2.libavutil/log.c:186: error: undefined reference to ‘stderr’

出错原因：
代码中使用了大量的标准IO设备：stderr 等，这些在NDK15以后，这些都不被支持了，代码本身没问题，只是编译器链接时找不到对应的静态库定义了；

解决方案：
在编译选项中添加语句-DANDROID_API=[你的android API版本号]即可；比如我的测试手机为 android 5.1.1 对应 API = 22，编译选项中应该添加：-DANDROID_API=22
adb shell 获取 android 系统版本： adb shell getprop ro.build.version.release adb shell 获取 android 系统 API 版本： adb shell getprop ro.build.version.sdk

3.libavformat/utils.c:513: error: undefined reference to ‘av_parser_close’

出错原因：链接静态库先后顺序不正确，引起的符号定义找不到。
解决方案：
修改静态库的链接顺序。
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target_link_libraries( 
	native-lib 
	avfilter avformat avcodec avutil swresample swscale log
)
忽略静态库的链接顺序。
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target_link_libraries( 
    native-lib 
    -Wl,--start-group 
    avcodec avfilter avformat avutil swresample swscale -Wl,--end-group 
    log
)

4.libavformat/http.c:1649: error: undefined reference to ‘inflateEnd’

出错原因：找不到的z库中的函数的实现。因为 ffmpeg 依赖了z库。编译ffmpeg的时候如果仔细看编译时输出的日志，就可以看到 External libraries: zlib
解决方案：添加z库的依赖。
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target_link_libraries( 
    native-lib 
    -Wl,--start-group 
    avcodec avfilter avformat avutil swresample swscale -Wl,--end-group 
    log 
    z 
)

5.libavformat/hls.c:845: error: undefined reference to ‘atof’

出错原因：
Google have moved some of the C standard library functions like atof() from being inline functions in header files to normal functions. The latest NDKs will default to building a .so that is only compatible with the latest Android devices that have the atof() function in the device’s standard C library (libc.so). This means if you run a library on an older device that has an older version of the C library, you will get an error loading the dll as the expected atof() function will not exist.
解决方案：修改ffmpeg编译脚本，指定Android API版本为17，重新编译。

这里又有一个问题：
libavcodec/v4l2_buffers.c:434:44: error: call to ‘mmap’ declared with attribute error: mmap is not available > with _FILE_OFFSET_BITS=64 when using GCC until android-21. Either raise your minSdkVersion, disable > _FILE_OFFSET_BITS=64, or switch to Clang.

所以21版本以下，需要取消 _FILE_OFFSET_BITS宏定义。添加编译参数： -U_FILE_OFFSET_BITS

6.混合编译FFmpeg和Rtmp

6.1 下载最新库

// 下载rtmp
wget https://codeload.github.com/yixia/librtmp/zip/refs/heads/master
unzip master
    
// 下载最新ffmpeg
wget https://ffmpeg.org/releases/ffmpeg-4.2.2.tar.bz2
tar -xvf ffmpeg-4.2.2.tar.bz2

6.2 单编rtmp脚本

编译androideabi架构

#!/bin/bash

NDK_ROOT=/home/jackou/tools/android-ndk-r17c

CPU=arm-linux-androideabi

TOOLCHAIN=$NDK_ROOT/toolchains/$CPU-4.9/prebuilt/linux-x86_64

export XCFLAGS="-isysroot $NDK_ROOT/sysroot -isystem $NDK_ROOT/sysroot/usr/include/arm-linux-androideabi -D__ANDROID_API__=17"
export XLDFLAGS="--sysroot=${NDK_ROOT}/platforms/android-17/arch-arm "
export CROSS_COMPILE=$TOOLCHAIN/bin/arm-linux-androideabi-

make install SYS=android prefix=`pwd`/result CRYPTO= SHARED=  XDEF=-DNO_SSL

编译arm64-v8a架构

#!/bin/bash

NDK_ROOT=/home/jackou/tools/android-ndk-r17c

CPU=aarch64-linux-android

TOOLCHAIN=$NDK_ROOT/toolchains/$CPU-4.9/prebuilt/linux-x86_64

export XCFLAGS="-isysroot $NDK_ROOT/sysroot -isystem $NDK_ROOT/sysroot/usr/include/aarch64-linux-android -D__ANDROID_API__=17"
export XLDFLAGS="--sysroot=${NDK_ROOT}/platforms/android-17/arch-arm "
export CROSS_COMPILE=$TOOLCHAIN/bin/aarch64-linux-android-

make install SYS=android prefix=`pwd`/result CRYPTO= SHARED=  XDEF=-DNO_SSL

6.2混编FFmpeg和rtmp

6.2.1 修改configure文件

6.2.1.1 最新版本的ffmpeg默认使用clang编译，可以修改configure文件来关闭

注释4210-4213行，关闭掉： 
4209 
4210 #set_default target_os 
4211 #if test "$target_os" = android; then 4212 #   cc_default="clang" 
4213 #fi 
4214

6.2.1.2 由于ffmpeg 默认开启librtmp需要pkgconfig，这里我们手动关闭，修改ffmpeg的configure文件：

##注解掉6256行
6254 enabled libpulse          && require_pkg_config libpulse libpulse pulse/pulseaudio.h pa_context_new
6255 enabled librsvg           && require_pkg_config librsvg librsvg-2.0 librsvg-2.0/librsvg/rsvg.h rsvg_handle_render_cairo
6256 # enabled librtmp           && require_pkg_config librtmp librtmp librtmp/rtmp.h RTMP_Socket
6257 enabled librubberband     && require_pkg_config librubberband "rubberband >= 1.8.1" rubberband/rubberband-c.h rubberband_new -lstdc++ && append librubberband_extralibs "-lstdc++"
6258 enabled libshine          && require_pkg_config libshine shine shine/layer3.h shine_encode_buffer

