What about creating a new branch for subtitles？

[Shirtiny]

An old version with libass was compiled successfully. It's based on commit b60b362885e306b9c453613cbb57a8062a45ff50, before you removed libass dependency. My project really needs ffmpeg with subtitle filter support, so I found b60b362885e306b9c453613cbb57a8062a45ff50 and tried to compile it. Now, it works. The environment is:

# docker run -it ubuntu:18.04 /bin/bash
./emsdk install node-8.9.1-64bit && ./emsdk install emscripten-1.38.30 && ./emsdk install fastcomp-clang-e1.38.30-64bit

To facilitate my project, I slightly modified Makefile and ffmpeg-default-font.patch. Details: https://github.com/Shirtiny/ffmpeg.js/tree/subtitles maybe it can help someone like me who are looking for this.