I tried to enable libass for ffmpeg with this
--enable-libass in command but it didn't recognise the command.
Does anyone know how to enable libass on Linux?
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First you need to make sure that your particular version of
ffmpeg was built with and supports that switch. You'll also likely need to make sure that the library
libass is installed as well.
You don't specify your Linux distro but I did notice that
libass is available in my stock Fedora 19 repository so it's trivial to install.
$ sudo yum install libass
Now back to
ffmpeg's support of
libass. You can confirm how it was built by simply running it without any arguments.
$ ~/ffmpeg |& grep libass configuration: --prefix=/root/ffmpeg-static/64bit --extra-cflags='-I/root/ffmpeg-static/64bit/include -static' --extra-ldflags='-L/root/ffmpeg-static/64bit/lib -static' --extra-libs='-lxml2 -lexpat -lfreetype' --enable-static --disable-shared --disable-ffserver --disable-doc --enable-bzlib --enable-zlib --enable-postproc --enable-runtime-cpudetect --enable-libx264 --enable-gpl --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-gray --enable-libass --enable-libfreetype --enable-libopenjpeg --enable-libspeex --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-version3 --enable-libvpx
So the version that I have, does include this support,
--enable-libass. If your version of
ffmpeg doesn't support it you can simply download a static build:
recompile ffmpeg with:
make sudo make install
Then check the new ffmpeg without arguments:
Mine says "libass" is in the new config.
Then, to convert videos I use:
ffmpeg -i input.avi -vf "ass=subs.ass" out.avi
To obtain the subtitles in
.srt I use:
ffmpeg -i subs.srt subs.ass