sub: add filter text utils, use from filter-regex (no-op)

Add two stand-alone function to help with the text-extraction task
which ass filters need. Makes it easier to add new filters without
cargo-culting this functionality.

Currently, on malformed event (which shouldn't happen), a warning is
printed when a filter tries to extract the text, so if few filters
are enabled, we'll get multiple warnings (like before) - not critical.

The regex filter now uses these utils, the SDH filter not yet.

1 files changed, 11 insertions, 0 deletions

diff --git a/sub/sd.h b/sub/sd.h
index 38bab3aa7a..2d107d1769 100644
--- a/sub/sd.h
+++ b/sub/sd.h
@@ -89,4 +89,15 @@ struct sd_filter_functions {
 extern const struct sd_filter_functions sd_filter_sdh;
 extern const struct sd_filter_functions sd_filter_regex;
 
+
+// convenience utils for filters with ass codec
+
+// num commas to skip at an ass-event before the "Text" field (always last)
+// (doesn't change, can be retrieved once on filter init)
+int sd_ass_fmt_offset(const char *event_format);
+
+// the event (pkt->buffer) "Text" content according to the calculated offset.
+// on malformed event: warns and returns (bstr){NULL,0}
+bstr sd_ass_pkt_text(struct sd_filter *ft, struct demux_packet *pkt, int offset);
+
 #endif