Windows 10 平台下编码 libav

注： 编译完成的文件可以从这里下载
参考：
[1]: https://libav.org/documentation/platform.html#Compilation-under-Cygwin
[2]: https://blog.csdn.net/wangpingfang/article/details/8133622

编码 libav

Centos 6.0 x86_64
命令 ./configure --prefix=/usr/local/libav/ --enable-shared --enable-gpl --enable-libx264 --extra-cflags=-I/usr/local/x264/include --extra-ldflags=-L/usr/local/x264/lib --extra-libs=-ldl

windows10
命令 ./configure --target-os=mingw32 --arch=x86 --enable-shared --enable-static --enable-dxva2 --enable-gpl --enable-libx264 --enable-hwaccel=dxva2 --extra-cflags=-O3 --enable-pthreads

编译 ffmpeg

Centos 6.0 x86_64
命令 ./configure --enable-shared --prefix=/usr/local/ffmpeg --enable-gpl --enable-libx264 --extra-libs=-fPIC

遇到的问题：

问题1：“错误： ‘M_SQRT2’ 未声明”

解决方案：

1. 在引用的 <math.h> 中增加下面的代码（不包含 #####…####），

    	###################### BEGIN #############################
    	#if defined(_USE_MATH_DEFINES) && !defined(_MATH_DEFINES_DEFINED)
    	#define _MATH_DEFINES_DEFINED
   
    	/* Define _USE_MATH_DEFINES before including math.h to expose these macro
    	 * definitions for common math constants.  These are placed under an #ifdef
    	 * since these commonly-defined names are not part of the C/C++ standards.
    	 */
   
    	/* Definitions of useful mathematical constants
    	 * M_E        - e
    	 * M_LOG2E    - log2(e)
    	 * M_LOG10E   - log10(e)
    	 * M_LN2      - ln(2)
    	 * M_LN10     - ln(10)
    	 * M_PI       - pi
    	 * M_PI_2     - pi/2
    	 * M_PI_4     - pi/4
    	 * M_1_PI     - 1/pi
    	 * M_2_PI     - 2/pi
    	 * M_2_SQRTPI - 2/sqrt(pi)
    	 * M_SQRT2    - sqrt(2)
    	 * M_SQRT1_2  - 1/sqrt(2)
    	 */
   
    	#define M_E 2.71828182845904523536
    	#define M_LOG2E 1.44269504088896340736
    	#define M_LOG10E 0.434294481903251827651
    	#define M_LN2 0.693147180559945309417
    	#define M_LN10 2.30258509299404568402
    	#define M_PI 3.14159265358979323846
    	#define M_PI_2 1.57079632679489661923
    	#define M_PI_4 0.785398163397448309616
    	#define M_1_PI 0.318309886183790671538
    	#define M_2_PI 0.636619772367581343076
    	#define M_2_SQRTPI 1.12837916709551257390
    	#define M_SQRT2 1.41421356237309504880
    	#define M_SQRT1_2 0.707106781186547524401
   
    	#endif /* _USE_MATH_DEFINES */
    	####################### END ############################
   

2. Makefile 中需要在 CPPFLAGS 增加 -D_USE_MATH_DEFINES

参考链接：
[1]: https://blog.csdn.net/ssyitwin/article/details/83016844
[2]: https://bbs.csdn.net/topics/90353622?list=110995

问题2：“x264_bit_depth 未定义”

解决方案：

在头文件 x264_config.h 中增加 #define x264_bit_depth 0 （里面有 #define X264_BIT_DEPTH 0，猜测维护人员的编译环境是可以兼容大写的）

参考链接：
[1]: https://juejin.im/post/5d8acf83f265da5bb318d3a4

问题3： x264 not finded

解决方案：

查看 config.log，可以看到解决办法的提示：

pkg-config --exists --print-errors x264
Package x264 was not found in the pkg-config search path.
Perhaps you should add the directory containing `x264.pc'
to the PKG_CONFIG_PATH environment variable
Package 'x264', required by 'virtual:world', not found
ERROR: x264 not found

参考链接：
[1]: https://blog.csdn.net/jacke121/article/details/80352857
[2]: https://www.xuebuyuan.com/726320.html