SMI to SCC Subtitle Converter
Transform Synchronized Accessible Media Interchange subtitles into SCC format instantly and privately in your browser.
Drag & drop your SMI file here
or click to browse
Supports .smi, .sami, .html files up to 50 MB
Free Online SMI to SCC Converter
Our SMI to SCC converter reads Synchronized Accessible Media Interchange input and produces Scenarist Closed Captioning output entirely in your browser. Source SMI timing (whole milliseconds (Start=...)) is converted to SCC timing (SMPTE HH:MM:SS:FF at 29.97fps). SMI styling and markup are stripped, and unsupported characters are replaced in the basic ASCII caption stream. The conversion runs client-side, so your subtitle files are never uploaded to a server.
SMI to SCC Code Syntax & Structure Inspection
Side-by-side code inspection illustrating header definitions, timestamp syntax, and cue payload formatting
SMI vs SCC Technical Specifications
SMI
SMI (SAMI, Synchronized Accessible Media Interchange) is a Microsoft subtitle format built from HTML-like <SYNC> elements whose Start attribute is given in milliseconds. SMI supports multiple language tracks through CSS classes and was widely used for Windows Media Player captions and accessibility content.
SCC
SCC (Scenarist Closed Captioning) is the industry-standard format for delivering CEA-608 (Line 21) closed captions to North American broadcast television and streaming services. SCC encodes caption text as hexadecimal byte pairs paired with SMPTE timecodes at 29.97 fps and begins with a Scenarist_SCC V1.0 header.
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
Broadcast Caption Delivery
Produce basic SCC files for broadcast-oriented workflows, then verify them against the recipient's CEA-608 specification.
Streaming Delivery
Generate SCC when a streaming platform explicitly accepts it, and confirm the current delivery specification.
FCC Context
Create SCC as part of a compliance workflow; professional delivery requires final specification checks.
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.
STL (Spruce Subtitle)
The DVD/broadcast alternative: convert to STL for Spruce or DVD authoring workflows.
How It Works
- 1
Upload your .smi file by dragging it in or browsing.
- 2
The parser reads the Synchronized Accessible Media Interchange structure and extracts each cue's start, end, and text.
- 3
Source SMI timing (whole milliseconds (Start=...)) is converted to SCC timing (SMPTE HH:MM:SS:FF at 29.97fps).
- 4
SMI styling and markup are stripped, unsupported characters become ?, and cues are formatted to the SCC specification.
- 5
The output .scc file is generated and ready to download.
More Subtitle Tools
Frequently Asked Questions
It reads a Synchronized Accessible Media Interchange file, parses each cue's timing and text, strips SMI markup, and writes a .scc file. Source SMI timing (whole milliseconds (Start=...)) is converted to SCC timing (SMPTE HH:MM:SS:FF at 29.97fps).
Absolutely. Every conversion runs client-side in your browser. No subtitle data, file contents, or metadata is ever transmitted to a server.
SMI styling and markup are dropped. Unsupported characters are replaced with ?, and timing is quantized to 29.97 fps SCC frames, so review delivery-critical output before use.
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 SMI timing (whole milliseconds (Start=...)) is converted to SCC timing (SMPTE HH:MM:SS:FF at 29.97fps).
Yes. The converter is fully responsive and works in any modern mobile browser on iOS and Android.
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