I would like the ability to specify center-left justification within subtitle text, via (for example) a leading <center-left> pseudo-tag prepended to the subtitle text, so that this works with SRT files and other subtitles without explicit positioning/formatting capabilities.
If specified, vsfilter would render the subtitle center-left, which means that the text block would be centered, but each line within that block would be left-justified. i.e. the longest line of a multi-line subtitle is centered as normal, and shorter lines are positioned so that they line up on their left side. This is the typical justification for subtitled dialog involving more than one speaker, as well as a few SDH uses.
If this can't be done in the main vsfilter project, some hints about where I would go to implement this change on my own would also be appreciated.
I've managed to implement this mod myself, so just keep it in mind as a "nice-to-have"…