SSA to STL Subtitle Converter
Transform SubStation Alpha subtitles into Spruce STL privately in your browser.
Drag & drop your SSA file here
or click to browse
Supports .ssa files up to 50 MB
Free Online SSA to STL Converter
Our SSA to STL converter reads SubStation Alpha input and produces Spruce Subtitle text output entirely in your browser. Source SSA timing is converted to SMPTE-style HH:MM:SS:FF timecodes at 29.97 fps. SSA override tags are stripped, and cue line breaks become pipe characters. The conversion runs client-side, so your subtitle files are never uploaded to a server.
SSA to STL Code Syntax & Structure Inspection
Side-by-side code inspection illustrating header definitions, timestamp syntax, and cue payload formatting
SSA vs STL Technical Specifications
SSA
SSA (SubStation Alpha v4) is the predecessor to ASS and shares the same section-based structure: [Script Info], [V4 Styles], and [Events] with Dialogue lines. SSA supports fonts, colors, and basic positioning but predates some ASS additions such as blur. Because SSA and ASS use the same Dialogue layout, they are parsed identically.
STL
STL (Spruce Subtitle) is a text-based subtitle format used in DVD authoring and some broadcast workflows. Entries use comma-separated start and end timecodes followed by subtitle text, with the pipe character (|) for line breaks. The output is accepted by DVD authoring tools and Spruce-based workflows.
Format Differences
Conversion Troubleshooting & Gotchas
Practical solutions for player compatibility, character encoding, and timing synchronization
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.
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.
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.
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
Why Convert?
Common Use Cases
DVD Authoring
Produce STL subtitle files for DVD authoring tools that expect the Spruce format.
Broadcast Workflows
Generate Spruce STL text for tools that expect this subtitle layout.
Frame-Accurate Timing
Output frame-based timecodes quantized to the generator's 29.97 fps grid.
Related Formats
SRT (SubRip)
The universal plain-text alternative: convert to SRT for maximum device compatibility.
VTT (WebVTT)
The web alternative: convert to VTT if your target is HTML5 video or YouTube.
SCC (Scenarist Closed Captioning)
The North American broadcast alternative: convert to SCC for CEA-608 caption delivery.
How It Works
- 1
Upload your .ssa file by dragging it in or browsing.
- 2
The parser reads the SubStation Alpha structure and extracts each cue's start, end, and text.
- 3
Source SSA timing (H:MM:SS.cc centiseconds) is converted to STL timing (SMPTE HH:MM:SS:FF frame timecodes).
- 4
Override tags are stripped, and cue line breaks become pipe characters.
- 5
The output .stl file is generated and ready to download.
More Subtitle Tools
Frequently Asked Questions
It reads a SubStation Alpha file, parses each cue's timing and text, and writes a Spruce STL text file with the standard header, comma-separated timecodes, and pipe-separated cue lines. Source SSA timing is converted to SMPTE-style HH:MM:SS:FF values at 29.97 fps.
Absolutely. Every conversion runs client-side in your browser. No subtitle data, file contents, or metadata is ever transmitted to a server.
Yes. SSA styling and override tags are dropped, line breaks become pipe characters, and timing is quantized to the output frame grid.
Yes, completely free with no sign-up, no watermarks, and files up to 50 MB each. All processing happens in your browser, so your files are never uploaded to a server.
Source SSA timing (H:MM:SS.cc centiseconds) is converted to STL timing (SMPTE HH:MM:SS:FF frame timecodes).
Yes. The responsive page works in modern mobile browsers.
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