What encoding does the output use?

The converted SRT is written as UTF-8 text. Unsupported source characters may be changed during text cleanup.

Can I edit the SRT after conversion?

Yes. The output is standard plain-text SRT and can be opened in a text editor or subtitle editor.

What happens to malformed STL lines?

Lines that do not contain recognizable start time, end time, and text are skipped. Empty subtitle entries are not written to the SRT output.

Can I batch convert STL files?

Drop several valid files on this page and they open together in the workspace Batch tool with SRT preselected. The batch workflow supports up to 200 files.

What is the maximum file size?

Each subtitle file can be up to 50 MB.

Can I use the SRT output on the web?

SRT is broadly supported, but HTML5 video commonly uses VTT. Convert STL to VTT if your web player requires WebVTT.

STL to SRT Subtitle Converter

Turn text-based Spruce STL subtitle entries into sequential SRT cues with start and end times.

Drag & drop your STL file here

or click to browse

Supports .stl files up to 50 MB

Core Engine Architecture

Free Online STL to SRT Converter

This converter reads text-based Spruce STL subtitle entries and writes standard SubRip cues. Pipe-separated STL lines become subtitle line breaks, common bracketed inline tags are removed, and the output is numbered SRT text with start and end timestamps. Parsing and conversion stay in your browser, so the subtitle file is not uploaded.

Payload & Syntax Inspector

STL to SRT Code Syntax & Structure Inspection

Side-by-side code inspection illustrating header definitions, timestamp syntax, and cue payload formatting

Millisecond Sync

input.stl

STL SOURCE

// Spruce Subtitle File
// Format: Start Time, End Time, Subtitle Text
 
00:00:01:00 , 00:00:04:00 , Hello, world!
00:00:04:15 , 00:00:08:00 , This is a subtitle file.
00:00:08:15 , 00:00:12:00 , Converted locally!

output.srt

SRT RESULT

1
00:00:01,000 --> 00:00:04,000
Hello, world!
 
2
00:00:04,500 --> 00:00:08,000
This is a subtitle file.
 
3
00:00:08,500 --> 00:00:12,000
Converted locally!

Specification Sheet

STL vs SRT Technical Specifications

Standard Compliant

Input Format

STL

STL here refers to the text-based Spruce Subtitle format. Its cue lines commonly contain a start time, an end time, and subtitle text, with vertical bars used as line separators. The STL family also includes the binary EBU broadcast format, but this converter does not parse EBU GSI or TTI blocks.

Output Format

SRT

SRT (SubRip) is a widely supported plain-text subtitle format. Each cue has a sequential number, an HH:MM:SS,mmm --> HH:MM:SS,mmm timestamp line, and one or more text lines. SRT keeps text and timing but does not preserve source styling or positioning metadata.

Format Differences

Spruce STL cue lines contain start time, end time, and text; SRT uses numbered blocks.

STL often represents line breaks with vertical bars; SRT uses physical text lines.

STL inline tags and formatting are not part of standard SRT cue text.

SRT timestamps use hours, minutes, seconds, and milliseconds.

SRT does not carry source styling or screen-position metadata.

Conversion Troubleshooting & Gotchas

Practical solutions for player compatibility, character encoding, and timing synchronization

4 Common Gotchas

GOTCHA #1

Subtitle timing drifts or appears out of sync on media players

Video files frequently differ in framerate (e.g., 23.976 fps vs 25 fps). If the timing drifts steadily, use our Subtitle Sync tool to adjust the global offset or framerate stretch.

GOTCHA #2

Characters appear as garbled symbols or question marks (Mojibake)

Legacy files saved in Windows-1252, Shift-JIS, or GBK may render incorrectly. Our exporter standardizes output to clean UTF-8. Use our Subtitle Encoding Converter if the source file is corrupted.

GOTCHA #3

Overlapping captions when multiple speakers talk simultaneously

Different formats handle overlapping dialogue differently. If your target player cannot render stacked cues cleanly, open the file in our Subtitle Editor to adjust individual cue timings.

GOTCHA #4

Video editing software (Premiere, DaVinci, Final Cut) rejects the file

Professional NLE software enforces strict syntax rules. Our converter eliminates malformed line breaks and non-standard tags, producing clean, standardized files.

Features

Reads text-based Spruce STL cue lines

Converts supported STL time formats to SRT millisecond timestamps

Turns STL vertical-bar line separators into SRT line breaks

Removes common bracketed inline tags from subtitle text

Writes sequentially numbered, UTF-8 SRT output

Processes files locally in your browser without uploads

Why Convert?

SRT is easier to inspect and edit as plain text than the STL formats used by authoring tools.

SRT is widely recognized by media players, editors, and subtitle workflows.

STL line separators can be converted into normal SRT line breaks.

SRT uses explicit start and end times for every cue.

Converting to SRT can make older subtitle text easier to reuse in modern tools.

Scenarios

Common Use Cases

Subtitle Reuse

Convert text-based Spruce STL material into SRT for reuse in players and editors that expect SubRip input.

Text Cleanup

Turn vertical-bar line separators into normal SRT line breaks while removing common bracketed inline tags.

Timing Review

Move explicit STL start and end times into SRT cues for easier timing inspection and editing.

Format Standardization

Include supported STL files in a project that is being standardized around SRT delivery.

Format Ecosystem

Related Formats

VTT (WebVTT)

Convert STL to VTT when you need the plain cue format commonly used with HTML5 video.

ASS (Advanced SubStation Alpha)

Convert STL to ASS when your destination workflow accepts a styled subtitle document.

TXT (Plain Text)

Convert STL to TXT when you only need the subtitle text and not the timing.

How It Works

1
Select or drop a text-based STL file on this page.
2
The parser looks for start time, end time, and text on each cue line.
3
Vertical bars are converted to line breaks and bracketed inline tags are removed.
4
Each valid cue is written with a sequential number and SRT timestamp line.
5
Download the converted SRT file after processing finishes.

moreTools.fromFormat

STL VTT STL ASS STL LRC STL TXT STL TTML STL SCC STL SMI

moreTools.toFormat

VTT SRT ASS SRT LRC SRT JSON SRT SBV SRT SSA SRT TTML SRT SCC SRT

More Subtitle Tools

Subtitle Format Cleaner

Remove formatting, tags and noise

Subtitle Editor

Edit subtitle content and timings

Subtitle Sync & Timing Calibration

Adjust timing with millisecond precision

Subtitle Merger

Combine multiple subtitle files

AI Subtitle Translator

Translate to 19 built-in target languages

Frequently Asked Questions

No. It parses text-based Spruce STL cue lines. Binary EBU STL files with GSI and TTI structures are not supported by this converter.

Common bracketed inline tags are removed from the text before the SRT cues are generated.

No. The converter keeps the text and timing, but does not map STL formatting or positioning to SRT.

Vertical bars in STL text are converted into normal line breaks in the SRT output.

Yes. There is no registration or watermark, and parsing happens in your browser.

No. Processing stays in your browser and the subtitle file is not uploaded.

Ready to convert your subtitles?

Drop your STL file here and convert to SRT instantly.

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Related Resources

What is STL?What is SRT?SRT vs STL ASS vs STL LRC vs STL SBV vs STL