6.2.2 编译androideabi架构

#!/bin/bash

NDK_ROOT=/home/jackou/tools/android-ndk-r17c

CPU=arm-linux-androideabi

TOOLCHAIN=$NDK_ROOT/toolchains/$CPU-4.9/prebuilt/linux-x86_64

ANDROID_API=17

PREFIX=./android/armeabi-v7a/ffmpeg_rtmp

#rtmp路径
RTMP=/root/KevinStudyNDK/MyFFmpeg3/librtmp/result

./configure \
--prefix=$PREFIX \
--enable-small \
--disable-programs \
--disable-avdevice \
--disable-encoders \
--disable-muxers \
--disable-filters \
--enable-librtmp \
--enable-cross-compile \
--cross-prefix=$TOOLCHAIN/bin/$CPU- \
--disable-shared \
--enable-static \
--sysroot=$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 -I$RTMP/include" \
--extra-ldflags="-L$RTMP/lib" \
--extra-libs="-lrtmp" \
--arch=arm \
--target-os=android 

make clean

make install

编译arm64-v8a架构

#!/bin/bash

NDK_ROOT=/home/jackou/tools/android-ndk-r17c

CPU=aarch64-linux-android

TOOLCHAIN=$NDK_ROOT/toolchains/$CPU-4.9/prebuilt/linux-x86_64

ANDROID_API=21

PREFIX=./android/arm64-v8a/ffmpeg_rtmp

#rtmp路径
RTMP=/home/jackou/ndk/ffmpeg/librtmp-master/result

./configure \
--prefix=$PREFIX \
--enable-small \
--disable-programs \
--disable-avdevice \
--disable-encoders \
--disable-muxers \
--disable-filters \
--enable-librtmp \
--enable-cross-compile \
--cross-prefix=$TOOLCHAIN/bin/$CPU- \
--disable-shared \
--enable-static \
--sysroot=$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 -march=arm64-v8a -mfloat-abi=softfp -mfpu=vfpv3-d16 -mthumb -Wa,--noexecstack -Wformat -Werror=format-security  -O0 -fPIC -I$RTMP/include" \
--extra-ldflags="-L$RTMP/lib" \
--extra-libs="-lrtmp" \
--arch=aarch64 \
--target-os=android 

make clean

make install

6.2.3 集成到AS中CMakelist脚本

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

# 导入FFmpeg的库文件 
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} - 
L${CMAKE_SOURCE_DIR}/ffmpeg/libs/${CMAKE_ANDROID_ARCH_ABI}") # 导入Rtmp的库文件 

set(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} - 
L${CMAKE_SOURCE_DIR}/rtmp/libs/${CMAKE_ANDROID_ARCH_ABI}") 

target_link_libraries( 
    my-player 
    ${log-lib} 
    -Wl,
    --start-group 
    avcodec avfilter avformat avutil swresample swscale -Wl,
    --end-group 
    z 
)

7.搭建rtmp服务器

7.1 下载Nginx和rtmp-module

#下载Nginx
wget http://nginx.org/download/nginx-1.15.3.tar.gz tar xvf nginx-1.15.3.tar.gz

#下载rtmp-module
wget https://codeload.github.com/arut/nginx-rtmp-module/tar.gz/v1.2.1

7.2 执行配置和安装

# 生成makefile
./configure --prefix=./bin --add-module=../nginx-rtmp-module-1.2.1
# 生成结果在bin
make install

成功之后，会在/bin下生成conf html logs sbin几个文件。

7.3 配置Nginx

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#进入到成果目录，并且配置nginx
cd /bin/conf
vim nginx.conf

配置文件

#启动nginx服务器就会报错，权限被拒绝
user root;

worker_processes 1;

#如果启动错误，这个就是错误日志详情
error_log logs/error.log debug;

events {
	worker_connections 1024;
}

rtmp {
	server {
		#注意端口占用  流媒体服务器的端口
		listen 1935;
		
		#如果不加，可能会失败
		application myapp {
			live on;
			#丢弃闲置5s的连接
			drop_idle_publisher 5s;
		}
	}
}

#下面就是为了测试 http://139.224.136.101:8080/stat 控制面板的意思
http {
	server {
		#注意端口占用
		listen 8080;
		location /stat {
			rtmp_stat all;
			rtmp_stat_stylesheet stat.xsl;
		}
		
		location /stat.xsl
		{ 
			root /home/jackou/ndk/Nginx_RTMP/nginx-rtmp-module-1.2.1/;
		}
		
		location /control
		{ 
			rtmp_control all;
		}
		
		location /rtmp-publisher
		{ 
			root /home/jackou/ndk/Nginx_RTMP/nginx-rtmp-module-1.2.1/test;
		}
		
		location / {
			root /home/jackou/ndk/Nginx_RTMP/nginx-rtmp-module-1.2.1/test/www;
		}
	}
}

7.4 启动服务

1	jackou@ubuntu:~/ndk/Nginx_RTMP/nginx-1.15.3$ sudo bin/sbin/nginx

nginx: [emerg] bind() to 0.0.0.0:1935 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:8080 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:1935 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:8080 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:1935 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:8080 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:1935 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:8080 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:1935 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:8080 failed (98: Address already in use)
nginx: [emerg] still could not bind()
#端口被占用需要停止服务