ffmpeg.c: In function 'sub2video_flush':
ffmpeg.c:302:9: warning: ignoring return value of 'av_buffersrc_add_frame', declared with attribute warn_unused_result [-Wunused-result]
av_buffersrc_add_frame(ist->filters[i]->filter, NULL);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AR libavdevice/libavdevice.a
AR libavfilter/libavfilter.a
CC libavformat/os_support.o
In file included from libavformat/os_support.h:112:0,
from libavformat/os_support.c:29:
libavformat/os_support.c: In function 'ff_gai_strerror':
libavformat/os_support.c:230:10: error: 'ERROR_NOT_ENOUGH_MEMORY' undeclared (first use in this function)
case EAI_MEMORY:
^
libavformat/os_support.c:230:10: note: each undeclared identifier is reported only once for each function it appears in
make: *** [libavformat/os_support.o] Error 1
c:\Users\admin\AppData\Local\Android\sdk\ndk-bundle\toolchains\aarch64-linux-android-4.9\prebuilt\windows-x86_64\bin\aarch64-linux-android-ld.exe: cannot find libavcodec/libavcodec.a: No such file or directory
libavfilter/libavfilter.a: member libavfilter/libavfilter.a(aeval.o) in archive is not an object

使用提供的文件(中间根据自己的配置改了sh的一些路径)，也看了博文，改了配置文件，试过很多次，还是编译失败。不知道什么原因。