Text Files

Alongside media assets, Stellar works with text files — the subtitle, caption, audio description, dubbing and metadata files that carry the timed text for a piece of media.

This page lists the text file formats Stellar supports, so you can check that a file will be accepted before you add it to a Task or Local Project.

Supported formats

Stellar supports and edits the following text file formats:

Format	File extension	Typically used for
Aegisub ASS file	.ass	Subtitles, including styling and positioning information
Cavena 890	.890	Broadcast subtitles created in Cavena subtitling systems
Cavena CIP	.cip	Cavena subtitling files
EBU STL	.stl	Broadcast subtitle exchange (EBU subtitling data exchange format)
ESEF Audio Description	.esf	Audio description scripts
FPC	.fpc	Subtitle and caption data
IMSC Rosetta	.imscr	XML-based timed text subtitles
Lambdacap JPN	.cap	Japanese caption files
OOONA File	.ooona	Subtitle files created in OOONA tools
PAC	.pac	Broadcast subtitles
SRT File	.srt	Plain-text subtitles — the most widely used subtitle format
srtad Audio Description	.srtad	SRT-based audio description scripts
srtdub Dubbing file	.srtdub	SRT-based dubbing scripts
TTAL AD/Dub	.ttal	Audio description and dubbing scripts
YU Meta File	.yumeta	Metadata used within Stellar

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Formats by type of work

The same list, grouped by the kind of work each format is normally used for.

Subtitles and captions

• Aegisub ASS file (.ass)
• Cavena 890 (.890)
• Cavena CIP (.cip)
• EBU STL (.stl)
• FPC (.fpc)
• IMSC Rosetta (.imscr)
• Lambdacap JPN (.cap)
• OOONA File (.ooona)
• PAC (.pac)
• SRT File (.srt)

Audio description

Audio Description (.esf)

• srtad Audio Description (.srtad)
• TTAL AD/Dub (.ttal)

Dubbing

Dubbing file (.srtdub)

• TTAL AD/Dub (.ttal)

Metadata

YU Meta File (.yumeta)

• Yumeta (.yumeta)

Choosing a format

A few points to keep in mind when deciding which format to work with:

• Check the delivery requirement first. If the finished file is being delivered to a broadcaster, platform or client, use the format they have asked for. Broadcast deliveries commonly specify EBU STL or PAC.
• Match the type of work. Audio description and dubbing scripts hold information that plain subtitle formats do not carry, so use a format intended for that work — for example TTAL AD/Dub, srtad or srtdub — rather than a standard subtitle format.
• Consider what the format can hold. Simpler formats such as SRT carry timings and text only. Richer formats such as Aegisub ASS and IMSC Rosetta can also carry styling and positioning, so converting from a richer format to a simpler one may not preserve every detail.
• Keep the original file. If you convert between formats, keep the original as well, so you can return to it if information is lost in the conversion.

If a file is not accepted

If a text file will not load, check the following:

1. The file extension is on the list above. Formats that are not listed are not supported.
2. The extension matches the file's actual format. Renaming a file does not convert it — a file renamed to .srt is still in its original format.
3. The file is complete and not corrupted. Try opening it in the application it was created in to confirm it is intact.
4. The file is the right type of text file for the work. For example, a dubbing script needs to be supplied in a dubbing format.

If the file still wil

All Supported File Formats

Stellar uses files of different types to support subtitle, caption, audio description, voiceover and dubbing workflows.

This page lists the file formats Stellar supports, and what you can do with each one.

What the support levels mean

Each format is marked with one or more of the following:

Level	What it means
Open and edit	Open the file in Stellar, make changes, and save your work in the original file format.
View only	Open the file in Stellar to view its contents. The file cannot be edited.
Convert	Stellar can convert to and from this format, even where the file cannot be opened for editing directly.

Some formats support more than one level. For example, a format marked Open and edit and Convert can be worked on directly in Stellar and used as a conversion source or target.

Subtitle file formats

The table below is as comprehensive as possible but subject to change as new formats arrive or are added.

Format	Open and edit	View only	Convert
Apple STL	–	–	✓
ASS	✓	–	✓
890	✓	–	✓
CIP	✓	–	–
DFXP	–	✓	✓
EBU-TT	–	✓	✓
EBU-TT-D	–	✓	✓
EztXml	–	–	✓
FinalCut	–	–	✓
FinalCut BDN	–	–	✓
FoxIMSC	–	–	✓
FPC (Unicode PAC)	✓	–	–
Generic XML	–	–	✓
IMSC	–	✓	✓
IMSC – Rosetta	✓	–	–
ITT	–	✓	✓
JSON (various formats)	–	–	✓
LAMBDACAP	✓	–	✓
Ooona	✓	–	✓
PAC	✓	–	–
SAMI	–	✓	✓
SIF	–	✓	✓
SMI	–	–	✓
SMPTE-428	–	–	✓
SMPTE-2052	–	✓	✓
SMPTE-TT	–	✓	✓
SMPTE-TT-NBCU	–	✓	✓
Sony BDN	–	–	✓
SRT	✓	–	–
STL	✓	–	–
TTAL (Netflix)	✓	–	–
TTXT / TTML	–	✓	✓
ULT	–	✓	✓
VTRON	–	–	✓
WebVTT	–	✓	✓
XIF	–	✓	✓

Closed caption formats

Format	Open and Edit	View Only	Convert
Lambda CAP	–	–	✓
SCC	✓	–	–
SMPTE-TTCC	–	–	✓
Spruce BDN	–	–	✓
SUB	–	–	✓
TDS	✓	–	–
UTL	–	–	✓

Audio description file formats

Format	Open and Edit	Convert	Notes
SRTAD	✓	–	Open format from Yella Umbrella.
TTAL	✓	–	Netflix format. Also used for dubbing.
CSV script formats	–	✓	Various script formats supplied as CSV.

Dubbing file formats

Format	Open and Edit	Convert	Notes
TTAL	✓	–	Netflix format. Also used for audio description.
CSV script formats	–	✓	Various script formats supplied as CSV.

Transcript file formats

Stellar supports transcripts in JSON, which are mostly AI word-list outputs.

Metadata file formats

Stellar supports YUMETA files, used for timed metadata tagging for video markup and compliance.

Audio file formats

Stellar supports WAV and OGG audio files.

Video and media file formats

Stellar supports the common video and media containers, including:

• AVI
• FLV
• M4V
• MKV
• MOV
• MP4
• MPG / MPEG
• MXF
• OGV
• PS
• TS
• WMV

For the full list of supported codecs and containers, see the FFmpeg supported formats list.