Formats carry different information
SubRip commonly stores numbered timing blocks and text. WebVTT can add cue identifiers, placement settings, regions, style blocks and inline markup. ASS can carry layers, style definitions, effects and drawings, while TTML has an extensive styling and timing model. A shared extension does not imply that all of those features travel between formats.
This workbench deliberately builds an editable plain-text cue model. It records detected loss categories and requires acknowledgement before exporting when source features are omitted. Keep the original source for later rework. An exported SRT should not become the only surviving copy of a richly styled ASS project.
Read the supported timing matrix
SRT and WebVTT cue boundaries become integer milliseconds. ASS centiseconds are converted exactly to multiples of ten milliseconds. Simple TTML cue-level clock, second and millisecond expressions are supported. Frame-based timing, tick rates, inherited timed containers and timed spans are rejected because flattening them incorrectly would produce misleading output.
Segmented WebVTT timestamp maps refer to an external media timeline. A standalone local caption editor cannot infer that timeline from the map alone, so it refuses these inputs. ASS drawing sequences are also rejected rather than mistaken for spoken text. Export a flattened subtitle track from the authoring application if your source uses these constructs.
Check the actual receiving player
The output formats are SRT, WebVTT, simple TTML, CSV and plain transcript text. The caption formats sort cues by start time and escape text so characters cannot become unintended markup. CSV contains millisecond values and a safe text representation; the transcript intentionally drops timing. Choose the format that matches the next task.
Test the exported file with representative non-English text, multiline cues, overlaps and long durations in the destination application. This confirms practical compatibility with that player, not universal preservation of every source feature. Keep the edit audit beside the export when a reviewer needs to understand what was changed or omitted.