Format Support Matrix

This matrix summarizes core support per format. "Limited" means partial coverage of the format feature or a constrained subset.

Format	Parse	Serialize	Timing	Styling	Positioning	Images
ASS	Yes	Yes	Timecode (H:MM:SS.cc)	Common override tags	Pos/Move/Clip	No
SSA	Yes	Yes	Timecode (H:MM:SS.cc)	Limited override tags	Alignment/Margins	No
SRT	Yes	Yes	Timecode (HH:MM:SS,mmm)	Basic tags + font color	No	No
VTT	Yes	Yes	Timecode (HH:MM:SS.mmm)	Basic tags (b/i/u); v/c/lang parsed only	Regions	No
SBV	Yes	Yes	Timecode (H:MM:SS.mmm)	None	No	No
LRC	Yes	Yes	Timecode (MM:SS.xx)	Word timing	No	No
MicroDVD	Yes	Yes	Frame-based	Inline tags	No	No
TTML	Yes	Yes	Clock or offset	Basic styling	Regions (default)	No
DFXP	Yes	Yes	Clock or offset	Basic styling	Regions (default)	No
SMPTE-TT	Yes	Yes	Clock time	Basic styling	Regions (default)	No
SAMI	Yes	Yes	Milliseconds	CSS classes	Align/Margins	No
RealText	Yes	Yes	Clock time	Basic tags	No	No
QuickTime Text	Yes	Yes	Timecode	Header directives	No	No
EBU-STL	Yes	Yes	Frame-based	None	No	No
Spruce STL	Yes	Yes	Frame-based	None	No	No
PGS	Yes	Yes	90 kHz PTS	N/A	N/A	Yes
DVB	Yes	Yes	PTS + timeouts	N/A	N/A	Yes
VobSub	Yes	Yes	Timecode	N/A	N/A	Yes
PAC	Yes	Yes	Frame-based	Limited (italic/underline)	No	No
SCC	Yes	Yes	SMPTE timecode	None	No	No
CAP	Yes	Yes	Frame-based	None	No	No
Teletext	Yes	Yes	Packet-based (placeholder timing)	None	No	No

Notes

• For bitmap formats (PGS, DVB, VobSub), Subforge stores bitmap payloads on event.image with metadata on event.pgs or event.vobsub.
• "Positioning" indicates explicit placement or region support.
• Teletext parsing currently assigns a default duration when no PTS is available.