Draw subtitles on top of input video using the libass library.

To enable compilation of this filter you need to configure FFmpeg with --enable-libass. This filter also requires a build with libavcodec and libavformat to convert the passed subtitles file to ASS (Advanced Substation Alpha) subtitles format.

This filter accepts the following named options, expressed as a sequence of key=value pairs, separated by ":".

filename, f

Set the filename of the subtitle file to read. It must be specified.

original_size

Specify the size of the original video, the video for which the ASS file was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to correctly scale the fonts if the aspect ratio has been changed.

If the first key is not specified, it is assumed that the first value specifies the filename.

For example, to render the file sub.srt on top of the input video, use the command:

subtitles=sub.srt

which is equivalent to:

subtitles=filename=sub.srt