subpicture_t * ( *pf_sub_filter ) ( filter_t *, mtime_t );
int ( *pf_render_text ) ( filter_t *, subpicture_region_t *,
subpicture_region_t * );
+ int ( *pf_render_html ) ( filter_t *, subpicture_region_t *,
+ subpicture_region_t * );
/*
* Buffers allocation