TTML / DFXP to SRT Converter

What this does

TTML is the format streaming platforms actually deliver. Netflix, Amazon, Disney+ and the BBC all ship captions as TTML or one of its profiles — DFXP and IMSC — which is why a caption file pulled from a broadcaster will not open in VLC and will not hand off cleanly to a video editor. The cues are XML <p> elements with begin and end attributes, and the times inside them can be written four different ways. This converter reads all four and writes SubRip.

How to use it

1. Paste the .ttml, .dfxp or .xml file into the box, or drop it onto the page.
2. Every <p> element is read, its begin time and its end or dur time are converted to milliseconds, and inline markup is stripped from the text.
3. Copy the result or download it as a .srt file.

Four ways TTML writes a timestamp

Clock time with milliseconds — 00:01:02.350. This is the common case and the one closest to SubRip. A comma separator (00:01:02,350) is accepted as well, because some exporters emit it by mistake.

Clock time with frames — 00:01:02:11. The fourth field is frames, not milliseconds, so it only means something once it has been divided by the frame rate. That rate comes from ttp:frameRate on the root <tt> element; when the file does not declare one, 30 fps is assumed. A file authored at 25 fps and read as if it were 30 fps drifts by roughly 17 percent, which is the single most common reason TTML-to-SRT timing is right at the start of a file and wrong at the end.

Offset times — 10s, 100ms, 1.5m, 3h. These are durations rather than points on a clock, and TTML permits them in begin as well as in dur. The converter understands h, m, s and ms.

Frame and tick offsets — 30f and 100t. Frames are divided by the frame rate, ticks by the rate declared as ttp:tickRate. Both turn up in broadcast files where timing is authored on a frame grid rather than in wall-clock seconds.

Entities are decoded. Because the source is XML, an ampersand arrives as & and a quote as ". Named and numeric entities are both decoded before the text reaches SubRip, so what you see in the output is what the caption was meant to say.

Worked example

<tt xmlns="http://www.w3.org/ns/ttml" xmlns:ttp="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling" ttp:frameRate="25">
  <body><div>
    <p begin="00:00:01.000" end="00:00:04.000">Hello there.</p>
    <p begin="00:00:04.200" dur="2.8s"><span tts:fontStyle="italic">Music playing</span><br/>Sign on wall: EXIT</p>
  </div></body>
</tt>

1
00:00:01,000 --> 00:00:04,000
Hello there.

2
00:00:04,200 --> 00:00:07,000
Music playing
Sign on wall: EXIT

The second cue had no end attribute — its dur of 2.8s was added to the begin time. The span was unwrapped and the br became a real line break.

FAQ

Troubleshooting

1. No cues found at allThe file needs <p> elements that carry a begin attribute. A TTML file whose cues were emptied out, or a file that is really a plain XML config with a .ttml extension, will produce nothing. Open it in a text editor and look for the word begin.
2. Every cue is a few seconds off, and the error growsA frame-rate mismatch. Times written as hh:mm:ss:ff were divided by the wrong rate. Note the ttp:frameRate value in the file header and re-time the output — the ratio presets on the resync tool cover the common 23.976 / 24 / 25 / 30 combinations.
3. The text contains stray ampersands or question marksThe source used an entity the decoder does not know, or the file is not UTF-8. Re-save it as UTF-8 from the editor that produced it. Unrecognised named entities are left as written rather than guessed at.
4. Two languages came out in one cueThat is how the file was authored — one <p> containing both languages, usually separated by a <br/>. Split them into separate files if you need one language per track; the converter preserves the text exactly as written.
5. The player shows the subtitles but they look plainExpected. SubRip has no font, colour or positioning fields, so all of that is discarded on the way through. Keep the original TTML as the master if appearance matters, and treat the SRT as a delivery or review copy.

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