MPEG program streams often come from optical media, broadcast masters, and preservation transfers. Subtitle editing must account for incomplete indexes, discontinuities, and the possibility that a restored copy has a different timeline from its original source.
Where this workflow fits
- Disc archive subtitles
- Broadcast program captions
- Preservation transfer review
Anchor cues around media gaps
Create cue anchors before and after every known discontinuity. Where frames or audio are missing, preserve the gap and resume timing from the first reliable event rather than stretching surrounding captions over absent material.
Finish with a linear playback pass
Proof the subtitle in uninterrupted playback after all local corrections. Check that cue numbering remains sequential and that the final captions do not outlast a shortened or recovered program ending.
Before cue editing
- Verify the intended audio element and compare the running time with the archive record.
- Mark recovered sections, reel changes, and edits as mandatory synchronization checkpoints.
Limits worth knowing
- Sector loss or timestamp repair can create local gaps that are not solved by shifting the entire SRT.
- Program streams may expose several audio elements without modern language or role metadata.
Questions from the workflow
Why does an MPEG subtitle need timing checkpoints?
Older program streams can have timestamp discontinuities or damaged sectors. Review synchronization at multiple checkpoints, especially after edits and recovered sections.
Reviewed sources
- IANA Media Types registry · checked 2026-07-20
- RFC 2046: MPEG media types · checked 2026-07-20