Overview
IEC 61866:1997 is an international standard developed by the International Electrotechnical Commission (IEC) focusing on audiovisual systems, specifically the Interactive Text Transmission System (ITTS). ITTS defines a mechanism for encoding sound-associated text data on prerecorded media and transporting this data across various equipment interfaces. The standard delineates the higher protocol layers of ITTS, emphasizing system characteristics independent of the recording or interconnection medium.
This comprehensive document provides detailed descriptions of ITTS packet structures, data presentation, control commands, character sets, and interactive functionalities. It serves as a vital reference for professionals involved in designing, implementing, or maintaining interactive text transmission systems in audiovisual and multimedia applications.
Key Topics
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ITTS Packet Structure
The standard details the format and composition of ITTS data packets, including:
- Packet headers (bytes 0–7) describing language, application item, packet index, function controls, and character set selection.
- Data fields (bytes 8–47) supporting text, graphics, and interactive commands.
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Text and Graphics Encoding
ITTS supports a rich repertoire of characters and graphical elements, including:
- Latin-based and extended Latin alphanumeric character sets.
- Mosaic and lined graphics font sets enabling graphical text enhancement.
- Japanese font tables and language indexing for multilingual support.
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Interactive Display Functions
The standard specifies practical display features such as:
- One-line display functions with text validation and horizontal scrolling.
- Screen clearing and color management, including default colors and highlighting constraints.
- Menu systems with vertical and horizontal layouts supporting interactive command processing.
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Character Set Control
ITTS allows dynamic redefinition of characters via Dynamically Redefinable Character (DRC) packets in single and double font size modes, enhancing flexibility in character display.
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Data Integrity and Validation
Provisions ensure data integrity through validation routines, maintaining reliable and consistent transmission of interactive text information.
Applications
IEC 61866:1997 is instrumental in applications involving interactive audiovisual content where synchronized text and sound data transmission is required. Typical use cases include:
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Broadcasting and Media Production
Encoding and transmission of captions, subtitles, and interactive text on prerecorded audiovisual media.
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Multimedia Interfaces
Delivery of interactive text menus and graphics in consumer electronics, such as digital TV receivers and set-top boxes.
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Assistive Technologies
Accessibility features enabling hearing-impaired users to interact with audiovisual content through synchronized text displays.
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Multilingual Content Delivery
Supporting content in multiple languages with flexible character sets and interactive commands for user-friendly navigation.
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Communication Equipment
Facilitating text-based interactive information alongside audio streams in communication devices.
Related Standards
Professionals working with IEC 61866:1997 may also find the following IEC standards relevant to ensure comprehensive system compatibility and interoperability:
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IEC 60050 – International Electrotechnical Vocabulary (IEV): Provides consistent terminology used within ITTS and related audiovisual systems.
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IEC 60027 – Letter Symbols to be Used in Electrical Technology: Defines graphical and literal symbol standards complementing character encoding.
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IEC 60417 – Graphical Symbols for Use on Equipment: Offers standardized graphical symbols vital for interface representation.
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IEC 60617 – Graphical Symbols for Diagrams: Supports graphical schematic representations linked with audiovisual system components.
By integrating IEC 61866:1997 with these related standards, developers and engineers can ensure robust, interoperable interactive text transmission capabilities across various equipment and media platforms.
Keywords: IEC 61866, Interactive Text Transmission System, ITTS, audiovisual systems, text encoding, packet structure, multimedia interfaces, character sets, interactive menus, data integrity, IEC standards, audiovisual media, subtitles transmission, interactive display functions.