There are over a hundred legitimate subtitle file formats, each designed to support different applications and functional requirements. In this series of articles, we explain the main characteristics of each subtitle file format. This article provides further detail about the Scenarist Closed Captions (SCC) subtitle file format.

The Scenarist Closed Captions (SCC) format is a legacy file format initially developed to comply with the EIA-608 standard for closed captions. The 608 closed captioning format was created for analog television, but remains in use today. SCC files encode caption data as hexadecimal code, representing each caption as it would be transmitted over line 21 of the analog television signal. Despite being based on an older standard, SCC remains relevant for delivering captions in workflows requiring compatibility with broadcast or traditional linear television systems.

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File Structure of an SCC File


SCC files contain the baseline text and timing information necessary for all closed captions in a highly structured manner, but also support caption styling information such as positioning, italics, and music notes – all of which are valuable tools for expert subtitle operators to visually convey audio elements, such as dialogue spoken off-screen and lyrics being sung. Each line in the file corresponds to a specific timestamp and the accompanying hexadecimal-encoded caption data. The format uses precise timing to ensure captions are displayed at the correct moment in the video.


Key Components of an SCC File


Timecodes


SCC files use timecodes to specify when captions should appear and disappear. The timecode format is hh:mm:ss:ff (hours:minutes:seconds:frames), where frames represent the frame count at the specified frame rate (e.g., 29.97fps for NTSC).


Hexadecimal Caption Data


The hexadecimal codes represent the captions and control commands, such as line breaks, position settings, or text styling (e.g., italics or underlines). Each pair of hexadecimal digits corresponds to a specific character or instruction.


Carriage Return (CR) Command


The carriage return command signals the end of a caption row. SCC captions can span multiple rows, with each row limited to 32 characters.


Example SCC File


Below is an example illustrating the structure and content of an SCC file:


Scenarist_SCC V1.0

00:00:01:15    9420 9454 9470 947A 94AE 91AE 20 54686973 206973 206120746573742E

00:00:05:00    942C 9454 9470 947A 94AE 91AE 54657374206C696E6520322E


Explanation of the Example:

  • The first line contains the format declaration: Scenarist_SCC V1.0.
  • Each subsequent line begins with a timecode (e.g., 00:00:01:15) followed by a tab character and the hexadecimal caption data.
  • The hexadecimal sequences define both the text to display (e.g., "This is a test.") and the associated styling or placement commands.


Features and Limitations of SCC


Features:

  • Precise Timing: using SMPTE timecode format to support frame-accurate timing for captions
  • Styling: Provides basic text styling, including italics, underline, and color changes, using hexadecimal commands.
  • Positioning: Captions can be positioned on different rows of the screen.
  • Compatibility: Widely supported in legacy broadcast workflows and by video editing tools.


Limitations:

  • Special Characters: restricted to Latin language characters, but with possibility to use "?" to mark music 
  • Limited Text Length: Each caption row is restricted to 32 characters.
  • No Rich Text: Unlike modern formats, SCC does not support advanced text styling or multimedia enhancements.


Limecraft Support for SCC Files


Limecraft provides robust support for SCC files, enabling import as part of its media workflow solutions. Limecraft accepts SCC files and parses the hexadecimal data to extract captions and timing information. Styling information, including italics and underlining, is retained during import.